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    25 November 2021, Volume 42 Issue 11 Previous Issue    Next Issue
    Special Column: Plant Protection of Rubber, Areca and Coconut
    Advances in Main Diseases and Insect Pests of Areca Palm
    MENG Xiuli, SONG Weiwei, TANG Qinghua, NIU Xiaoqing, LI Chaoxu, ZHONG Baozhu, LYU Chaojun, HUANG Shanchun, QIN Weiquan
    2021, 42 (11):  3055-3065.  doi: 10.3969/j.issn.1000-2561.2021.11.002
    Abstract ( 160 )   HTML ( 15 )   PDF (1442KB) ( 103 )  

    Areca catechu L. is not only a kind of important tropical medicinal plant but also the second largest cash crop in Hainan, China. Diseases and pests are crucial factors damaging the yield and quality of areca nuts. There are a lot of achievements in the diseases and pests control of A. catechu in recent years. This paper summarized the research progresses of eight diseases and five pests of A. catechu and proposed the problems and prospects, which would provide a reference for the researchers and growers.

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    Molecular Detection and Phylogenetic Relationship of Areca Palm Yellow Leaf Phytoplasma in Hainan, China
    YU Shaoshuai, SONG Weiwei, QIN Weiquan
    2021, 42 (11):  3066-3072.  doi: 10.3969/j.issn.1000-2561.2021.11.003
    Abstract ( 74 )   HTML ( 13 )   PDF (4569KB) ( 55 )  

    Areca palm yellow leaf (AYL) disease caused by phytoplasma is a devastating disease in the cultivation of areca palm, an important economic crop in Hainan. Through PCR amplification and sequencing, multiple sequence alignment and phylogenetic analysis, the sequence information and phylogeny of the lethal pathogen infecting areca palm from part representative regions of Hainan were analyzed. The 16S rDNA sequence of the AYL phytoplasma in part representative areas of Hainan, such as Baoting, Tunchang, Wanning County, were identical. BLAST analysis based on 16S rDNA showed that the phytoplasm in the study was 100% homology with 16SrI group phytoplasma. Multiple sequence alignment indicated that the phytoplasma in the study was 100% homology with the phytoplasma strains of Chinaberry witches’-broom, Periwinkle virescence, Melochia corchorifolia phyllody, Pepper yellow crinkle, Waltheria indica virescence, Pericampylus glaucus witches’-broom in Hainan and Onion yellows in Japan, Aster yellow witches’-broom in USA. Homology with the AYL phytoplasma from Wanning, Sanya (Hainan, China) and India was 99.9%, 99.9% and 99.8%, respectively. Phylogenetic analysis indicated that AYL strains in the study were clustered into one clade with the phytoplasma strains infecting the plant hosts like chinaberry, periwinkle, Melochia corchorifolia, pepper, Waltheria indica, Pericampylus glaucus in Hainan with 100% bootstrap value. Furthermore, the phytoplasma could be detected in the leaves, flower spikes, and heart leaves from the diseased areca palm. The study indicated that the homology of the AYL phytoplasmas was significantly high with the strains of chinaberry witches’-broom, periwinkle virescence, Melochia corchorifolia phyllody, pepper yellow crinkle, Waltheria indica virescence, Pericampylus glaucus witches’-broom. AYL disease is very likely to spread using the host plants as pathogen transmission vectors.

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    Investigation and Symptom Analysis of Areca Palm Leaf Yellowing Virus Disease in Wanning, Hainan, China
    NIU Xiaoqing, LIN Zhaowei, YANG Dejie, MENG Xiuli, TANG Qinghua, SONG Weiwei
    2021, 42 (11):  3073-3078.  doi: 10.3969/j.issn.1000-2561.2021.11.004
    Abstract ( 121 )   HTML ( 4 )   PDF (18621KB) ( 69 )  

    The objectives of this study is to investigate the occurrence of areca plan leaf yellowing virus disease caused by Areca palm velarivirus 1 (APV1) in Wangning, Hannan, China. During September to November 2020, all betel palm planting areas from 13 towns of Wanning were investigated and a total of 1454 leaf samples were collected and further detected by the RT-PCR method. The results showed that APV1 seemed to be the dominating pathogens affecting betel palm, with a detection rate from 75% to 100%. Meanwhile, the symptoms in betel palm infected by APV1 could be grouped into six different types. The results reported in this study would provide useful insights in the identification, prevention and control of the viral disease of betel palm.

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    A New Insect Pest of Coconut and Areca, Morphological Identification of Pseudococcus cryptus
    HUANG Shanchun, YUAN Xiongfeng, QIN Weiquan, SONG Weiwei, TANG Qinghua, MENG Xiuli, LI Chaoxu
    2021, 42 (11):  3079-3086.  doi: 10.3969/j.issn.1000-2561.2021.11.005
    Abstract ( 78 )   HTML ( 4 )   PDF (7343KB) ( 44 )  

    Mealybug, which has a wide range of species, distribution areas and hosts, is a harmful pest in agriculture and forest, and it is difficult to identify. A mealybug which caused serious damage to coconut and areca palm was observed during field investigations for palm plant diseases and insect pests from 2018 to 2020. The pest was identified as Pseudococcus cryptus (Hempel), and its main morphological characteristics were characterized. It had 17 pairs of white wax wires on the edge of the body. The front pairs were shorter, while the back ones were longer, and the end one was the longest, about as the same length as its body. The, another one pair of small wires at the tail was sandwiched by the end one pairs of wires. Antennae of the female adult had 8 segments, without companion hole at the edge of the eye base. It had 17 pairs of cerarii. C1, C4, C7 had 3 conical punctures, and C3 had 3 to 5 conical punctures. The multilocuar pores were mainly distributed in the 3rd to 8th abdominal segment ventral surface. It had three types of oral collar tubular ducts, most of the larger ones were distributed at the edge of the abdominal segment. There were two types of oral rim ducts, most of the larger ones were distributed on the back side of the body and in the middle, one was behind C1, and the smaller ones were more distributed on the segmental venter, in particular, the margin of the chests was more distributed. In this paper, the characteristics of each state of P. cryptus were described, and the index table of P. cryptus and its allied species were established to provide the basis for its identification.

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    Development of a TaqMan Real-Time Fluorescent Quantitative PCR Method for Detection of Areca Palm Velarivirus 1
    LIN Zhaowei, NIU Xiaoqing, TANG Qinghua, SONG Weiwei, MENG Xiuli, QIN Weiquan
    2021, 42 (11):  3087-3092.  doi: 10.3969/j.issn.1000-2561.2021.11.006
    Abstract ( 61 )   HTML ( 6 )   PDF (3044KB) ( 69 )  

    It is aimed to develop a rapid, precision and quantitative detection method for Areca palm velarivirus 1 (APV1). A pair of specificity RT-PCR primers were designed based on the APV1 complete genome sequence registered in GenBank to clone the sequence between the conservative region of p21 and the conservative region of p60, and a positive recombinant plasmid was constructed. Fluorescence quantitative PCR specificity primers and TaqMan-MGB probes were designed in the conservative region of p60 and a positive recombinant plasmid was constructed to establish a standard curve to verify the sensitivity, specificity, stability and application effect of the detection method. The sensitivity of this method to the detection of positive plasmid standards was up to 3.0×10 1 copies /μL, which was 100 times the sensitivity of conventional RT-PCR. The standard curve showed that the Ct value had a linear relationship with the logarithm of the copy number. The standard curve equation was y=-3.2748x+42.957, the amplification efficiency was 102%, and the correlation coefficient R2 was 0.9992. The method has good specificity for the detection of APV1, and other areca pathogens and endophytes will not be affected by this method. The intra batch repeat test and inter batch repeat test results showed that this method had good repeatability and stability in the detection of APV1. This method was used to detect 181 suspected samples collected from 4 cities and counties in Hainan, including Wanning, Qionghai, Ding’an, and Wenchang. The positive rate was 91.95%, 86.95%, 89.65%, and 73.68%, respectively, and the number of positive virus copies was up to 1.59×107 copies/μL. It shows that APV1 virus load is relatively high and the epidemic situation is relatively serious in some areas of Hainan.

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    Omics & Biotechnology
    Cloning and Expression Analysis of MiSTPP3 and MiSTPP7 from Macadamia integrifolia
    CAI Yuanbao, YANG Xiangyan, PANG Xinhua, LI Jidong, LIN Yuhong
    2021, 42 (11):  3093-3100.  doi: 10.3969/j.issn.1000-2561.2021.11.007
    Abstract ( 88 )   HTML ( 9 )   PDF (3931KB) ( 68 )  

    Two serine / threonine phosphatase genes were named MiSTPP3 and MiSTPP7, with coding sequences 2095 bp and 1700 bp in length, respectively, which were cloned by RT-PCR from macadamia cultivar ‘O.C.’ (Macadamia integrifolia). Sequence analysis and evolution analysis indicated that MiSTPP3 with the MPP_PP5_C domain belonged to PP5 subfamily, and MiSTPP7 with the MPP_PP7 domain belonged to PP7 subfamily. Physicochemical properties of protein and subcellular localization analysis showed that MiSTPP3 as a stable hydrophilic protein may be located in the plasma membrane, and MiSTPP7 as an unstable hydrophilic protein may be located in the mitochondrial matrix. Bioinformatics analysis indicated that MiSTPP3 and MiSTPP7 were non-secreted transmembrane proteins, α-helix, random coil and extended strand were the backbone of the secondary and 3D protein structures. RT-qPCR analysis indicated that MiSTPP3 and MiSTPP7 expressed differently in roots, stems, leaves, flowers and small fruits of M. integrifolia; MiSTPP3 was down regulated by low temperature stress, while MiSTPP7 was up-regulated, and both of them were up-regulated by drought stress. The results suggested that MiSTPP3 and MiSTPP7 may be involved in the growth and development of M. integrifolia and the stress response.

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    Genome-wide Identification and Expression Analysis of CTL Gene Family Memebers in Capsicum annuum L.
    LIU Zhuoyi, YU Wenfei, CAI Wenli, LIU Zishan, ZHANG Yu, YUAN Yuan, WU Binghua, LYU Meiling
    2021, 42 (11):  3101-3110.  doi: 10.3969/j.issn.1000-2561.2021.11.008
    Abstract ( 71 )   HTML ( 6 )   PDF (7354KB) ( 37 )  

    Chitinase (EC is chitin-degrading glycosidase, which plays important roles in the abiotic and biotic defense of plants. In this study, we conducted whole-genome annotation, molecular evolution, and gene expression analyses on the Capsicum annuum chitinase-like (CaCTL) gene family members. Thirty-one CaCTL genes (CaCTLs) were identified from the latest Capsicum genome database. According to the phylogenetic analysis, the genes were divided into GH18 and GH19 subgroups and further subdivided into five classes (Class I to Class V). Conserved motif arrangements indicated the functional relevance within each group. Homology analysis of CTL gene family members in pepper, petunia and tomato indicated that there were 7 and 11 homologous genes of CaCTL members in petunia and tomato, respectively. By qRT-PCR analysis, in the normal growing plants, we found that 64.2% GH18 subgroup CaCTLs showed a very low expression level, 64.7% GH19 subgroup CaCTLs were differentially expressed in different tissues. Cis-acting element analysis showed that many hormone responses, as well as biotic and abiotic stress elements were found in the promoters of CaCTLs. Correspondingly, qRT-PCR showed that many CaCTLs had upre gulated expression profiles when the plants suffered different abiotic stress conditions, especially when plants are subjected to high temperature and drought conditions. The results would enrich the evolutionary process of the CTL gene family and provide a foundation for the exploration of the function of CaCTLs.

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    Characteristics of the Complete Chloroplast Genome of Dendrobium ochreatum and Its Comparative Analysis
    DU Zhihui, YANG Lan, ZHANG Chaojun, XU Hongjuan, CHEN Zhilin
    2021, 42 (11):  3111-3119.  doi: 10.3969/j.issn.1000-2561.2021.11.009
    Abstract ( 73 )   HTML ( 10 )   PDF (3946KB) ( 103 )  

    In this research, the complete chloroplast genome (cpDNA) of D. ochreatum was sequenced through the combination of high-throughput and nanopore sequencing, and the full-length sequence (154 935 bp) of chloroplast genome (cpDNA) was assembled and annotated. A total of 125 genes (103 unigenes) were annotated in the cpDNA, including 73 protein-coding genes, 26 tRNA genes and 4 rRNA genes. Characteristic analysis showed that the number of SSR sites in the cpDNA of D. ochreatum was 58, most of which were mononucleotide or dinucleotide repeats with A/T base preference. Codon bias analysis showed that there were 32 biased codons and the majority of the biased codons were ended with A/U base. The phylogenetic tree of D. ochreatum and 13 Dendrobium species was constructed using cpDNA sequences. Result indicated that D. chrysotoxum and D. strongylanthum were closely related to D. ochreatum, and the IR/SC junctions analysis of Dendrobium species was consistent with the former. Global alignment of cpDNA of 4 Dendrobium species showed that the sequence variations were mainly concentrated in single copy regions, and variations in the intergenic region were significantly higher than that in the gene coding region.

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    Construction and Verification of Editing Vector for EBE Region of MeSWEET10a Promoter in Cassava
    ZHANG Tong, WANG Yajie, GUO Wenya, LI Ruimei, LIU Jiao, GUO Jianchun, HU Xinwen, YAO Yuan, GENG Mengting
    2021, 42 (11):  3120-3125.  doi: 10.3969/j.issn.1000-2561.2021.11.010
    Abstract ( 59 )   HTML ( 4 )   PDF (3366KB) ( 64 )  

    Cassava bacterial blight (CBB) is an important cassava disease caused by Xanthomonas axonopodis pv. manihotis (Xam), which affects the yield of cassava. The main cassava varieties in China are not resistant to Xam. The TAL20 effector protein secreted by Xam, could bind to the EBE region of the cassava MeSWEET10a promoter, activate the gene expression, promote the transport of sugars to the site of Xam infection, and provide carbohydrates for the reproduction of the pathogen. In this study, the gene editing target of EBE region was designed by using online software CRISPR-Pv2.0, and the CRISPR/Cas9 gene editing plasmid pCAMBIA1301-Cas9-EBE-sgRNA was constructed. The recombinant plasmid was transformed into Agrobacterium tumefaciens LBA4404, and the fragile embryogenic calli of cassava was infected by the A. tumefaciens-mediated method. DNA was extracted from the fragile embryogenic calli of infected and uninfected cassava. The target EBE region and potential miss sites were amplified by PCR, and the editing effect was analyzed by Sanger sequencing. It was found that the EBE region was edited successfully without off-target phenomenon. This study is helpful to further obtain cassava mutants in the EBE region of MeSWEET10a promoter and enhance the resistance of cassava to bacterial blight.

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    Identification and analysis the endogenous reporter gene of Cyclin C1 gene FocFCC1 in Fusarium oxysporum f. sp. cubense
    ZENG Fanyun, WANG Yanwei, QI Yanxiang, XIE Yixian, ZHANG Xin, PENG Jun
    2021, 42 (11):  3126-3133.  doi: 10.3969/j.issn.1000-2561.2021.11.011
    Abstract ( 64 )   HTML ( 5 )   PDF (20624KB) ( 59 )  

    In this study, the Fusarium Cyclin C1 gene FocFCC1 in F. oxysporum f. sp. cubense race 4 (Foc4) was cloned and identified. The ΔFocFCC1 gene-knockout mutants were obtained by the Split-marker homologous recombination technique. The growth rate, sporulation, pathogenicity were studied to investigate the biological function of FocFCC1 in Foc4. Additionally, we evaluated whether the FocFCC1 could serve as an endogenous reporter gene applied in Foc4. The results demonstrated that ΔFocFCC1 showed slow growth rate, hyphal deformity, decreased conidium production, and significantly reduced pathogenicity to banana (Cavendish, AAA). Therefore, we hypothesized that FocFCC1 gene might play an important role in the growth, sporulation and pathogenicity of Foc4. Further, a comparative study of the efficiency of two different homologous DNA disruption construct methods was carried out, one is Split-marker recombination approach, another termed Multi-fragment assembly by In-fusion cloning, requires only one standard PCR reaction and one fragment assembly reaction. Using the red phenotype as the judging basis, the transformants with red phenotype on the regeneration plate were selected for PCR detection. The results showed the percentage of positive transformants of Split-marker recombination approach was 91.7%, while that of the Multi-fragment assembly by In-Fusion cloning method was 64%. Next, ΔFocFCC1 showed typical red colony distinguished with Foc4, and the red colony phenotypes coupled with the positive PCR amplification bands. It is important that positive transformants can pick up according to the red phenotype by eyes without PCR procedures, and can serve as endogenous reporter gene for further Foc4 molecular biology research.

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    Sxpression Patterns of Flesh Color Related Genes in Red Pitaya (Hylocereus costaricensis) at Different Developmental Stages
    ZHAO Guowen, JIA Ruizong, GUO Jingyuan, GUO Anping
    2021, 42 (11):  3134-3145.  doi: 10.3969/j.issn.1000-2561.2021.11.0012
    Abstract ( 78 )   HTML ( 7 )   PDF (5867KB) ( 59 )  

    Pitaya belongs to the genus of Cactaceae and is one of the tropical fruits with important economic and nutritional value. Its fruits are rich in anthocyanins and betaine. In the late stage of fruit maturity, the accumulation of beta red pigment causes the phenomenon of red-hearted dragon fruit fruit color change. The color of the pulp is one of the important indicators to evaluate the quality of the dragon fruit. However, the gene expression regulation mode behind the color change of the fruit is unclear. In-depth study of the molecular mechanism of the color regulation of the pitaya fruit during the development of the dragon fruit will help to enrich the theoretical basis for the formation of pitaya quality. In this study, ‘Meihong No. 1’ red-hearted dragon fruit was used as the experimental material. Nine samples from different stages of fruit development were collected. A total of 96 differentially expressed genes were identified through comparative transcriptomics. Finally, 15 genes were found to be related to pigments. Genes related to metabolic pathways were significantly differentially expressed at different stages of fruit development. GO functional enrichment analysis found that differentially expressed genes were mainly enriched in functional classifications related to binding activity, catalytic activity, transport activity and structural molecule activity, and were importantly related to pigment metabolism. The results of KEGG metabolic pathway enrichment showed that there were many enriched genes in the biometabolite synthesis pathway, amino acid and nucleic acid metabolism pathway, and tyrosine metabolism pathway. Real-time fluorescent quantitative PCR technology was used to verify 15 the differentially expressed genes related to pigments, and the results were consistent with the results of transcriptome analysis. The results of physiological analysis and transcriptome analysis showed that the development of red skin and red flesh dragon fruit was accompanied by the synthesis of a large number of beet pigments, and the DODA gene in the beet pigment synthesis pathway was gradually up-regulated. During the fruit color change, there was an obvious upward trend in the P4 period. The expression of key genes is gradually down-regulated. This study explored the related genes related to fruit color change in dragon fruit, and provided an important target gene and genetic basis for subsequent genetic improvement of dragon fruit.

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    Transcriptome Analysis of Resistant and Susceptible Cassava Infested by Tetranychus urticae and Verification of Differentially Expressed Genes in Salicylic Acid and Jasmonic Acid Pathways
    DOU Hongshuang, LIANG Xiao, CHEN Qing, WU Chunling, LIU Ying, FAN Dongzhe, WU Yan
    2021, 42 (11):  3146-3155.  doi: 10.3969/j.issn.1000-2561.2021.11.013
    Abstract ( 48 )   HTML ( 5 )   PDF (9602KB) ( 38 )  

    To the best of our knowledge, there is no report on transcriptome difference while resistant and susceptible cassava cultivars were infested by pests. In this study, by comparing the transcriptome differences of resistant and susceptible cassava cultivars before and after Tetranychus urticae infestation, we screened the differentially expressed genes, and verified the differential expression of salicylic acid and jasmonic acid pathway genes through qPCR. The results of transcriptome analysis showed that there were 589 and 587 differentially expressed genes in mite-resistant cassava cultivar C1115, 1271 and 930 differentially expressed genes in mite-susceptible cassava cultivar BRA900, and 383 and 251 differentially expressed genes between C1115 and BRA900 respectively. In addition, the Go and KEGG enrichment analysis showed that the differentially expressed genes were significantly enriched in the secondary metabolite biosynthesis, phenylpropane biosynthesis, flavonoid biosynthesis and redox related reactions. qPCR verification indicated that after infested by T. urticae for 1 d and 8 d, the transcriptions of salicylic acid signaling pathway genes such as PAL2, 4CL3, WRKY7 and NPR3 in the standard mite-resistant cassava cultivar C1115 were first significantly increased and then decreased, while the expression level of the four genes in the standard mite-resistant cassava cultivar BRA900 was significantly higher than those before infestation. Besides, the transcription of jasmonic acid signal pathway genes like JAR1, LOX2 and OPR11 in C1115 was also significantly higher than those before infestation, while the transcription of the three genes in BRA900 was significantly lower than those before infestation. The results speculated that mite-resistant cassava cultivar C1115 could activate salicylic acid and jasmonic acid signaling pathways to defend T. urticae infestation. This study would lay a theoretical foundation for further elucidating the molecular mechanism of cassava resistance to mite, and for breeding and creating mite-resistant cassava cultivars.

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    Cloning and Functional Identification of Setaria viridis U6 Promoter
    GUO Jingyuan, ZHAO Hui, QU Jing, ZHANG Lili, GUO Anping
    2021, 42 (11):  3156-3164.  doi: 10.3969/j.issn.1000-2561.2021.11.0014
    Abstract ( 67 )   HTML ( 5 )   PDF (3739KB) ( 47 )  

    Setaria viridis is an important model plant and an excellent model for C4 photosynthesis, which has typical characteristics of tropical plants. U6 promoter is mainly used to construct RNAi and CRISPR expression vectors. It has the function of initiating the expression of the interference hairpin structure and the expression of the compound structure of the gene editing guide sequence. The promoter has a special start site G, which can ensure the integrity of the RNA structure after transcription. With the development of CRISPR technology, there are more and more researches on gene editing by Setaria viridis. At present, there is no cloning and functional identification of U6 promoter of S. viridis. The U6 promoter is species-specific. In transgenic technology, using the U6 promoter of the transformed species itself or relative species can achieve higher activation efficiency. In this study, two U6 promoter genes of S. viridis were cloned, and U6 promoter sequences with different length were constructed to drive GUS gene expression. GUS fusion expression vector was transformed into embryogenic callus of S. viridis, and the transient expression verification showed that the two cloned U6 promoters of S. viridis had strong activation efficiency on S. viridis. After the vector was transformed into S. viridis, the transgenic plants were obtained which could stably expressing GUS gene. The U6 promoter was used to construct CRISPR editing vector of PDS gene of S. viridis, and the albino seedlings with stably expressing GUS gene were obtained, which indicated that the cloned U6 promoter of S. viridis could well start the transcription of gene editing vector.

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    Plant Cultivation, Physiology & Biochemistry
    Investigation and Analysis on Soil Properties of Litchi Orchards in South China
    SU Xuexia, LIU Qinghui, BAI Cuihua, ZHOU Changmin, YAO Lixian
    2021, 42 (11):  3165-3172.  doi: 10.3969/j.issn.1000-2561.2021.11.015
    Abstract ( 61 )   HTML ( 6 )   PDF (1568KB) ( 56 )  

    470 soil samples were collected from litchi orchards in main production areas in South China. According to the Soil Nutrient Classification Norms of the Second National Soil Survey, the soil nutrient fertility status of the litchi orchards was evaluated, and the main nutrient contents in different provinces were compared. The relation among soil properties was investigated as well. The results showed that soils in most of the litchi orchards in South China were in low pH, with more than 90% of them of being acid (pH 4.5-5.5) and highly acid (pH<4.5). Generally, soil cation exchange capacity of litchi orchards was low and weak in water and nutrient holding capacity. The content of soil organic matter, alkali-hydrolyzable nitrogen, available potassium and available molybdenum was in lower medium levels, while soil exchangeable calcium, exchangeable magnesium and available boron were deficient, and available phosphorus and zinc were in medium values. However, soil available sulfur and copper were abundant in litchi orchards. On the whole, soil nutrient fertility in litchi orchards was low and unbalanced. Soil nutrient fertility in different production areas were variable. Soil organic matter, alkali-hydrolyzable nitrogen, available phosphorous, copper and zinc in Hainan province were higher than those in all other production areas in South China. Soil available potassium, exchangeable calcium and magnesium, and available copper in Yunnan Province ranked the highest in all production areas, however, soil organic matter, available phosphorus, sulfur and molybdenum were the lowest. Totally, soil available boron in Guangdong Province ranked first in all the production areas. Pearson correlation analysis showed that close relation among soil properties was observed. Among them, soil pH was positively correlated to soil exchangeable calcium and magnesium, respectively (P<0.01). Positive correlation was found between exchangeable calcium and exchangeable magnesium, and between available copper and zinc, and between available potassium and exchangeable calcium as well (P<0.01). Owing to the universally low soil pH and unbalanced soil nutrient fertility, great attention should be paid to soil pH improvement and application of organic fertilizer. Meanwhile, proper combination of nitrogen, phosphorous and potassium fertilizers and supplement of calcium, magnesium and boron fertilizers need to be highlighted.

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    Yield and Nutrient Absorption and Utilization Characteristics of Cassva under Reduced Fertilizer Application
    LUO Liangyuan, XUE Xinxin, WEI Yunxia, HUANG Jie, ZHANG Yongfa, ZHAO Chunmei, LUO Xuehua, WANG Wenbin
    2021, 42 (11):  3173-3179.  doi: 10.3969/j.issn.1000-2561.2021.11.016
    Abstract ( 67 )   HTML ( 5 )   PDF (1530KB) ( 47 )  

    Excessive fertilization in cassava planting will cause excessive top growth and reduce tuber root yield. To provide theoretical basis for practices with high yielding and high uptake efficiency of fertilizer, a field experiment was carried out with four treatments i.e. no fertilization (UT), conventional fertilization (CFT), 25% reduction in fertilization (RFT) and simultaneous fertilization with 25% reduction (RSFT). The effects of different fertilizer amounts and split application on cassava yield and nutrient uptake and utilization were studied. The results showed that fertilization could significantly increase plant height, stem diameter and biomass of cassava. The tuber root yields of RFT and RSFT were significantly higher than that in CFT and UT. The fresh weight of cassava in RFT increased by 28.15% and 32.73%, respectively,compared with that in UT and CFT. Yield increments of 15.46% and 19.57% were obtained in RSFT. The starch content in tuber root increased with fertilizer application. The results showed that reducing fertilization in a certain extent would not cause starch content decline in tuber root. Compared with CFT, the uptake rate of N and P increased by 8.52 and 5.01 percent, respectively, in RFT, while similar uptake rate of K was observed in both CFT and RFT. Higher increment of N, P and K uptake rate was observed in RSFT, uptake rate of N, P and K increased by 12.65, 8.09 and 6.26 percent, respectively. Under the conditions of this experiment, significantly higher root tuber yield was obtained in RFT and RSFT, which reached to 44.93 t/hm2 and 40.08 t/ha, while a lower tuber root yield of 32.58 t/ha was found in CFT. The uptake rate of fertilizer was significantly improved, which indicated that higher economic efficiency could be obtained with reduced fertilization.

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    Effects of Different Fertilization on Yield and Nutrient Composition of Passion Fruit
    ZHANG Limin, CAI Guojun, PEN Xi, GUO Chunyan, REN Chunguang, LI Anding
    2021, 42 (11):  3180-3187.  doi: 10.3969/j.issn.1000-2561.2021.11.017
    Abstract ( 91 )   HTML ( 5 )   PDF (1397KB) ( 68 )  

    In order to select the best fertilization mode for passion fruit, five different fertilization treatments were set up in this study: no fertilization (CK), nitrogen, phosphorus and potassium fertilizer (NPK), organic fertilizer (M), nitrogen, phosphorus and potassium combined with organic fertilizer (MNPK), high amount of nitrogen, phosphorus and potassium and high amount of organic fertilizer (2MNPK). After the analysis and comparison of the difference of yield and nutritional components of passion fruit, the principal component analysis and comprehensive evaluation were done by the multivariate statistical analysis method (PCA). The results showed that compared with CK, the growth of passion fruit treated with NPK, MNPK and 2MNPK was the fastest, especially after 66 days of planting. NPK, M, MNPK and 2MNPK increased the yield and quality, MNPK and 2MNPK treatments was the most obvious. Compared with CK, the yield of passion fruit treated with NPK, M, MNPK and 2MNPK increased by 112.86%, 74.40%, 191.00% and 244.30%, respectively, and the content of vitamins, mineral elements, sugars and amino acids increased, while the contents of total acids decreased. The content of total amino acids, essential amino acids and flavor amino acids increased by 82.40%, 76.11% and 76.89%, respectively, and the total acid content decreased by 22.61% in 2MNPK. Based on the multivariate statistical analysis of 36 indexes, three principal component factors were extracted, and the contribution rate of cumulative variance was 97.925%. According to the variance contribution rate of the three principal components, the comprehensive evaluation model was established to calculate the comprehensive total scores of different fertilization treatments, and the order was 2MNPK (123.04)>MNPK (39.06)>M (-12.01)>NPK (-45.36)>CK (-104.73). It shows that among the five fertilization treatments, 2MNPK is the best fertilization mode in the process of passion fruit planting. This study could lay a theoretical foundation for the large-scale popularization and application of passion fruit.

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    Effect of Intercropping with Different Legume Crops on Endophytic Bacterial Diversity of Sugarcanes
    XIAO Jian, CHEN Siyu, SUN Yan, YANG Shangdong, TAN Hongwei
    2021, 42 (11):  3188-3198.  doi: 10.3969/j.issn.1000-2561.2021.11.018
    Abstract ( 74 )   HTML ( 5 )   PDF (1911KB) ( 69 )  

    To evaluate the effects of intercropping with different legume crops on the health and resistance of sugarcane plants,endophytic bacterial diversity in the roots of sugarcane were analyzed. The diversity and richness of endophytic bacteria in the roots of sugarcanes under sugarcane / soybean intercropping system were significantly increased than those of monoculture (CK). Even though the diversity and richness of endophytic bacteria in the roots of sugarcanes under sugarcane / mung bean system were higher than those of CK, there was no significant differences between each other. Moreover, they were significantly decreased under sugarcane / peanut systems compared to CK. At the phylum level, the abundances of Proteobacteria, Actinobacteria and the phylum of other were all increased under sugarcane intercropping systems compared to CK. At the genus level, the abundances of Pantoea and Burkholderia- Paraburkholderia were decreased, but that of Rhodococcus was increased under sugarcane intercropping systems compared to CK. In addition, compared to CK, the unclassified_f__Micrococcaceae and Pseudarthrobacter were the specific dominant endophytic bacterial genera, but also lost the Herbaspirillum and Williamsia in roots of sugarcanes under different intercropping systems. Moreover, the Rubrobacter, norank_f__MSB-1E8, Nocardioides, norank_c__Actinobacteria, norank_f__Euzebyaceae, Gaiella, Defluviicoccus, norank _f__Elev-16S-1332, norank_o__Acidimicrobiales, norank_f__Propionibacteriaceae, norank_o__Gaiellales, norank_f__Gemmatimonadaceae were the specific dominant endophytic bacterial genera in roots of sugarcanes under sugarcane/soybean intercropping (A) system. The Streptomyces, Massilia, Mycobacterium, Methylobacterium, Sinomonas, Rhodanobacter, Chryseobacterium and Rhizomicrobium were the specific dominant endophytic bacterial genera in roots of sugarcanes under sugarcane/mung bean intercropping (B) system. And there were no specific dominant endophytic bacterial genera in roots of sugarcanes under sugarcane/peanut intercropping (C) system. However, the Herbaspirillum and Williamsia were the specific dominant endophytic bacterial genera in roots of sugarcanes under monoculture (CK) system. The diversity and richness of endophytic bacteria were not only promoted, but also the composition of endophytic bacterial communities in roots of sugarcanes was improved by intercropping with soybean and mung bean. In particularly, the better effect was intercropping with soybean. By contrast, not only the diversity and richness, but also the composition of endophytic bacterial communities in roots of sugarcanes was all deceased under sugarcane/peanut intercropping system.

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    High-yield Cultivation Techniques of Morchella spp. in South China
    LIU Fuyang, WANG Aixian, WU Rengao, WANG Yixuan, ZHAO Junmin, DENG Wenming
    2021, 42 (11):  3199-3205.  doi: 10.3969/j.issn.1000-2561.2021.11.019
    Abstract ( 65 )   HTML ( 5 )   PDF (6844KB) ( 38 )  

    The strains and cultivation techniques on the growth of Morchella spp. in south china were varied to investigate the conditions for a high-yield cultivation practice. Four strains, 5 sowing date, 3 sowing methords, 6 formulas of external nutrition bags and 5 soils were applied for the experiment to determine the optimal conditions for Morchella spp. LM-s had a primordium of medium density, concentrated mushroom, highest yield and good commercial character. TL-s had large density but few effective for primordium, low yield and worse commercial character. Between late November and December, local stable temperature below 20 ℃ was suitable for sowing and there was no significant difference in the yield. But before late November, the growth of mycelia was weak and the yield was low after sowing because of high temperature. In the three different sowing methods, the time was different for mycelia to emerge to the surface of the soil layer and the growth of mycelia was strong or weak, but there was no significant difference in the fruiting stage. In the six formulas of external nutrition bags, treatment 1 and 2 had higher yields, but the harvest date was late. In the five soils treatments, sandy loam was the most productive, the second was paddy soil. In conclusion, LM-s with strong resistance should be selected, sowed in late November to December with broadcast sowing, furrow sowing or dibbling, the raw materials of the external nutrition bag were mainly wheat or corn kernels, and sandy loam or paddy soil are preferred.

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    Effects of Different Substrates on the Growth and Development of Costus speciosus
    LIU Xiaorong, WU Zhi, XU Yang, HAN Qingbin, WANG Dairong
    2021, 42 (11):  3206-3211.  doi: 10.3969/j.issn.1000-2561.2021.11.020
    Abstract ( 54 )   HTML ( 5 )   PDF (1596KB) ( 48 )  

    In this study, the effects of six substrates consisting of red soil, peat, coir, and perlite in different proportions on the growth of Costus speciosus were investigated. The physical and chemical properties of the six substrates were measured after mixed. The sprouting rate, leaf number, stem diameter, plant height, plant width, diurnal variation of photosynthetic characteristics, rhizome fresh weight (RFW) and rhizome dry weight (RDW) were measured. The results revealed that the net photosynthetic rate (Pn) in the peat + coir + perlite, 1∶2∶2 (S4), was the greatest. The Pn curves of the six substrates varied in single or double peaks, while the transpiration rate (Tr) curves displayed a single peak. The greatest plant height, RFW and RDW were also observed in S4. Based on the findings, S4 was considered a suitable substrate for C. speciosus growth and dry matter accumulation.

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    Physiology and Biochemistry of Cassava in Response to in Vitro Dehydration Stress
    DONG Shiman, LI Zhibo, GUO Xin, LI Shuxia, YU Xiaoling, PENG Ming
    2021, 42 (11):  3212-3218.  doi: 10.3969/j.issn.1000-2561.2021.11.021
    Abstract ( 43 )   HTML ( 4 )   PDF (1743KB) ( 44 )  

    Cassava is an important food and economic crop in tropical and subtropical areas. The cassava stems are currently the only way to reproduce. However, it is not clear how cassava stems respond to dehydration stress and the expression of glucose metabolism genes in cassava after harvest. In this study, the variation of water and sugar content in cassava stems of control and treatment at different time after harvest was investigated respectively to explore the role of sugars in cassava stems in vitro conditions. The metabolic relationship among different sugars and the activity of cassava stem in vitro were analyzed through the expression of genes related to carbohydrate metabolism. The results showed that the contents of fructose, glucose and sucrose in cassava stem decreased firstly and then increased with the prolongation of postharvest time in the treatment, and the contents were significantly higher than those in the control, while the change and content of trehalose was just the opposite. qPCR analysis demonstrated that the expression of glycolytic genes in cassava stem was improved when exposed to severe dehydration stress. The conclusions suggested that the interconversion of sugars in cassava stems was affected significantly exposed to dehydration stress. Thus, it was speculated that trehalose was synthesized in the first 20 days of dehydration stress in response to dehydration stress, and then was decomposed in the second 20-30 days to provide necessary energy substances for cassava stem. In addition, the storage period of cassava stem increased by glycerol treatment, providing a new method for cassava stem storage.

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    Effects of Starvation Stress on Energy Metabolism in the Fruitlet and Carpopodium of Macadamia
    YANG Weihai, XIANG Peijin, LU Chaozhong
    2021, 42 (11):  3219-3226.  doi: 10.3969/j.issn.1000-2561.2021.11.022
    Abstract ( 49 )   HTML ( 3 )   PDF (1794KB) ( 57 )  

    In order to explore the relationship of fruit abscission with energy metabolism in macadamia under starvation stress, a treatment of girdling plus defoliation was made on the bearing shoots of macadamia cultivar ‘H2’ at the early stage of fruit development, and the changes in the energy contents (ATP, ADP and AMP), energy charge (EC) levels, and the activity of key enzymes related to energy metabolism (H +-ATPase and Ca2+-ATPase) in the carpopodium and the different fruit tissues were investigated regularly. The results showed that a severe fruitlet drop occurred under the starvation stress induced by girdling plus defoliation treatment. From the beginning of treatment to the starting of severe fruit shedding (0-3 d after treatment), the contents of AMP and ADP in pericarp, ATP and ADP in seed and fruit stalk increased significantly, the activity of H+-ATPase in pericarp and seed and the capacity of H+-ATPase and Ca2+-ATPase in carpopodium were significantly enhanced, and the EC level of carpopodium and seed was elevated obviously, but the EC value of pericarp decreased significantly. With the intensification of fruit abscission at the later stage of treatment (4-5 d after treatment), the significantly increased activity in the Ca2+-ATPase of carpopodium and the H+-ATPase and Ca2+-ATPase of pericarp and seed occurred, and the content of ATP in carpopodium and pericarp and the level of AMP in pericarp and seed were obviously raised, while the EC level was significantly increased only in carpopodium. The results suggested that starvation stress might affect early fruit abscission by influencing the energy metabolism characteristics of macadamia pedicel and fruit.

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    Pigment Composition of Sepals in Cymbidium ensifolium
    ZHENG Qingdong, WANG Yan, WANG Yi, MA Shanhu, AI Ye
    2021, 42 (11):  3227-3235.  doi: 10.3969/j.issn.1000-2561.2021.11.023
    Abstract ( 50 )   HTML ( 2 )   PDF (603KB) ( 49 )  

    In order to understand the flower color diversity of C. ensifolium and its formation mechanism, this paper carried out flower color phenotype analysis and preliminary analysis of anthocyanin components on the sepals of 58 C. ensifolium varieties. Combined with visual analysis, colorimetric colorimetry and colorimeter test, the sepals of 58 C. ensifolium varieties were divided into four major colors, purple-red, red, yellow-green, and white. Representative varieties of each color were selected to perform color reaction, characteristic color response of flavonoids and ultraviolet-visible spectrum scanning, and analyze the pigment components contained in the sepals of different flower color. The results showed that the pigment components in the white sepals were relatively simple, without chlorophyll and carotenoids, and flavones existed; the main pigment components in the purple-red and red sepals were flavonoids and anthocyanins; the yellow-green sepals contain the most types of pigments, including chlorophyll, carotenoids and flavones. This experiment would lay a theoretical foundation for the further study of the pigment composition of C. ensifolium and the formation mechanism of the flower color of C. ensifolium, and provided a reference for the cultivation of colorful varieties of C. ensifolium.

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    Plant Cultivation, Physiology & Biochemistry
    Dynamic Changes of Endogenous Hormones and Polyamine in Paphiopedilum hirsutissimum Leaves During Floral Bud Formation
    LI Xiuling, FAN Jizheng, LIAO Hongying, HE Jingzhou, ZENG Yanhua, LONG Qiangyu, BU Zhaoyang
    2021, 42 (11):  3236-3241.  doi: 10.3969/j.issn.1000-2561.2021.11.024
    Abstract ( 56 )   HTML ( 2 )   PDF (5266KB) ( 64 )  

    The Paphiopedilum orchid industry has developed rapidly recently. However, flowering regulation has become the bottleneck restricting the development of the industry. P. hirsutissimum, which is easy to bloom, was used as the experiment materials, the content changes of endogenous hormones and polyamine in functional leaves were detected by high performance liquid chromatography (HPLC) to provide a theoretical basis for the flowering regulation of the orchids. High content of ZT, IAA, GA3, PAs and high ratio of GA3/IAA in leaves were beneficial to inducing the bud differentiation. Higher content of ZT, IAA, GA3, PAs and high ratio of Spd/Put, Spm/Put in leaves were beneficial to floral morphological differentiation. GA3 could regulate IAA and Put levels, there was a close relationship between polyamines and hormones.

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    Plant Protection & Bio-safety
    Evaluation of Nutrition Properties of Banana Variety ‘Zhongjiao No 9’ with High Resistance to Fusarium Wilt Disease
    ZHANG Xiaolong, ZHANG Lidan, DONG Tao, LI Zhonghua, LI Yuanqiong, HE Weidi, JIANG Jiaquan, CHEN Jing, FAN Xiaolin
    2021, 42 (11):  3242-3249.  doi: 10.3969/j.issn.1000-2561.2021.11.025
    Abstract ( 134 )   HTML ( 2 )   PDF (2433KB) ( 50 )  

    In order to apply fertilizer rationally and manage nutrient effectively during the promotion of banana variety of panama fusarium wilt resistant cultivar ‘Zhongjiao No. 9’, the accumulation and allocation of nitrogen, phosphorus and potassium (NPK) nutrients in the root, stem, leaf and fruit organs of ‘Zhongjiao No. 9’ under normal field management were studied by using the whole plant dismember method. The average fresh weight and dry weight of single plant of ‘Zhongjiao No. 9’ was (145.35±6.42) and (18.18±0.70) kg/plant, and ash content in dry matter was only 8%. The order of fresh weight of the four organs was as followings stem (93.53 kg/plant)>fruit (33.38 kg/plant)>leaves (14.93 kg/plant)>roots (3.51 kg/plant). The pattern of dry matter accumulation and allocation was consistent with fresh weight order. The dry weight of the stem was 8.44 kg/plant, and the dry matter was mainly distributed in pseudostem (76%) and corm (24%). The dry weight of leaves was 2.77 kg/plant, and the proportion of dry matter allocation in leaves and petioles was 56% and 44% respectively. The dry weight of the fruit was 6.71 kg/plant, the dry matter allocation of the fruit comb was up to 94%, and the fruit axis accounted for only 6%. About two-thirds of the dry matter was allocated to the root, stem and leaf, meaning two-thirds of the photosynthetic products were used for root, stem and leaf growth, while only about one-third of the photosynthetic products were used for fruit growth. On average, the cumulative absorption of pure nitrogen, pure phosphorus and pure potassium per plant was 116.89 g, 23.67 g and 510.29 g, and the ratio of N, P and K was 1.0:0.20:4.37. The N, P and K absorption accumulation in the four organs was distributed in the order of the stem>fruit>leaf>root. The ratio of N:P2O5:K2O in root, stem, leaf and fruit was 1.0:0.21:6.82, 1.0:0.25:7.38, 1.0:0.13:1.96 and 1.0:0.21:3.10, respectively. Among the four organs, stems absorbed and accumulated most N, P and K. A noteworthy feature of the nutrient management of ‘Zhongjiao No. 9’ was that the accumulation of dry matter and potassium in rhizome and leaves, especially in stems, was much higher than that of Brazilian banana. The supply of nutrient and water should be controlled properly before pregnancy buds to limit the growth of stem and leaf to reduce nutrient consumption. The ratio of fertilizer N:P2O5:K2O could be referred to the nutritional characteristics of Brazilian banana, and the formula of 2.0:0.5-1.0:1.0 should be adopted before pregnancy buds, 1.0:0.5:2.0 from pregnancy buds to extraction buds, and 1.0:0.5:2.5-3.0 after extraction and before harvest.

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    Functional Analysis of MoKin1 as Putative Substrate of the Small GTPase MoRho3 in Rice Blast Fungus, Magnaporthe oryzae
    CAI Yan, LIN Jie, HE Jin, YANG Fuchang, ZHANG Dongmei, ZHANG Lianhu, WANG Zonghua
    2021, 42 (11):  3250-3260.  doi: 10.3969/j.issn.1000-2561.2021.11.026
    Abstract ( 55 )   HTML ( 3 )   PDF (19988KB) ( 33 )  

    Small GTPase MoRho3 plays an important biological role in the rice blast fungus, Magnaporthe oryzae. The preamble research elucidated that the deletion of MoRho3 in this fungus caused serve phenotypic defects, such as abnormal morphology of conidia, reduction of germination and penetration of appressoria and reduced pathogenicity. In order to understand the mechanism of the regulatory pathways of MoRho3, we adopted the bioinformatics to search the putative interacting protein of MoRho3. We found the homologus protein of Saccharomyces cerevisiae KIN1 and KIN2 in the proteins, named MoKin1. Because the over-expression of KIN1 and KIN2 could rescue some phenotypic defects of △rho3 in S. cerevisiae, in order to verify whether there was a similar regulatory pathway between Mokin1 and MoRho3 in M. oryzae, the study revealed the functional characteristics of Mokin1 by analyzing the evolutionary relationship, sequence structure, localization status and related interaction proteins, which would provide a new basis for the further study of the interaction between Mokin1 and MoRho3 and the pathogenic mechanism of M. oryzae.

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    Pathogen and Molecular Identification of Mubbery (Morus alba L.) Bacterial Wilt in Hainan
    LOU Dezhao, WU Huazhou, LU Fuping, GENG Tao, TU Nana, WANG Shuchang
    2021, 42 (11):  3261-3268.  doi: 10.3969/j.issn.1000-2561.2021.11.027
    Abstract ( 68 )   HTML ( 1 )   PDF (3147KB) ( 59 )  

    Bacterial wilt of mulberry is a bacterial disease caused by Ralstonia solanacearum. It is serious in tropical and subtropical areas, which restricts the development of sericulture industry. The pathogenicity and host of R. solanacearum are different from each other, and the control strategy is also different. Accurate isolation and identification of the pathogen is the prerequisite for the effective control of bacterial wilt. In this study, we collected and isolated the pathogenic bacteria of mulberry (‘Guisangyou 62’) in Qiongzhong County, Hainan Province. The strains were selected and tested for pathogenicity, race and biovar, combined with 16S rDNA molecular identification, specific primers, multiplex PCR detection system and sequence variation, and with phylogenetic analysis. All the three strains were R. solanacearum. According to the traditional classification the pathogen belongs to physiological race 5 and biovar V. The genetic evolution of the pathogen was further analyzed by molecular biology methods. The pathogen belonged to phylotype I (the Asiaticum division), sequevar 12. The results would lay a foundation for the effective control of mulberry bacterial wilt in Hainan.

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    Identification and Biological Characteristics of Epicoccum sorghinum, pathogen of Tea Leaf Spot
    HUANG Honglin, YIN Qiaoxiu, JIANG Shilong, BAO Xingtao, WU Xian, WANG Delu, CHEN Zhuo
    2021, 42 (11):  3269-3277.  doi: 10.3969/j.issn.1000-2561.2021.11.028
    Abstract ( 90 )   HTML ( 3 )   PDF (7110KB) ( 41 )  

    In order to effectively control the occurrence and damage of tea leaf spot in Dushan County, Guizhou Province, this paper studied the pathogen and biological characteristics of tea leaf spot in the region. The results showed that the colonies, pycnidia, conidia and chlamydospores of the representative strain GZDS2018BXT10 were identical with the strain Epicoccum sorghinum. The gene or nucleic acid of ITS, RPB2, TUB and LSU were sequenced, then the phylogenetic analysis was conducted by PAUP software with the method of Maximum parsimony based on multi-locus sequences. The strain GZDS2018BXT10 and E. sorghinum model strain CBS179.80 were grouped together in the phylogenetic tree, and the clade was supported by 100%. The pathogenicity test showed that the strain GZDS2018BXT10 could induce the lesion on tea leaves using wound mode under the conditions of laboratory and field, in accordance with Koch’s rule. Therefore, the pathogen of tea leaf spot was identified as E. sorghinum. The strain GZDS2018BXT10 could grow on PDA, OA and MEA medium. The strain GZDS2018BXT10 grew quickly on OA medium, and the growth rate was (0.76±0.01) cm/d, which was significantly higher than that on MEA and PDA medium (P<0.05). The optimum growth temperature and pH value on PDA medium were 22 ℃ and 6.0. Both carbon and nitrogen nutrition can affect the growth of mycelia.

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    Effect of Fourteen Arbuscular Mycorrhizal Fungi on Growth of Fructus aurantii
    ZHANG Jinlian, LI Mingyan, KANG Yihao, LIU Jinhua, CHEN Tingsu, LI Xianliang, SONG Juan, LIU Shengqiu
    2021, 42 (11):  3278-3283.  doi: 10.3969/j.issn.1000-2561.2021.11.029
    Abstract ( 58 )   HTML ( 0 )   PDF (7597KB) ( 32 )  

    Bitter orange (Fructus aurantii) is commonly used as the rootstock for citrus. In this experiment, the arbuscular mycorrhizal fungi isolated from Guangxi soil were inoculated into the potting mix where bitter orange seedlings were grown, and the growth characteristics of mycorrhizal and non-mycorrhizal plants were compared. The data showed that all 14 arbuscular mycorrhizal fungi strains employed in the experiment could form symbiotic relationship with the root system of F. aurantii. The overall average infection rate was 36.16%, with Redeckera fulvum having the highest infection rate (92.83%). Glomus coronatum exhibited the lowest infection rate (0.23%). Redeckera fulvum, Glomus mosseae, and Glomus coronatum significantly increased plant height, stem diameter, leaf number, and petiole length of F. aurantii seedlings, when compared to the mock inoculation control group. The study demonstrates that the inoculation of the arbuscular mycorrhizal fungi could significantly promote the growth of bitter orange plants.

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    Post-harvest Treatment & Quality Safety
    Changes in Latex Physiological Parameters During the Recovery from Tapping Panel Dryness (TPD) in Hevea brasiliensis Promoted by TPD Rehabilitation Nutrient Agent
    LIU Hui, FENG Chengtian, HU Yiyu, YUAN Kun, WANG Zhenhui
    2021, 42 (11):  3284-3292.  doi: 10.3969/j.issn.1000-2561.2021.11.030
    Abstract ( 54 )   HTML ( 0 )   PDF (2041KB) ( 44 )  

    To investigate the physiological basis of the recovery from tapping panel dryness (TPD) in rubber trees (Hevea brasiliensis), the experimental materials with different degrees of TPD recovery were made by treating TPD trees with TPD rehabilitation nutrient agents, and the change laws of latex physiological parameters among the healthy, TPD, and different degrees of TPD recovery trees were determined and analyzed, including dry rubber content, total solid content, pH value, lutoid bursting index, thiol content, inorganic phosphorus content, sucrose content, and invertase activity. The results showed that the latex yield, inorganic phosphorus content, thiol content and invertase activity significantly decreased, whereas the dry rubber content, total solid content, pH value, lutoid bursting index and sucrose content significantly increased after TPD occurrence. TPD rehabilitation nutrient agent treatment could promote TPD recovery, and had a certain control effect. During the TPD recovery, the dry rubber content, total solid content, lutoid bursting index and sucrose content decreased gradually, the inorganic phosphorus content, thiol content, invertase activity and latex yield increased gradually, but the pH value did not change obviously. The results indicate that the abnormality of latex physiological parameters is closely related to the occurrence of TPD in rubber trees. During the TPD recovery, the latex physiological parameters such as dry rubber content, total solid content, lutoid bursting index, thiol content, inorganic phosphorus content, sucrose content, and invertase activity returned to normal level, and modulating the physiological parameters of latex to normal level would be helpful to rubber tree TPD recovery. This study would provide a theoretical basis for developing highly effective agents for the prevention and treatment of TPD.

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    Determination of Iodopropynyl Butyl Carbamate in Treated Rubber Wood by High Performance Liquid Chromatography
    LI Xiaowen, HAN Liping, LI Tongtong, ZHANG Jingpeng, JIANG Mingliang
    2021, 42 (11):  3293-3300.  doi: 10.3969/j.issn.1000-2561.2021.11.031
    Abstract ( 60 )   HTML ( 1 )   PDF (1418KB) ( 46 )  

    Rubber wood is known to be very susceptible to mold and sap stain fungi attacks because of its extraordinary high starch content. 3-iodo-2-propynyl butyl carbamate (IPBC) is suitable for rubber wood preservation as it is highly effective in mold and sap stain fungi, and environmentally friendly. However, few studies on the quantitation methods of IPBC in treated rubber wood have been reported. To determine IPBC in treated rubber wood accurately, a high-performance liquid chromatography (HPLC) method was developed, and the optimization of extracting IPBC from rubber wood was conducted by comparing the effects of different extraction methods, solvents, and particle sizes of wood powder. The HPLC conditions were as follows: C18 reversed-phase column, acetonitrile-water (55︰45, V/V) as mobile phase, flow rate 1.0 mL/min, detection wavelength 204 nm, the retention time of IPBC about 6.45 min. There was a good linear correlation between the mass concentration of IPBC and the peak area with a correlation coefficient of 0.9998 in the range of 2~80 mg/L. The limit of detection (LOD) was 0.2 mg/L, and the average recovery of spiked samples was 99.61%. The comparison of extraction methods showed that ultrasonic extraction was significantly better than the Soxhlet extraction. Methanol or methanol-water (9︰1, V/V) mixed solution was the best solvent to extract IPBC from wood, but ethyl acetate and petroleum ether were not suitable for extracting. Using methanol-water (9︰1, V/V) as the solvent could eliminate the leading peak, which was helpful to improve the accuracy of the analytical method. The difference in wood powder particle size had little effect on the analysis results of IPBC extracted by ultrasonic. The enormous degradation of IPBC due to high temperature greatly affected the analysis results, therefore, high-temperature conditions should be avoided during the analysis process. With the advantages of low detective limit, good reproducibility, and high accuracy, the developed method may have great potential for the analysis of IPBC in preservative woods.

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    Comparative Analysis of Flavonoids in Different Flesh Color Jackfruit
    CEN Yi, CHENG Jun, DING Yuanhao, WU Gang, WU Baoduo, FAN Rui, TAN Lehe, HU Lisong
    2021, 42 (11):  3301-3306.  doi: 10.3969/j.issn.1000-2561.2021.11.032
    Abstract ( 94 )   HTML ( 1 )   PDF (8316KB) ( 31 )  

    Flavonoids are important pigments and active substances in plants. Here, the composition and content of flavonoids in jackfruit were investigated based on the ultra performance liquid chromatography-electrospray ionization-tandem mass spectrometry system. 82 flavonoids with differential accumulation were identified, including 27 flavones, 24 flavonol, 12 flavanone, 11 flavone C-glycosides and eight others. The overall quantitative and qualitative analysis showed that the composition and content of flavonoids in red fruit were significantly super to that of yellow fruit. The comparative analysis between red and yellow fruit showed that there were 19 flavonoids predominantly accumulated in the red fruit, and only 3 flavanones accumulated in yellow fruit, the differential accumulated flavonoids in red flesh was also super to that of yellow flesh.

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    Activation Regulation of Activated Carbon from Macadamia Nut Shell Biomass and Its Microwave Absorbing Properties
    CUI Haipeng, LONG Aichun, HU Benxiang, ZHAO Yanfang, SONG Ximei, LIAO Jianhe, LIAO Lusheng
    2021, 42 (11):  3307-3315.  doi: 10.3969/j.issn.1000-2561.2021.11.033
    Abstract ( 66 )   HTML ( 2 )   PDF (9487KB) ( 36 )  

    High-temperature carbonization technology was used to prepare Macadamia nut shell biomass activated carbon (MNAC) materials. The effects of phosphoric acid, potassium hydroxide and zinc chloride as activators on the microscopic morphology and microwave absorbing properties of MNAC materials were studied. The activators had obvious pore-forming effect on the Macadamia nut shell biochar (MNC) and could facilitate the formation of pore-rich structure. Compared with MNC, the microwave absorption performance of the activated was improved. Specifically, the reflection loss of the biocarbon was activated by zinc chloride reaches -16 dB. The reflection loss of the biocarbon activated by potassium hydroxide was up to -26 dB, and the effective absorption bandwidth could cover 14 GHz by adjusting the thickness. The good absorbing performance of MNAC could be attributed to the porous structure resulted by the activation process. The porous structure further promoted the attenuation of electromagnetic waves, such as conduction loss, interface polarization, and multiple scattering. The order of the MNC microwave absorbing properties regulated by different activators was finally determined as: MNAC-K (KOH activation) > MNAC-Zn (ZnCl2 activation) > MNAC-H (H3PO4 activation) > MNC (no activation).

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    Effects of Roasting Speed on the Volatile Components of Xinglong Coffee Beans
    YU Fei, DONG Wenjiang, HU Rongsuo, LONG Yuzhou, CHEN Zhihua, JIANG Kuaile
    2021, 42 (11):  3316-3326.  doi: 10.3969/j.issn.1000-2561.2021.11.034
    Abstract ( 77 )   HTML ( 3 )   PDF (4418KB) ( 58 )  

    This study investigated the physicochemical properties and volatile components of coffee beans (C. robusta) from Xinglong, Hainan at three conditions (fast, medium, and slow roasting speed). Headspace solid phase microextraction - gas chromatography-mass spectrometry (HS-SPME-GC-MS) was used to identify the volatile components generated at three roasting speed, and principal component analysis (PCA) combined with electronic nose was used to further distinguishing the differences of overall flavor among different roasted bean samples. A total of 82, 72, and 76 volatile components were identified in fast, medium and slow roasted coffee beans respectively. The content of volatile components was different among the roasting samples, and the level of volatile components at medium roasted beans was the highest and reached a maximum of 1080.51 µg/g. Electronic nose analysis showed significant differences in volatile components among coffee samples roasted by different methods. Results from PCA using the data of major volatile class as input variables showed that there were obvious differences among the three. And there were overlaps in section between medium and slow roasted coffee samples, which was a big difference from fast roasted samples. This research could provide some reference for the improvement of the roasting process and the optimization of quality in coffee production.

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    Exploration of the Accelerated Oxidation Process and Change Rule of Bioactive Components from Green Coffee Oil Based on Thermal Induction
    HONG Qidi, DONG Wenjiang, MEI libao, LONG Yuzhou, HU Rongsuo, CHU Zhong, WANG Hairu
    2021, 42 (11):  3327-3338.  doi: 10.3969/j.issn.1000-2561.2021.11.035
    Abstract ( 78 )   HTML ( 2 )   PDF (2490KB) ( 58 )  

    Green coffee oil is a kind of functional oil rich in biologically active ingredients, which is easily oxidized and rancid during storage and affects product quality. In this paper, green coffee oil was extracted from Xinglong coffee in Hainan area, and the changes in the oxidation index, biologically active components and spectral characteristic peaks that characterize oxidation were systematically studied within 36 days of accelerated storage at 60 ℃. The results showed that the initial values of peroxide value, anisidine value, thiobarbituric acid and total oxidation value was 0.97±0.04 meq/kg, 4.19±0.14, 55.08±1.98 nmol/mL, 8.05±0.06, respectively. After 36 days of oxidation, it significantly increased to 28.56±0.15 meq/kg, 19.19±0.13, 102.38±2.18 nmol/mL, and 133.43±0.45. A total of 11 fatty acids were identified in this study. During the oxidation of green coffee oil, the ratio of saturated fatty acids to unsaturated fatty acids rose from 1.14 to 1.49. High performance liquid chromatography was used to determine diterpenoids and tocopherol in green coffee oil. The initial content of cafestol and kahweol was 21.01±0.31 mg/g and 23.44±0.52 mg/g, respectively, which increased to 8.21±0.10 mg/g and 8.99±0.02 mg/g after 24 days of oxidation, and then the content tended to be stable. This experiment qualified α, δ and γ-tocopherols. The content of total tocopherols increased from the initial 49.75±0.88 mg/100 g to a maximum value of 53.70±1.72 mg/100 g after 18 days of oxidation, and dropped to 34.58±0.05 mg/100 g at the end of oxidation. Fourier transform infrared spectroscopy (FTIR) was used to analyze the oxidation process of green coffee oil from the perspective of characteristic functional groups. The oil had characteristic absorption peaks at 3008, 2927, 2854, 1745, 1461, 1375, 1238, 1164 and 721 cm-1. Raman spectroscopy was used to characterize the oxidative deterioration of green coffee oil during accelerated storage, and the peak intensity in the 1000-1800 cm-1 band had a significant weakening trend. This study showed that the green coffee oil undergone a significant oxidation reaction during the thermally induced storage process, which can provide a theoretical reference for improving the storage stability of green coffee oil.

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    Mitigation Effect of Nicotinamide on Manganese Toxicity in Sugarcane
    QIN Mei, XIAO Jinglin, WANG Xiaoxia, LING Guizhi, TANG Xinlian, LI Xiaofeng
    2021, 42 (11):  3339-3344.  doi: 10.3969/j.issn.1000-2561.2021.11.036
    Abstract ( 47 )   HTML ( 0 )   PDF (2181KB) ( 40 )  

    This study revealed the secretion of nicotinamide from sugarcane roots under the stress of manganese toxicity and its role, and provided a basis for solving the problem of manganese toxicity in sugarcane. The liquid-mass spectrometry was used to isolate and identify nicotinamide in sugarcane exudates. The effects of nicotinamide on root elongation, callose and reactive oxygen species accumulation, and related enzyme activity of sugarcane induced by manganese toxicity were studied by hydroponic experiments. There were nicotinamide mass spectrum peaks in sugarcane root exudates, and the nicotinamide signal was stronger under manganese stress. Under the stress, the root elongation of sugarcane was blocked and the root activity decreased, while the root tip accumulated callose, the contents of hydrogen peroxide, reactive oxygen species and malondialdehyde and the activity of superoxide dismutase, oxidase and ascorbate oxidase in the roots were significantly increased. Nicotinamide added to culture medium under manganese stress significantly reduced or eliminated the above effects of manganese. It can be seen that excessive manganese induces the secretion of nicotinamide from sugarcane roots, and nicotinamide significantly inhibits the damage of excessive manganese to sugarcane growth and peroxide stress.

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    Agricultural Ecology & Environmental Protection
    GEE-based Extraction of Rubber Forest Distribution in Main Producing Areas of Southeast Asia
    LI Weiguang, ZHANG Jinghong, LIU Shaojun, CHEN Xiaomin, ZOU Haiping, BAI Rui, LYU Run
    2021, 42 (11):  3345-3350.  doi: 10.3969/j.issn.1000-2561.2021.11.037
    Abstract ( 90 )   HTML ( 3 )   PDF (3033KB) ( 61 )  

    In order to monitor the growth of rubber forest in the main rubber foresttree producing areas of the world by remote sensing, we carried out the remote sensing extraction of rubber forest distribution based on Google Earth engine (GEE) in Thailand, Malaysia and Indonesia, which are the three largest rubber producing countries in the world. The typical sample areas were selected through visual interpretation, and the classification regression tree CART classification model was established based on the multi-band spectral albedo of Landsat 7 and the vegetation phenological characteristics reflected by MODIS NDVI. The overall classification accuracy of the model was 95.8%, the Kappa coefficient was 0.94, the producer accuracy was 94.8%, and the user accuracy was 88.2%, reaching a high level. The extraction results show that rubber plantations are concentrated in central and southern peninsula of Thailand, the eastern and southern parts of Malay Peninsula and Sumatra Island, while rubber plantations are relatively sparse in northern Thailand, Kalimantan Island and other islands.

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    Mapping Land Use in Hainan Island Based on Google Earth Engine and Landsat Time Series Data
    DAI Shengpei, YI Xiaoping, LUO Hongxia, LI Hailiang, LI Maofen, ZHENG Qian, HU Yingying
    2021, 42 (11):  3351-3357.  doi: 10.3969/j.issn.1000-2561.2021.11.038
    Abstract ( 129 )   HTML ( 6 )   PDF (13356KB) ( 57 )  

    Land use/cover change (LUCC) is one of the core contents of global change research. Land use remote sensing monitoring is an important technical for land use change research, especially the emergence of high-resolution remote sensing technology and Google Earth Engine (GEE) cloud computing platform, which provides a new way and method for obtaining land use spatial information. Based on the Landsat-8 OLI time series data provided by GEE cloud platform, the random forest (RF) and support vector machines (SVM) classification algorithm was used to mapping land use in Hainan Island. The results show that both RF and SVM algorithms have higher classification accuracy for water and building land, and have lower accuracy for cultivated land, garden land and forest land. Compared with SVM method, RF classification method could identify all kinds of land features more accurately and is more suitable for the study of land use classification in Hainan Island. The largest proportion of forest land (including natural forest, rubber forest, etc.) in Hainan Island is mainly distributed in the central part of Hainan Island. The area of cultivated land and garden land are distributed alternately in most areas of Hainan Island. The area of water body and construction land is small, which are scattered in Hainan Island, mainly in coastal areas. GEE platform is an useful tool for land use classification and remote sensing dynamic monitoring in large areas.

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    High-throughput Sequencing Analysis of Fungal Diversity in Agarwood Wound Locations
    SONG Jie, ZHANG Ningnan, ZHANG Zhonghui, ZHOU Zaizhi, LIANG Junfeng, LU Junkun
    2021, 42 (11):  3358-3368.  doi: 10.3969/j.issn.1000-2561.2021.11.039
    Abstract ( 45 )   HTML ( 0 )   PDF (2243KB) ( 48 )  

    Aquilaria sinensis (Lour.) Spreng, an economic plant in Guangdong, was selected as the object of this study. Using the high-throughput sequencing method, we analyzed the community structure and distribution of fungi in agarwood wound locations of four agarwood varieties in Maoming and Dongguan, China. Combining the agarwood formation characteristics of different varieties, fungal groups were further investigated which were significantly related to the agarwood formation. Under the same habitat condition, fungi community structure at different height sampling sites in the same varieties were remarkably similar, despite the different fungi abundance. The fungal community composition were significantly different in the same varieties under different habitats, and the difference of habitat may be one of the main factors leading to the difference of fungal community structure. There were significant differences in the fungal community structure among different varieties under the same habitat condition. Different agarwood varieties may be one of the main factors leading to the difference of fungal community structure. The unique fungi with high abundance maybe result in special feature of agarwood formation. Fusarium spp. and Hypomontagnella spp., which are widely distributed with high abundance in the easy agarwood formation varieties, are the best illustrations for this conclusion.

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    Prediction of Potential Distribution Area of Etlingera littoralis (J. Koenig) Giseke in China under Climate Change Based on MaxEnt
    TANG Mengshi, YUAN Shuna, YU Wengang, SHI Qi, HOU Tianze, WU Junnan, LIU Ziyu
    2021, 42 (11):  3369-3375.  doi: 10.3969/j.issn.1000-2561.2021.11.040
    Abstract ( 79 )   HTML ( 1 )   PDF (1916KB) ( 81 )  

    Zingiberaceae Etlingera littoralis (J. Koenig) Giseke is a endangered perennial herb with high medicinal value,the natural distribution in China is Hainan. Predicting the potential suitable areas and key environmental factors are critical to the conservation of E. littoralis. Based on the data of 45 current distribution points of E. littoralis in global and 20 environmental factors the key environmental factors and the potential suitable areas under current and future two scenarios (2050 s RCP 2.6, 2050 s RCP 8.5) in China were dtudied using the MaxEnt and ArcGIS, and the potential distribution changes of E. littoralis in China was analyzed, using the SDM toolbox of ArcGIS software, Under the present climatic conditions, E.littoralis is mainly distributed from North latitude 18° to 32°, and East longitude from 27° to 122°, with a total suitable area about 1.24×106 km2. The current potential distribution areas are Hainan, Guizhou, Fujian, Guangdong, Guangxi, Yunnan, Sichuan, Chongqing, Tibet, Hunan, Hubei, Taiwan. Dominant environmental factors affecting the distribution of E. littorali. were precipitation of the wettest month, precipitation of the warmest quarter, temperature annual range, mean temperature of the coldest month, altitude and mean temperature of the warmest quarter, with a cumulative contribution rate of 87%. Under future climate scenarios of RCP2.6 and RCP8.5 by the 2050 s, the loss of potential suitable areas of E. littoralis would be up to 95%, and the potential distribution areas would be limited to Yunnan, Sichuan, Tibet, Guizhou and Taiwan. The increased areas are in southeastern Tibet and south-central Sichuan. The centers of total suitable areas and most suitable areas would be moved towards northwest.

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