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25 September 2021, Volume 42 Issue 9
Omics & Biotechnology
 Expression and Function of an ACC Oxidase Gene (HbACO7) from the Bark of Hevea brasiliensis WANG Yiwei, FENG Renjun, HUANG Yacheng, LIU Xiaodong, FANG Yongjun, LUO Hongli, TANG Chaorong 2021, 42 (9):  2435-2442.  doi: 10.3969/j.issn.1000-2561.2021.09.001 Abstract ( 115 )   HTML ( 174 )   PDF (3823KB) ( 78 )   Natural rubber is an important industrial raw material, mainly harvested from the rubber-producing laticifers residing in the bark of rubber tree (Hevea brasiliensis). Previous studies reveal that ethylene promotes both latex flow and regeneration, and the application of ethrel (an ethylene generator) or ethylene on bark could stimulate latex yield. In this study, based on the Hevea genome and transcriptome database we previously constructed, eight HbACO genes encoding the Hevea ACC oxidase (ACO), a key enzyme in ethylene biosynthesis, were cloned and examined for their expression patterns in seven Hevea tissues. Although the HbACO genes exhibited varying degrees of redundant expression in the seven tissues examined, each retained a distinct pattern of tissue expression. Of the eight HbACOs, HbACO7 showed the highest expression in the bark. The expressions of HbACO7 fluctuated greatly with the change of tapping months, showing the highest level in August. The prokaryotic expression vector HbACO7 was successfully constructed, and the expression of HbACO7 protein was induced in E. coli BL21. The purified HbACO7 recombinant protein successfully catalyzed ethylene synthesis in vitro, indicating its functionality as an active ACO enzyme. This study would lay a foundation for further research on the regulatory mechanism of ethylene biosynthesis in the bark of rubber tree.
 Identification and Expression Analysis of profilin Gene Family in Hevea brasiliensis DENG Zhi, LI Dejun 2021, 42 (9):  2443-2450.  doi: 10.3969/j.issn.1000-2561.2021.09.002 Abstract ( 70 )   HTML ( 168 )   PDF (2709KB) ( 81 )   Actin cytoskeleton might play an important role in laticifer wound plugging of Hevea brasiliensis. Although profilin is a vital regulator in actin dynamics, there is still no systematic study on profilin gene family in Hevea brasiliensis. In this study, six profilin genes were identified from the genome and transcriptome of Hevea brasiliensis. The six genes were analyzed in details, including gene basic characteristics, conserved protein motifs, structure features, evolutionary relationships, and expression profiles. Gene structure analyses demonstrated that the six profilin genes contained three exons and two introns. Conserved domain analyses indicated that the six profilin proteins possessed unique motifs of profilin protein, KYMVIQGE and VIRGKKG motifs. Evolutionary analyses showed that Hevea profilins were not strictly divided into vegetative and reproductive subclasses. The main secondary structures of profilin proteins were random coil and tertiary structures consist of three α helices and seven β turns. Expression analyses showed that four profilin genes were highly expressed in latex, and regulated by latex flow and potassium iodide treatment, suggesting that profilin genes might be involved in latex flow. These results would lay a foundation for further elucidating profilin roles in laticifer wound plugging and latex flow of Hevea brasiliensis.
 Cloning and Expression Analysis of a β-cyanoalanine Synthase Gene HbCAS in Hevea brasiliensis ZHANG Yiwen, LIU Hui, FENG Chengtian, HU Yiyu, WANG Zhenhui, YUAN Kun 2021, 42 (9):  2451-2457.  doi: 10.3969/j.issn.1000-2561.2021.09.003 Abstract ( 63 )   HTML ( 165 )   PDF (13855KB) ( 68 )   β-cyanoalanine synthase (β-CAS), a key enzyme involved in cyanide detoxification in plants, plays an important role in regulating the growth and development and stress response. In this study, HbCAS was cloned from H. brasiliensis. The results indicated that HbCAS had an open reading frame (ORF) of 1113 bp, encoding 370 amino acids with a theoretical molecular weight 40.15 kDa and an isoelectric point of 8.90, belonging to the superfamily of tryptophan synthase beta. Quantitative real-time PCR analysis showed HbCAS was found to express in all tested tissues with the highest expression in latex. Compared with the healthy trees, HbCAS expression significantly decreased in the tapping panel dryness (TPD) infected trees. Hydrogen peroxide (H2O2) and various hormones of ethephon (ETH), Methyl jasmonate (MeJA), salicylic acid (SA) and abscisic acid (ABA) all regulated the expression of HbCAS. Meanwhile, HbCAS expression was regulated by diverse abiotic stresses of drought, low temperature, methyl viologen and high salt. These results suggest that HbCAS might play key roles in TPD onset, reactive oxygen species signaling, hormone regulating, as well as various abiotic stresses responses.
 Parameter Optimization and Accessory Improvement of GDS-80 Handheld Gene Gun for Rubber Tree Genetic Transformation FAN Jingzhang, $\boxed{\hbox{HUA Yuwei}}$ , FAN Yueting, XIN Shichao, DAI Xuemei, HUANG Tiandai, HUANG Huasun, LI Ji 2021, 42 (9):  2458-2467.  doi: 10.3969/j.issn.1000-2561.2021.09.004 Abstract ( 68 )   HTML ( 9 )   PDF (2288KB) ( 43 )   GDS-80 handheld gene gun is a gene delivery system launched by Wealtec Company in 2009, which is easy to operate and efficient. All the published researches on the transformation of Hevea brasiliensis by gene gun are based on desktop gene gun. In this paper, Coomassie Brilliant Blue was firstly used to bombard filter paper to screen out obviously not suitable parameters, and then the green fluorescent protein (GFP) gene was used as the reporter gene to bombard the somatic embryos and callus of H. brasiliensis, finally the green fluorescence was observed by fluorescence microscope to explore the suitable bombardment parameters for H. brasiliensis. The difference in fluorescent spot numbers calculated by Image J software and naked-eye and the difference between GDS-80 handheld gene gun and PDS-1000/He desktop gene gun was compared. The results showed that it was difficult to obtain good transformation efficiency by using original accessories for somatic embryos and callus of H. brasiliensis. In this paper, a filter screen with a diameter of 3cm (same as the bombardment range), the height of 2.5 cm and pore diameter of 60 mesh was designed. At the same time, a petri dish containing the experimental materials was improved. A circle with a diameter of 3cm was cut out in the center of the petri dish by a blade. The filter screen designed above was clamped on the circle with forwarding direction, and the embryos were put into the filter screen. When bombarding, the petri dish was put on the test tube rack, and the pressure would decompose from the mesh and the cavity at the bottom, and the micro bullet would completely bombard the embryos. The optimal parameters for embryos were as follows: bombardment pressure 60 psi, needle-shaped regulating valve 3 circles, and target spacing plate 6 cm. When the callus was bombarded, the material was placed in the center of a traditional petri dish and covered by the designed filter screen reversely. The optimal bombardment parameters for callus were as follows: bombardment pressure 50 psi, needle-shaped regulating valve 4 circles, and target spacing disc 6 cm. In this paper, Image J software was used to count fluorescent spots. The accuracy was equivalent to that counted by naked eyes, but it saved time. The transformation efficiency of the GDS-80 handheld gene gun was similar to that of the PDS-1000 / He desktop gene gun, but the GDS-80 handheld gene gun was 12 minutes faster than PDS-1000 / He desktop gene gun for one shot. The research results would provide an efficient gene gun transformation system for H. brasiliensis genetic transformation and a efficient software to count fluorescent spots.
 Analysis of the T-DNA Flanking Sequence and Event-specific Detection for Insect-resistant Transgenic Sugarcane BtG-2 FENG Cuilian, WAN Yue, FENG Xiaoyan, WANG Jungang, ZHAO Tingting, WANG Wenzhi, SHEN Linbo, ZHANG Shuzhen 2021, 42 (9):  2468-2477.  doi: 10.3969/j.issn.1000-2561.2021.09.005 Abstract ( 54 )   HTML ( 10 )   PDF (2448KB) ( 58 )   Sugarcane BtG-2 is an insect resistance transgenic sugarcane strain, developed by introducing the Cry1Ac- 2A-gna fusion gene into ‘ROC22’ with the Agrobacterium-mediated method. It has strong insect resistance and excellent agronomic traits. In order to clarify the molecular characteristics and detection of transgenic sugarcane BtG-2, and promote biological safety evaluation, the T2 generation of BtG-2 was selected, and the copy number of foreign genes in the transgenic sugarcane genome was detected by Southern hybridization. The flanking sequence of the insertion site of the foreign gene was isolated using the chromosome walking technology, and an efficient specific PCR detection method of the strain was established. The results showed that the foreign T-DNA insertion of BtG-2 strain was a single copy. After three times amplifications of thermal asymmetric interlaced PCR, 984 bp of the left flanking sequence and 705 bp of the right flanking sequence of the foreign gene T-DNA were obtained. According to the flanking sequences, three pairs of detection primers were designed respectively, then the event-specific PCR detection for transgenic sugarcane BtG-2 was established. The primer pairs with the highest amplification efficiency were LS011/LA451 and RS160/RA588, with 440 bp and 428 bp specific amplified fragments respectively. Among them, the pair of primers LS011/LA451 designed on the left side of T-DNA had high sensitivity and specificity for detection, and this method could detect the genetically modified ingredients in samples containing 0.1% genomic DNA of sugarcane BtG-2. This study completed the molecular characteristics and event-specific detection of the transgenic strain BtG-2, which provided a technical basis for the detection and identification of the transgenic sugarcane and its derivatives.
 Bioinformatics and Expression Analysis of SEPALLATA3 in Mango XIE Xiaojie, YU Haixia, FAN Zhiyi, HUANG Fang, LIU Yuan, MO Xiao, ZENG Xuemei, HE Xinhua, LUO Cong 2021, 42 (9):  2487-2493.  doi: 10.3969/j.issn.1000-2561.2021.09.007 Abstract ( 65 )   HTML ( 9 )   PDF (9577KB) ( 57 )   SEPALLATA3 (SEP3) belongs to MADS-box gene family and is related to the flowering time and floral organ development of plants. In this study, two MiSEP3s genes which named MiSEP3-1 and MiSEP3-2 were obtained from mango transcriptome data. Bioinformatics analysis showed that the genomic length of MiSEP3-1 and MiSEP3-2 was 4189 bp and 3721 bp, respectively. Both genes had the same length of open reading frame and encoded 244 amino acids, with molecular weights 59.29 kD and 59.28 kD, respectively. Furthermore, MiSEP3-1 and MiSEP3-2 contained typical MADS and K-box domains. Promoter sequences analysis showed that MiSEP3s promoters both contained photoresponse elements, hormone response elements, stress response elements and transcription factor binding sites, but there were differences in the types and number of regulatory elements. Expression analysis showed that MiSEP3s were lower expressed in stem, leaf and bud at the vegetative stage, but significantly continuously up-regulated expression with the development of the flower and reached the expression peak in the flower. This study would provide references for the function study of MiSEP3.
 Identification of mapkkk15 Mutant from Arabidopsis and Function Analysis to Abiotic Stress LIANG Qun, DENG Zhi, LEI Keyi, HUANG Huasun, AN Zewei, CHENG Han 2021, 42 (9):  2494-2500.  doi: 10.3969/j.issn.1000-2561.2021.09.008 Abstract ( 57 )   HTML ( 7 )   PDF (7756KB) ( 43 )   Abiotic stress severely affects the natural rubber yield in China, so it is necessary to clarify the resistant mechanism of rubber tree to improve natural rubber yield. In previous studies, we found that a MAPPKKK was induced by low temperature in rubber tree. Sequence alignment showed that HbMAPKKK was homologous with MAPKKK15 from Arabidopsis. However, the function of AtMAPKKK15 is unclear. Function of AtMAPKKK15 was identified in responding to stress and provide theoretical basis for further elucidating the function of MAPKKK in rubber tree. The homozygous T-DNA insertion mutants of AtMAPKKK15 were identified at DNA and transcription level, and evaluated resistance under low temperature and drought treatments. The results showed that the expression of AtMAPKKK15 was inhibited by low temperature. Two homozygous null mutants of MAPKKK15 were obtained from Arabidopsis. The mapkkk15 mutant improved low temperature tolerance by increasing survival and decreasing electrolyte leakage compared with the wild-type. However, the dehydration ration of mutant leaves increased with the extension of in vitro time. The results indicate that MAPKKK15 negatively regulated tolerance to low temperature and postively regulated resisitance to drought.
 Analysis of HSP70 Gene Family and Adaptive Evolution in Calanthe (Orchidaceae) ZHU Yating, YU Xia, LI Xiaoping, LIU Zhongjian, WU Shasha, LAN Siren, ZHAI Junwen 2021, 42 (9):  2501-2511.  doi: 10.3969/j.issn.1000-2561. 2021.09.009 Abstract ( 56 )   HTML ( 8 )   PDF (5644KB) ( 27 )   Heat shock proteins (HSPs) emerge quickly when organisms are stimulated, especially by high temperature, which help the denatured protein return to its normal folding state so as to maintain its normal growth. Calanthe R. Br. (Orchidaceae) is an ideal group of plant to study the HSP gene family as they present an altitude distribution range from 0 m up to 3 500 m. In this study, HSP70s genes of seven Calanthe plants were identified through transcriptome data; consequently physical and chemical parameters, gene family tags, conserved domains and selection pressure of the each gene were analyzed. A total of 47 HSP70 gene sequences were confirmed in the seven plants, and the gene numbers increased in descending order along with the altitude. Among them, there were four sequences in C. striata and C. tricarinata, five in C. triplicata, seven in C. odora, eight in C. sylvatica, nine in C. argenteo-striata and ten in C. sinica. HSP70 genes had three typical domains and tags, and the number of N-terminal motifs was the largest. The selection pressure Ka/Ks<1, which revealed the gene family was conservative, subject to purification selection. Phylogenetic analysis showed that HSP70s were clustered into 6 groups. The genes from the same subcells were clustered into one group, which inferred that the HSP70 from the same organelle had similar functions. The results of this study would provide a new perspective for the study of the function and adaptive evolution of HSP family genes in the genus Calanthe, and provide suggestions for the adaptive breeding.
 Identification and Gene Mapping of a White Leaf and White Panicle Mutant wlwp7 in Rice LI Zheli, ZHANG Linjin, TAN Ying, WU Zhaohui, XIAO Feng, SU Yuting, TAN Yanning, XIAO Yinghui 2021, 42 (9):  2512-2517.  doi: 10.3969/j.issn.1000-2561.2021.09.010 Abstract ( 44 )   HTML ( 7 )   PDF (6268KB) ( 35 )   Rice mutants varied both in leaf color and panicle color are valuable genetic resources for revealing the link of chlorophyll biosynthesis between different organs. Here, a white leaf and white panicle 7 mutant (wlwp7) was identified and analyzed from morphological, physiological and genetic levels. It showed that the seedling plants of wlwp7 was sensitive to low temperature with white leaves at 20 ℃. While, it became green at a high temperature of 30 ℃. The paddy plants of wlwp7 was observed to present white hulls at heading. The chlorophyll content in the hulls of wlwp7 was reduced to 40.73% of its wild type T98B. Except for the seed-setting rate (with a decrease of 6.28%), other yield traits remained unaffected. Further genetic analysis confirmed there was no recombinant plant with a phenotype of white leaf/green panicle or green leaf/white panicle in two F2 groups derived from wlwp7/T98B and T98B/wlwp7. Moreover, it found the theoretical segregation ratio of mutant plants to wild-type plants was consistent with 1:3 by chi square test, supporting wlwp7 would be controlled via one recessive nuclear gene. Finally, wlwp7 was mapped within 280Kb on chromosome 3 using BSA strategy, and there is no reported gene controlling white leaf and white panicle in this area. This study reveals that wlwp7 functions in regulating the chlorophyll bio-synthesis in leaves and panicles, and the gene mapping results provides a basis for the cloning of wlwp7.
Germplasm Resources, Genetics & Breeding
 Phenotypic Diversity of 45 Cultivars of Cymbidium tortisepalum LU Pengcheng, ZHENG Yan, ZHOU Xiaoqin, XU Zhe, AI Ye, ZHOU Yuzhen, ZHU Weiyin, PENG Donghui 2021, 42 (9):  2518-2525.  doi: 10.3969/j.issn.1000-2561.2021.09.011 Abstract ( 68 )   HTML ( 9 )   PDF (2663KB) ( 45 )   Forty-five main cultivars of Cymbidium tortisepalum were collected and variable coefficient analysis principal component analysis, correlation analysis, cluster analysis were conducted on 29 phenotypic traits. The genetic relationship and genetic difference between C. tortisepalum cultivars were explored in order to provide scientific reference for genetic breeding of C. tortisepalum germplasm resources. The results showed that the 45 cultivars had rich genetic diversity with the variation range of 10.1%~133.1%. Principal component analysis showed that 7 main components with characteristic values greater than 1 were obtained, and the cumulative variance contribution rate was as high as 75.461%, among which the first and second principal components mainly represented the comprehensive traits of flower parts. The results of correlation analysis showed that most traits were correlated, among which 93 traits were significantly correlated, and 65 traits were significantly correlated. The results of cluster analysis showed that 45 cultivars of C. tortisepalum were divided into 3 groups in Euclidian genetic distance 15, and the same species had a tendency of clustering together.
 Study on Genetic Diversity of Cymbidium Ensifolium Germplasm Based on ISSR Marker WANG Hongli, BU Chaoyang, ZENG Yanhua, LONG Qiangyu 2021, 42 (9):  2526-2534.  doi: 10.3969/j.issn.1000-2561.2021.09.012 Abstract ( 51 )   HTML ( 9 )   PDF (3834KB) ( 43 )   To reveal the genetic relationship between C. ensifolium germplasm, promote the effective protection and utilization of C. ensifolium germplasm resources. In this study, ISSR markers were used to analyze 39 C. ensifolium varieties originating from various parts of China, and cluster analysis was performed using UPGMA method. The results showed that 6 ISSR primers amplified the genomic DNA of 39 C. ensifolium varieties, and a total of 64 clear bands were amplified, including 57 polymorphic bands. The average number of bands detected per primer was 11, polymorphic bands were 10 and the polymorphic ratio was 89.88%. Cluster analysis by UPGMA method showed that the genetic similarity coefficient of the test materials was between 0.500-0.953, and the test materials were divided into 6 clusters, indicating that ISSR markers are rich in polymorphism in C. ensifolium varieties, which can Reveal the relationship between C. ensifolium varieties. The results of this study can provide a basis for the identification and cross breeding of C. ensifolium germplasm resources.
 Phenotypic Variation and Resource Evaluation of Paris polyphylla var. yunnanensis and Its Relative Species WANG Yuanzhong, SHEN Tao, ZHANG Jinyu 2021, 42 (9):  2535-2541.  doi: 10.3969/j.issn.1000-2561.2021.09.013 Abstract ( 62 )   HTML ( 7 )   PDF (1741KB) ( 52 )   In the present study, the phenotypic characteristics of Paris polyphylla var. yunnanensis and its relative species were investigated and analyzed. The variations of the phenotypic traits were studied through the investigation of traits and multiple statistical analyses. The plant height, stem diameter, leaf shape index, leaf width, petiole length, and traits had high values of interspecies variation coefficient (CV > 40.00%). Meanwhile, the traits of flowers, such as calyx length and calyx width, had lower CV value (< 25.00%). Genetic diversity indexes (H') was ranged from 2.03 to 0.82. Paris polyphylla var. yunnanensis and P. polyphylla had the highest mean value of H' in the five species. The principal component analysis combined with Partial least squares-discrimination analysis showed the phenotype of leaf and flower were the key traits for discrimination between P. polyphylla and Paris polyphylla var. yunnanensis. Compared P. vietnamensis and P. cronquistii var. xichouensis with the other three species, plant height, stem diameter, leaf width, rhizome length, rhizome diameter, and rhizome fresh weight were different. The samples of P. vietnamensis, and P. cronquistii var. xichouensi were hard to distinguish from each other. Correlation analysis found that overground traits were significantly positively correlated with underground traits (P < 0.05 or P < 0.01). Combined with VIP analysis, it could be found that rhizome diameter, rhizome length, petiole length, leaf length, leaf width, pedicel length, plant height, and petal length were key traits for selecting germplasm resources of high-yielding medicinal Paris species.
 Russula indocatillus, a New Record Species in China CHEN Bin, SONG Jie, WANG Qian, LIANG Junfeng 2021, 42 (9):  2542-2548.  doi: 10.3969/j.issn.1000-2561.2021.09.014 Abstract ( 77 )   HTML ( 7 )   PDF (1798KB) ( 42 )   Russula indocatillus was reported as new species to China. A detailed morphological description, illustrations and phylogeny are provided, and comparisons with related species are made. It is morphologically characterized by a brownish orange to yellow ochre pileus center with butter yellow to pale yellow margin, white to cream spore print, subglobose to broadly ellipsoid to ellipsoid basidiospores with bluntly conical to subcylindrical isolated warts, always one-celled pileocystidia, and short, slender, furcated and septated terminal elements of pileipellis. The combination of detailed morphological features and phylogenetic analysis based on ITS-nrLSU-RPB2 sequences dataset indicated that the species belonged to Russula subg. Heterphyllidia sect. Ingratae.
Plant Cultivation, Physiology & Biochemistry
 Rubber Yield and Latex Mineral Nutrients Variation under Different Nitrogen Application Rates WANG Dapeng, WU Min, WEI Jiashao, XUE Xinxin, MA Zhaoma, WANG Guihua, CHA Zhengzao 2021, 42 (9):  2549-2554.  doi: 10.3969/j.issn.1000-2561.2021.09.015 Abstract ( 61 )   HTML ( 7 )   PDF (1777KB) ( 49 )   A field experiment was conducted to study the rubber yield and latex mineral nutrients variation under 4 nitrogen (N) levels(0; Low N 100 kg/hm2; Medium N 230 kg/hm2; High N 400 kg/hm2). Together with phosphate and potash fertilizer, the dry rubber yield of different N treatments was 4.65-6.37 kg, and the dry rubber yield was significantly increased by high N application(P<0.05). With the increase of N application rate, the dry rubber yield increased. The dry rubber content(30.84%-33.96%) and total solids(34.80%-37.92%) both tended to decrease, but no significant difference was found among different treatments. The contents of N(7.77-8.49 g/kg) and K(6.42-7.24 g/kg) in latex tended to increase, while little effect occurred on the contents of P(3.35-3.51 g/kg) and Mg(1.99-2.23 g/kg). With the presence of N application, the content of N, P and K in latex was positively correlated with the dry rubber yield. N application increased the amount of N, K and Mg removed by latex tapping, and tended to be enlarged with the increase of N application. In conclusion, application of N fertilizer contributes to the dry rubber yield increase which is also at the expense of nutrient loss in latex.
 Comparison of Change Rules of Fruit Growth and Quality of Different Early Season Longan Varieties (Lines) PENG Jiechun, HE Jianan, WU Yu, DENG Yingyi, PAN Jiechun, XU Jiongzhi 2021, 42 (9):  2563-2570.  doi: 10.3969/j.issn.1000-2561.2021.09.017 Abstract ( 65 )   HTML ( 7 )   PDF (2414KB) ( 38 )   In this study, five early season longan varieties (lines) of ‘Guifengzao’ ‘Guiguanzao’ ‘Guilong No.1’ ‘Gushan No.2’ and ‘Shixia’ were taken as study materials to study the change rules of their fruit growth and quality. During fruit development, the transverse and longitudinal diameter, single fruit weight, edible rate, a * and c* values of color difference of the five early season longan varieties (lines) increased or fluctuated. Color difference L* and b* values increased rapidly and then slowly fluctuated. Soluble solids and vitamin c of most varieties increased rapidly and then decreased slowly. hº value of color difference and titratable acid of most varieties decreased gradually or fluctuated. Soluble sugar increased gradually before ripening and fluctuated in the later stage. Soluble protein fluctuated in the form of “M” or “W”. ‘Guifengzao’ and ‘Guiguanzao’ entered the mature stage one week earlier than ‘Shixia’. ‘Guilong No.1’ had the slowest sugar withdrawal. ‘Guifengzao’ had the largest transverse diameter, single fruit weight and soluble protein. ‘Guiguanzao’ had the largest longitudinal diameter. ‘Guilong No.1’ had the highest soluble solids, vitamin C and soluble sugar contents and the lowest titratable acid content. ‘Shixia’ had the highest edible rate. Comprehensive evaluation of fruit quality at mature stage, ‘Guifengzao’ was the best, followed by ‘Shixia’ ‘Guilong No.1’, ‘Gushan No.2’ and ‘Guiguanzao’.
 Effect of Arecanut and Pandan Intercropping on Soil Nutrient and Nutrient Absorption TANG Jinxuan, QIN Xiaowei, YU Huan, JI Xunzhi, DENG Wenming, ZHANG Ang, ZONG Ying 2021, 42 (9):  2571-2578.  doi: 10.3969/j.issn.1000-2561.2021.09.018 Abstract ( 46 )   HTML ( 7 )   PDF (3570KB) ( 43 )   In order to evaluate the effect of arecanut and pandan intercropping on soil nutrient and nutrient absorption, the soil physical and chemical properties, and nutrient absorption of arecanut and pandan were studied in arecanut and pandan monoculture and intercropping system with pot experiment. After arecanut intercropped with pandan, the soil EC value and alkali hydrolyzable nitrogen content of arecanut significantly decreased by 47.15% and 25.74%, and the soil available phosphorus content significantly increased by 32.32%. Available nitrogen was significantly negatively correlated with catalase and peroxidase, and available phosphorus was positively correlated with total root length, total root surface area, root volume, root number, urease and acid phosphatase. There was a very significant positive correlation between available phosphorus and catalase and peroxidase. The concentration of nitrogen in the aboveground part of arecanut and the concentration of phosphorus and potassium in the aboveground part of pandan increased significantly by 41.56%, 26.56% and 25.69%. The content of nitrogen, phosphorus and potassium in the roots and aboveground parts of arecanut and pandan was higher than those in monoculture, and the content of phosphorus and potassium in root of arecanut and the content of potassium in root of pandan increased significantly. Meanwhile, after intercropping, the absorption efficiency of nitrogen was higher than those in monoculture, and the absorption efficiency of phosphorus and potassium of pandan was slightly higher than that of arecanut. The absorption efficiency of phosphorus and potassium was significantly positively correlated with total root length, total surface area, root volume, and root number. The absorption efficiency of nitrogen had no significant correlation with root morphology. To sum up, after intercropping, the content of soil available phosphorus increased, and promoted the absorption of nitrogen, phosphorus and potassium by betel nut and pandan. The increase of soil available phosphorus content and the improvement of nutrient absorption efficiency are significantly positively correlated with related to the root morphology.
 Diurnal Changes of Photosynthetic Characteristics of 3 Giant Alcantareas Exposure to Summer Sunlight and Their Relationship with Environmental Factors LI Ping, ZHUANG Qiuyi 2021, 42 (9):  2579-2586.  doi: 10.3969/j.issn.1000-2561.2021.09.019 Abstract ( 41 )   HTML ( 4 )   PDF (1708KB) ( 29 )   Species of Alcantarea (Brommeliaceae) was introduced to China quite recently. Different from the most commercial bromeliads available from the market which are low tolerant of strong light, most species of Alcantarea prefer higher light intensity. In additional, most species in this genus are large in size, as well as the high ornamental feature both for foliage and flower, which make them quite suitable to the outdoor gardens. Meanwhile, different species and cultivars have different requirements on light, especially their tolerance to high light intensity at hot summer is not clear. In order to study on the adaptability of different Alcantarea taxa exposure to full sun outdoor at summer time, the diurnal changes of photosynthetic characteristics of three large-sized Alcantarea in mature size were measured by Li-6400 photosynthetic analyzer, and the correlation between photosynthetic physiological indexes and environmental factors was also analyzed. The results showed that the net photosynthetic rate (Pn) of the three species was high, with the highest values between 8.3-11μmol·m-2s-1. The diurnal variation curves of the three species indicate double-peak curves, and reached to the first peak at 8:00, reaches the bottom at 11:00. The diurnal variation curve of Pn of Alcantarea imperialis (red leaf form) was relatively gentle, the valley bottom was high and shallow, the Pn at noon was significantly higher than the other two species (P<0.01), which showing the strongest tolerance to intensive light and high temperature, it was proved that the decrease of Pn from 9:00 to 13:00 was caused by stomatal limitation, with Pn and the intercellular CO2 concentration (Ci) decreased at the same time, The bottom of the variation curves of A. ‘Grace’ and A. glaziouana was deeper and sharper. The secondary peak of A. ‘Grace’ appeared at 13:00, which was relatively low. The variate curve of Pn of A. glaziouana varied extremely strong, with higher Pn in the morning and later afternoon when the light and temperature were relatively low. It was proved that the decrease of Pn from 9:00 am to 13:00 for A. ‘Grace’ and A. glaziouana was caused by none stomatal limitation. In summer, stomatal conductance (Gs) was the main photosynthetic physiological parameter which affecting the Pn of three Alcantareas greatly with extremely significant difference at 0.01 standard. However, the correlation coefficient between other photosynthetic physiological parameters and environmental factors were low, which may be caused by the interaction among various factors. Among the three species, A. imperialis (red leaf form) was more durable to the outdoor full sunlight, with the characteristic of higher Pn at noon and higher transpiration rate (Tr) to dissipate the heat on the leaves, plants grow well. While A. glaziouana and A. ‘Grace’ were more sensitive to the intensive light at hot summer, with leaves of A. glaziouana turned yellow and new leaves of A. ‘Grace’ in the center of the rosette became compact abnormally. As a result, it is recommended to plant the latter two at the site with partial shade especially at noon. This study provides a theoretical supporting to plant different Alcantareas at the suitable site.
 Changes of Physiological Indexes and Endogenous Hormone Content of Watercore Pineapple Fruit YAO Yanli, FU Qiong, ZHOU Di, ZHU Zhuying, YANG Yumei, ZHANG Xiumei 2021, 42 (9):  2587-2593.  doi: 10.3969/j.issn.1000-2561.2021.09.020 Abstract ( 55 )   HTML ( 7 )   PDF (1775KB) ( 34 )   In order to understand the variation characteristics of physiological indexes and endogenous hormone content of watercore pineapple fruit, the main pineapple cultivar “Bali” was used as the material in this study, and the content of the endogenous hormones, monosaccharides, soluble solids, titratable acids, vitamin C (Vc), malondialdehyde (MDA ), the activity of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) was determined by liquid chromatography-mass spectrometry (LC-MS), high-performance liquid chromatography (HPLC) and so on. The correlation among the degree of watercore, endogenous hormone and antioxidant enzyme activity was analyzed. The results showed that the content of soluble solids, Vc and sugar, the activity of SOD and POD and the content of ZT, JA and ABA decreased significantly in different degrees of watercore, and the decreasing extent increased with the deepening of disease degree. The activity of CAT, the content of MDA and SA in different degrees of watercore were significantly higher than those in the control. Titratable acid content, fructose and glucose content in mild watercore fruit increased significantly compared with the control, and decreased significantly in moderate watercore fruit, while the variation trend of 1-aminocyclopropane carboxylic acid (ACC) content was just opposite to them. The correlation analysis showed that the degree of watercore was negatively correlated with ZT, JA and ABA contents, the correlation coefficients were-0.98, -0.98 and-0.94, respectively, and positively correlated with SA contents, the correlation Coefficient was 0.93.
 Effects of Organic Fertilizer Replacing Part of Chemical Fertilizer on Yield, Quality and Soil Environment with ‘Guitiannuo 525’ WANG Jiping, HE Tieguang, ZHANG Yu, XU Liang, SU Tianing, LI Jiawei, QIN Bo 2021, 42 (9):  2594-2600.  doi: 10.3969/j.issn.1000-2561.2021.09.021 Abstract ( 50 )   HTML ( 6 )   PDF (1588KB) ( 40 )   In this study, the effects of different organic fertilizers on corn yield quality and soil environment were studied with no fertilizer (T1), chemical fertilizers (T2) and different organic fertilizers replacing partial chemical fertilizers (T3 and T4) by field experiments. The agronomic traits of maize plants under fertilizer treatments were better than those under T1. Compared with T2, the growth of maize plants was promoted under organic fertilizer treatment (T3 and T4). The stem diameter and leaf length of maize plants under T3 treatment were significantly increased compared with T2 (P<0.05, the same below) by 11.94% and 4.53%, respectively. Compared with the control, the maize yield could be significantly increased with 14.27%-17.17% under fertilizer treatments, but it was insignificant (P>0.05, the same below) between T2-T4. Compared with T2, the ear length of T3 was significantly increased 7.12%, the protein and fat content under T4 were significantly increased with 7.21% compare with T3, and the soluble sugar content under T3 was significantly increased with 61.54% and 77.97% compare with that of T1 and T4, and the organic matter content in soil were increased by 64.52% and 27.38% under T3 and T4, respectively. In the correlation analysis of all indexes, the content of protein and fat in kernel was significantly positively correlated with the content of total nitrogen (r = 0.868, P <0.01), which indicated that the accumulation of protein, fat and other nutrients in kernels could be promoted by improving the absorption of nitrogen. In conclusion, the growth of corn plants, ear quality and content of soil organic matter were be improved under organic fertilizers replacing partial chemical fertilizers, which could be used as the recommended fertilization strategy for improving the quality and yield of spring maize under regional fertilizer application reduction.
 Yield, Quality, Nutrient Use Efficiency and Economic Profit of Tea under Different Fertilizer Reduction Techniques in Tea Garden LIU Shengchuan, LIN Kaiqin, LIANG Sihui, HE Ping, WEI Jie, YAN Donghai, XU Lin, HE Guoju, ZHOU Yufeng 2021, 42 (9):  2601-2609.  doi: 10.3969/j.issn.1000-2561.2021.09.022 Abstract ( 58 )   HTML ( 8 )   PDF (1950KB) ( 51 )   To provide valuable resources and techniques for saving fertilizer and improving fertilizer efficiency in tea garden, a tea garden planted with 9-year-old clonal cultivar ‘Fudingdabaicha’, located in northeast Guizhou Province, was selected to conduct field tests. We performed the analysis of the effects of five treatments on tea yield, quality, nutrient use efficiency and economic profit. The five treatments were 1) the control (CK), no fertilizer, 2) conventional fertilization (CF), 3) treatment 1, 2 and 3 (T1, T2, T3). 32.1%, 33.8% and 46.0% chemical fertilizer was reduced in T1, T2 and T3 compared with CF, respectively. The annual yield of dry tea from T1, T2 and T3 was 3524.1, 3644.4 and 3835.7 kg/hm 2, respectively, which was significantly higher than that of CF (3127.3 kg/hm2 ), while the value in T1, T2, T3 and CF was significantly higher than that of CK (2172.6 kg/hm2). The lowest the ratio of tea polyphenols to free amino acids (TP/AA) in each season among five treatments was observed in T1. No significant difference for TP/AA were observed among CF, T1 and T2 in autumn. There were no significant difference of TP/AA among CF, T2 and T3 in spring and summer. In general, the annual nitrogen (N), phosphorus (P) and potassium (K) uptake amount and use efficiency was higher in T1, T2 and T3 than in CF, the best effect was observed in T3. The annual net income of each fertilization treatment was significantly higher than that of CK (36 900 yuan/hm2). Compared with CF, the annual net income could be increased by 14 800, 13 900 and 15 200 yuan/hm2, respectively. Our data showed that fertilizer furrow application is better than broadcast application in tea garden, and indicated that T1 and T3 contributed more to saving fertilizer and improving fertilizer efficiency compared to CF, while T3 was better. Our results suggested that the proportion of N, P and K should be adjusted, and the content of organic fertilizer and organic matter should be increased in tea special fertilizer. Additionally, the replacement ratio of organic fertilizer should be increased in T3.
 Effects of Application of Photosynthetic Bacteria and Fertilizer on Growth and Nutrient Content in Camellia vietnamensis CAI Kailang, CHEN Weiyu, YAO Hairong, MAI Zhitong, LUO Jing, HONG Wenjun 2021, 42 (9):  2610-2615.  doi: 10.3969/j.issn.1000-2561.2021.09.023 Abstract ( 44 )   HTML ( 5 )   PDF (1409KB) ( 31 )   In order to provide scientific basis for fertilization and management of Camellia vietnamensis, the growth, photosynthesis and nutrient content effect of photosynthetic bacteria(PB) of two concentrations on Camellia vietnamensis (C. vietnamensis vs. ‘Haiyou 1’, ‘Haiyou 2’, ‘Haiyou 3’ and ‘Haiyou 4’) were studied. The net growth of most cultivars was the highest, except ‘Haiyou1’, with the dilution 30 times. The height and diameter growth of ‘Haiyou 3’ was higher than that of other varieties. The instantaneous net photosynthetic rate of the four varieties showed a trend of increase first then decrease under increasing the concentration of PB, and the performance of dilution 30 times was better than that of dilution 60 times. However, there were differences in the instantaneous transpiration rate of the four varieties under different treatment. The content of N and K in the leaves of ‘Haiyou 1’, ‘Haiyou 2’ and ‘Haiyou 4’ showed an upward trend, and the content of P showed a trend of increase first then decrease under increasing the concentration of PB, respectively. The correlation analysis results showed that the height was extremely significantly related to the instantaneous net photosynthetic rate and the instantaneous transpiration rate, and was significantly related to the P content. The N content was extremely significantly related to the K content. It indicates that PB could significantly promote the seedling growth and increase photosynthesis, leaf element content on C. vietnamensis.
 Impacts of Exogenous Nitric Oxide on Growth of Alfalfa Seedlings Exposed to Aluminum Stress ZHANG Yan, PENG Kaiyue, MA Xiangli, WANG Hui, LING Rugui, REN Jian 2021, 42 (9):  2616-2622.  doi: 10.3969/j.issn.1000-2561.2021.09.024 Abstract ( 37 )   HTML ( 6 )   PDF (3919KB) ( 29 )   The effects of exogenous nitric oxide (NO) application on the morphological and physiological characteristics of alfalfa (WL525HQ) seedlings under aluminum stress (0.1 mmol/L) were studied through hydroponics to reveal the physiological mechanism of NO alleviating aluminum toxicity of alfalfa. The results indicated that aluminum stress inhibited the growth of alfalfa seedlings shown by the significant decrease in plant height, root length, leaf area, aboveground and belowground biomass. Free proline content and superoxide dismutase (SOD) activity in the leaves were significantly reduced, whereas proline in the roots was significantly increased (P<0.05). Exogenous NO application affected its morphological and physiological responses to aluminum stress, and it was related to the concentration applied. Low concentration of exogenous NO alleviated the inhibiting effect of aluminum stress on the main root length. Medium concentration increased plant height, surface area and volume of root system under aluminum stress, which led to increases of above and below ground biomass. High concentration significantly increased free proline and SOD activity. In summary, exogenous NO alleviates the inhibitory effect of aluminum stress on the growth of alfalfa seedlings through processes like free proline accumulation and SOD, hence, contribute to enhancement of above and below ground biomass.
 Effect of Light Intensity and Water Content on the Seedling Growth and Physiological Characteristics of Carex diaoluoshanica YANG Hubiao, LIN Peng, LIU Guodao 2021, 42 (9):  2623-2630.  doi: 10.3969/j.issn.1000-2561.2021.09.025 Abstract ( 40 )   HTML ( 7 )   PDF (5474KB) ( 32 )   In order to explore the characteristics of the demand for light and soil moisture of Carex diaoluoshanica, the effects of light intensity and soil moisture on its growth were studied by controlling light intensity and soil moisture content. Low water content seriously inhibited the growth of C. diaoluoshanica, but the interaction of 40% light and 30% water showed relatively good performance, indicating that appropriate shading could reduce the damage caused by water deficit. Under the condition of full light, the net photosynthetic rate (Pn) decreased significantly, while the malondialdehyde (MDA) content increased significantly, and the growth was inhibited. The highest Pn occurred under 40% light intensity. Under the condition of sufficient water, there was no significant difference in chlorophyll content and net photosynthetic rate between 40% and 10% light treatments, but there were significant differences between them under full light and 70% light conditions, which fully indicated that C. diaoluoshanica was sensitive to high light and was not conducive to its growth. In conclusion, it is not suitable for low caopy density and low water content in the habitat selection for C. diaoluoshanica, and 40% light intensity and 70% soil moisture are the best environment for its growth.
 Causes of Protea magnifica Seed Dormancy and Methods for Breaking Dormancy WU Huaiyan, GUO Zhiming, SHAN Jinfeng, CHEN Jie, WU Xiangchong, LIU Zijia, ZHU Zunling 2021, 42 (9):  2631-2637.  doi: 10.3969/j.issn.1000-2561.2021.09.026 Abstract ( 44 )   HTML ( 4 )   PDF (1591KB) ( 26 )   The seeds of Protea magnifica have dormancy and it is difficult to germinate without any treatment. P. magnatica seeds were used as the experimental materials. The viability, germination rate and the effects of crude extracts from different parts of seeds on the germination of Chinese cabbage were measured, and seeds were treated with different methods (short-term high temperature + variable temperature stratification, acid etching + variable temperature stratification, gibberellin treatment + variable temperature stratification) to research the dormancy reason and release method of P. magnatica seeds. The results showed that: the viability of P. magnatica seeds was as high as 90.00%, the intact seeds without removing seed coat would not germinate within 30 days. The crude extract of seed coat not only inhibited the germination of Chinese cabbage seeds, but also significantly affected the growth of its roots and aboveground parts. The seed dormancy of P. magnatica may be a combinational dormancy caused by the mechanical barrier of seed coat and the endogenous inhibitor of seed coat. Different high temperature (40-120 ℃) treatment for 2 min + variable temperature stratification, different time (10-70 min) of 98% concentrated sulfuric acid etching + variable temperature stratification and different concentrations (0.3, 0.5, 0.7 mg/L) of gibberellin solution + variable temperature stratification could break the dormancy of the seeds, and improve the germination rate and germination potential of P. magnatica seeds. Among them, short-time high temperature treatment at 60 ℃, acid etching treatment for 30 min, and 0.7 mg/L gibberellin solution treatment were the best. Comprehensive comparison, acid etching for 30 minutes was the best way to release the seed dormancy. In addition, gibberellin treatment had a certain promoting effect on the dormancy release of P. magnatica seeds, but the effect was not ideal compared with the other two treatments.
 Relationship Between Endogenous Hormone Changes and Flowering in the Leaves of Paphiopedilum concolor LI Xiuling, FAN Jizheng, HE Jingzhou, LIAO Hongying, ZENG Yanhua, LONG Qiangyu, NING Yunfen, BU Zhaoyang 2021, 42 (9):  2638-2644.  doi: 10.3969/j.issn.1000-2561.2021.09.027 Abstract ( 42 )   HTML ( 3 )   PDF (1616KB) ( 42 )   In the recent years, the Paphiopedilum orchid industry has developed rapidly. However, the flowering regulation has become the bottleneck restricting the development of the industry. P. concolor, which is easy to bloom, was used as the experiment materials in the paper, the length and width of the functional leaves and the morphological changes of the flowers were observed, and the changes of endogenous hormones in the functional leaves were detected by enzyme-linked immunoassay to provide a theoretical basis for the flowering regulation. The functional leaves had high content of ZR and low content of IAA at the bud development stage, which were beneficial to inducing the bud differentiation. In the study of hormone balance, it was found that the functional leaves had high ratio of IAA/GA3 and ABA/GA3 and low ratio of ZR/ABA and ZR/IAA when the terminal bud was transformed from vegetative growth to reproductive growth (large seedling stage). During floral morphological differentiation (bud development stage), the functional leaves had low ratio of IAA/ABA, IAA/GA3 and high ratio of ZR/GA3 and ZR/IAA. The content and ratios of the source hormones at seedling stage and bud development stage had important effects on bud induction and bud differentiation.
 Effects of PEG Drought Stress on Photosynthetic System of Phalaenopsis pulcherrima ZHANG Han, LI Han, CHEN Qi, YANG Fusun 2021, 42 (9):  2645-2652.  doi: 10.3969/j.issn.1000-2561.2021.09.028 Abstract ( 37 )   HTML ( 4 )   PDF (1909KB) ( 33 )   Three year old tissue culture seedlings of Phalaenopsis pulcherrima were treated with 5%, 10% and 20% PEG 6000 solution respectively to study the effects of drought on photosynthetic system. Drought led to the decrease of stomatal density, opening and length, and the decreasing trend became more obvious with the prolongation of PEG stress time. More than 10% treatments were significantly different from CK. With the extension of PEG treatment time, the decline trend of malic acid content was slowed down. The content of malic acid in leaves measured in the early morning was significantly higher than that in the evening. After 15 days of treatment, the difference of malic acid content between PEG 20% treatment and CK was significant, which was 27.16% lower than that of CK. The net photosynthetic rate, transpiration rate and stomatal conductance of leaves decreased gradually with the prolongation of PEG stress time. The change of intercellular CO2 concentration showed an opposite trend, and water use efficiency increased first and then decreased. After 15 days of treatment, the difference between the treatment of PEG 5% and CK was significant. Drought caused the initial fluorescence value (Fo) to increase gradually, but the variable fluorescence value (Fv), maximum fluorescence value (Fm), PSⅡ actual photochemical efficiency (Fv/Fm), PSⅡ potential photochemical efficiency (Fv/Fo) decreased gradually. The apparent electron transfer rate (ETR), photochemical quenching coefficient (qP), and PSⅡ actual quantum efficiency (Yield) decreased with the increase of PEG stress. The non photochemical quenching coefficient (NPQ) increased significantly with the increase of PEG stress concentration. After 15 days of treatment, the difference between the treatment of PEG 5% and CK was significant. Conclusion: 10%, 20% PEG treatment could reduce photosynthesis and inhibit the synthesis of malic acid by affecting stomatal closure and stomatal density of leaves in a short period of time. At the same time, it affected the absorption and transmission of light energy and photochemical conversion in leaves of P. pulcherrima. 5% PEG treatment did not show the phenomenon of inhibition of photosynthetic physiology until 10 days after treatment, indicating that moderate and severe drought could be achieved in a short time. The stomatal characters of leaves were affected, and the photosynthetic capacity of leaves was reduced. Finally, the synthesis of photosynthetic products was blocked, and the photosynthetic system was inhibited under drought stress.
Plant Protection & Bio-safety
 Functional Analysis of Histone Acetyl-transferase CgGCN5 in Regulation of Pathogenicity of Colletotrichum gloeosporioides from Hevea brasiliensis LIU Shike, AN Bang 2021, 42 (9):  2653-2658.  doi: 10.3969/j.issn.1000-2561.2021.09.029 Abstract ( 36 )   HTML ( 3 )   PDF (9100KB) ( 30 )   The anthracnose caused by Colletotrichum gloeosporioides is one of the major reasons for resulting in reduction of rubber yield in Hainan. Figuring out the molecular mechanisms of pathogenicity of C. gloeosporioides could provide basis for controlling strategy against the pathogen. The histone acetyl-transferase encoding gene CgGCN5 was identified in the genome of C. gloeosporioides. In the present study, the CgGCN5 knock-out mutant and the complementation mutant strains were constructed by homologous recombination strategy. Phenotype analysis revealed that the vegetative growth and sporulation were significantly reduced in the knock-out mutant. The pathogenicity of the mutant to rubber leaves was also significantly impaired. Further analysis suggested that the knock-out of CgGCN5 lead to the loss of penetration ability of the pathogen to cellophane. In addition, the impair of growth and virulence were restored in the complementation strain. The results suggested that CgGCN5 plays important roles in the regulation of growth and pathogenicity of C. gloeosporioides.
 Pathogen Identification for the New Leaf Spot Disease of Capsicum annuum L. and Its Biological Characteristics PEI Yueling, SUN Yanfang, FENG Tuizi, CHEN Yuan, LONG Haibo 2021, 42 (9):  2659-2665.  doi: 10.3969/j.issn.1000-2561.2021.09.030 Abstract ( 39 )   HTML ( 3 )   PDF (1938KB) ( 32 )   A new leaf spot disease was firstly observed during a survey from 2015—2019 in Capsicμm annuμm field of Hainan Province, which was different with other common leaf diseases. The sample was collected and the pathogen was isolated. The results of microscopic examination and molecular analysis confirmed that the disease was caused by Curvularia lunata (Wakker) Boedijin, which was the first report of the Capsicum disease caused by C. lunata in China. The optimum condition for mycelial growth was 30 ℃, pH 7, light or alternative light, D-maltose and yeast extract, while the optimum temperature for conidia germination was 22-33 ℃ and the lethal temperature for conidia was 60 ℃ for 10 min. 12 fungicides were screened in laboratory, 45% Prochloraz EW was found to have the best inhibition activity against the pathogen, which had 97.8% inhibition when the concentration was 1.0 mg/L, 16% diethofencarb 10% pyrimethanil WP, 25% triadimefon WP, 65% Tiezene WP and 80% Mancozeb WP were also effective, while 70% Thiophanate-methyl and 80% carbendazim were almost futile.
 Detection and Genetic Relationship Analysis of Sweet Potato Leaf Curl Virus and Sweet Potato Badnavirus Infecting Sweet Potato Germplasm Resources in Hunan, China HUANG Yanlan, ZHANG Chaofan, ZHANG Daowei, DONG Fang, ZOU Xuexiao 2021, 42 (9):  2666-2673.  doi: 10.3969/j.issn.1000-2561.2021.09.031 Abstract ( 42 )   HTML ( 3 )   PDF (2885KB) ( 28 )   180 sweet potato germplasm resources from different regions of Hunan were used to detect sweet potato leaf curl virus (SPLCV) and sweet potato badnavirus (SPBV) during 2015-2016. The genetic relationship of the two viruses was analyzed based on the sequence of PCR amplification products. 22 sweet potato germplasm resources were infected with SPLCV, making up 12.2% of the total, and 32 sweet potato germplasm resources were infected with SPBV, or 17.8% of the total. There were 8 sweet potato germplasm resources infected with both SPLCV and SPPV, accounting for 3.9% of all 180 sweet potato germplasm resources. SPLCV was detected in Changsha, Yongzhou, Huaihua, Shaoyang, Chenzhou, Changde, Loudi, Yiyang, Yueyang and Zhuzhou. SPBV was detected in Changsha, Yongzhou, Huaihua, Hengyang and Shaoyang. Both SPLCV and SPBV were detected in Huaihua, Changsha, Yongzhou and Shaoyang. Based on the whole genome sequence analysis of the virus, 36 SPLCV isolates reported in the world were divided into 3 groups. The 12 strains isolated from Hunan obtained in this study could be classified into 3 groups, six of them belonged to groupⅠ and one of them to groupⅡ, five of them to groupsⅢ, meaning that sweet potato leaf curl virus was highly diverse in Hunan. Based on the partial sequence analysis of viral movement protein and coat protein coding genes, 36 SPBV isolates reported in the world could be divided into 4 groups, the most of isolates belong to group I, and one Anhui isolate in China was divided into groupⅡalone. Two Shandong isolates and one Henan isolate in China constituted groupⅢ. One of the two Hunan isolates obtained in this study belongs to groupⅠ, and the other was significantly different from the reported isolates, only 74.92% similarity, classified groupⅣ. The results indicate that SPBV have high variability and many types of variation in China. This study could offer a useful reference for prevention and control of these two kinds of sweet potato virus diseases in China.
Post-harvest Treatment & Quality Safety
 Structure and Mechanical Properties of Natural Rubber from Five Typical Processing Technologies SHI Jia, ZHANG Fuquan, DENG Donghua, LI Gaorong, PENG Zheng, LIAO Jianhe, LIAO Lusheng 2021, 42 (9):  2674-2681.  doi: 10.3969/j.issn.1000-2561.2021.09.032 Abstract ( 76 )   HTML ( 7 )   PDF (4260KB) ( 45 )   The structure of natural rubber (NR) is not only affected by the biosynthesis of rubber trees, but also has a lot to do with the processing technology. In order to scientifically compare the effects of the processing technology, in this paper, the latex produced by the same rubber tree was collected to prepare NR using five typical processing technologies according to the current factory production conditions, namely WF, RSS, ADS, CV, TSR. The analysis of the raw rubber structure showed that the decomposition of non-rubber components and the structuring of rubber hydrocarbons caused by maturation would occur during the processing. The specific manifestations were reduced nitrogen content, increased number average molecular weight, narrowed molecular weight distribution, and higher gel content, which caused the increase of initial value of plasticity and Mooney viscosity. Among them, TSR had the highest degree of structure, while CV could retain its inherent molecular structure and had the lowest degree of structure. The performance analysis of the vulcanizates showed that the decomposition of non-rubber components was beneficial to increasing the curing rate and crosslinking density of natural rubber, thereby improving the static mechanical properties of the vulcanizates. The structuring of the rubber hydrocarbon could increase the physical entanglement in the vulcanizates. The network made it more prone to strain-induced crystallization and improve dynamic fatigue performance by increasing energy dissipation. Taken together, the order of the static and dynamic mechanical properties of vulcanizates is: TSR > ADS > RSS > WF > CV.
 Effects of Freezing on Textural Properties of Coconut Meat and Rheological, Fat Globules Particle Size Distribution Properties after Squeezing WANG Yuanyuan, SHEN Xiaojun, WANG Hui, ZHANG Yufeng, LI Yongdong, SONG Fei 2021, 42 (9):  2682-2688.  doi: 10.3969/j.issn.1000-2561.2021.09.033 Abstract ( 48 )   HTML ( 5 )   PDF (1546KB) ( 27 )   Frozen storage is one of the safest food preservation methods, which has been widely used in industrialization. Four temperatures commonly used in frozen storage food, -80, -40, -18 and -10 ℃, were used in this experiment to freeze the coconut meat after air thawing, the textural properties of coconut meat and the rheological, fat globules particle size distribution properties were studied and analyzed. The hardness of coconut meat decreased significantly after freezing, and decreased with the increase of freezing temperature. Coconut milk showed the characteristics of pseudoplastic fluid. The viscosity, shear stress and fat globules particle size of coconut milk increased with the increase of freezing temperature, the particle uniformity of fat globule decreased.
 Effect of Different Preparation Methods on Properties of Pitaya Fruit Powder LIU Yangyang, GONG Xiao, LIU Yijun, YUAN Yuan, LIU Fei, LI Jihua, ZHOU Wei 2021, 42 (9):  2689-2695.  doi: 10.3969/j.issn.1000-2561.2021.09.034 Abstract ( 51 )   HTML ( 5 )   PDF (1935KB) ( 34 )   In order to obtain the suitability evaluation for processing pitaya fruit powder and study the application prospect of three kinds of red pitaya fruit powder made by different preparation procedures during the industrial production, namely the whole fruit powder with starch (WFPS), the whole fruit powder with maltodextrin (WFPM), and instant powder with maltodextrin (IPM), the physicochemical properties,including flowability, color, total phenolic content and total flavonoid content of powders were investigated to compare the differences. The results of physical property showed that WFPS, a spherical shape, particle had better liquidity with the repose angle of 36.6° and CI 18.3 than WFPM with the repose angle of 38.6°and CI of 20 and IPM with the repose angle of 42.1°and CI of 31.6. The value of a* of WFPS was 34.64 with a red color, lower than 37.27 of WFPM with a brighter color and higher than 24.62 of IPM with a pink color. 75 s, 135 s and 156 s were needed for IPM, WFPS and WFPM to be dispersed in water respectively. WFPM had more quantities in nutrient and active components such as protein 1.7 g/100 g, total flavonoids13.06 mg/g, total polyphenols 14.29 mg/g, beet glycosides 3.94 mg/g. IPM could be used to produce some products which needed to be completely dissolved, such as the solid beverage, while WFPS and WFPM be suitable for pressed candy, nutritional fortifier and other products with low solubility requirements. In conclusion, all three kinds of power have their own advantages which can offer a choice to meet different processing method needs.
 Analysis of Flavanol Compounds Changes and Antioxidant Activity of Cocoa Bean During Processing FANG Yiming, LI Rui, HE Shuzhen, ZHU Zihui, ZHAO Xizhu 2021, 42 (9):  2696-2703.  doi: 10.3969/j.issn.1000-2561.2021.09.035 Abstract ( 42 )   HTML ( 6 )   PDF (1577KB) ( 30 )   In this study, high-performance liquid chromatography and enzyme-labeled detection technology were used to determine the changing trend of flavanols and analyze the antioxidant activity during the processing of cocoa beans. The content of catechin (C), epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (ECG), proanthocyanidin B1 (PC B1), proanthocyanidin B2 (PC B2) during fermentation and roasting were assayed. The content of for EGC, C, EC, ECG, PC B1, PC B2 was 8.521-3.017 mg/g, 15.521-6.633 mg/g, 19.615-3.142 mg/g, 0.236-0.084 mg/g, 19.152-10.774 mg/g, 4.254-2.083 mg/g, respectively during 7 days fermentation. The content of catechins and oligomers greatly reduced in cocoa beans during fermentation. The content of EGC, C, EC, ECG, PC B1, PC B2 was 3.079-2.221 mg/g, 8.611- 5.143 mg/g, 3.956-0.982 mg/g, 0.111-0.070 mg/g, 10.987-8.223 mg/g, 2.385-1.534 mg/g, correspondingly roasted at 135 ℃ for different times. The clearance rates of DPPH and ABTS+? showed a downward trend during high-temperature roasting of cocoa beans. The antioxidant activity has reduced of cocoa bean. This would provide a theoretical basis for related health care functionality on cocoa processing.
 Modeling and Simulation Parameters Calibration of Coconut Coir Particles Based on DEM WANG Gang, WANG Qian, XUE Zhong, GUO Changjin, SONG Gang, WANG Shuo 2021, 42 (9):  2704-2710.  doi: 10.3969/j.issn.1000-2561.2021.09.036 Abstract ( 43 )   HTML ( 6 )   PDF (1835KB) ( 30 )   In order to determine the reasonable simulation parameters of coconut coir in the DEM process, based on the DEM Mindlin (no slip) contact model, a coconut coir model is established in the simulation software EDEM 2018 and the particle factory is generated. The simulation parameters were calibrated by comparing the physical test and virtual test of coconut coir repose angle. Firstly, the intrinsic parameters of coconut coir such as repose angle and bulk density were measured by physical tests, and the level of factors to be calibrated were obtained by comprehensive analysis using the GEMM database embedded in EDEM 2018 and relevant literature. A Plackett-Burman test design was carried out to screen out the factors that have significant influence on the repose angle of coconut coir: static friction coefficient of coconut coir with coconut coir, rolling friction coefficient of coconut coir with coconut coir, shear modulus of coconut coir. Through Box-Behnken experimental design, a regression model of repose angle and three significant influencing factors were established, using the optimization function of design expert software, taking the physical test of stacking angle of 45.69° as the objective, the regression equation was optimized and solved, and the best combination of significant influencing factors were obtained. Coconut coir shear modulus was 1.44 MPa, static friction coefficient of coconut coir with coconut coir was 1.11, and rolling friction coefficient of coconut coir with coconut coir was 0.15. The experimental results showed that the combined parameters could be used in the discrete element simulation of coconut coir materials, and provide theoretical references for the design of coconut coir conveying, mixing and other mechanical equipment.
Agricultural Ecology & Environmental Protection
 Communities of Adults Dragonflies in Rice Fields in Tropic and Subtropic Region in Hainan, China ZHOU Xia, TAN Yanhua, YI Xiaoping, WU Suran, ZHANG Lili, GUO Anping 2021, 42 (9):  2711-2716.  doi: 10.3969/j.issn.1000-2561.2021.09.037 Abstract ( 48 )   HTML ( 5 )   PDF (1550KB) ( 34 )   Dragonflies are increasingly used as the biological indicators to evaluate environmental quality. There are also many species of dragonflies in rice fields in Hainan Province. In order to make clear the community composition of dragonflies in rice fields in Hainan Province, the adult dragonflies were sampled in first and second rice seasons in 2017 in Sanya and Wenchang. The dragonfly community was stable in different growth stages of two rice seasons in Hainan, with 5-15 species and (3.7±0.67) - (14.0±0.57) dragonflies per hundred clusters. The diversity index of dragonfly community was 2.007-2.193, the evenness index was 0.786-0.808, and the dominant concentration index was 0.148-0.190. 15 species from 3 families of adult dragonflies were collected in rice ecosystem in tropic region and 17 species from 2 families in subtropic region respectively and 11 species were both in Sanya and Wenchang. The similarity of community species was 0.701, and the similarity of dominant species was 0.857. In the first and second seasons there were significant differences in the number of individuals at tillering, flowering and fruiting stages in Sanya, while there were no significant differences in Wenchang. Agriocnemis Femina, Ceriagorion auranticum and Neurothemis tullia may be sensitive to the change of environmental pollution in rice fields.
 Diversity Analysis of Fungal in Rhizosphere Soils of Rice under Different Tillage Methods Based on High-throughput Sequencing Technique LAO Chengying, SHEN Zhangyou, LI Yanying, WEI Benhui, ZHOU Lingzhi, ZHOU Jia, HU Po, HUANG Yulan 2021, 42 (9):  2717-2726.  doi: 10.3969/j.issn.1000-2561.2021.09.038 Abstract ( 44 )   HTML ( 5 )   PDF (2345KB) ( 41 )   To study the diversity of the rhizosphere soil fungal communities in rice under different tillage practices, this research was carried out using rotary tillage, no tillage, smash and ridging tillage treatments. The structure and diversity of fungal communities were analyzed using high-throughput sequencing techniques in the rhizosphere soil, and Pearson’s correlation analysis was performed combined with soil environmental factors. Ascomycota, Zygomycota Basidiomycota and Glomeromycota were the dominant phyla, and Fusarium, Mortierella, Pyrenochaetopsis, Zopfiella, Chaetomium, Acremonium, Cryptococcus, Westerdykella, Gaeumannomyces, Metarhizium were the top10 dominant genera in the rice rhizosphere soils of the three tillage treatments. Relative abundance of Zygomycota and Mortierella, Acremonium, Cryptococcus and Gaeumannomyces among the three treatments was significantly different. Alpha diversity index analysis showed no significant differences among the three farming treatments. Principal co-ordinates analysis showed that the distribution characteristics of the soil fungal communities under different tillage treatments were significantly different. Redundancy analysis showed that the variation of the soil fungal communities was 87.46% by the first two ranking axes together among the three tillage treatments. The Pearson’s correlation analysis showed that soil pH was highly significantly positively correlated with the abundance of Zygomycota fungi. While the content of soil available phosphorus, alkaline hydrolytic nitrogen and organic matter was highly significantly negatively correlated with the abundance of Zygomycota fungi. And the content of soil available phosphorus was significantly positively correlated with the abundance of Basidiomycota fungi. In summary, it is shown that the structure and diversity of the rhizosphere soil fungal communities in rice are different under short-term different tillage treatments. The distribution of fungal communities is influenced by soil pH, organic matter, alkaline hydrolytic nitrogen and available phosphorus.
 Effects of Different Organic Fertilizer Rates on the Bacterial Community of Off-season Syzygium samarangense Park Soil WU Bin, HUANG Dongmei, MA Funing, WANG Bizun, SONG Shun, HE Yingdui, WANG Lixia, LIU Yongxia 2021, 42 (9):  2727-2734.  doi: 10.3969/j.issn.1000-2561.2021.09.039 Abstract ( 39 )   HTML ( 5 )   PDF (9583KB) ( 26 )   The effects of different organic fertilizer rates on the bacterial community diversity of soil in the off-season Syzygium samarangense plantation were analyzed using the Illumina MiSeq high-throughput sequencing technology. 741 391 effective sequences and 32 778 operational taxonomic units (OTU) were detected, including 28 phyla and 418 genera. Acidobacteria, Chloroflexi and Proteobacteria were the dominant soil bacterial communities under different fertilizers in S. samarangense plantation. The order of the soil bacterial communities diversity and richness was the BML (organic fungi-manure for banana stalks, low concentration, 2 kg per plant) = the GML (organic manure of sheep manure, low concentration, 2 kg per plant) > the GMM (organic manure of sheep manure, medium concentration, 4 kg per plant) = the BMH (organic fungi-manure for banana stalks, high concentration, 6 kg per plant) > the CK (Control) > the GMH (organic manure of sheep manure, high concentration, 6 kg per plant) = the BMM (organic fungi-manure for banana stalks, medium concentration, 4 kg per plant). 37 significantly different species (5 classes, 7 orders, 9 families, 8 genera and 8 species) in the different fertilization treatment (CK treatment group, GM treatment group, BM treatment group) were found using the linear discriminant analysis effect size (LEfSe) analysis, which was consistent with the results from Venn, i.e.. The soil bacterial community structure was similar, but still had some differences under different concentrations of organic manure treatments. Moreover, the soil bacterial community diversity under low concentration of sheep and banana stalk manures was significantly higher than those of the other treatments. It indicates that low concentration of organic fertilizer could not only improve the soil bacteria diversity and soil bacterial community structure stability, but also save fertilizer use.
 Geographical Distribution Pattern of Pteris terminalis MA Changwang, LANG Yueting, GUO Rui, YU Jing, YANG Dongmei 2021, 42 (9):  2735-2742.  doi: 10.3969/j.issn.1000-2561.2021.09.040 Abstract ( 52 )   HTML ( 16 )   PDF (8084KB) ( 26 )   In order to explore the geographical distribution of Pteris terminalis, based on field investigations, specimen information of P. terminalis was collected from 30 major plant specimen databases in the world, and was analyzed by Arc-GIS software and Excel software to establish geographic distribution maps and altitude distribution maps. The correlations between the geographic distribution of P. terminalis and the distribution of rivers, climate factors, topography, and so on were discussed. Asia is the distribution center of P. terminalis in the world. China and Japan are its distribution centers in Asia. The vicinity of the Yangtze River is its distribution center in China. The central and southern regions along the river area is its distribution center in Japan. For climate type, P. terminalis is mainly distributed in the subtropical monsoon climate zone near the Tropic of Cancer, and few are distributed in the tropical monsoon climate zone and tropical rain forest climate zone near the equator, indicating that P. terminalis prefers a warm environment. Besides, P. terminalis is mainly distributed near rivers, seaside areas and islands, indicating that it likes a humid environment. In terms of altitude, there are obvious differences in the altitude distribution range of P. terminalis among continents, countries, and provinces, which may be affected by latitude, longitude, topography and cytotypes.