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    25 October 2019, Volume 40 Issue 10 Previous Issue    Next Issue
    Genomics and Gene Editing of Tropical Plant
    Research Progresses of Tropical Plant Genome
    LI Dan,CHEN Xiaohui,LAI Zhongxiong
    2019, 40 (10):  1875-1888.  doi: 10.3969/j.issn.1000-2561.2019.10.001
    Abstract ( 1194 )   HTML ( 19817 )   PDF (880KB) ( 890 )  

    Based on genome-wide sequencing results, the development of genome-wide sequencing of 13 tropical plants including banana (Musa spp.), longan (Dimocarpus longan), papaya (Carica papaya), pineapple (Ananas comosus), coconut (Cocos nucifera), durian (Durio zibethinus), rubber (Hevea brasiliensis), cassava (Manihot esculenta), date palm (Phoenix dactylifera), cocoa (Theobroma cacao), oil palm(Elaeis guineensis), coffee (Coffea canephra) Tiepi-shihu (Dendrobium officinale) was discussed, and the tropical plant genome research was summarized.

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    Genome-wide Identification and Expression Analysis of SDG Gene Family During Early Somatic Embryogenesis in Dimocarpus longan Lour.
    SHEN Xu,CHEN Xiaohui,XU Xiaoping,HUO Wen,LI Xiaofei,JIANG Mengqi,ZHANG Jing,LIN Yuling,LAI Zhongxiong
    2019, 40 (10):  1889-1901.  doi: 10.3969/j.issn.1000-2561.2019.10.002
    Abstract ( 813 )   HTML ( 17 )   PDF (5656KB) ( 455 )  

    The SET domain group (SDG) gene family controls histone lysine methylation, which is an important part of the regulation of chromatin function and epigenetic regulation of gene expression. To understand the biological function of longan (DlSDG) family, the whole SDG family members of longan genome were identified by bioinformatics analysis, and the protein domain, conserved motif, gene structure, promoter homeopathic elements, evolutionary tree, protein interaction of related genes and gene expression at the early stage of somatic embryogenesis were predicted and analyzed. There were 32 members of longan DlSDG gene family, which could be divided into seven subfamilies, Suv, Ash, ATXR5/ATXR6, Trx, E(z), SMYD and SETD, and Suv had the largest subfamily members. The number of exons varied from 1 to 22, and protein domains were conserved, all containing a SET domain. DlSDG protein conserved motif had large differences among different subfamilies. DlSDG promoters contained many abiotic stress response elements such as low temperature, drought, stress and hormone response elements. SDG members could be expressed to different degrees in the early stage of somatic embryogenesis. DlSUVR4b might play an important role in EC and ICpEC stages. DlSUVH4 could interact with DNA methyltransferase MET1. The study showed that the longan DlSDG 32 histone lysine methylation transferase genes maight directly involved in the regulation of stress response and somatic embryogenesis, possibly in DNA methylation, chromatin remodeling, formation in the process of somatic embryogenesis of collaborative control network in addition to the regulation of the circadian clock, branch number, root growth and development, seed germination, the growth of flowers and plants of morphogenesis with diversity and complexity.

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    Genome-wide Identification and Expression Analysis of RNA Methylation Related Genes During Somatic Embryogenesis in Dimocarpus longan Lour.
    WANG Jingyu,CHEN Xiaohui,SHEN Xu,XU Xiaoping,ZHANG Zihao,LIN Yuling,LAI Zhongxiong
    2019, 40 (10):  1902-1913.  doi: 10.3969/j.issn.1000-2561.2019.10.003
    Abstract ( 737 )   HTML ( 17 )   PDF (2557KB) ( 326 )  

    To understand the biological function of the longan RNA methylation related genes, based on the genome and transcriptome data, the RNA methylation related genes in longan genome were identified, the protein domains and characteristics, the molecular evolution tree, and the tissues and organs somatic embryogenesis gene expression level and the analysis of the quantitative expression of ABA treatment were analyzed using the bioinformatics analysis method. The results showed that seven key genes were involved in the RNA methylation, including five RNA methyltransferase genes and two RNA demethylase genes. The number of introns in each member varied greatly, ranging from 4 to 28. The result of evolutionary tree analysis showed that longon RNA methyltransferase and demethylase proteins were most closely related to Citrus sinensis. Protein domain analysis showed that RNA methylation related enzymes had conserved protein domain. The promoter region of RNA methylation related genes mainly contained light response elements, hormone response elements, stress response elements and meristem expression response elements. It is speculated that RNA methylation related genes may have a certain regulatory effect on plant growth and development and maladaptive environment. Some members of RNA methylation related genes showed significant differences in the expression of longan somatic embryo at different stages of development and in different tissues and organs. It was speculated that longan RNA methylation related genes might be involved in different somatic embryo development stages and tissue and organ morphogenesis. The expressions of RNA methylation related genes in longan EC were different under ABA treatment at different concentrations. The relative expression of DlVIR, DlALKBH10B and DlMTB was inhibited to some extent, while DlFIP37 showed up-regulated expression, suggesting that longan RNA methylation related genes were involved in the hormone response pathway. In this study, longan RNA methylation related genes may play an important role in leaf formation, flower development and plant morphogenesis, and may also be involved in regulating embryo development and responding to abiotic stress. It is speculated that longan RNA methylation related genes had differences and diversity in function.

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    Biological Information and Expression Analysis of HD-Zip Gene Family in Dimocarpus longan Lour.
    ZHANG Chunyu,XU Xiaoping,CHEN Xiaohui,SHEN Xu,LIN Yuling,LAI Zhongxiong
    2019, 40 (10):  1914-1923.  doi: 10.3969/j.issn.1000-2561.2019.10.004
    Abstract ( 648 )   HTML ( 19 )   PDF (1754KB) ( 321 )  

    In order to understand the function of the longan HD-Zip gene family, this study was based on the longan genome and transcriptome database, and analyzed the promoters, alternative splicing and regulated miRNA species of 19 longan HD-Zip family members, and the expression pattern of HD-Zip members in longan embryogenic callus under ABA treatment and the expression patterns of some members at different somatic stages was analyzed by real-time fluorescent quantitative PCR. The longan HD-Zip family contained a large number of photoresponsive elements, hormone response elements and stress response elements in addition to TATA-box and CAAT-box, suggesting that longan HD-Zip family members may be involved in photoreactivity, hormone response and non-biological stress. The alternative splicing mode of longan HD-Zip in different tissue parts and different somatic embryo stages was mainly intron retention. The longan HD-Zip gene family members were mainly regulated by miRNA166a. The expression patterns of some members of the HD-Zip family in the longan EC stage under the treatment of exogenous hormone ABA and the expression patterns of some members in different somatic embryo stages were diverse. It is speculated that longan HD-Zip participates in the regulation of different somatic embryo development in longan, and may affect the growth and development of embryogenic callus and the formation of morphology by regulating the concentration of endogenous ABA.

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    Genome-wide Identification and Regulation of Expression Analysis of Cysteine-rich Receptor-like Kinase in Longan
    SUN Ying,LIN Yiling,ZHAO Pengcheng,XU Xiaoping,CHEN Xiaohui,SHEN Xu,LIN Yuling,LAI Zhongxiong
    2019, 40 (10):  1924-1937.  doi: 10.3969/j.issn.1000-2561.2019.10.005
    Abstract ( 738 )   HTML ( 16 )   PDF (6920KB) ( 152 )  

    In order to understand the basic characteristics and functions of cysteine-rich receptor-like kinase (CRK) family in longan, a series of bioinformatics methods were used to analyze and identify 98 members of CRK gene family members, including constructing the molecular evolutionary tree, analyzing protein domains and characteristics, promoters, homeopathic elements, somatic embryogenesis and tissue-organ specific expression. Results showed that the CRK gene of longan and Arabidopsis could be divided into seven subfamilies according to the distance of the relationship by evolutionary tree analysis, and the protein characteristics (the quantity of amino acids, the relative molecular weight, the isoelectric point, the signal peptide and sites of glycosylation) of different subfamilies were different. Structural characteristics of the genes of each member, promoter homeopathic elements and protein domain characteristics were closely related to family members in the evolutionary tree. The specific expression of 98 CRK family members during somatic embryogenesis (NEC, EC, ICpEC, GE) and growth were different, particularly higher in non-embryogenic callus and young fruits, but they were almost not expressed in seeds and matured fruits. In addition, cysteine-rich receptor-like protein kinases played important roles in biological stress, abiotic stress (insect-induce diseases, drought resistance, cold resistance, salt resistance, etc.) and it played important roles in plant growth and development as well.

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    Genome-wide Identification and Expression Analysis of MSIL Gene Family During Somatic Embryogenesis in Dimocarpus longan Lour.
    XU Xiaoqiong,CHEN Xiaohui,SHEN Xu,XU Xiaoping,LIN Yuling,LAI Zhongxiong
    2019, 40 (10):  1938-1948.  doi: 10.3969/j.issn.1000-2561.2019.10.006
    Abstract ( 713 )   HTML ( 18 )   PDF (1693KB) ( 449 )  

    The MSIL (Multicopy suppressor of IRA homolog1-Like) gene is a subfamily of WD repeat proteins and plays an important role in growth and development of plants. In order to understand the biological function of the longan MSIL (DlMSIL) gene family, biological analysis was used to identify DlMSIL gene membersand the protein structure physical and chemical properties, promoter cis-acting element, expression of longan somatic embryo stage and different tissues and organs, and quantitative expression under GA3 treatment were analyzed, based on genome and transcriptome data. The DlMSIL gene family was consisted of six members belonging to the WD40 and CAF1C_H4-bd superfamily, which could be divided into three categories. The DlMSIL protein encoded 393-551 amino acids, and the isoelectric point was between 4.68 and 7.62. It was secreted protein. The number of introns of the gene family members was between 4 and 14. The DlMSIL promoter sequence contained many abiotic stress response elements and MYB binding sites, suggesting that the DlMSIL gene family maight be involved in some abiotic stress responses. The DlMSIL maight be involved in the morphogenesis of different embryonic development processes and different tissues and organs. The expression analysis of GA3 treatment showed that the relative expression of DlMSI1a and DlMSI1c was inhibited with the increase of the concentration at high concentration, while the expression of DlMSI4a decreased first, then increased and then decreased. It is speculated that DlMSIL may be involved in the hormone response pathway. The study shows that the members of the DlMSIL gene family may be involved in various biological functions such as embryonic development, hormone signaling pathways and abiotic stress responses, reflecting the diversity of longan MSIL gene family functions.

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    Identification and Expression Analysis of Phenylalanine Ammonia- lyase Gene Family in Banana
    YANG Huixiao,SUN Yuanyuan,JIA Caihong,JIN Zhiqiang,XU Biyu,WANG Zhuo
    2019, 40 (10):  1949-1957.  doi: 10.3969/j.issn.1000-2561.2019.10.007
    Abstract ( 650 )   HTML ( 16 )   PDF (7982KB) ( 167 )  

    Phenylalanine ammonia-lyase gene (PAL) is one of the key enzymes associated with plant growth and stress resistance in the secondary metabolism pathway. In this study, we used four L-phenylalanine ammonia-lyase genes in Arabidopsis thaliana as qurry and acquired 53 candidate PAL gene sequences by BLASTp in banana A genome database. And then we used conserved domain search of NCBI, only 8 gene members were found containing typical PAL domain in the protein sequence. In the phylogenetic tree, eight PALs could be classified into 2 groups, Class I and Class II. The transcriptome data showed that all MaPAL genes were highly expressed at fruit development stages. And MaPAL5 was differential expression in banana fruit postharvest stages. Under the drought, low temperature and salt stresses, MaPAL1, MaPAL2, MaPAL3, MaPAL4 and MaPAL5 members were up-regulated and MaPAL6 was down-regulated. All 8 MaPALs were down-regulated under the Foc TR4 infection. The results suggested that all MaPAL genes played important roles in banana fruit development and ripenning, responding to abiotic and biotic stresses. This study would provide a theoretical basis for further exploration the function of MaPALs in banana fruit ripening and under stresses.

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    Bioinformatics and Gene Expression Analysis of Pineapple R2R3- MYB Gene Family
    CHEN Zhe,HU Fuchu,RUAN Chengcheng,FAN Hongyan,GUO Lijun,ZHANG Zhili
    2019, 40 (10):  1958-1971.  doi: 10.3969/j.issn.1000-2561.2019.10.008
    Abstract ( 770 )   HTML ( 28 )   PDF (3701KB) ( 506 )  

    R2R3-MYB transcription factors are very important in plant growth and development, ich are involved in the regulation of many life activities of plants. In this study, the R2R3-AcMYB transcription factors were screened and identified from the pineapple genome by bioinformatics analysis. Based on the transcriptome data and fluorescence-quantitative PCR analysis, the expression patterns of MYB genes in the apical meristem of pineapple treated with ethylene were studied. The results showed that there were 103 R2R3-AcMYB transcription factors in the pineapple genome, of which 67 gene were composed of 3 (exons) +2 (introns) and 17 were 2 (exons) +1 (introns). Of the 103 R2R3-AcMYB proteins, 31 were alkaline, 55 were acidic and 17 were neutral, and the main secondary structure in 83 proteins was random curl. Subcellular localization predictions showed that 67 proteins were located in the cytoplasm and 20 in the nucleus. Conservative motif analysis found that 91 of the R2R3-AcMYB sequences contained motif 1 and motif 2 of the SANT structure. Phylogenetic analysis showed that 81 R2R3-AcMYB transcription factors could be classified into 18 subgroups, and the remaining 22 R2R3-AcMYB transcription factors could not be clearly classified. Based on transcriptome data and fluorescence-quantitative PCR analysis, it was found that the expression of several MYB genes in the apical meristem of pineapple was induced or inhibited by ethrel, suggesting that the genes may be involved in the responses of pineapple growth and development including the induction of flowering to ethrel. The results would provide data supports for further excavation of genes involved in hormone response, growth and development, and flowering regulation, which would contribute to revealing the regulation mechanism of pineapple growth and development.

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    Transcriptome-wide Identification and Expression Profiling of the Auxin Response Factor (ARF) Gene Family in Agave.hybrid No.11648
    LU Zhiwei,HOU Xiaowan,YANG Ziping,ZHANG Yanmei,LI Junfeng,ZHOU Wenzhao
    2019, 40 (10):  1972-1978.  doi: 10.3969/j.issn.1000-2561.2019.10.09
    Abstract ( 930 )   HTML ( 26 )   PDF (2569KB) ( 383 )  

    Auxin response factors (ARFs) are plant-specific polygenic transcription factor families involved in the regulation of plant growth and development. In this study, the members of the agave ARF gene family were identified and analyzed by bioinformatics methods, based on transcriptome data. The results showed that 15 ARF genes were identified in agave and named from AhARF 1 to AhARF 15 in turn, its encoded protein varied from 409 to 1011 amino acid residues in length, the molecular weight ranged from 45.17 to 112.13 ku, and the isoelectric point varied from 5.17 to 9.34. Subcellular localization prediction showed that 13 AhARFs were localized in the nucleus and 2 AhARFs were located in the chloroplast. Conservative domain analysis results indicated that there were eight members among the AhARFs gene family which containing three relatively conserved domains, B3, ARF, and Aux/IAA. The other members contained only the two domains, B3 and ARF. Phylogenetic tree analysis indicated that the AhARFs protein could be divided into five subfamilies. The 15 AhARFs genes showed different expression patterns in different stages of agave purple leaf curl disease. This research would lay an important theoretical foundation for further study of the function of the AhARFs gene family.

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    miRNA Expression Profile and Target Gene Analysis of Different Color Peels in Wild Banana (Musa itinerans)
    DENG Sufang,CHENG Chunzhen,LIN Yuling,LAI Zhongxiong
    2019, 40 (10):  1979-1990.  doi: 10.3969/j.issn.1000-2561.2019.10.010
    Abstract ( 705 )   HTML ( 17 )   PDF (3644KB) ( 270 )  

    In this paper, the transcriptome sequencing of different color peels (green and purple) of Minhou wild banana (Musa itinerans) was carried out to investigate the role and the possible regulatory pathways of miRNA involved in the post-transcriptional level regulation of peel color, which would lay the foundation for the study of the peel color molecular regulation mechanism of the genus Musa. In the experiment, different color (purple and green) peel tissues on the same fruit comb of wild banana were used for miRNA analysis. Through miRNA sequencing and bioinformatics analysis, the miRNA expression profiles of different color peel tissues in wild banana were obtained. The differentially expressed miRNAs were screened and the related target genes were predicted. Through the target gene analysis, the signal pathways which is related to peel color traits were proposed. As a result, a total of 34.11 million original reads and 28.73 million clean reads were obtained from the green and purple peel tissues. Among them, 132 known miRNAs and 122 new miRNAs were identified; 36 differentially expressed miRNAs were screened out, of which 10 were up-regulated in purple peel and 26 were up-regulated in green peel. The miRNA with the highest expression was mit-miR167, and the one with the largest difference was mit-miR172a-3p-2. A total of 1164 target genes of differentially expressed miRNAs were predicted, which may be involved in the regulation of wild banana peel color, and were mainly enriched in functions such as DNA binding, anion transmembrane transporter activity, and plant pathogen interaction pathways. Among them, there were 7 genes directly related to the phenylpropanoid biosynthesis pathway, and were mainly regulated by the miR156 and miR482 families. At the same time, six differentially expressed miRNAs were selected for quantitative verification. The results showed that three miRNAs were up-regulated in green peel and three miRNAs were up-regulated in purple peel. The quantitative results were consistent with the results of high-throughput sequencing. In this study, the miRNA expression profiles of wild banana peels were obtained, and the miRNAs and metabolic pathways which may be related to the regulation of color traits of wild banana peel were obtained by bioinformatics analysis. These results indicated that the color trait of wild banana peel may be regulated by a variety of miRNAs and involves multiple metabolic pathways, which would help to further understand the post-transcriptional level regulation of anthocyanins in the peel and lay the foundation for further functional verification.

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    Analyses of Leaf Transcriptome under Heat Stress in Narcissus
    SONG Jiaomin,XU Xiaoping,CHEN Yukun,CHEN Guixin,LAI Zhongxiong
    2019, 40 (10):  1991-2000.  doi: 10.3969/j.issn.1000-2561.2019.10.011
    Abstract ( 569 )   HTML ( 18 )   PDF (3070KB) ( 283 )  

    To explore the pathways of response to heat stress and mechanism of heat-tolerance of Narcissus tazetta var. chinensis, we used the BGISEQ-500 sequencing technology and de novo transcriptome assembly to gain a comprehensive overview of the transcriptome of the leaves under heat temperature (30 ℃, 35 ℃) and normal growth conditions (15 ℃). The data of RNA-Seq treated 24 h at 15, 30, 35 ℃ were de novo assembled using Trinity software. Gene annotation was performed using BLAST software, and differentially expressed genes were detected by DEGseq and PossionDis. A total of 112 160 unigenes were generated with a toal length of 128 733 815 bp, average length of 1147 bp and N50 of 1770 bp. For annotation functional, Narcissus was highly similar to Asparagus officinalis species. On the basis of clusters of euKaryotic Orithologous Groups (KOG) analysis, 5560 unigene sequences were distributed over 25 functional regions. Gene Ontology (GO) enrichment of DEGs showed significant enrichment of GO term associated with photosynthetic systems and membrane systems. KEGG analysis showed significant enrichment of the pathways about the biosynthesis of secondary metabolites, phenylpropanoid biosynthesis, metabolic pathways, photosynthesis, glycosaminoglycan degradation, glyoxylic acid and dicarboxylic acid metabolism, photosynthesis-antenna proteins, monoterpenoid biosynthesis, etc. And the thiamine metabolc pathway was the only one that was significantly enriched under high temperature stress conditions. The study annotated a large number of related gene sequences, and would provide abundant data resources and molecular basis for improving the heat tolerance and heat tolerance of Narcissus.

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    Genome Survey Analysis of Relative Wild Species Ipomoea Littoralis in Sweetpotato
    HUO Kaisen,CAO Qinghe,WAND Yao,CHEN Yanli,ZHU Guopeng
    2019, 40 (10):  2001-2005.  doi: 10.3969/j.issn.1000-2561.2019.10.012
    Abstract ( 520 )   HTML ( 17 )   PDF (1138KB) ( 444 )  

    Ipomoea littoralis is one of the wild relatives of sweet potato. Its genome-wide research can provide reference for the innovation of sweet potato germplasm resources and for the mapping of the whole genome.This study used a second-generation high-throughput sequencing technology (Illumina Hiseq 2500) with a sequencing depth of approximately 60× and filtered to obtain 22.45 G data. Bioinformatics was used to estimate genome size, heterozygosity, repeat sequence and GC. The predicted genome size was 676.27 Mb. The K-mer analysis showed that the ratio of repeats was 60.98%, and the heterozygosity rate was 0.81%. The contigs N50 was 684 kb after preliminary assembly. The total reading length was 0.538 Gb, scaffolds N50 was 12.09 kb, and the total reading length was 0.602 Gb. The average depth and content distribution of GC were stratified.

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    Research Progress on Improving CRISPR/Cas Genome Editing Efficiency
    ZHANG Yumiao,LI Rong,LU Yao,LIN Yuling,LAI Zhongxiong,XU Han
    2019, 40 (10):  2006-2015.  doi: 10.3969/j.issn.1000-2561.2019.10.013
    Abstract ( 807 )   HTML ( 25 )   PDF (2334KB) ( 534 )  

    CRISPR genome editing technology has developed rapidly and provided technical support for the functional genes research and genetic improvement. High efficiency of genome editing is critical for the application of the technology, and important progresses have been made recently. The present review summarized historic events in the improvement of the technology especially of the editing efficiency in relation to the functional mechanism and structure of the CRISPR/Cas system, and proposed several technological hints to the improvement of the editing efficiency.

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    Progress of Determinate Growth Genes and Gene Editing Breeding
    GUO Pinpin,REN Gang,LI Zhong,ZENG Shaohua,DE Tana,WANG Ying
    2019, 40 (10):  2016-2021.  doi: 10.3969/j.issn.1000-2561.2019.10.014
    Abstract ( 546 )   HTML ( 21 )   PDF (412KB) ( 372 )  

    With the increase of labor cost, there will be a gradually transition for the harvesting of fruits and vegetables from manual harvesting to mechanical harvesting. Therefore, developing new compact and mechanical harvest plant varieties with synchronized ripening period has become the main target of genetic improvement. This review summarized the flower development related genes, especially FT and homologous genes controlling the indeterminate and determinate growth at the top of the main stem of plants, and the successful breeding model of promoting the apical flower formation using the CRISPR/CAS9 gene editing system, which leads to the transformation of the top of the main stem into flower development and stops continuing to grow. In addition, gene editing of multiple genes relating to plant apical structure and fruit characters were successfully used for new cultivar development. Apical flower and determinate growth can promote the synchronized fruit ripening and faciliate mechanical harvest, which would provide a theoretical and practical guidance for the future breeding alternating plant structure or plant type.

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    Construction of CRISPR Plant Expression Vectors Resistant to Papaya Leaf Curl Virus
    LONG huan,ZHAO Hui,WANG Xupeng,JIA Ruizong,HE Pingping,KONG Hua,GUO Yunling,GUO Anping
    2019, 40 (10):  2022-2028.  doi: 10.3969/j.issn.1000-2561.2019.10.015
    Abstract ( 708 )   HTML ( 20 )   PDF (2878KB) ( 279 )  

    The Geminivirus are characterized by strong destructiveness, diverse hosts, and wide geographical distribution. They have always been a major problem in the crop production of the world . The use of physical and chemical methods to control them is not only costly, but also has low efficacy, and may also have a negative impact on the environment. Therefore, it is one of the effective ways to cultivate disease-resistant varieties by molecular breeding technology. The CRISPR/Cas9 gene editing technology and Golden Gate cloning technology were used to design and construct a gene editing multi-cut expression vector resistant to papaya leaf curl virus. The vector was transferred into Agrobacterium tumefaciens AGL1 and injected into the tobacco leaves for transient expression. After 48 h, the presence of green fluorescence was observed by a laser confocal microscopy. It was located in the nucleus and cytoplasmic membrane. The work would provide a theoretical basis for the study of papaya leaf curl virus.

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    Crop Culture and Nutrition, Genetic Breeding
    Storage Root Configuration of Cassava and the Influence for Mechanical Harvesting
    SU Bimeng,WANG Juan,HUANG Jie,WEI Yunxia,DENG Ganran,HE Fengguang,YU Changde,CHEN Chen,LIU Zhi
    2019, 40 (10):  2029-2033.  doi: 10.3969/j.issn.1000-2561.2019.10.016
    Abstract ( 602 )   HTML ( 15 )   PDF (1008KB) ( 307 )  

    The storage root configuration (SRC), which is the spatial distribution characteristics of cassava storage root under soil, will directly affect the mechanical harvesting effect. The SRC of 3 cassava varieties, South China 205 (SC205), Nanzhi 199 (NZ199) and Xinxuan 048 (XX048) was studied to find out the appropriate varieties and technological parameters for mechanical harvesting. The SRC of SC205 and NZ199 were good for mechanical harvesting. The best half harvesting width per plant and best harvesting depth for SC205 also NZ199 was 0.0-35.0 cm and 0.0-25.0 cm respectively. Under the condition, the harvesting rate of storage root number and weight of SC205 was 100.0%, and that of NZ199 was above 96.0%. It is recommended that the half width per plant and harvesting depth is 35.0 cm and is 25.0 cm correspondingly for the mechanical harvesting of cassava.

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    Response Characteristics of the Mineral Element Contents of Young Macadamia Trees to Different Phosphorus Levels
    YANG Weihai,ZENG Lizhen,ZENG Hui,WAN Jifeng,ZHANG Hanzhou,ZOU Minghong,LU Chaozhong,ZHU Wenhua
    2019, 40 (10):  2034-2040.  doi: 10.3969/j.issn.1000-2561.2019.10.017
    Abstract ( 566 )   HTML ( 14 )   PDF (649KB) ( 255 )  

    Using macadamia variety ‘HAES741’ as materials, the sandy culture experiments were employed to investigate the changes of the contents of mineral elements (K, P, Ca and Mg) in the potted young trees of macadamia under different phosphorus levels (0, 0.01, 0.1, 0.5, 2.5 and 10 mmol/L H2PO4 - ) of nutrient solution. The results indicated that with the increase of phosphorus application level, the elements contents of K and P in leaf, stem and root of the young macadamia trees had a small growth or no significant change under the condition of low phosphorus nutrition level (0-0.5 mmol/L), while those increased significantly when supplied with high phosphorus level (2.5-10 mmol/L). In addition, there were highly significant correlations between the K and P contents of different organs and the phosphorus nutrition level. The effect of different phosphorus levels on the Ca and Mg contents in stem was not obvious, but the contents of Ca and Mg in leaf decreased significantly as phosphorus level increased, while those in root reduced firstly and then increased, and their minimums occurred under the 0.1 mmol/L phosphorus level.

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    Inhibitory Effect of Winter Crops on Growth of Early Rice at Returning Green Stage and Slow Seedling Stage under Triple Cropping System
    LI Tianyuan,LIANG He,WEI Shanqing,CHEN Nianping,JIANG Ligeng,DU Fangfang,KONG Feiyang,ZHAO Quan
    2019, 40 (10):  2041-2046.  doi: 10.3969/j.issn.1000-2561.2019.10.018
    Abstract ( 489 )   HTML ( 15 )   PDF (622KB) ( 236 )  

    A field experiment was conducted to study the effects of winter crops on the growth of early rice at returning green stage and slow seedling stage by comparing three-cropping systems in rice field with the “winter fallow+Early rice+Late rice” system control. The returning green period and slow seedling stage of rice were prolonged about two to three days and one to three days, respectively. And the plant height, leaf age, chlorophyll content and dry matter of rhizome and leaves decreased during the two periods under the triple cropping system. The root-shoot ratio of rice under the triple cropping system was smaller than that of the control during the period from transplanting to slow seedling stage. The growth rate of rice under the triple cropping system was lower than that of the control during transplanting to returning green stage, while it was opposite during returning green stage to slow seedling stage. The conclusion is that winter crops significantly inhibits the plant growth of early rice under the triple cropping system at returning green stage and slow seedling stage, and the inhibiting effect becomes smaller after rice plants return to green.

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    Photosynthetic Characteristics and Yield of Machine-transplanted Rice in Southern Double-season Rice Areas under Water-saving Irrigation
    DU Yifan,LIU Fen,LIU Kun,WU Wangpin,WANG Yue,CHEN Guanghui
    2019, 40 (10):  2047-2053.  doi: 10.3969/j.issn.1000-2561.2019.10.019
    Abstract ( 493 )   HTML ( 17 )   PDF (452KB) ( 435 )  

    In order to compare the characteristics of different varieties under dry-wet alternate irrigation, 11 rice varieties were used as the materials to analyze the differences of seedling quality, photosynthetic characteristics, yield and yield components. There were significant differences in seedling quality among different varieties, mainly in seedling height, white root number and total root number. Among them, 24d61 (A2) was the most suitable mechanical transplanting variety. The net photosynthetic rate of 24d44 (A6) was 27.01 μmol/(m 2·s). The stomatal conductance and transpiration rate of Zhongzao39 (A7) was 1.69 mmol/(m 2·s) and 12.10 mmol/(m 2·s), respectively. The intercellular CO2 concentration of Zhongjianuo (A1) was significantly higher than that of the other varieties [376.09 μmol/(m 2·s)]. The plant height, yield per plant, seed setting rate and grain number per panicle of Luliangyou 996 (A10) were the highest. The correlation analysis between photosynthetic characteristics and yield components at heading stage showed that net photosynthetic rate was positively correlated with transpiration rate, effective panicles per plant and 1000-grain weight, negatively correlated with intercellular CO2 concentration and seed setting rate, positively correlated with grain number per panicle and seed setting rate, positively correlated with plant height and 1000-grain weight, and negatively correlated with each index of photosynthetic characteristics. But the difference was not significant. Therefore, this study is of great significance to the selection of suitable varieties for rice mechanical planting under water-saving irrigation conditions.

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    Investigation and Strategies for Winter Potato Fertilization in Guangdong Province
    LI Chengchen,AN Kang,SUO Haicui,LIU Xiaojin,LI Xiaobo
    2019, 40 (10):  2054-2060.  doi: 10.3969/j.issn.1000-2561.2019.10.020
    Abstract ( 493 )   HTML ( 14 )   PDF (427KB) ( 244 )  

    In order to understand the current situation of fertilizer applying and the existing problems in production on the potato in Guangdong province in recent years, an investigation of 160 households of winter potato planting in Eastern, Western, Northern Guangdong, and the Pearl River Delta in Guangdong were conducted, analyzed and evaluated. Most varieties of winter potato were Favorita series in Guangdong Province, and the sowing time was from the end of October to the beginning of November. The fertilization method was basal application with compound fertilizer and organic manure, and covered with black mulch. The potato yield was ranged from 33.5 to 45.0 t/hm 2, while the average yields in the Pearl River Delta region and Huidong County was up to 40.40 t/hm 2 and 42.39 t/hm 2, respectively. The chemical fertilizer application in the province was 2289 kg/hm 2, and the rate of nutrient N, P2O5 and K2O was 360 kg/hm 2, 288 kg/hm 2 and 430 kg/hm 2, respectively, or the ratio of N:P2O5:K2O was 1∶0.8∶1.19, which is not con-sistent with the potato formula fertilization ratio [1∶0.53∶(1.46~1.95)]. The input of organic fertilizer was 8615 kg/hm 2. In summary, the fertilization method of the potato planting in Guangdong was not scientific, and the chemical fertilizer was applied too much, especially excessive nitrogen and phosphorus. It is suggested to reduce the input of chemical fertilizer, add potassium fertilizer appropriately, increase organic fertilizer, popularize water and fertilizer integration technology, improve potato yield and planting efficiency, and achieve cost-saving efficiency and sustainable use of farmland according to the law of potato fertilizer requirement.

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    Spatial and Temporal Variability of Soil pH in Longyan Tobacco Planting Areas
    QIAN Xiaojie,XIAO Jing,HONG Yafang,SHI Guoqiang,TAN Qian,ZENG Wenlong,CAI Haiyang,XIONG Dezhong
    2019, 40 (10):  2061-2067.  doi: 10.3969/j.issn.1000-2561.2019.10.021
    Abstract ( 649 )   HTML ( 36 )   PDF (850KB) ( 317 )  

    The spatial and temporal variation of pH value of tobacco-growing soil in Longyan tobacco-growing areas was studied by the combination of traditional statistics and geostatistics. pH values of tobacco planting soil in Longyan tobacco-growing areas in 1982, 2001 and 2011 was 5.34, 5.03 and 5.23, respectively, meaning soil acidification was effectively inhibited. The semi-variance function model of soil pH in 1982, 2001 and 2011 was a linear model, linear model and exponential model correspondingly. In terms of spatial distribution, the high-value areas in 1982, 2001 and 2011 was in the form of block, dot and block accordingly. The areas that are not suitable for growing flue-cured tobacco show a trend of increasing first and then decreasing, and the area of the most suitable area is reduced.

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    Sugarcane Pollen Germination in vitro
    CHANG Hailong,ZHANG Wei,CHEN Junlyu,GUO Yuqiang,FANG Na,QIU Yongsheng,ZHOU Feng,WU Jiantao,LIU Zhuang,LIU Shaomou,WANG Qinnan
    2019, 40 (10):  2068-2075.  doi: 10.3969/j.issn.1000-2561.2019.10.022
    Abstract ( 564 )   HTML ( 17 )   PDF (986KB) ( 306 )  

    The pollens of sugarcane cultivar ROC22 were used as the main experimental material to seek for the basic conditions of the pollen germination in vitro by a single factor experiment, and the most appropriate culture medium formula was explored by an orthogonal experiment L16(4 5) in order to investigate the effects on sugarcane pollen germination under different temperatures. In the single factor experiment, the culture medium solidified slightly had the best effect. In certain range of concentration, sucrose, boric acid and calcium nitrate might promote pollen germination and inhibit pollen germination over the critical concentration. In addition, magnesium sulfate worked unsteadily, and the effect of potassium nitrate was little. In the orthogonal experiment, sucrose influenced significantly on the pollen germination rate in vitro and the pollen tube growth rate, boric acid took the second place, magnesium sulfate had little effect. The optimum temperature for pollen germination was 30 ℃, the pollen germination rate was 89.93% and the pollen tube length was 143.03 μm. It is concluded that, under 30 ℃, the pollen had the highest germination rate and the pollen tube grew well using the best culture medium formulas (200 g/L sucrose, 400 mg/L boric acid, 100 mg/L calcium nitrate, 400 mg/L magnesium sulfate and 1 g/L agar), which might help to identify the difference of various sugarcane pollen efficiently.

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    Evaluation of Markers Linked to Sex-specific and Development of SCAR Makers in Seed Hemp (Cannabis sativa L.)
    ZHAO Mingsen,FANG Shusheng,CHEN Yao,KANG Hongmei,GAO Jinhu,CHEN Siyuan,YANG Xin,FENG Xuping,ZHANG Liwu
    2019, 40 (10):  2076-2082.  doi: 10.3969/j.issn.1000-2561.2019.10.023
    Abstract ( 596 )   HTML ( 16 )   PDF (2091KB) ( 396 )  

    Hemp (Cannabis sativa L.) is a dioecious and cross pollinated plant. Sex identification of plants at seedling stage is of great significance for breeding and production in hemp. To develop new SCAR markers linked to sex-specific, three Chinese local seed hemp varieties, Fenma No.3, Yushema and Cangshanma, were used as the experimental materials to investigate the application of 11 markers linked to sex-specific in Chinese local seed hemp varieties in this study. The results showed that three makers (OPD-05 and UBC-354 as well as MADC2) were male-specific, while no female specific bands were found. Novel SCAR markers were developed on the basis of sequences of male specific bands. Among them, MADC2-8 was the best. Furthermore, 123 samples with known sex identification were used to assess the accuracy of MADC2-8. The average accuracy was 98.34%. These results would not only enrich the molecular markers linked to sex-specific, but also lay a foundation for the research and practical application of sex identification in hemp.

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    Fitting Models of Photosynthetic and Light-response for Autotetraploid and Diploid of Benincasa hispida (Thunb.) Cogn.
    WAN Zhenglin,ZHOU Yanxia,WU Peng,DENG Jianying,LI Lizhi,LONG Minghua
    2019, 40 (10):  2083-2090.  doi: 10.3969/j.issn.1000-2561.2019.10.024
    Abstract ( 478 )   HTML ( 14 )   PDF (574KB) ( 261 )  

    The purpose of the experiment was to choose fitting models of photosynthetic and light response for autotetraploid and diploid Benincasa hispida (Thunb.) Cogn., and to provide a theoretical basis for its breeding. Eight extensively applied models of photosynthetic and light response were compared to choose the most suitable light response curve model for autotetraploid and diploid B. hispida. The binomial regression model could deal with the photoinhibiton phenomenon, but it existed some problems during fitting, such as the respiration rate (Rday) value was above zero, the light compensation point (LCP) value was below zero, and impossible to explain the rapid decline of photosynthetic rate when light intensity reached saturation. The model of rectangular hyperbola, nonrectangular hyperbola, exponential functionⅠand exponential functionⅡcould not calculate LSP and LCP value directly, while the value calculated by combining other methods existed large deviation compared with the measured value, the exponential function Ⅱ showed obvious artificiality when calculating LSP value, and could not explain photoinhibition phenomenon. However, the values of LCP calculated by the four models were no large deviation with the measured values. Because of the coefficient β of the modified exponential function model was negative, the LSP and Pnmax value of the autotetraploid B. hispida cannot be calculated, and the LCP value of autotetraploid B. hispida was also obviously lower than the measured value. The Rday and LSP value of diploid B. hispida fitted by the modified rectangular hyperbola model were obviously lower than measured values, but the Pnmax value of autotetraploid and diploid B. hispida was the closest to the measured value, and it had advantage in fitting the Pnmax by the modified rectangular hyperbola model. The average relative error (RE) of all photosynthetic parameters and measured values was lowest fitted by the subsection function, and was also the closest to the measured value, and could deal with the photoinhibiton phenomenon well. Subsection function had better a fitting effect than other models, and the most suitable photosynthetic model of B. hispida was subsection function.

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    SmCCoAOMT Positively Regulates the Peel Coloring in Eggplant under High Temperature Stress
    LYU Lingling,FENG Xuefeng,LI Ke,LI Wei
    2019, 40 (10):  2091-2096.  doi: 10.3969/j.issn.1000-2561.2019.10.025
    Abstract ( 462 )   HTML ( 16 )   PDF (3334KB) ( 263 )  

    Caffeoyl-CoA-O methyltransferase (CCoAOMT) is a key enzyme in the lignin synthetic pathway and also plays an important role in abiotic stresses. According to the eggplant reference genome, SmCCoAOMT was cloned from eggplant. The maximum opening reading frame (ORF) of SmCCoAOMT was 564 bp, encoding 187 aa and its relative molecular weight was 20.95 ku. The bioinformation analysis indicated that SmCCoAOMT showed 90.67% sequence identity with CCoAOMTs of other plants and had all the conservative sequences in CCoAOMT. The expressions in eggplants with different peel colors and at different stages of fruit development were analyzed by qRT-PCR. The results showed that the expression of SmCCoAOMT was significantly higher in purplish red and blackish purple peels than in white and green peels, which was positively correlated with peel color. Comparing to control, on the 10 th and 20 th days after flowering (10DAF, 20DAF), the expressions of SmCCoAOMT were significantly down-regulated under high temperature (HT) stess, especially on 10DAF, the expression decreased to 9.23%. Which might lead to the light peel color. The results suggested that SmCCoAOMT positively regulated the peel coloring in eggplant under HT stress.

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