Genetic & Breeding·Germplasm Resources·Molecular Biology

• Function Study of Peptide Coding Gene MhCLE8 in Regulating Anthocyanin Accumulation in Apple（Malus × domestica）
• SHI Yan, ZHANG Tian'en, ZHU Baihui, LI Tong, LI Xiuming, YOU Chunxiang
• Acta Horticulturae Sinica. 2023, 50(12): 2541-2550. DOI:10.16420/j.issn.0513-353x.2021-0717
• Abstract ( 662 ) HTML ( 324 ) PDF (2746KB) ( 324 ) 　　　

• In this study，the role of MhCLE8（CLAVATA3/EMBRYO SURRSURROUNDING REGION 8）peptide hormone gene in regulating anthocyanin accumulation was investigated using the meterials Arabidopsis and apple calli. The results showed that the accumulation of anthocyanin in Arabidopsis seedlings and apple calli was significantly inhibited when treated with MhCLE8 peptide （referred to as MhCLE8p）which was synthesised in vitro. Phylogenetic analysis and multiple protein sequences alignment showed that MhCLE8 and its homologues in other plant species contain a highly conserved CLE-motif，and MhCLE8 showed high homology with Prunus armeniaca（CAB4276204.1）and Malus baccata（TQE01035.1）. The MhCLE8 gene was cloned to binary vector pRI，and transferred to Arabidopsis and apple calli to obtain the stable overexpression materials by Agrobacterium-mediated transgenic technology. The transgenic Arabidopsis seedlings and apple calli showed decresed accumulation of anthocyanin. The qRT-PCR analysis showed that the expression of anthocyanin biosynthesis structural genes in MhCLE8 overexpressed plant materials was inhibited to varying degrees. In summary，all the results suggested that the peptide encoding gene MhCLE8 was a negative regulator of anthocyanin accumulation.

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• Preliminary Study on the Mechanism of Flower Organ Development and Sex Formation in Different Grapes
• HAN Kai, LUO Yaoxing, JIAO Xiaobo, YAN Zhao, NAOMI Abe-Kanoh, MA Xiaohe, JI Wei
• Acta Horticulturae Sinica. 2023, 50(12): 2551-2567. DOI:10.16420/j.issn.0513-353x.2023-0010
• Abstract ( 526 ) HTML ( 164 ) PDF (5538KB) ( 164 ) 　　　

• In the current study，the flowers of three grape varieties‘Beichun'（hermaphrodite），‘1613C'（male） and‘520A'（female）were chosen. Hormone determination and transcriptome sequencing were performed at the early bud stage，large bud stage and blooming stage. The accumulation of various plant hormones in flowers of different genders was different，and so was that in flowers of the same gender at different developmental stages. The contents of IAA，ABA and MeJA were the highest in the large bud stage of female flowers. A total of 31 965 expressed genes were obtained，and 1 535 genes were directly related to flower development and were mainly involved in phenylpropane synthesis and plant hormone signal transduction pathways. Some genes are continuously up-regulated or down-regulated at different developmental stages. The genes that are continuously up-regulated are mainly involved in Phenylpropane synthesis，plant hormone signal transduction and other pathways. The genes that are continuously down-regulated are mainly involved in starch and sugar metabolism，and amino acid synthesis. MADS-box genes，such as AP1，SEP1，AG2 and SOC1 were significantly differently expressed in different floral organs at developmental stages. During flower sex differentiation，the differential expression of the MADS-box gene，the flower-induced integron gene，and the detoxification and stress-related genes play important roles.

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• Analysis of Genetic Diversity of Wild Jujube Germplasm Resources Based on Quantitative Characters
• DUAN Kaihang, WANG Xiaoling, MAO Yongmin, WANG Yao, REN Yongxiang, REN Liuliu, SHEN Lianying
• Acta Horticulturae Sinica. 2023, 50(12): 2568-2576. DOI:10.16420/j.issn.0513-353x.2022-0931
• Abstract ( 367 ) HTML ( 235 ) PDF (678KB) ( 235 ) 　　　

• Twenty-one quantitative characters（weight of single fruit，stone weight，a thouthand kernel weight，total sugar content，titratable acid content，etc.）of Ziziphus jujuba Mill. var. spinosa（Bunge）Hu ex H. F. Chow fruits'genetic variation rule and genetic diversity were studied in 393 wild jujube germplasm from follow provinces of Hebei，Liaoning，Shandong，Shaanxi．The results showed that the wild jujube germplasm was rich in genetic diversity. The obvious variety was observed with18 quantitative characters. The Shannon's index of the 18 quantitative characters exceeded 1.0. The degree of genetic diversity between various regions was distinctly different，and the upper-to-lower order of the various regions based on Shannon's index was Xingtai（H' = 1.198），Handan（H' = 1.147），Chaoyang（H' = 1.120），Baoding（H' = 1.069），Yulin（H' = 0.953），and Tai'an（H' = 0.733）. Cluster analysis divided the wild jujube germplasm into three groups，North China，Shaanxi，Liaoning. The wild jujube germplasm in North China（mainly represented by Xingtai）was the richest in quantitative diversity，which provides a wealth of material to choose for the breeding. The principal component analysis on quantitative characters result showed that the accumulative contribution rate of the first four principal components accounted for 71.85% in the total variation accounted，and the first principal component mainly reflected the fruit mass and a thouthand kernel weight，while the second principal component reflected the titratable acid content. The third and fourth principal component reflected stone vertical diameter and vitamin C content，respectively.

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• Expression of S-RNase in vitro and Identification of Its Interacting Protein FviFPA from Fragaria viridis
• NI Zhiyou, XU Linlin, Du Jianke, WANG Jing, WANG Tao, PAN Jiaoyan, ZHAO Mizhen, QIAO Yushan
• Acta Horticulturae Sinica. 2023, 50(12): 2577-2590. DOI:10.16420/j.issn.0513-353x.2022-1017
• Abstract ( 166 ) HTML ( 76 ) PDF (3423KB) ( 76 ) 　　　

• The self-incompatible style determinants S_a-RNase，S_b-RNase and their interacting protein FviFPA were studied based on the selfing progenies of Fragaria viridis 10-42 line. The results showed that the recombinant S-RNase protein obtained by prokaryotic expression technology could specifically inhibit self-pollen growth，both the pollen germination rate and pollen tube length decreased with the increase of the recombinant protein concentration. FviFPA protein that interacts with S_a-RNase was screened from Fragaria viridis style cDNA library in the early stage. In this study，the full-length of FviFPA was cloned and the bioinformatics was analyzed，the authenticity of the interaction between FviFPA and S-RNase was verified by yeast two-hybrid and bimolecular fluorescence complementation assay，and there was no haplotype specificity in the interaction.

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• Optimization of Gene Editing System Based on Heat-treated CRISPR/Cas9 Potato Plants
• XIONG Wenwen, LIU Huimin, CHEN Kaiyuan, DU Juan, SONG Botao, JING Shenglin
• Acta Horticulturae Sinica. 2023, 50(12): 2591-2600. DOI:10.16420/j.issn.0513-353x.2022-1168
• Abstract ( 262 ) HTML ( 103 ) PDF (3027KB) ( 103 ) 　　　

• The development of endogenous promoters driven CRISPR/Cas9 gene editing system in diploid potato cultivar AC142 and tetraploid cultivar E3 were reported. The StPDS gene was targeted by Agrobacterium-mediated potato microtuber transformation. Through the analysis of transformation efficiency and phenotypic mutation rate，HM4 driven by potato endogenous promoter StU6 and StUBI10 was selected as the optimal CRISPR vector. The short-term cycle of eight heat treatment（37 ℃ 24 h，22 ℃ 24 h）was performed on the lateral buds of 37 AC142 all-green lines and chimeric lines and four E3 all-green lines obtained from HM4 for 15 days. Phenotypic analysis and sequencing showed that short-term heat treatment of knockout lines could significantly improve the editing efficiency of CRISPR/Cas9. At room temperature，the phenotypic mutation rates of AC142 and E3 knockout lines were 16.2%（6/37）and 0（0/4），respectively. After one short-term heat treatment，the phenotypic mutation rates were increased to 54.1%（20/37）and 75%（3/4），respectively. Among them，AC142 knockout lines can obtain 10.8%（4/37） lines that maintain the albino phenotype，while E3 can only obtain 75%（3/4）chimeras with white spots. Four consecutive short-term heat treatments could result in 2.1%（3/144）albino mutants at room temperature in E3 knockout lines. TA cloning was performed on the albino lines after short-term heat treatment. The sequencing results showed that 8-12 single clones of the diploid knockout line CR-AC142-StPDS-17，21 and the tetraploid knockout line CR-E3-StPDS-3，four did not contain wild type，indicating that the knockout system in this study could induce mutations in the target sequence. The results provide a technical basis for functional genomics research and precise improvement of target traits in potato.

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• Identification of Luffa Under Low Temperature and Weak Light Stress Gene Co-expression Modules by WGCNA
• WANG Xuanzhen, CHEN Mindong, LIU Jianting, ZENG Meijuan, YE Xinru, LI Yongping, WEN Qingfang, ZHU Haisheng
• Acta Horticulturae Sinica. 2023, 50(12): 2601-2618. DOI:10.16420/j.issn.0513-353x.2022-0769
• Abstract ( 167 ) HTML ( 82 ) PDF (4931KB) ( 82 ) 　　　

• To study coexpression network of Luffa cylindrica（L.）Roem under low temperature and weak light stress，weighted gene co-expression network analysis was introduced. WGCNA to screen out the core genes that respond to low temperature and weak light. Based on 15 transcript sequencing samples of common Luffa treated with low temperature and weak light，phenotypic matrix was created with low temperature and weak light samples as processing traits，and 29 module were clustered，among which 13 module were correlated with low temperature and weak light treatment traits. The three module with the highest positive correlation were predicted and 108 transcription factors were obtained，among which the top three types were ERF（18），MYB（10）and NAC（10）. According to the enrichment of KEGG pathway，the three module are involved in peroxisome，plant hormone signal transduction，photosynthesis and MAPK signal pathway，respectively. Three core genes were screened from the module according to topological overlap matrix（TOM），module member-ship（MM）and connectivity（K.in），and identified as ATPβ，G6PDH and PER5 by protein homology analysis. The analysis of up-expression and down-expression differentially expressed genes （DEG）of the three core genes showed that 93.97% of down-expression genes of G6PDH were down-regulated in the downstream genes，and the up-expression expression of G6PDH gene induced by low temperature and weak light might inhibit the expression of downstream associated genes. The promoters of the three core genes had elements such as low temperature response，methyl jasmonate response，gibberellin response and light response. The co-expression networks of the three core genes predicted ERF transcription.

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• Effects of Three Auxin-Related Genes LfiPIN1，LfiPIN6 and LfiARF9 on Branching of Lagerstroemia indica
• HUANG Jiayu, LIU Jieru, KANG Jiayin, CHI Xiufeng, SHEN Ping, CAI Ming, CHENG Tangren, WANG Jia, ZHANG Qixiang, PAN Huitang
• Acta Horticulturae Sinica. 2023, 50(12): 2619-2632. DOI:10.16420/j.issn.0513-353x.2022-1136
• Abstract ( 170 ) HTML ( 78 ) PDF (3170KB) ( 78 ) 　　　

• To investigate the mechanism underlying branching in Lagerstroemia indica，both standard and dwarf compact L. indica strains were used as material，the function of three genes involved in auxin transport and response，namely LfiPIN1，LfiPIN6 and LfiARF9，were analyzed using virus-induced gene silencing（VIGS）in L. indica and overexpression techniques in Nicotiana tabacum. The effects of these genes on lateral bud initiation and lateral branch length in L. indica were examined. The results showed that LfiPIN6 and LfiARF9 negatively regulate the number of lateral branches in L. indica by inhibiting the sprouting of lateral buds. LfiPIN1 and LfiPIN6 positively regulate the length of lateral branches by regulating the auxin content in newly formed lateral branches. LfiARF9 was found to have no effect on lateral branch length.

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Cultivation Physiology & Biochemistry

• Effects of TDZ，CPPU and GA₃ on Fruit Quality of‘Shine Muscat'Grape
• ZHANG Feixue, ZHANG Shuhong, MA Yandong, CHEN Feng, SONG Xianjie, LIU Ruijie
• Acta Horticulturae Sinica. 2023, 50(12): 2633-2640. DOI:10.16420/j.issn.0513-353x.2023-0083
• Abstract ( 448 ) HTML ( 147 ) PDF (713KB) ( 147 ) 　　　

• The‘Shine Muscat'grapes were used as the experimental material. Combined treatments of gibberellic acid（GA₃），forchlorfenuron（CPPU），tiabenon（TDZ）were used to study their effects on fruit quality under different application methods，treatment periods，concentrations and combinations. The results from this were then used to screen for the best combination of growth regulators，and provide scientific basis for its cultivation of denuclearization. Results showed that：dipping 2 mg · L^-1 TDZ + 1 mg · L^-1 CPPU + 15 mg · L^-1 GA₃ into flower spikes within 24 h of blooming，dipping 4 mg · L^-1 TDZ + 25 mg · L^-1 GA₃ in the early stage of fruit expansion had the best effect. The cluster mass and single fruit weight were 779.24 g and 9.84 g，respectively，which were increased by 35.14% and 22.24% compared with the water control group. The longth of the fruit was 27.69 cm，the width of fruit grain was 24.75 cm，and the seedless rate was 96%，which increased by 8.97%、16.53% and 118.18% compared with the control. The total acid content was 3.98 g · kg^-1，decreased by 7.44% compared with the control group，vitamin C content was 7.98 μg · g^-1，increased by 48.60% compared with the control group，soluble sugar content was 16.28%，increased by 21.95% compared with the control group. This treatment had larger fruit size and better taste，and could significantly improve the fruit quality of‘Shine Muscat'. It is the most suitable combination of planting and conditioning for‘Shine Muscat'grape.

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• The Culture Technique of Isolated Microspore in Tetraploid Chinese Cabbage
• LIU Xiaodong, WU Fang, MENG Chuan, MU Jingui, WANG Yuhai, WANG Mingqiu
• Acta Horticulturae Sinica. 2023, 50(12): 2641-2652. DOI:10.16420/j.issn.0513-353x.2023-0046
• Abstract ( 164 ) HTML ( 64 ) PDF (8255KB) ( 64 ) 　　　

• The gametes produced during the meiosis process of tetraploid Chinese cabbage are diverse. The purpose of carrying out free microspore culture of tetraploid Chinese cabbage is to obtain more new homozygous diploid resources with a large degree of variation. In this study，four easy embryogenic materials were selected from 14 early-maturing tetraploid Chinese cabbages. The technical system of isolated microspore culture of tetraploid Chinese cabbage was established in the aspects of flower bud phenotype，heat shock temperature，rooting hormone and ploidy identification. The results were as follows：For different genotypes of tetraploid Chinese cabbage，when petal/anther of flower buds was 0-0.5，the microspore was in the stage of mononuclear sideline，and the embryo rate was the highest at this time. When the heat shock temperature was 33.5 ℃ and dark culture for 24 h，they were beneficial to microspore embryogenesis. For rooting medium，the combination of indole butyric acid（IBA）and naphthylacetic acid（NAA）was better than single hormone. The optimum concentration was IBA 0.3 mg · L^-1 and NAA 0.1 mg · L^-1. The ploidy was detected by flow cytometry，chromosome microscopy and cross pollination. The results showed that the probability of diploid was 94.87% and the probability of tetraploid was 5.13% in 39 regenerated plants.

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• Effects of Spectral Matching-based Light Conversion Greenhouse Films on Growth and Fruit Quality of Capsicum annuum
• GAO Jinhui, ZHANG Danqiu, LIAN Shixun, WANG Chuanqing, WEI Min, MI Qinghua, LI Yan
• Acta Horticulturae Sinica. 2023, 50(12): 2653-2664. DOI:10.16420/j.issn.0513-353x.2022-1003
• Abstract ( 139 ) HTML ( 64 ) PDF (1452KB) ( 64 ) 　　　

• In order to screen special greenhouse films suitable for the protected cultivation of sweet pepper，the coating-anti-fog ethylene vinyl acetate copolymer（EVA）colorless greenhouse films with the addition of light conversion agents of GTR650 and VTR660，respectively，were applied with the red sweet pepper variety of‘Kaitelin'as plant material in this study. This type of EVA greenhouse film without light conversion agent was used as control. Then，the fluorescence spectrum and mechanical properties of different light conversion greenhouse films and the light conversion characteristics under solar greenhouse when covered by these films as well as their effects on the growth，fruit yield and main quality of sweet pepper were studied. The results showed that the films with the addition of GTR650 and VTR660 were excited by 520 nm of green light and 335 nm of ultraviolet light，and then，produced red light emission peaks at 645 nm and 654 nm，respectively. Compared with control，the light conversion greenhouse films of GTR650 and VTR660 could significantly improve the transmittance of red-orange and far-red light under solar greenhouse，and it was found to be higher under film of VTR660 than that of GTR650. However，the transmittance of violet and green light was significantly reduced under light conversion greenhouse films，among which，the transmittance of violet light under VTR660 film and green light under GTR650 film was the lowest. In addition，compared with control，the mechanical strength of the light conversion greenhouse films was significantly higher，while the light transmittance was significantly lower. Moreover，the vertical and horizontal tensile strength and elongation at break of VTR660 film was increased by 4.9%，10.4% and 11.2%，11.5%，relative to control，respectively. The stem diameter，leaf numbers，net photosynthetic rate，fruit yield and content of vitamin C，total phenols，anthocyanins，total sugar，starch and glucose of sweet pepper under VTR660 film were significantly higher than those of control and GTR650 film，and the yield and anthocyanin content of sweet pepper fruit under VTR660 film was increased by 8.1% and 40.8% relative to control，separately. Covering this greenhouse film could evidently enhance the activities of penylalaninelyase，chalcone isomerase，dihydroflavonol reductase，anthocyanin synthase，sucrose synthase，sucrose phosphate synthase，neutral invertase，acid invertase and β-amylase in sweet pepper fruit. In summary，in the present study，the emission spectrum of EVA greenhouse film added by light conversion agent of VTR660 could match well with the photosynthetic absorption spectrum of sweet pepper，and optimize the light environment under solar greenhouse by converting the transmitted light qualities，namely by enhancing the transmittance of red-orange and far-red light. This was conducive to the plant growth of sweet pepper and promoted the anthocyanin and sugar metabolism in fruit，subsequently improved the fruit quality.

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• Effects of Pumpkin Rootstock Grafting on the Expressions of Basic DUS Characteristics and Fruit Quality Indicators in Cucumber
• FU Shenzao, REN Jun, WANG Xin, WANG Ningning, FANG Jian, XU Donghui, YANG Kun
• Acta Horticulturae Sinica. 2023, 50(12): 2665-2679. DOI:10.16420/j.issn.0513-353x.2023-0524
• Abstract ( 328 ) HTML ( 78 ) PDF (876KB) ( 78 ) 　　　

• Using one variety each for North China type，South China type，and European type as scion，and one pumpkin variety as rootstock，the effects of rootstock grafting on the expression of 50 basic DUS characteristics and five fruit quality indicators of cucumber varieties were studied in accordance with the“NY/T 2235-2012 guidelines for the conduct of tests for distinctness，uniformity and stability- cucumber”and UPOV Testing Guidelines TG/61/7. The results showed that：（1）Among the 50 basic DUS characteristics，ten qualitative characteristics，seven pseudo-qualitative characteristics，and seven quantitative characteristics which were visually assessed remained unchanged between the grafted and self-rooted treatments of the three varieties，indicated that these characteristics had good stability and they could be used as the main characteristics for identifying cucumber varieties grafted with rootstocks;the notes of other six quantitative characteristics which were visually assessed differed by one between the grafted and self-rooted treatments，resulting in the difference was not significant，so these characteristics could be used as the alternative characteristics for identifying cucumber varieties grafted with rootstocks. While，grafting had an impact on the quantitative characteristics which were measured by individuals，with significant differences in internode length of main vine and length of leaf blade between the grafted and self-rooted treatments of the three varieties，making them unsuitable for identifying cucumber varieties grafted with rootstocks.（2）Compared with the self-rooted plant，the protein content of the fruits in the grafted plant of three varieties was significantly increased，while the soluble solid content，vitamin C content and soluble sugar content did not significantly change. The dry matter content in the grafted plant of North China type variety was significantly reduced，while there was no significant change in the South China and European type varieties.

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Plant Protection

• Arbuscular Mycorrhizal Fungi Improve Drought Tolerance of Trifoliate Orange Seedlings by Regulating Root Polyamines
• LIANG Shengmin, ZHANG Fei, WU Qiangsheng
• Acta Horticulturae Sinica. 2023, 50(12): 2680-2688. DOI:10.16420/j.issn.0513-353x.2022-1036
• Abstract ( 187 ) HTML ( 106 ) PDF (939KB) ( 106 ) 　　　

• In order to clarify whether and how arbuscular mycorrhizal fungi regulate polyamines to enhance drought tolerance of citrus，trifoliate orange（Poncirus trifoliata）seedlings were inoculated with an arbuscular mycorrhizal fungus Rhizophagus intraradices，and the changes in growth，leaf water potential，reactive oxygen species levels，polyamines and polyamine precursors levels，and polyamine synthesis/cleavage enzyme activities were analyzed under well-watered and drought stress. The drought with nine weeks inhibited the colonization rate of R. intraradices in roots by 16.85%. Drought also significantly inhibited the growth and leaf water potential of trifoliate orange，while inoculation with R. intraradices considerably mitigated the inhibitive effect. Inoculation with R. intraradices significantly increased agmatine，S-adenosyl-L-methionine，putrescine，and cadaverine concentrations in roots under drought stress，along with the significant reduction in spermidine，spermine，L-arginine，L-ornithine，hydrogen peroxide，and superoxide anion radicals levels in roots. R. intraradices inoculation also distinctly elevated activities of various polyamine synthetases，such as arginine decarboxylase，ornithine decarboxylase，spermidine synthetase，spermine synthetase，and S-adenosyl methionine decarboxylase，and also increased activities of polyamine metabolism enzymes，such as diamine oxidase and polyamine oxidase. In addition，putrescine and cadaverine concentrations were significantly and negatively correlated with root superoxide anion radicals levels，while spermidine concentrations were positively correlated with root hydrogen peroxide and superoxide anion radicals levels. Therefore，it is concluded that arbuscular mycorrhizal fungi alter polyamine levels in roots of drought-stressed trifoliate orange to reduce reactive oxygen species burst.

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• In Situ Hybridization Analysis of Distinctive Ribonucleotide Reductase β Subunit Gene from Candidatus Liberibacter Asiaticus of Citrus
• ZHANG Shaoran, ZONG Qi, LIU Yang, JIANG Ling
• Acta Horticulturae Sinica. 2023, 50(12): 2689-2700. DOI:10.16420/j.issn.0513-353x.2022-1095
• Abstract ( 141 ) HTML ( 49 ) PDF (4737KB) ( 49 ) 　　　

• Candidatus Liberibacter asiaticus（CLas），can be determined by qPCR detection. However，the selection of different tissue samples will affect the results of qPCR detection. Therefore，it is necessary to study the location of CLas in citrus tissues. Based on the specific gene sequence of ribonucleotide reductase（RNR）β subunit of CLas of citrus Huanglongbing disease（HLB），123 bp antisense RNA probe and sense RNA probe was designed and prepared. In situ hybridization analysis was performed on the pathogen gene of CLas in shoot tip，leaf vein，petiole，clade and root tip，meanwhile，the pathogens were detected by qPCR. The results showed that the visual blue hybridization signals in sieve tube and companion cells of phloem in CLas-infected plants could be clearly observed under the microscope and the distribution of pathogens in the different organs was significantly different，compared with root tip and shoot-tip，RNR gene distribution in phloem of bark，petiole and vein was more accurate locating. The HLB-infected condition detected by qPCR and the visualization results of in situ hybridization shared the consistency in citrus nursery plants.

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• Studies on Function and Mechanism of CsNAC2 Transcription Factor in Resistance to Green Mold in Citrus
• CHEN Qi, LI Ting, CHEN Jialin, CHEN Ou, WANG Wenjun, YAO Shixiang, ZENG Kaifang
• Acta Horticulturae Sinica. 2023, 50(12): 2701-2712. DOI:10.16420/j.issn.0513-353x.2022-1208
• Abstract ( 155 ) HTML ( 53 ) PDF (3043KB) ( 53 ) 　　　

• In order to investigate the effect of citrus transcription factor CsNAC2 on resistance to green mold，the coding sequence of CsNAC2 was cloned using‘Jincheng 447'as study material. Bioinformatics analysis，yeast one-hybrid assay，RNA-Seq，EMSA and qRT-PCR were employed to explore the regulatory function of CsNAC2 on fruit green mold resistance. The results showed that the coding sequence of CsNAC2 is 909 bp，encoding 302 amino acids，and the molecular weight of the protein is 34.40 kD. CsNAC2 possesses the structural characteristics of the NAC family and contains conserved NAC domain in the N terminal. Transient overexpression of CsNAC2 on citrus fruit could effectively reduce the incidence of green mold in fruit，with a considerable decrease in incidence and spot diameter. Transcriptomic analysis showed that CsNAC2 can participate in several metabolic pathways related to disease resistance in fruits. Further studies on lignin synthesis pathway，amino acid and nucleotide sugar metabolism pathway showed that CsNAC2 can bind the CsLAC7 and CsEP3 gene promoters in these two pathways，respectively. Transient overexpression of CsNAC2 increased the expression of CsLAC7 and CsEP3 genes. The comprehensive results indicated that CsNAC2 may activates the expression of CsLAC7 and CsEP3 genes to enhance the resistance to green mold in citrus fruits.

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• Endophytic Fungi and the Relations to the Fruit Drop of Citrus
• CUI Xuejing, ZHANG Jianing, CHEN Jianghua, JIA Jichun, LIN Yang, FU Yanping
• Acta Horticulturae Sinica. 2023, 50(12): 2713-2722. DOI:10.16420/j.issn.0513-353x.2022-1000
• Abstract ( 134 ) HTML ( 47 ) PDF (3894KB) ( 47 ) 　　　

• In order to explore the relation of endophytic fungi and fruit drop，the diversity of fungi in the dropping and healthy fruits of Newhall navel orange during the second fruit drop stage was studied by Illumina MiSeq sequencing technology. It was found that there were significant increases in the richness，evenness of the fungal community in the dropping fruits compared to the healthy fruits，and the composition structure was also different between them. Twenty-three endophytic fungal strains were isolated successfully from the dropping fruits and classified based on ITS sequences. Through artificial inoculation，some endophytic fungal strains could cause yellowing of the young citrus fruits and increase the content of abscisic acid and ethylene release in the fruits. The results suggest that the change of the endophytic fungal communities and the resulting change in the ABA and ETH might be involved in the second drop of citrus fruit.

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• Identification and Biological Characteristics of the Pathogens Causing Marigold Wilt in Xinjiang
• Nursimangul·Aihaiti, Aigamarie·Abdulzaire, SUN Yongmin, HAN Wenjie, GUO Qingyuan, WANG Lili
• Acta Horticulturae Sinica. 2023, 50(12): 2723-2734. DOI:10.16420/j.issn.0513-353x.2022-0999
• Abstract ( 149 ) HTML ( 65 ) PDF (3354KB) ( 65 ) 　　　

• The purpose of the study was to clarify the species and biological characteristics of the pathogens of marigold wilt in Xinjiang Uygur Autonomous Region. A series of experiments were conducted through tissue isolation，single spore purification，pathogenicity determination，morphological Characteristics，phylogenetic analysis of ITS and EF-1α sequences and identification of biological characteristics. The results showed that four pathogens were identified as Fusarium fujikuroi，F. solani，F. equiseti and F. culmorum. The optimum temperature for the growth of all Fusarium species was 25 ℃ and the optimum pH range was 6-7. Full-darkness was conducive to the mycelial growth of F. fujikuroi，but full-light was suitable for the rest species. They differed in their optimum growing conditions. The mycelial of F. fujikuroi grew better on media of PDA and PSA，and was in favor of lactose and potassium nitrate as the optimal carbon and nitrogen sources. For F. equiseti，the optimal medium was PDA，and the optimal carbon and niteogen sources were lactose and yeast extract. For F. solani，the best medium was Czapek medium，and the best carbon and nitrogen sources were lactose and peptone. For F. culmorum，the beneficial media were PSA，PDA and CA，and the beneficial carbon and nitrogen sources were soluble starch，yeast extract and ammonium chloride. Their mycelial lethal temperature were at 64 ℃，63 ℃，63 ℃，52 ℃ for 10 min respectively. Among of them，F. solani is the most dominant pathogenic species causing marigold wilt in Xinjiang because of highest separation frequency of 68%.

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• Determination and Analyses of the Complete Genome Sequences of Apple Stem Grooving Virus Isolates Infecting Tree Peony
• CHEN Ling, GUO Cheng, JIA Anning, DENG Congliang, CHONG Yan, SHI Xiju, LI Yongqiang
• Acta Horticulturae Sinica. 2023, 50(12): 2735-2747. DOI:10.16420/j.issn.0513-353x.2023-0277
• Abstract ( 114 ) HTML ( 46 ) PDF (5691KB) ( 46 ) 　　　

• Apple stem grooving virus（ASGV）was detected in tree peony（Paeonia sect. moutan）plants cultivated in Beijing region in previous study，and the complete genome sequence of one ASGV-tree peony isolate was obtained. To analyze the genetic diversity of tree peony-infecting ASGV，the complete genome sequences of nine ASGV-tree peony isolates were obtained using overlapping RT-PCR and rapid amplification of cDNA ends（RACE）techniques with specific primers designed according to the conserved regions of 118 reported ASGV complete genome sequences. Pairwise alignment of the complete genome sequences of total ten ASGV-tree peony isolates showed the nucleotide identity of 81.9%-97.6%. Alignment of ASGV-tree peony isolates and other isolates showed the nucleotide identity of 80.8%-91.2%. Sequence analyses indicated that the molecular diversity of ASGV-tree peony isolates mainly located in the regions between Mtr and P-Pro，RdRp and CP，which were the conserved domains of ASGV-encoded polyprotein. Five ASGV-tree peony isolates were identified as recombinants，including one recombinant whose recombinant parents developed from different host plants in different countries，performed by recombination analyses using the complete genome sequences of 127 ASGV isolates. Phylogenetic tree constructed using 79 non-recombinant ASGV complete genome sequences suggested that ASGV-tree peony isolates clustered into the first group closely with ASGV isolates from apple，pear，citrus and so on，and ASGV-tree peony isolates clustered into different clades. These results revealed the genetic diversity of tree peony-infecting ASGV，and recombination is a factor that likely contributes to this diversity.

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Review

• Advances in Functional Genes for Important Traits in Watermelon
• ZHANG Lei, WU Jingchun, ZHANG Haiying, GONG Guoyi, LIU Tangjing, ZHANG Jie, XU Yong
• Acta Horticulturae Sinica. 2023, 50(12): 2748-2764. DOI:10.16420/j.issn.0513-353x.2022-1218
• Abstract ( 221 ) HTML ( 171 ) PDF (806KB) ( 171 ) 　　　

• This paper reviews the latest researches on functional gene of important plant traits，fruit quality traits，and disease resistance traits in watermelon. The application prospect of pyramiding multiple genes for molecular breeding technology in watermelon is discussed，to provide references for the development of watermelon molecular breeding system.

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New Cultivars

• A New Plum Cultivar‘Congzao 1 Zaoli'
• HE Yehua, PAN Jianjun, YANG Xianghui, LIU Chaoyang, LI Chuhao, XIA Jingxian, ZHANG Wei, PENG Weizhuo, HAO Jingjing, XU Rongbo, KONG Wenhui, ZHONG Yizhong
• Acta Horticulturae Sinica. 2023, 50(12): 2765-2766. DOI:10.16420/j.issn.0513-353x.2021-0317
• Abstract ( 142 ) HTML ( 69 ) PDF (3098KB) ( 69 ) 　　　

• A new plum cultivar，‘Congzao 1 Zaoli'is selected from the‘Zaoli'population propagated by root tiller in Conghua District，Guangzhou City，using the individual selection method. This cultivar has characteristics such as high and stable yield，easy blooming and early ripening. The fruit ripens from late April to middle May. The fruit shape is nearly round and the average fruit weight is 25.3 g. The peel is red and flesh is yellow，with sweet and sour flavor. The fruit is suitable for fresh-eating and processing. The yield is about 26 700 kg · hm^-2 in the fifth year of planting. It can be well cultivated in plum-growing regions in Guangdong Province.

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• A New Lentinula edodes Cultivar‘Huxiang F7'
• YU Hailong, ZHANG Lujun, Song Chunyan, SHANG Xiaodong, FENG Peng, ZHANG Meiyan, TAN Qi
• Acta Horticulturae Sinica. 2023, 50(12): 2767-2768. DOI:10.16420/j.issn.0513-353x.2021-0994
• Abstract ( 115 ) HTML ( 28 ) PDF (973KB) ( 28 ) 　　　

• ‘Huxiang F7'is a new cultivated strain of Lentinula edodes obtained by spore mon-mon mating between factory production strain‘Huxiang F3'and main cultivar in Northern China‘0912'. The growth age of‘Huxiang F7'is 85-90 days，the fruiting temperature is about 20 ℃，the deformity rate of fruitbody is less than 1%. Fruitbodies of‘Huxiang F7'grow individually，the pileus is round，brown and convex with a diameter of（6.33 ± 0.57）cm which belongs to medium to large grade. The average weight of single fruitbody is（26.8 ± 2.72）g. The scales on the surface of pileus are light brown and medium in size. The stipe is columnar with brown cilia and the length is（5.22 ± 0.47）cm，belonging to medium length. The arrangement of gill is regular and flat.‘Huxiang F7'is suitable for industrialized mushroom production in South China in summer.

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• A New Mini Yellow Flesh Watermelon Cultivar‘Huangfei'
• YUAN Shengkai, WANG Mingqiang, ZHAO Lifeng, FANG Zhenxiong, CAO Baobing, WU Jianzhi, LI Guangjie, LIU Xiaoyun, JIA Yuzhen, MA Qiang, ZHANG Mengdan, ZHAO Zhikun, MA Changsheng
• Acta Horticulturae Sinica. 2023, 50(12): 2769-2770. DOI:10.16420/j.issn.0513-353x.2020-0020
• Abstract ( 238 ) HTML ( 81 ) PDF (2267KB) ( 81 ) 　　　

• ‘Huangfei'is a new mini yellow flesh watermelon cultivar inbred line YYYH26 as female parent and a inbred line YYHX-16 as male parent. Its whole growth period is 85-95 days，and the fruit development period is 32-35 days in protected cultivation. The plant is tendril，and growth potential is normol，with light yellow green leaves. It's easy to sit fruit，and the fruit shape index is 1.1. Its skin color is light yellow covered with dark yellow strips. The average fruit weight is about 1.5-2.0 kg. The rind is about 0.3-0.5 cm in thickness，so it's resistant to storage and transportation. Also，the flesh is crisp. Average soluble solids content is about 12.1% in the center and 10.0% in the edge. The yield is 22 500-30 000 kg · hm^-2 in creeping-culture;and its yield is 36 000-48 000 kg · hm^-2 in hanging vine cultivation. It's suitable for planting in North China，Huang-huai River Basin，Northwest and other regions.

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• A New Dendrobium Cultivar‘Zixia'
• CHEN Heming, LÜ Fubing, LI Zuo, XIAO Wenfang
• Acta Horticulturae Sinica. 2023, 50(12): 2771-2772. DOI:10.16420/j.issn.0513-353x.2020-0529
• Abstract ( 403 ) HTML ( 382 ) PDF (1148KB) ( 382 ) 　　　

• The new cultivar‘Zixia'is derived from the cross Dendrobium Ekapol‘Big Panda'and Dendrobium‘Yuki'. The flower color is purple and bright and the average single branch has 5.3 flowers with flower diameter of 6.8 cm and the branch length is 35.0 cm. The beginning flower of this cultivar is in October and full bloom is November and December when cultured in greenhouse of guangzhou，and can be widely planted in South China.

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• A New Osmanthus fragrans Cultivar ‘Dongxiang'
• CHEN Jiyu, XIAO Xia, LI Yuan, YU Xiajun, DU Huaping, WANG Yuanhui, CHEN Yuan, QIN Haiying
• Acta Horticulturae Sinica. 2023, 50(12): 2773-2774. DOI:10.16420/j.issn.0513-353x.2022-0012
• Abstract ( 243 ) HTML ( 50 ) PDF (1303KB) ( 50 ) 　　　

• ‘Dongxiang'is a new cultivar selected from the seedlings of‘Xiaoronghuang'in Osmanthus fragrans Siji Group. The crown naturally grow into a spherical shape with fast growth，without pruning or just slightly pruning. New shoots grow three times a year in spring，summer and autumn. It has dense flowering，rich aroma，with high ornamental value.

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• A New Cerasus campanulata Cultivar‘Zhuangyuan'
• ZENG Zhaojia, RAO Xianlong, HU Xiaomin, YE Xiaoling, ZHU Jun, YANG Zibin
• Acta Horticulturae Sinica. 2023, 50(12): 2775-2776. DOI:10.16420/j.issn.0513-353x.2021-0750
• Abstract ( 132 ) HTML ( 51 ) PDF (1188KB) ( 51 ) 　　　

• ‘Zhuangyuan'is a new cultivar bred from the seedlings of Cerasus campanulata. The flowers are vivid purplish red，with five ovate petals separated from each other. The sepals are reflexed and sparsely hairy. The flowering period is in February.

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