Research Papers

• Identification of Apple POD Gene Family and Functional Analysis of MdPOD15 Gene
• MA Weifeng, LI Yanmei, MA Zonghuan, CHEN Baihong, MAO Juan
• Acta Horticulturae Sinica. 2022, 49(6): 1181-1199. DOI:10.16420/j.issn.0513-353x.2021-0275
• Abstract ( 788 ) HTML ( 485 ) PDF (5503KB) ( 485 ) 　　　

• To explore the role of peroxidase（POD）gene family members under stress conditions in apples,51 apple POD（MdPOD）family members were identified through multiple sequence alignments in which the reported Arabidopsis thalianaPOD genes were adopted,and their expression under stresses are analyzed. The results show that the 51 family members scatter in 13 chromosomes,encoding 95 to 1 433 amino acids,protein molecular weight ranges 10.18 to 161.02 kD,and isoelectric point（pI）ranges from 4.36 to 9.90. Further analysis indicates that the gene family is divided into six subfamilies,and the number of exon is 1 to 40. Selective pressure analysis shows that 20 gene pairs are subjected to purification selection in the evolutionary process. Subcellular localization shows that MDPOD15 is mainly presented in the cell membrane,cytoplasm,nucleus and chloroplast. The expression profile of gene chips displays that MdPOD are highly expressed in apple’s flowers,leaves and fruits. Real-time quantitative PCR （qRT-PCR）indicates that the expressions of most genes increased after ABA treatment for 2 h,and then decreases. Under PEG treatment,the expressions of 51 MdPODgenes firstly increase and reach the peak value at 12 h,while under the NaCl treatment,the expressions of MdPOD genes increase with the prolongation of time and reach the peak value at 24 h. The transient expression of MdPOD15 in tobacco leaves shows that MdPOD15 is expressed in the cell wall,cytoplasm and nucleus,and the overexpression of MdPOD15 in apple callus can mitigate the degree of cell damage caused by abiotic stress. Therefore,MdPOD genes may play different roles in different periods of time under different abiotic stresses.

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• Correlation Between Anatomical Structure and Resistance to Powdery Mildew in Chinese Wild Vitis Species
• WEI Xiaoyu, WANG Yuejin
• Acta Horticulturae Sinica. 2022, 49(6): 1200-1212. DOI:10.16420/j.issn.0513-353x.2021-0367
• Abstract ( 601 ) HTML ( 311 ) PDF (10374KB) ( 311 ) 　　　

• Ten different of grape berries（including Vitis davidii Foëx,V. quinquangularis,V. pseudoreticulata and V. vinifera‘Thompson Seedless’）were used as materials to explore the relationship between grape fruit epidermis tissue structure and powdery mildew resistance. The results showed that the following grapes showed disease resistance：V. davidii‘Tangwei’,‘Fujian-4’;V. quinquangularis ‘Danfeng-2’,‘Taishan-12’,‘Shang-24’,V. vinifera‘Thompson Seedless’,‘Red Globe’and‘Carinena’are susceptible varieties. The cuticle of the epidermis of Chinese wild V. davidii,V. quinquangularis and V. pseudoreticulata were thicker than that of European grape. The cuticle of the epidermis of V. davidii and V. quinquangularis were regularly arrangedand tight,and the epidermis of V. vinifera‘Thompson Seedless’was thinnest,the epidermal cuticle was the thinnest and the cells of the epidermal layer of the fruit skin were irregularly shaped and loosely arranged. The epidermis and subepidermis of V. davidii‘Tangwei’were the thickest,followed by V. quinquangularis‘Danfeng-2’and V. pseudoreticulata‘Baihe 35-1’,and the epidermis and subepidermis of V. vinifera‘Thompson Seedless’were the thinnest. Correlation analysis showed that there was a significant positive correlation between the thickness of cuticle and epidermal layer of fruit skin and resistance to powdery mildew in grapes,and the cuticle and epidermal layer thicknesses of fruit skin of disease-resistant plants were generally thicker than those of disease-susceptible plants.

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• Identification of HSP20 Family Genes in Citrus and Their Expression in Pathogen Infection Responses Citrus Canker
• ZHANG Kai, MA Mingying, WANG Ping, LI Yi, JIN Yan, SHENG Ling, DENG Ziniu, MA Xianfeng
• Acta Horticulturae Sinica. 2022, 49(6): 1213-1232. DOI:10.16420/j.issn.0513-353x.2021-0331
• Abstract ( 598 ) HTML ( 202 ) PDF (5681KB) ( 202 ) 　　　

• Citrus canker,caused by is a bacterial disease,which severely influence citrus industry,and its pathogenicity is significantly enhanced under higher temperature and humidity environmental condition. HSP20 genes are abundant and highly conserved in higher plants,they play vital defense roles when plants are under biotic or abiotic stress. In order to investigate the role of HSP20 genes in response to Xanthomonas citri subsp. citri infection,the genes of HSP20 family in Citrus sinensis were identified. The analysis of biological information showed that there are 42 members,which can be divided into 11 subfamilies,they encode 135-373 aa and are distributed on nine chromosomes,their protein molecular weight are from 15.17 to 41.71 kD,isoelectric point are from 4.53 to 10.07,almost 92.9% of them not contain any intron or only one,and each subfamily share highly similar structures and conserved motifs,their promoter also has cis-acting elements response to hormones or stress. In order to access the role of CsHSP20 in response to Xcc and abiotic stress in resistant germplasm Citron C-05 with susceptible sweet orange,we have injected Xcc into the leaves of Citron C-05 and conducted a series of heat stress with small Citron C-05 plants. The relative expression levels of CsHSP20 have been screened by qRT-PCR,the results showed that HSP17.9,HSP23.3,HSP18.5 and HSP18.0 were up-regulated in both Xcc and heat stress,but their relative expression level in Citron C-05 is notably different from that of sweet orange under Xcc infection,especially HSP23.3. Interestingly,the induced expression patterns are consistent with the result of the transcriptomic analysis infected by Xcc. Then,these genes have been transiently overexpressed in sweet orange leaves,and Xcc quantitative analysis of Citron C-05 HSP23.3 showed that Xcc reproduction was inhibited.

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• Population Genetic Structure of Xanthomonas citri pv. citri in Guangdong Province Based on the STR Locus
• LI Wenting, LI Cuixiao, LIN Xiaoqing, ZHENG Yongqin, ZHENG Zheng, DENG Xiaoling
• Acta Horticulturae Sinica. 2022, 49(6): 1233-1246. DOI:10.16420/j.issn.0513-353x.2021-0297
• Abstract ( 301 ) HTML ( 97 ) PDF (2266KB) ( 97 ) 　　　

• Citrus canker is one of the most serious diseases in citrus production,which is caused by Xanthomonas citri pv. citri（Xcc）. In order to systematically and comprehensively learn the genetic structure of citrus canker strains in Guangdong Province,six highly variable locus were selected by comparing and analyzing the short tandem repeat loci of the whole genome sequence of eight Chinese strains,and the genetic diversity of 352 strains of 14 varieties from 15 cities（counties）in Guangdong Province was analyzed. The results showed that based on the genetic diversity and genetic distance of Guangdong Province in different parts of the citrus canker strains identified six groups：Ⅰgroup（Chaozhou and Shanwei）,Ⅱ group（Meizhou and Heyuan）,Ⅲ group（Zhaoqing,Guangzhou,Jiangmen,Foshan and Huizhou）,Ⅳ group（Yangjiang,Maoming and Zhanjiang）Ⅴ group（Yunfu）,Ⅵ group（Shaoguan and Qingyuan）. Based on the genetic diversity and genetic distance on the different varieties of citrus canker in Guangdong strains identified five groups：Ⅰgroup（Wogan,Gonggan,Zhushaju,Shatamhju,Chazhigan,Hongjiangcheng and Mashuiju）,Ⅱ group（Qicheng and Ningmeng）,Ⅲ group（Jiaogan,Maogugan and Chuntianju）,Ⅳ group（Shatianyou）. The results can provide a theoretical basis for the epidemic regularity of citrus canker disease in Guangdong province.

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• CsSWEET2a Promotes the Infection of Xanthomonas citri subsp. citri
• MA Mingying, HAO Chenxing, ZHANG Kai, XIAO Guihua, SU Hanying, WEN Kang, DENG Ziniu, MA Xianfeng
• Acta Horticulturae Sinica. 2022, 49(6): 1247-1260. DOI:10.16420/j.issn.0513-353x.2021-0323
• Abstract ( 350 ) HTML ( 147 ) PDF (6221KB) ( 147 ) 　　　

• After the infection of citrus canker pathogen Xanthomonas citri subsp. citri（Xcc）,infected the leaves of the susceptible germplasm‘Bingtang’Sweet Orange,it formed typical crater bulge symptoms at the infected site,but gradually showed brown necrosis at the infected site of the leaves of the resistant germplasm Citron C-05,without typical symptoms of canker disease. Based on the transcriptome sequencing analysis of‘Bingtang’Sweet Orange and Citron C-05. leaves inoculated with Xcc,the expression of 20 CsSWEET induced by Xcc was compared. The results showed that SWEET2a and SWEET17d were up-regulated by Xcc in‘Bingtang’Sweet Orange,and SWEET12b was up-regulated by Xcc in Citron C-05;qRT-PCR verification only SWEET2a induced by Xcc high expression in ‘Bingtang’Sweet Orange and no significant change in Citron C-05,The amino acids sequence similarity of SWEET2a in different citrus germplasm homologs was 94.6%. The cis-acting elements of the promoter in‘Bingtang’Sweet Orange and Citron C-05 were significantly different in types and quantities. The transient overexpression of SWEET2a in‘Bingtang’Sweet Orange and Citron C-05 showed that SWEET2a promoted the reproduction of Xcc,and the transgenic Arabidopsis thaliana lines inoculated with the virulence strain Pst.DC3000（Pseudomonas syringae tomato DC3000）was significantly higher than that of the wild type. The SWEET2a protein is partially localized to the plasma membrane,suggesting that SWEET2a may be hijacked by Xcc for transmembrane transport of sugar extracellular to supply Xcc with energy needed for intercellular colonization.

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• Effects of Leaf and Fruit Quantity Regulation on Growth,Fruit Quality and Yield of Tomato
• LU Tao, YU Hongjun, LI Qiang, JIANG Weijie
• Acta Horticulturae Sinica. 2022, 49(6): 1261-1274. DOI:10.16420/j.issn.0513-353x.2021-0387
• Abstract ( 537 ) HTML ( 344 ) PDF (2695KB) ( 344 ) 　　　

• The effects of different numbers of leaves and fruit on plant growth,leaf photosynthetic characteristics,fruit quality and yield were studied in the cultivation of coconut husk in autumn and winter of tomato in greenhouse of North China,so as to obtain the optimal amount of functional leaves and fruit,which will provide a theoretical basis for improving the simplified technology of facility tomato production. A variety of large-fruit tomato named‘Fenkang 1’was used as the test material,seven ears of fruit were reserved for topping. Six treatments were set up,including 7,9 and 11 fully developed functional leaves from top to bottom with 3 fruit per ear（21 fruit in total）or 4 fruit per ear（28 fruit in total）. The photosynthesis and respiration of leaves in different canopy,development of leaves and fruit,quality and yield were analyzed. The results showed that,there were no significant differences in plant height and stem diameter after topping. The net photosynthetic rate（P_n）,light saturation point（LSP）,CO₂ saturation point（CSP）,apparent quantum efficiency（AQE）and carboxylation efficiency（CE）of the middle canopy leaves of 9-leaf with 21 fruit and 9-leaf with 28 fruit treatments were significantly higher than those of other treatments,while the dark respiration rate（R_d）is lower. The above parameters and chlorophyll content of the bottom canopy leaves were better for 7-leaf with 21 fruit and 7-leaf with 28 fruit treatments. The yields of single plant and single trough of 9-leaf with 28 fruit treatment were significantly higher than other treatments,besides,the fruit sugar-acid ratio was stable and optimal. To conclude,in the facility tomato production in North China,after reserved 7 ears fruit for topping,retaining 9 functional leaves and 4 fruit on each ear is the best way to regulate the amount of leaves and fruits. This technology can effectively improve population structure,facilitate the synthesis and accumulation of photosynthetic pigments,and effectively enhance the leaf photosynthesis,so as to improve the yield and maintain good quality of tomato.

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• Promoting Effects of Uniconazole on Grafting Formation of Tomato Seedlings and Underlying Mechanisms
• MENG Xianmin, CUI Qingqing, DUAN Yundan, ZHUANG Tuanjie, PU Dan, DONG Chunjuan, YANG Wencai, SHANG Qingmao
• Acta Horticulturae Sinica. 2022, 49(6): 1275-1289. DOI:10.16420/j.issn.0513-353x.2021-0306
• Abstract ( 540 ) HTML ( 140 ) PDF (5354KB) ( 140 ) 　　　

• Uniconazole（S3307）,a gibberellin inhibitor,is often used to regulate plant growth and development,however,its effect on graft formation remains unclear. Here,tomato scion‘Yingfen 8’and stock‘Zhenai 1’were foliar sprayed twice with 0.25 mg · L^-1 uniconazole on 15 d and 21 d after sowing. The results showed that uniconazole inhibited the growth of scion and stock seedlings,the plant height decreased by 20.58% and 12.75% respectively compared with the control with deionized water at 27 d after sowing,that is 0 h after grafting;from 12 h to 72 h after grafting,uniconazole reduced the contents of GA₁₅ and GA₈,promoted the accumulation of GA₃,IAA,MEIAA,ICAld,TRP and iP7G;and it increased the expression difference in IAA1 above and below the graft union,GA20ox1,IAA1,and ARR17 expression was up-regulated above the graft union,while GA20ox1 and ARR17 expression were down-regulated below. From 6 h to 168 h after grafting,uniconazole also increased the relative expression of TMO6 and CyclinB1;2 both above and below the graft union,and WIND1,WOX4 and VND7 expression above;uniform expression of IAA1,ARR17,WIND1,TMO6,WOX4 and VND7 above and below the graft union occurred earlier,and xylem and phloem of the graft union were connected in advance. In addition,the graft union of uniconazole began to connect at 72 h after grafting,the connection between xylem and phloem was basically completed at 96-120 h after grafting,which was 24 h earlier than control. These results suggested that foliar sprayed uniconazole before grafting promoted tomato graft formation by regulating endogenous hormone levels in the graft union.

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• Methylene Blue Combined Agarose Assay for Single-spore Isolation of Plasmodiophora brassicae and Pathotype Differentiation
• RUI Tingting, GAO Qingyun, LI Xiaojing, SHI Yanxia, XIE Xuewen, LI Lei, ZHANG Hongjie, XU Wenjuan, CHAI Ali, LI Baoju
• Acta Horticulturae Sinica. 2022, 49(6): 1290-1300. DOI:10.16420/j.issn.0513-353x.2021-0421
• Abstract ( 286 ) HTML ( 64 ) PDF (986KB) ( 64 ) 　　　

• The traditional water agar method for single-spore isolation of Plasmodiophora brassicae was improved,and the optimum concentrations of methylene blue and agarose were determined. Methylene blue agarose gel layers were prepared by mixing 0.01% methylene blue and 1.5% agarose solution with a volume ratio of 1︰300,on which single-spore of P. brassicae could be successfully isolated under the microscope. The best seedling age for single-spore inoculation was germinating for 24 h. After inoculation,the seedlings were then cultured in darkness for 24 h before transplanted to bowls. A total of 79 single-spore strains of P. brassicae were isolated from 11 provinces in China by using methylene blue combined agarose assay developed in this study. And 12 pathotypes such as P2,P3,P4,P5,P6,P7,P8,P9,P10,P12,P13 were identified using the Williams identification system. Among which,P4 was the dominant pathotype,with a frequency of 49.37%. The pathotype differentiates and distributions of P. brassicae from 11 provinces of China were clarified,and the results may provide important resources for breeding disease-resistant varieties of crucifer vegetables.

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• Identification and Analysis of PAP1/2 Homologous Genes in Brassica rapa,B. oleracea and B. napus
• CHEN Daozong, LIU Yi, SHEN Wenjie, ZHU Bo, TAN Chen
• Acta Horticulturae Sinica. 2022, 49(6): 1301-1312. DOI:10.16420/j.issn.0513-353x.2021-0629
• Abstract ( 503 ) HTML ( 86 ) PDF (2800KB) ( 86 ) 　　　

• PAP1/2 transcription factors are the main MYB transcription factors involved in the formation of MBW complex to regulate anthocyanin biosynthesis. Using Arabidopsis PAP1/2 transcription factor（TF）nucleic acid and protein sequence alignment and Pfam verification to study the exact homologous copy number,evolutionary relationship and expression of PAP1/2 TFs regulating anthocyanin metabolism in Brassica plants such as Brassica rapa,B. oleracea and B. napus. The number of homologous copies of PAP1/2 TFs identified in B. rapa,B. oleracea and B. napus were three,four and nine,respectively. The evolutionary relationship between different copies of PAP1/2 TFs was further clarified by evolution analysis and microcollinearity analysis of the segment where the homologous copies of PAP1/2 TFs were located. The relationship between different copies of PAP1/2 TFs on chromosomes A7 and C6 was clarified. Finally,combined with the transcriptome sequencing data of different tissues of B. rapa,B. oleracea and B. napus,the expression analysis was carried out,and the expression of homologous copies of PAP1/2TFs in different tissues was clarified.

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• The Negative Regulation of DcERF-1 on Senescence of Cut Carnation
• WANG Yan, SUN Zheng, FENG Shan, YUAN Xinyi, ZHONG Linlin, ZENG Yunliu, FU Xiaopeng, CHENG Yunjiang, Bao Manzhu, ZHANG Fan
• Acta Horticulturae Sinica. 2022, 49(6): 1313-1326. DOI:10.16420/j.issn.0513-353x.2021-0478
• Abstract ( 705 ) HTML ( 141 ) PDF (2481KB) ( 141 ) 　　　

• In order to explore the mechanism of ethylene regulated flower senescence in cut carnation,we screened a transcription factor named DcERF-1 from the expression profile of carnation. Analysis of deduced amino acid sequence and phylogenetic tree found that DcERF-1 showed high homology with Arabidopsis thaliana AtERF-1,and belongs to Ⅸ（B3）sub-group. Real-time quantitative PCR showed that DcERF-1 was highly expressed in flower,and the expression trend of DcERF-1 was firstly increased and then decreased during both the natural flower senescence and ethylene induced flower senescence progress. The subcellular localization assay showed that DcERF-1 was localized in the nucleus. Transient overexpression of DcERF-1 in the petals resulted that the petal fading rate was significantly delayed and the ion leakage rate was significantly reduced. After transient silencing of DcERF-1,the petal fading rate was significantly accelerated,the ion leakage rate was significantly increased,and the expression of senescence marker gene DcSAG12 was significantly up-regulated. In addition,yeast one hybrid assay showed that DcEIN3 could directly bind the promoter of DcERF-1,and dual luciferase assay showed that DcERF-1 could inhibit the expression of DcACO4. The comprehensive results indicated that DcERF-1 negatively regulates the flower senescence in cut carnation.

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• Preliminary Study on the Relationship Between Promoter Sequence Difference of PmTAC1 and Weeping Trait of Prunus mume
• LIU Yaoyao, WU Yanyan, Shi Yan, MAO Tianyu, BAO Manzhu, ZHANG Junwei, ZHANG Jie
• Acta Horticulturae Sinica. 2022, 49(6): 1327-1338. DOI:10.16420/j.issn.0513-353x.2021-0468
• Abstract ( 416 ) HTML ( 114 ) PDF (6179KB) ( 114 ) 　　　

• A candidate gene PmTAC1（TILLER ANGLE CONTROL 1）of the weeping trait of Prunus mume was cloned and analyzed based on our previous transcriptome data. The coding sequence of PmTAC1 was 915 bp,encoding 304 amino acids,and no differences was observed between upright and weeping cultivars of mei. The amino acid sequence alignment further confirmed that PmTAC1 had the typical domain of the IGT family,and evolutionary analysis showed that the genetic relationship between PmTAC1 and PpeTAC1 was the closest. Prediction of subcellular localization and hydrophobic analysis of protein showed that the protein was located in the nucleus and chloroplast,and was hydrophilic. The expression of PmTAC1 in branches of weeping cultivars was significantly higher than that in 1-year-old branches of upright cultivars,and there were differences in the adaxial and abaxial of the two types of branches. The promoter sequences of PmTAC1 in weeping and upright mei were 1 608 bp and 1 379 bp respectively,which were consistent among different cultivars of the same branch types of mei. Differences were detected in the number of light responses,gibberellin,and abscisic acid response cis-elements between the two promoter sequences. In conclusion,the promoter sequence and expression level of PmTAC1 in weeping and upright cultivars of mei may be related to the formation of weeping traits.

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• AFLP Analysis of Genetic Resources of Dendrobium from China
• ZHANG Meng, SHAN Yuying, YANG Yebo, ZHAI Feifei, WANG Zhaoshan, JU Guansheng, SUN Zhenyuan, LI Zhenjian
• Acta Horticulturae Sinica. 2022, 49(6): 1339-1350. DOI:10.16420/j.issn.0513-353x.2021-0625
• Abstract ( 400 ) HTML ( 102 ) PDF (3351KB) ( 102 ) 　　　

• Dendrobium plants are mainly distributed in Yunnan,Guizhou and Sichuan Province in China. China is the distribution center of Dendrobium plants in the world. In this study,Amplified Length Polymorphism（AFLP）was used to study the genetic diversity and phylogenetic relationship of 92 species of Dendrobium in China. Ten primer combinations were screened out from 24 pairs of primer combinations,and a total of 2 329 loci were amplified,among which 2 307 were polymorphic,accounting for 99.04% of the total loci. Phylogenetic analysis results showed that 92 Dendrobium samples were divided into four groups,and the genetic differentiation was significant. AFLP molecular markers supported that the two species of D. leptocladum and D. xichouense were classified into Sect. Dendrobium,and D. hookerianum was divided into Sect. Holochrysa. The results also showed that the shape and texture of the stem were important characteristics for the classification of Dendrobium,and the flower lip and enlargement of stem node were not the main factors for Dendrobium classification.

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Research Notes

• Identification of Peach Laccase Family Genes and Function Analysis of PpLAC21
• QIU Keli, WANG Yumin, HE Jinling, YU Hong, PAN Haifa, SHENG Yu, XIE Qingmei, CHEN Hongli, ZHOU Hui, ZHANG Jinyun
• Acta Horticulturae Sinica. 2022, 49(6): 1351-1362. DOI:10.16420/j.issn.0513-353x.2021-0767
• Abstract ( 376 ) HTML ( 127 ) PDF (4384KB) ( 127 ) 　　　

• The members of laccase（LAC）family in peach[Prunus persica L.（Batsch）] were identified by bioinformatics technology,and their evolutionary relationship,gene structure,cis-elements in promoter region and expression pattern were analyzed. The results showed that a total of 48 laccase genes were identified in peach genome. Through the analysis of expression pattern in peach cotyledon callus,it was found that a key member with high expression,PpLAC21,decreased the content of lignin in peach callus silenced by this gene. It is speculated that this gene may be involved in lignin synthesis in peach callus.

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• Comparison of Growth and Secondary Metabolites of Purple and White Flower Dracocephalum moldavica Under Field,Greenhouse and Greenhouse Shading Conditions
• LI Xiaoming, YU Junchi, WANG Chunxia
• Acta Horticulturae Sinica. 2022, 49(6): 1363-1370. DOI:10.16420/j.issn.0513-353x.2020-1057
• Abstract ( 427 ) HTML ( 96 ) PDF (2712KB) ( 96 ) 　　　

• Dracocephalum moldavica is an annual herb of Labiatae,which is used for Mongolian and Uyghur medicine in China. The growth characteristics and the secondary metabolites content of purple and white flower D. moldavica under three cultivation conditions of field,greenhouse and greenhouse shading were compared. The results showed that the plant height,internode length,leaf area and specific leaf area increased significantly under the three cultivation conditions; Leaf,palisade tissue（P）and sponge tissue（S）thickness,stomatal index and stomatal density decreased significantly,and P/S increased significantly. The increase of leaf area of purple flower D. moldavica was significantly higher than that of white D. moldavica,and the decrease of leaf thickness,palisade tissue thickness,sponge tissue thickness and stomatal density were lower than that of white D. moldavica. Under field conditions,the contents of chlorophyll,carotenoid and anthocyanin in purple flower D. moldavica were significantly higher than that in the white one,and the content of total flavonoids was significantly lower than that in the white one. Under greenhouse conditions,the anthocyanin content of stem epidermis of purple flower D. moldavica was significantly lower than that under open ground conditions,and the chlorophyll and carotenoid content of white flower D. moldavica were significantly lower. The anthocyanin content in leaves increased significantly. Under greenhouse shading conditions,the contents of chlorophyll,carotenoid and anthocyanin in the leaves of the purple and white flower D. moldavica were significantly higher than those in the greenhouse. Anthocyanins are almost free in the white flower D. moldavica,which is not affected by cultivation conditions. The main volatile components in the fresh samples are nerol,geraniol,nerolaldehyde and geraniol. The relative contents of nerolaldehyde and geraniol in white flower D. moldavica are higher than those in purple flower one. The yield of crude essential oil from the purple and white flower D. moldavica was 0.25%-0.27%,and there was no significant difference between them.

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Reviews

• Origin,Evolution and Cultivation History of the Pepper
• ZOU Xuexiao, ZHU Fan
• Acta Horticulturae Sinica. 2022, 49(6): 1371-1381. DOI:10.16420/j.issn.0513-353x.2021-0853
• Abstract ( 758 ) HTML ( 390 ) PDF (722KB) ( 390 ) 　　　

• The Pepper originated in the semi-arid area in central and southern Bolivia where the annual rainfall is less than 500 mm. This is a subtropical frost-free area. The original wild species are perennial herbs. According to the analysis and study of the starch granules,the Capsicum starch microfossils have been found dating from 8 000-7 500 years ago. Over thousands of years,Capsicum seeds spread out from Bolivia with the help of birds and indigenous peoples,thus spreading throughout South and Central America,then to the southwest of North America. In different ecological regions,more than 10 wild relatives and about 20 wild non-relatives of cultivated species have evolved. Capsicum cultivars evolved from the common ancestor Capsicum chacoense. The purple flower ancestors migrated to the Andes highlands and evolved to Capsicum pubescens. And the white flower ancestors migrated to the relatively dry area of southern Bolivia to evolve to Capsicum baccatum,continuing to migrate to the humid Amazon basin and evolve to the common ancestors of Capsicum annuum,Capsicum frutescens L. and Capsicum chinense Jacquin. They continued to migrate outward,evolving Capsicum annuum in Mexico and northern Central America,Capsicum frutescens L. in the Caribbean,and Capsicum chinense Jacquin in the northern valleys of the Amazon Basin. The pepper domestication started by removing the wild species from the original area for artificial cultivation. The wild species with the fruit small,single-color,upward-facing and easily falling off were domesticated into cultivated species with the fruit succulent,various-shaped,colorful,downward-facing,and not easy falling off,i.e. good economic benefits. Capsicum annuum was the first cultivated species domesticated in Mexico and Central America more than 6 000 years ago,and the other four cultivated species had been cultivated for at least 4 000 years,which are the oldest cultivated plants in America.

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• Advances on Mechanism of Cucurbit Crops in Response to Low- temperature Stress
• LI Qiong, LI Lili, HOU Juan, LUO Renren, WANG Ruidan, HU Jianbin, HUANG Song
• Acta Horticulturae Sinica. 2022, 49(6): 1382-1394. DOI:10.16420/j.issn.0513-353x.2021-0575
• Abstract ( 456 ) HTML ( 226 ) PDF (749KB) ( 226 ) 　　　

• On the basis of physiology and biochemistry,omics,and reverse genetics,this review summarizes the recent advances on cold-response genes and their regulation mechanisms in the major cucurbits,e.g.,cucumber,melon,and watermelon. Furthermore,the main problems in current researches were pointed out and the key points in future studies were also proposed,in the hope of offering theoretical reference for dissecting the molecular mechanisms underlying plant adaptation to low-temperature stress and genetically improving cucurbits for cold tolerance.

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New Cultivars

• A New Pepper‘Hangjiao 12’
• FU Hongfei, NIE Zhixing, CHEN Jianying
• Acta Horticulturae Sinica. 2022, 49(6): 1395-1396. DOI:10.16420/j.issn.0513-353x.2020-0964
• Abstract ( 264 ) HTML ( 85 ) PDF (1218KB) ( 85 ) 　　　

• ‘Hangjiao 12’is a new early ripening hot pepper F₁ hybrid. The biggest fruit is elongated in shape,light green in color,20 cm in length,2.0 cm in width,26 g in weight. The flesh thickness is 0.2 cm,which contains 975 mg · kg^-1 vitamin C. It is resistant to anthracnose,moderate resistance to Phytophthora capsici,and highly resistant to CMV. The average yield is 15 000-18 000 kg · hm^-2 for small pepper,and 42 000-48 000 kg · hm^-2 for medium pepper. It is suitable for protected cultivation in the middle and lower reaches of Yangtze River,and also suitable for long season cultivation over summer in mountainous area of high altitude in Zhejiang Province.

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• A New Melon Cultivar‘M1004’
• REN Jian, ZHANG Na, LI Yuhua, ZENG Hongxia, SUN Yuhong, CHEN Wei, XIONG Jianshun, TANG Mi
• Acta Horticulturae Sinica. 2022, 49(6): 1397-1398. DOI:10.16420/j.issn.0513-353x.2020-0315
• Abstract ( 216 ) HTML ( 88 ) PDF (2672KB) ( 88 ) 　　　

• ‘M1004’is a new mid-early ripening thick-skinned melon variety bred by crossing M2010-ZLK1-12-V as female parent and M2010-FZ-A as male parent. The fruit is oval,the weight of a single fruit is 1.45 kg,the peel is golden yellow,the pulp is milky white,the cavity color is red,the pulp is 2.45 cm thick,the meat is crisp,the pulp is pure sweet,and the content of soluble solids in the center is about 16.2%. The whole growth period is 88-95 days,and the fruit development period is 32-38 days. Moderate resistance to powdery mildew and downy mildew. The output is about 34 200 kg · hm^-2.

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• A New Ornamental Xanthoceras sorbifolium Cultivar ‘Yanxi’
• LUO Xiaofei, AO Yan, LIU Xuezeng, ZHANG Hongxi, ZHENG Lijuan, ZHANG Dongxu, WANG Kun, SAI Yinduleng
• Acta Horticulturae Sinica. 2022, 49(6): 1399-1400. DOI:10.16420/j.issn.0513-353x.2020-0336
• Abstract ( 238 ) HTML ( 78 ) PDF (1155KB) ( 78 ) 　　　

• ‘Yanxi’is a new Xanthoceras sorbifolium cultivar selected from X. sorbifolium seedlings in Dongying,Shandong. The flowers are double,with 16-20 petals. The pistil and stamens are all petaloid and it cannot bear fruit. The petals have yellow green base and white edge. The petals are dense,twisty,with long ribbon shape. The marginal petals are a little bigger,while central petals are small. The initial bloom stage of this cultivar starts at early May and flowering lasts up to 25 days in Dongying,Shandong.

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