Research Papers

• Analysis of Genetic Diversity of Apple Germplasms of Malus Using SLAF-seq Technology
• GAO Yuan, WANG Dajiang, WANG Kun, CONG Peihua, LI Lianwen, and PIAO Jicheng
• Acta Horticulturae Sinica. 2020, 47(10): 1869-1882. DOI:10.16420/j.issn.0513-353x.2019-1011
• Abstract ( 517 ) HTML ( 483 ) PDF (3154KB) ( 483 ) 　　　
• In this study，the specific-locus amplified fragment sequencing（SLAF-seq）was used to sequence 509 accessions of Malus Mill.，and 586 454 SLAF tags were obtained，including 463 612 polymorphic SLAF tags. After sequence alignment analysis，46 460 polymorphic single nucleotide（SNP）loci were screened out according to the filter with integrity > 0.94 and minor allele frequency（MAF）> 0.05. Based on these SNP loci，phylogenetic trees among different species of Malus Mill. were constructed and principal component analysis was done. The results showed that high-throughput SNP markers could be rapidly developed in the whole genome by SLAF-seq technology，and could be directly used in the genetic diversity research of apple germplasm resources. Thirty-four species of 509 apple accessions of Malus Mill. had high levels of diversity. Among groups with more than one accession，M. toringoides had the highest level of genetic diversity，and M. × domestica subsp. chinensis had the lowest level of genetic diversity. The results of cluster analysis and principal component analysis showed that the tested accessions of Malus Mill. were divided into 5 basic groups，the groupⅠwas M. baccata，the groupⅡwas wild species of Malus Mill.，the group Ⅲ was a cluster of apple cultivars，the group Ⅳ mainly contained M. × domestica subsp. chinensis，M. robusta，M. asiatica，M. prunifolia and M. spectabilis，and the groupⅤwas M. sieversii. M. rockii，M. komarovii，M. kansuensis，M. toringoides，M. transitoria，M. yunnanensis and M. ombrophila were clustered together. The relationships among cultivated species of Malus Mill. were relatively closer. Cultivars got together with M. orientalis，M. sylveseris and some other wild species. And the relationship between M. sieversii and the cultivated species of Malus Mill. in China needed further study. The results provided a reference for further study on the classification，origin and evolution of apple germplasm resources，and provided a basis for further collection and protection.
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• Identification of Plant Gly-RLK Gene Family and Expressional Analysis in Apple
• DUO Hu, Zhao Xinggang, LÜ Qianqian, WANG Dongdong, MAO Xia, LIU He, ZHAO Dan, and ZUO Cunwu,
• Acta Horticulturae Sinica. 2020, 47(10): 1883-1894. DOI:10.16420/j.issn.0513-353x.2019-0876
• Abstract ( 585 ) HTML ( 526 ) PDF (1174KB) ( 526 ) 　　　
• Receptor like kinase（RLK）take the crucial role in plant growth，development and environmental adaptation. In previous studies，one kind of apple（Malus × domestica）had glyco_18 RLK with extracellular domain（SM000636 or SM000704）named Glyco_18-RLK（MdGly-RLK）. In this test， Glyco_18 and Pkinase（SM000220）conserved domain whole protein sequences were seed sequences. Gly-RLK in 53 angiosperms was identified and its evolutionary characteristics were analyzed. Based on bioinformatics expression analysis，the physical and chemical properties，subcellular location，gene distribution on chromosome，cis-elements and expression patterns of promoter region of apple Gly-RLK were determined. The results showed that only 19 species of plants had Gly-RLK，and the number of family members ranged from 1 to 20. No family members were found in all monocotyledonous plants. According to the evolutionary analysis，it was divided into 8 subgroups，with more genes distributed in subgroup Ⅲ，Ⅶ and Ⅷ. We identified 6 Gly-RLKs from apple genome. Their amino acid sequence size，molecular weight and isoelectric point were 451–776，50.99–87.33 kD，and 5.95–8.21，respectively. They were mainly located in plasma membrane，and four of them were tandem repeat. There were different expression patterns of MdGly-RLK in different apple tissues and varieties. After inoculation with Valsa mali，the expression of six MdGly-RLKs in apples was different，and MdGly-RLK6（MD15G1156900）could be increased to 16.33 times of the control. To sum up，Gly-RLK only exist in some dicotyledons，and the expansion speed of family members is faster. MdGly-RLK can respond to the signals of apple growth and development and black rot fungus. MdGly-RLK6 can be used as a candidate gene for the study of apple anti rot.
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• Identification of Bacillus amyloliquefaciens BaA-007 and its Inhibitory Effect on Apple Canker
• LÜ Qianqian, ZHAO Xinggang, WANG Dongdong, MAO Xia, ZUO Cunwu, and YANG Jiangshan,
• Acta Horticulturae Sinica. 2020, 47(10): 1895-1904. DOI:10.16420/j.issn.0513-353x.2019-0554
• Abstract ( 408 ) HTML ( 339 ) PDF (1515KB) ( 339 ) 　　　
• In order to search for new microbial resources to antagonize Valsa canker of apple，a potential biocontrol strain was isolated and purified from the phloem tissue by a flat-panel test in this study. The strain was identified based on its colony，strain morphology，16S rDNA and gyrA gene sequence. The strain was identified as a Bacillus amyloliquefaciens，named as BaA-007（Agricultural Culture Collection of China，preservation number：ACCC60382）. We further confirmed the strong antifungal activity of the strain and its secondary metabolism to Valsa mali. Results showed the strain and its secondary metabolites could inhibit the growth of Valsa mali，and significantly reduced the spread rate of the rot spots. Based on BG medium，the best cultural condition was 0.5% sucrose，1% bacteriological peptone，0.1% potassium dihydrogen sulfate，pH 7.0 and temperature 36 ℃. After inoculation of BaA-007，the salicylic acid（SA）- responsive genes PR1，PR2 and NPR1，the jasmonic acid（JA）-responsive genes PDF1.2，CORONATINE INSENSITIVE 1（COI1）and AOS，the ethylene（ET）-responsive genes ETR1，ERF1 and HEL，as well as Chitin synthetase B genes were all upregulated at different points. Above all，the strain BaA-007 had a good antagonistic effect on Valsa canker，and it was expected to be used as a biocontrol strain to prevent apple Valsa canker.
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• Effects of Sod Culture on Soil Aggregates，Organic Carbon Characteristic and Fruit Quality of Nanfeng Tangerine Orchard
• FU Xueqin, YANG Xingpeng, CHEN Dengyun, GAN Yanyun, and HUANG Wenxin
• Acta Horticulturae Sinica. 2020, 47(10): 1905-1916. DOI:10.16420/j.issn.0513-353x.2020-0118
• Abstract ( 718 ) HTML ( 497 ) PDF (797KB) ( 497 ) 　　　
• The mechanical stable aggregates，water-stable aggregates，aggregate stability and the organic carbon content of aggregates in Nanfeng tangerine orchards intercroppig Trifolium repens and Lolium multtiflorum were investigated. The results showed that the mechanical stable aggregates（> 5 mm）occupied 28.52%–35.14% in sod culture Nanfeng tangerine orchards，while the aggregates（< 0.25 mm）were 35.51%–36.86% in clear tillage tangerine orchards. The water-stable aggregates（< 0.25 mm）were the dominant and accounted for 55.71%–80.47% in all treatments. The overall change trend of aggregate R0.25 was Lolium multtiflorum treatment > Trifolium repens treatment > control. At the 0–10 cm and 10–20 cm soil layers in tangerine-white clover intercropping system，the mean weight diameter（MWD）of mechanical stable aggregates and water-stable aggregates increased by 126.03%，106.8% and 57.69%，31.25% and the polyagglomerate destruction rate（PAD）reduced by 13.29% and 12.41% compared with the control respectively. Simultaneously，MWD of mechanical stable aggregates and water-stable aggregates increased by 140.41%，125.17% and 82.69%，64.58% and PAD decreased by 12.85% and 16.61% in tangerine-Lolium multtiflorum intercropping system compared with the control，respectively. It showed that sod culture contributed to the formation of large aggregates and improved the soil structure stability and quality. And the improvement effect on the soil by intercropping Lolium multtiflorum was better than that by intercropping Trifolium repens. The sod culture greatly increased the total organic carbon content of water-stable aggregates and organic carbon content in different aggregate size classes at the 0–10 cm top soil，and the influence of Trifolium repens cultivation was superior than that of Lolium multtiflorum cultivation. Correlation analysis showed that the MWD and GMD was positively related to the organic carbon content of particle size aggregate（1–5 mm）and PAD was on the contrary. Naturally grown grass could increase the soluble sugar，soluble solids and vitamin C content，reduce the titratable acid content and improve the fresh food quality of Nanfeng mandarin fruit. And Trifolium repens had better improvement effect on fruit quality than Lolium multtiflorum.
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• Genetic Diversity Analysis of 96 Plum Germplasm Resources by Phenotypic Traits in Northeast Cold Area
• LIN Cunxue, YANG Xiaohua, and LIU Hairong
• Acta Horticulturae Sinica. 2020, 47(10): 1917-1929. DOI:10.16420/j.issn.0513-353x.2019-0982
• Abstract ( 326 ) HTML ( 452 ) PDF (1079KB) ( 452 ) 　　　
• In order to further understand the genetic diversity of plum germplasm resources，20 descriptive phenotypic traits of 96 samples were kept in Mudanjiang Branch of Heilongjiang Academy of Agricultural Sciences were evaluated according to the‘Plums germplasm resources description specification and data standard’. Sixteen quantitative phenotypic traits were analyzed by correlation analysis，cluster analysis，principal component. The results showed that a total of 66 variant types were observed for the 20 descriptive traits. Among them，the leaf shape，the color of the peel and the shape of the core had a large variation range. The Shannon-Wiener information index H and Simpson genetic diversity index D ranged from 0.3768 to 1.3993 and 0.2188 to 0.7196，respectively，and the higer diversity indexes were observed in fruit color（H：1.2093，D：0.6814）and leaf shape（H：1.1227，D：0.5484）. Among the 16 quantitative traits，the single fruit mass coefficient of variation was the largest，being 61.32%；the fruit shape index coefficient of variation was the smallest，8.72%. The 96 plum germplasm resources were divided into 3 groups at the Euclidean distance of 22 according to cluster analysis，the first group could be used for selecting freestone and high resistant cultivars. Group II could be used for selecting high resistant and high yield cultivars；Group III could be used for selecting large fruit，high edible rate and freestone cultivars. Principal component analysis showed that the cumulative contribution rate of the first five principal components reached to 78.191%，such as fruit vertical diameter，fruit transverse diameter，and 1 year twig diameter and so on，which mainly reflect the fruit size and twig trait factors. Fruit traits contributed the most to the phenotypic trait variation of plum germplasm resources in cold area，followed by traits of 1 year twig. Combined to the correlation analysis results，16 quantitative traits could be simplified into seven main indicators：fruit vertical diameter，fruit transverse diameter，leaf width，kernel transverse diameter，fruit shape index and 1 year twig diameter，which improved the efficiency for evaluation and breeding selection of plum germplasm resources in northeast cold area.
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• Genome-wide Identification and Expression Analysis of Banana GLP Gene Family
• LIU Fan, TIAN Na, SUN Xueli, LIU Jiapeng, WU Junwei, HUANG Yuji, and CHENG Chunzhen
• Acta Horticulturae Sinica. 2020, 47(10): 1930-1946. DOI:10.16420/j.issn.0513-353x.2019-0983
• Abstract ( 540 ) HTML ( 561 ) PDF (6809KB) ( 561 ) 　　　
• In order to reveal the functions of banana germin-like protein（GLP），the banana GLP （MaGLP）gene family was identified. Series of bioinformatics analysis was performed to analyze the MaGLPs’ structures，chromosomal distributions and cis-elements and transcription factor binding sites （TFBS）distributions in their promoter sequences and the characteristics of their encoded proteins such as physical and chemical characteristics，motifs，and phylogenetic relationship. Additionally，based on our previous RNA-seq data，the expression of the MaGLP family members in leaves treated by 4 ℃ and 45 ℃，roots treated by Fusarium oxysporum f. sp. cubense tropical race 4（FocTR4），and fruits at different mature stages under natural condition and ethylene treatment were studied. Totally，we identified 44 MaGLP family members distributing in all the banana chromosomes except chromosome 10. The coding sequence of these genes ranges from 567 bp to 2 103 bp. Most MaGLP genes contained 1 – 2 exons，and most MaGLP proteins owned signal peptide and were predicted to be located in extracellular part. Phylogenetic analysis showed that MaGLPs could be divided into 8 subfamilies，of which subfamily M was banana specific. Prediction results of cis-acting elements and TFBS showed that there were multiple plant hormone- and stress-responsive elements and seven kinds of TFBS in the promoter regions of MaGLPs. Expression analysis revealed that the expression of MaGLP members varied a lot in different organs and were regulated by various stresses. For instance，the expression of MaGLP5-1 and MaGLP9-8 was found to be responsive to various treatments. MaGLP1-2 and MaGLP9-4 expression could be inhibited by both high and low temperature treatments，while MaGLP9-6 was induced. MaGLP5-4 expression was influenced by high temperature and FocTR4. MaGLP4-4 was found to be only high temperature responsive. Our present study indicated that MaGLPs played important roles in the stress responses of banana.
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• Pathogen Identification of Virus Disease and Evaluation for Germplasm Disease Resistance in Radish
• QIU Xiaojun, TAN Qunyun, XIAO Qingming, MEI Shiyong, and ZHANG Jifang
• Acta Horticulturae Sinica. 2020, 47(10): 1947-1955. DOI:10.16420/j.issn.0513-353x.2020-0047
• Abstract ( 470 ) HTML ( 277 ) PDF (3324KB) ( 277 ) 　　　
• In this study，the pathogen of radish virus disease in Changsha was identified by small RNA deep sequencing technology，and specific primers were further designed to detect and verify the pathogen by reverse transcription PCR. Further，60 core germplasms were identified by artificial inoculation at the seedling stage，and then all were subjected to RT-PCR detection and phenotypic resistance identification. The results showed that the radishes in this area were infected by a combination of four viral diseases，namely turnip mosaic virus（TuMV），Brassica napus RNA virus 1（BnRV1），Brassica yellows virus（BrYV），Raphanus sativus cryptic virus 3（RasCV3）. BnRV1 was detected in radishes for the first time. One high resistance and one disease resistance accession was selected according to the phenotype identification. The specific bands of TuMV，BnRV1，BrYV and RasCV3 were abtained by RT-PCR with specific primers in 60 core germplasms，indicating that all the tested accessions were infected by these four pathogens. TuMV is the main pathogen，and the detection rate is 100%. The composite infection rate of two or more pathogens was 83.33%.
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• Physiological Effects of Rapamycin Pretreatment on Delaying the Senescence of Cut Flower in Tree Peony‘Luoyanghong’
• Physiological Effects of Rapamycin Pretreatment on Delaying the Senescence of Cut Flower in Tree Peony‘Luoyanghong’
• Acta Horticulturae Sinica. 2020, 47(10): 1956-1968. DOI:10.16420/j.issn.0513-353x.2019-0680
• Abstract ( 353 ) HTML ( 291 ) PDF (2351KB) ( 291 ) 　　　
• In order to reveal effects of TOR on opening and senescence of tree peony cut flowers and its physiological mechanism，we studied vase life，energy substances content，sugar content，ethylene production rate，respiratory rate，MDA content and PsTOR，PsSnRK1 and PsHXK1 relative expression level using cut flowers of potted tree peony‘Luoyanghong’under the pretreatment of 0.01 μmol • L-1 rapamycin for 2 h. The results indicated that rapamycin increased the best viewing period and the maximum flower diameter，increased soluble sugar content and energy charge in the petals，decreased the respiration consumption and MDA content，down-regulated expression of PsTOR，PsSnRK1 and PsHXK1 genes in the early period，and up-regulated expression of PsTOR and PsSnRK1 genes in the later periods. The data suggest that rapamycin can regulate energy-aware through TOR pathway to delay the florescence and senescence of cut tree peony flowers，thus improving the quality of cut tree peony flowers during vase periods.
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Research Notes

• Physiological Response and Tolerance to Copper Toxicity of Four Citrus Rootstock Seedlings
• WANG Min, YUAN Meng, ZHU Panpan, LING Lili, HE Yizhong, FU Xingzheng, and PENG Liangzhi
• Acta Horticulturae Sinica. 2020, 47(10): 1969-1981. DOI:10.16420/j.issn.0513-353x.2019-0977
• Abstract ( 521 ) HTML ( 542 ) PDF (5221KB) ( 542 ) 　　　
• In order to explore the different tolerance to copper toxicity among different citrus rootstocks，and analyze the physiological responses of the citrus rootstocks seedlings under copper excess stress，180-day-old seedlings of four citrus rootstocks including trifoliate orange[Poncirus trifoliata（L.）Raf]，Ziyang Xiangcheng[Citrus junos（Sieb.）Tanaka]，red tangerine[Citrus tangerina Hort.ex Tanaka] and Shatian pomelo[Citrus grandis（L.）Osb.‘Shatianyou’] were used as materials. The plants were treated with CuSO4 solution of 1.5（control），7.5，37.5，187.5 and 937.5 mol • L-1. The results showed that the content of chlorophyll and photosynthetic capacity decreased under high concentration treatment，and the relative conductivity and MDA content of leaf cells increased significantly. The activities of SOD， POD increased. Under high concentration，the effect of rootstock on uptake and transport of K，P，Ca，Mg，Fe，Mn and Zn decreased. The high copper concentration caused the leaves to turn yellow and fall off，the roots to turn brown and short，the growth of rootstocks was blocked，and even died. The tolerance of different rootstocks to excessive copper stress was significantly different. Trifoliate orange was the first rootstock to show the decline of physiological indexes such as new leaf chlorosis，old leaf abscission，growth and photosynthetic capacity. Then，the Shatian pomelo，red tangerine，and Ziyang Xiangcheng seedlings appeared toxic symptoms in turn. The principal component analysis and subordinate function analysis were performed to evaluate the stress tolerance. The results showed that Ziyang Xiangcheng exhibited the strongest tolerance to excessive copper stress，followed by red tangerine and Shatian pomelo，and trifoliate orange was the most sensitive to excessive copper stress.
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• RNAi-mediated Suppression of CCD1 Gene Impacts Carotenoid Accumulation in Citrus Calli
• ZHANG Yin, WAN Yong, ZHANG Ting, YE Junli, and DENG Xiuxin
• Acta Horticulturae Sinica. 2020, 47(10): 1982-1990. DOI:10.16420/j.issn.0513-353x.2019-1007
• Abstract ( 416 ) HTML ( 398 ) PDF (2078KB) ( 398 ) 　　　
• arotenoid cleavage dioxygenase（CCD）can catalyze the oxidative cleavage of carotenoidsa t specific sites to generate a variety of bioactive compounds. To some extent，their activities determine the arotenoid content and composition in plants. In this study，the CCD1 gene was cloned from fruits of Cara Cara navel orange（Citrus sinensis L. Osbeck）. The RNAi construct，pHGRV-CCD1，was constructed by inserting CCD1 specific fragments into plasmid pHGRV via recombination，and then introduced into calli of Satsuma mandarin Guoqing 1，Valencia sweet orange and Marsh grapefruit by Agrobacterium-mediated transformation. As a result，6，4 and 4 transgenic lines were obtained respectively. Compared with the wild-type，expression level of the transgenic lines were significantly downregulated to various degrees，among which the CCD1 expression of Marsh grapefruit transgenic line Rm2 was only 8.4% of control as the greatest interference effect. Most transformed calli with CCD1 RNAi construct exhibited similar color phenotype to wild-type controls except for Rm2 line（macroscopic color changes）. Compared with the wild-type，the inhibition of CCD1 gene expression resulted in a significant increase of violaxanthin and 9-cis-violaxanthin content，suggesting these two compounds might be the preferred in vivo cleavage substrates of CCD1 in citrus calli.
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• Distribution of the Overwintering Eggs of Apolygus lucorum on the Branches of‘Lingwu’Jujube Orchard
• WANG Hui, ZHU Qin, ZHANG Yongfei, and WANG Xinpu,
• Acta Horticulturae Sinica. 2020, 47(10): 1991-1998. DOI:10.16420/j.issn.0513-353x.2019-0966
• Abstract ( 349 ) HTML ( 98 ) PDF (1597KB) ( 98 ) 　　　
• It was largely unknown about the distribution of overwintering eggs of Apolygus lucorum（Meyer-Dür）on the branches of‘Lingwu’jujube orchard in Ningxia region. An investigation on the location of the overwintering eggs of A. lucorum in the two-jujube orchard were carried on by using the method of“Z”type in March 2018，and their number and morphological traits in the pruning wounded position were analyzed. The results showed that the average number of eggs on the current-year branch was significantly greater in the pruning wounded position than in the both mother spur and cracks of old barks；there was significantly higher values in two-year-old and perennial pruning wounded positions than the one-year-old ones；there was significantly lower values located in periderm than in pith，whereas there was significantly higher egg-carrying rate located in the periderm than in pith. The length and plumpness of the overwintering eggs were significantly higher in periderm than in pith，whereas there was no significant difference in width and number of shriveled eggs between the two locations. It was suggested that the overwintering eggs of A. lucorum were mainly located at the dormancy pruning wounded positions，and it was projected observed in the periderm and the pith for their oviposition under well-management jujube orchard. It was concluded that both the closed pruning wounds and early spring pruning residues were the key measures to control the damage of A. lucorum in terms of their distribution.
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• Preliminary Analysis on the Molecular Differences of Fruit Colouring Between Yuexin Strawberry and Its Somaclonal Mutation
• YANG Xiaofang, ZHANG Zuying, MIAO Lixiang, ZHANG Yuchao, SHEN Lan, QIN Qiaoping, and JIANG Guihua,
• Acta Horticulturae Sinica. 2020, 47(10): 1999-2008. DOI:10.16420/j.issn.0513-353x.2019-0996
• Abstract ( 735 ) HTML ( 151 ) PDF (1165KB) ( 151 ) 　　　
• Fragaria × ananassa‘Yuexin’is a new strawberry cultivar selected by our group. The Yuexin mutant is a stable somaclonal variation from Yuexin found in the regeneration plants differentiated stem apex. The results showed that there were no significant differences between Yuexin and its mutant in plant morphology，onset of blooming and fruit，onset of fruit ripening，average fruit weight and plant yield，fruit shape and fruit flavor，etc. However，compared with Yuexin，the pricarp of its mutant was brighter with higher L* and lower a*，greater H and less CIRG index，and the mutant had colorless pulp. The total content of anthocyanin in the mutant was only 13.2% of Yuexin，of which the largest difference was the content of geranium-3-O-glucoside（Pg3G），the content of Pg3G in the mutant was only 12.9% of Yuexin. The expression levels of the structural genes FaF3H，FaCHS，FaDFR，FaANS，FaCHI and Fa3GT involved in the anthocyanin synthesis pathway were significantly reduced in the mutant fruit，indicating the possible direct factors that resulting in the lower levels of anthocyanin in the mutant. The expression levels of the transcription factors FaMYB10 and FaMYB1 in Yuexin mutant were decreased significantly，and the eigenvector absolute values of FaMYB10 in several principal components were significantly higher than other factors，which further proved that MYB10 was one of the main regulating factors involved in flavonoids/phenylpropanoids of anthocyanin pathway during strawberry maturation. KASP analysis using leaf genomic DNA showed that there was no genotype differentiation between Yuexin and its mutant based on 74 primer pairs amplification. The results in this study confirmed that the Yuexin mutant was genetically stable，and the mutation caused the significant decrease in the expression of key genes involved in the regulation of anthocyanin synthesis，resulting in decreasing of anthocyanin accumulation and reducing fruit coloration.
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• Isolation and Identification of the Pathogen Caused Potato Blackleg Disease in Fujian Province
• LI Huawei, LIN Zhijian, LUO Wenbin, XU Guochun, JI Rongchang, QIU Sixin, and TANG Hao
• Acta Horticulturae Sinica. 2020, 47(10): 2009-2018. DOI:10.16420/j.issn.0513-353x.2019-0942
• Abstract ( 361 ) HTML ( 348 ) PDF (4485KB) ( 348 ) 　　　
• In order to clarify the species and biological characteristics of the pathogen which caused potato blackleg disease in Fujian Province，the pathogens were collected and isolated from Qingkou，Xiapu and Zhouning，and the pathogens were identified with plate isolation，purification，pathogenicity，physiological and biochemical characteristics and molecular biological methods. The results showed that nine strains of potato blackleg pathogens were isolated from the pathogenic potato，two were identified as Pectobacterium atrosepticum，three as P. carotovorum subsp. carotovorum，and four as P. carotovorum subsp. brasiliensis. And the nine strains were different，the pathogen in Qingkou was P. atrosepticum，that in Xiapu was P. carotovorum subsp. carotovorum，and that in Zhouning was a mixture of P. carotovorum subsp. carotovorum and P. carotovorum subsp. brasiliense.
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• Studies on the Adventitious Buds Induction from in vitro Leaves of Rhododendron delavayi var. delavayi and Histocytological Observation on the Buds Formation
• TIAN Ge, PENG Lüchun, QU Suping, WANG Jihua, ZHAO Zhengxiong, LI Shifeng, JIE Weijia, and GUAN Wenling,
• Acta Horticulturae Sinica. 2020, 47(10): 2019-2026. DOI:10.16420/j.issn.0513-353x.2019-0812
• Abstract ( 404 ) HTML ( 308 ) PDF (2654KB) ( 308 ) 　　　
• The adventitious buds were induced from in vitro leaves of Rhododendron delavayi var. delavayi using NAA combined with TDZ or ZT，and morphological and histocytological studies were observed on the regeneration process. The results showed that TDZ was more effective than ZT in the induction of adventitious buds from the leaves of R. delavayi var. delavayi，and that WPM + TDZ 0.08 mg • L-1 + NAA 0.01 mg • L-1 was the best medium for adventitious buds regeneration. The differentiation rate was 83.33% and the number of sprouts per leave was 4.29. Its regeneration belonged to the direct occurrence of organs with multiple origins. The regeneration process underwent four key stages of cell proliferation，cell dedifferentiation，cell differentiation，bud primordium formation and development.
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• Identification of the R2R3-MYB Family of Osmanthus fragrans and Its Expression in the Process of Flower Opening
• YAO Yifan, DONG Bin, FENG Chengyong, YANG Liyuan, and ZHAO Hongbo
• Acta Horticulturae Sinica. 2020, 47(10): 2027-2039. DOI:10.16420/j.issn.0513-353x.2020-0023
• Abstract ( 370 ) HTML ( 558 ) PDF (16671KB) ( 558 ) 　　　
• Through the identification and bioinformatics analysis of Osmanthus fragrans，and the expression analysis of related genes during flower opening，the key genes that respond to the relatively low temperature regulation of osmanthus flower opening and coloring were obtained. Using transcriptome data to analyze osmanthus R2R3-MYB genes，a total of 35 R2R3-MYBs were obtained. These genes all contained R2R3 domains and were highly conserved. The MYB transcription factors were treated in 19 ℃（flowers can open）and 23 ℃（flowers can not open）and the relative expression of different tissues was found that OfMYB1，OfMYB12，OfMYB14，OfMYB23 and OfMYB24 with the opening of O. fragrans，the expression increased gradually. The expression of OfMYB1 and OfMYB14 was the highest among the petals in flowering stage，indicating that they might be involved in the process of osmanthus coloring. OfMYB4，OfMYB5，OfMYB17，OfMYB28，OfMYB34 expression increased first and then decreased during flower opening，which indicated that OfMYB4，OfMYB5，OfMYB17，OfMYB28 and OfMYB34 could be involved in the regulation of the process of flower opening.
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• Effects of Graphene Oxide on Growth and Physiological Characteristics of Festuca arundinacea
• MAO Jianyue, DUO Li’an, and ZHAO Shulan
• Acta Horticulturae Sinica. 2020, 47(10): 2040-2046. DOI:10.16420/j.issn.0513-353x.2019-0842
• Abstract ( 259 ) HTML ( 242 ) PDF (700KB) ( 242 ) 　　　
• Effects of graphene oxide（GO）on the growth and physiological characteristics of turfgrass were studied by pot experiment. The Festuca arundinacea was planted in soil with three levels（1%，2% and 3%）of GO added. The results showed that the contents of chlorophylls and carotenoids in Festuca arundinacea all significantly decreased under GO treatments，and the accumulation of dry weight was suppressed. The biomass and the contents of photosynthetic pigments decreased with the increase of GO treatment level. Compared with the control，the biomass，content of total chlorophylls and carotenoids were decreased by 14.0%，25.8% and 36.2%，respectively in first harvest，and by 19.2%，25.6% and 62.3%，respectively in the second harvest under 3% GO treatment. Increases of malondialdehyde（MDA）content and peroxidase（POD）activity were observed with the increment of GO treatment，while activities of catalase （CAT）and superoxide dismutase（SOD）increased first and then decreased with the increase of GO level. The CAT and SOD activities reached the highest values in 2% and 1% GO treatment levels，respectively. Therefore，the addition of GO had induced the oxidative stress in F. arundinacea，inhibited plant growth，and the inhibition was more significant at the high treatment level.
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Review

• A Review of MADS-box Genes，the Molecular Regulatory Genes for Floral Organ Development in Orchidaceae
• LI Chengru, DONG Na, LI Xiaoping, WU Shasha, LIU Zhongjian, and ZHAI Junwen
• Acta Horticulturae Sinica. 2020, 47(10): 2047-2062. DOI:10.16420/j.issn.0513-353x.2019-0740
• Abstract ( 493 ) HTML ( 465 ) PDF (796KB) ( 465 ) 　　　
• The paper reviewed the important achievements of the orchid genome，transcriptome, theories and models，combing with the latest research results of the whole genome of Apostasia shenzhenica，Dendrobium catenatum and Phalaenopsis equestris. The research on A，B，C，D and E genes that regulate the development of floral organs was summarized and the future research direction of orchid flower development was prospected，which aims to provide theoretical reference for solving important biological problems，breeding new varieties and creating new species of orchids.
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New Cultivars

• A New Mid-ripening and Big-fruit Apricot Cultivar‘Xiahua’
• YUAN Kejun, WANG Peijiu, NIU Qinglin, GE Furong, and LI Shenglong
• Acta Horticulturae Sinica. 2020, 47(10): 2063-2064. DOI:10.16420/j.issn.0513-353x.2020-0606
• Abstract ( 457 ) HTML ( 222 ) PDF (822KB) ( 222 ) 　　　
• ‘Xiahua’is a mid-ripening apricot cultivar derived from the cross of ‘Kaite’× ‘Badanshuixing’. The fruit is round-shaped，freestone，with sweet kernel. Its ground color and flesh color are yellow. The average fruit weight is 172.2 g and soluble solids content is 13.3%. It matures in late May or early June in Tai’an，Shandong Province. The fruit development period is about 75 d. The output is 42 300.0 kg • hm-2.
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• A New Chinese Cabbage Cultivar‘Jinqing 1’
• QI Xianhui, WU Dongtang, ZHAO Junliang, LI Gaizhen, and WANG Xiuying
• Acta Horticulturae Sinica. 2020, 47(10): 2065-2066. DOI:10.16420/j.issn.0513-353x.2019-0590
• Abstract ( 438 ) HTML ( 142 ) PDF (1531KB) ( 142 ) 　　　
• ‘Jinqing 1’is a new Chinese cabbage cultivar which developed by male sterile line 10-05-201 as a female parent and self-incompatible line 76-8-9-7-8-7-15 as a male parent. The plant height is 57 cm and expansion is 40 cm in average. The head weight is 3.0–3.5 kg，and the average net head rate is 81.4%，the net yield is 104 t • hm-2. It has a growth period of 80–85 days. It is resistant to downy mildew，virus and black rot diseases. The cultivar is suitable for planting in autumn in northeast，north and southwest of China.
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• A New Mid-early Ripening Pepper Cultivar‘Nongda 7’
• YUAN Shengkai, LI Qi, JI Miao, DONG Tiecheng, ZHANG Meng, ZHANG Xiaoping, ZHAO Mingqin, and Ma Changsheng,
• Acta Horticulturae Sinica. 2020, 47(10): 2067-2068. DOI:10.16420/j.issn.0513-353x.2019-0634
• Abstract ( 545 ) HTML ( 180 ) PDF (912KB) ( 180 ) 　　　
• ‘Nongda 7’is a new mid-early ripening pepper hybrid developed from the cross of HP1016（female parent） and Y0931（male parent）. It is characterized by vigorous growth with an average plant height of 78.7 cm. Fruits are horn-shaped，yellow-green in green ripe stage，smooth，with thick flesh. The average single fruit weight is 80 g and average fruit number per plant is 26.8. The vitamin C content is 0.56 mg • g-1. The crude fiber content is 1.15%. It is also resistant to tobacco mosaic virus，phytophthora blight，and anthracnose. It’s suitable for protected cultivation（incloding tobacco-growing areas）in the early spring in Henan Province.
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• A New Lilium Cultivar‘Sunflower’
• FENG Xiuli, YUE Ling, and ZHAO Xinghua
• Acta Horticulturae Sinica. 2020, 47(10): 2069-2070. DOI:10.16420/j.issn.0513-353x.2019-0355
• Abstract ( 392 ) HTML ( 212 ) PDF (937KB) ( 212 ) 　　　
• A new lily cultivar‘Sunflower’was bred from the hybrid offspring of Asian Lily‘Val di Sole’and Oriental Lily‘Siberia’. It is a strong plant，and the flower is bowl-shaped with full-opening diameter of 16.5 cm，petal length of 10 cm，and petal width of 5 cm. The upper part of the flower is yellow and the bottom part is orange. The vase life is 10 d. It has strong high temperature and disease resistance，and it is suitable for cultivation in northern areas.
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• ‘Siji Fanghua’—A New Osmanthus fragrans Cultivar with Colored Leaves
• TU Xunliang, WAN Bin, and QIN Fan
• Acta Horticulturae Sinica. 2020, 47(10): 2071-2072. DOI:10.16420/j.issn.0513-353x.2019-0422
• Abstract ( 558 ) HTML ( 160 ) PDF (1028KB) ( 160 ) 　　　
• ‘Siji Fanghua’is a new colorful Osmanthus fragrans cultivar selected from the asexual reproduction progeny of O. fragrans‘Jinyu Taige’. The new shoots are fuchsia，the middle of the tender leaves are atropurpureus and the edges are fuchsia. In the middle of the leaf during leaf forming stage，it changes in various colors such as gray purple，yellow-green，green，and dark green. The central green area is gradually expanding and the edges of the leaves are in red purple，light red，light orange，yellow orange，and light yellow. The colored leaves can beviewed throughout the year，which is especially suitable for garden layout and potted plants in the Sichuan Basin.
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