Original article

• An Analysis of Alternative Splicing Events During Browning Inhibition of Fresh-cut Apples by Hydrogen Sulfide Treatment
• CHEN Chen, LIU Chenghui, SHI Lijia, JIANG Aili, HU Wenzhong
• Acta Horticulturae Sinica. 2021, 48(11): 2121-2132. DOI:10.16420/j.issn.0513-353x.2020-0847
• Abstract ( 617 ) HTML ( 429 ) PDF (2623KB) ( 429 ) 　　　

• In order to explore the alternative splicing of the browning inhibition of fresh-cut apples by hydrogen sulfide（H₂S）treatment,RNA-Seq technology was used to identify the alternative splicing occurring in H₂S-treated and H₂O-treated fresh-cut apples at two storage time（0 and 6 d）. The results showed that the dominate alternative splicing types were alternative transcription start site（TSS）and alternative transcription termination site（TTS）in these four samples. The number of the specific alternative splicing genes of H₂S-treated fresh-cut apples at 0 and 6 d were 921 and 2 423,respectively. GO annotation showed that the specific alternative splicing genes in H₂S-treated fresh-cut apples at 0 and 6 d were mainly enriched in flavonoid biosynthetic process,cytoplasm,membrane,hydrolase and oxidoreductase. KEGG analysis showed that these genes mainly enriched in plant-pathogen interaction,plant hormone signal transduction,carbohydrate metabolism,phenylpropanoid biosynthesis and oxidative phosphorylation. Furthermore,expression of polyphenol oxidase（PPO）,peroxidase（POD）,lipoxidase （LOX）and phospholipase D（LPD）genes was down-regulated after H₂S treatment,whilst expression of phenylalanine ammonia-lyase（PAL）and NADH dehydrogenase was induced. In conclusion,H₂S controlled the browning of fresh-cut apples through changing the alternative splicing and expression pattern of peroxide,phenylpropanoid metabolism,membrane and energy metabolism related genes.

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• Studies on the Resistance of Apple MdMYB116 to Powdery Mildew
• JI Miaomiao, WAN Ye, ZHANG Yiping, MA Hai, WANG Xiping, GAO Hua
• Acta Horticulturae Sinica. 2021, 48(11): 2133-2145. DOI:10.16420/j.issn.0513-353x.2021-0060
• Abstract ( 506 ) HTML ( 314 ) PDF (3629KB) ( 314 ) 　　　

• The full-length cDNA sequence of MdMYB116 was cloned from the powdery mildew resistant‘Gala’apple. The open reading frame of this gene was 900 bp,encoded 299 amino acids and contained two conserved domains. The phylogenetic tree results showed that MdMYB116 shared close relationship with PbMYB108-like in pear,with a identity of 93.38%. Subcellular localization assay evidenced that MdMYB116 was targeted to the nucleus. The expression level of MdMYB116 increased gradually from 6 h to 12 h and it was induced to a peak at 12 h after inoculation with powdery mildew. Yeast transcriptional activation verification revealed that the full length of MdMYB116 exhibited self-activating activity. MdMYB116 was transformed into Arabidopsis thaliana heterologously,and transgenic plant was obtained. After being inoculated with powdery mildew,it was found that the resistance of the transgenic lines was significantly higher than that of the wild type and pad4 mutant plants. Histochemical staining assays displayed that compared with wild type and pad4 mutant plants,the transgenic lines had a higher level of reactive oxygen species（ROS）burst,and more dead cells and calluses accumulation,indicating that the transgenic lines had a serious allergic lethal situation,which proved that MdMYB116 participated in the plant^’s powdery mildew immunomodulatory response. Expression analysis of some disease related genes speculated that MdMYB116 may enhanced defense responses though SA and/or MeJA signal pathways.

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• Requirement Rule of Nitrogen,Phosphorus,Potassium,Calcium and Magnesium of‘Red Globe’Grapevine
• SHI Xiangbin, WANG Xiaodi, WANG Baoliang, WANG Zhiqiang, JI Xiaohao, WANG Xiaolong, LIU Fengzhi, WANG Haibo
• Acta Horticulturae Sinica. 2021, 48(11): 2146-2160. DOI:10.16420/j.issn.0513-353x.2020-0785
• Abstract ( 482 ) HTML ( 293 ) PDF (849KB) ( 293 ) 　　　

• Taking‘Red Globe’grape as the test material,we sampled the whole plant during its key growth periods in 2017 and 2018,analyzed and determined the content of essential macronutrient elements such as nitrogen,phosphorus,potassium,calcium and magnesium,and calculated the absorption of each element at different growth stages. To provide theoretical basis for the rational and precise fertilization of‘Red Globe’,the annual demand characteristics of nitrogen,phosphorus,potassium,calcium and magnesium of‘Red Globe’grapes were studied. The results showed that the accumulation of nitrogen,phosphorus,potassium,calcium,and magnesium of the‘Red Globe’grape plant and various organs behaved an increasing trend with the whole growth process,but there were big differences in the element increase of different organs in different periods. From the perspective of the distribution characteristics of nitrogen,phosphorus,potassium,calcium,and magnesium in various organs at different growth stages,the plant was given priority to vegetative growth in the early stage of growth,and the nutrients of the leaf and other vegetative organs increase greatly. The vegetative growth and reproductive growth were synchronized and balanced from fruit expansion stage to the harvest stage. The increase in nitrogen,phosphorus,and potassium in fruit gradually increased,and the increment of calcium and magnesium in leaf was the largest. After the harvest,the plant began to store nutrients,and the nutrient increase of the stem,perennial shoot and other storage organs was relatively large. From the distribution characteristics of nitrogen,phosphorus,potassium,calcium,and magnesium of plants at different growth stages,‘Red Globe’grape continuously absorbed various macronutrients throughout the growing season,and the absorption and distribution rules of various elements at different stages were different. The demand for each nutrient is the highest from the end flowering stage to the version stage,the absorption of nitrogen,phosphorus,potassium,calcium,and magnesium in those stages accounted for 51.36%,53.31%,59.57%,63.92%,63.60%,respectively. The absorption amount of each element in other growth stages was relatively low. From the perspective of the accumulation of nitrogen,phosphorus,potassium,calcium,and magnesium in the whole plant,all elements could be absorbed in each growth stage,but the absorption amount at different stages was varied greatly. Therefore,fertilization management in production should be balanced fertilize according to the characteristics of plant nutrient requirements. In this study,the requirements of nitrogen,phosphorus,potassium,calcium and magnesium for 1 000 kg fruit of‘Red Globe’grape were 4.72,1.91,4.98,5.41 and 1.23 kg,respectively.

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• Change of Fatty Acid During Storage Period of‘Qiuxiang’Walnut Based on Metabolomics Analysis
• XU Haifeng, CHEN Xin, ZHANG Shigang, XIANG Kun, ZHANG Meiyong, XU Ying, WANG Guifang
• Acta Horticulturae Sinica. 2021, 48(11): 2161-2170. DOI:10.16420/j.issn.0513-353x.2020-0731
• Abstract ( 637 ) HTML ( 277 ) PDF (4134KB) ( 277 ) 　　　

• The‘Qiuxiang’walnuts were set up three treatments:climate storage for one year（CS）,4 ℃ low-temperature storage for one year（LS）and without storage（WS）. Then the fatty acids of walnut kernels were analyzed qualitatively and quantitatively using LC/MS. The results show that a total of 969 differential metabolites were obtained in the CS_WS comparison group,and a total of 975 differential metabolites were obtained in the LS_WS comparison group. Through further screening according to variable weight value（VIP > 1）,the CS_WS and LS_WS have 35 and 31 different metabolites,respectively. Comparing with WS,the stearidonic acid is reduced in CS and LS,linoleic acid and α-linolenic acid are significantly reduced in CS,the oleic acid is slightly increased in CS,however,in LS,oleic acid,linoleic acid and α-linolenic acid have no significant difference. In addition,ubiquinone is down-regulated in CS,while keratinous substances are increased in LS. The analysis of KEGG pathway shows that differential metabolites are mainly involved in the synthesis of unsaturated fatty acids and the metabolism of α-linolenic acid and linoleic acid. In addition,some differential metabolites are involved in the synthesis of keratin and ubiquinone. The correlation analysis among differential metabolites shows that there is a positive correlation between unsaturated fatty acids and ubiquinone,and a negative correlation between stearidonic acid and keratin. In summary,the ubiquinone is decreased and the antioxidant capacity is reduced of walnut in natural storage,thereby leading to reduced α-linolenic acid and linoleic acid,but the walnut in cold storage at 4 ℃ can inhibit the reduction of α-linolenic acid and linoleic acid,in addition,it also increase the keratin content to adapt to low-temperature environment.

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• Screening and Culture Characteristics of Biocontrol Strains of Postharvest Anthracnose of Mango
• ZHANG Xiaoyong, LI Shujiang, YAN Kai, WENG Guiying, ZHANG Yunxia, LONG Qiaofang, LIANG Wen, JIANG Qinna, YANG Youlian
• Acta Horticulturae Sinica. 2021, 48(11): 2171-2184. DOI:10.16420/j.issn.0513-353x.2020-0760
• Abstract ( 310 ) HTML ( 110 ) PDF (3581KB) ( 110 ) 　　　

• Bacillus strains were isolated from Gentiana rhodantha stems with highly antifungal activity resist mango anthracnose was screened by confrontation culture with Colletotrachum gloeosporioides. The fungistatic effect of mycelial growth and conidia germination was measured by in vivo experiment. The control efficiency of antagonistic strain against anthracnose was tested by surface coating method using wounded mango fruit. The structure of the antifungal substances in fermentation broth of antagonistic bacteria was detected by high performance liquid chromatography-mass spectrometry（HPLC-MS）,and single factor experiment was used to study on the optimal growth and fermentation conditions,respectively. Based on morphological,physiological and 16S rDNA and gyrB sequences analysis,the strain SB023 which significant antifungal activity against mango anthracnose was identified as Bacillus velezensis. The mycelial growth and spore germination of pathogen were significantly inhibited by the fermentation broth of strain SB023. The control effect of SB023 to against anthracnose of mango reached 100% then coated with 0.1% Tween-80,2% sodium alginate and 10% fermentation broth. The main antifungal substances were Surfactin C,Bacillomycin D,Bacillomycin L and Iturin A in broth. The fermentation study showed that the optimal culture medium for KMB with yeast extract,maltose,magnesium sulfate,initial pH 7.0 and incubated at 28-30 ℃.

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• A Primary Study on FvMOB1 Interact with FvM4K1 and Response to Auxin Regulation in Fragraria vesca
• LIU Lu, GU Si, ZHANG Weiwei, ZHAO Shuaiqi, LI Anran, XING Yu
• Acta Horticulturae Sinica. 2021, 48(11): 2185-2196. DOI:10.16420/j.issn.0513-353x.2020-0859
• Abstract ( 593 ) HTML ( 151 ) PDF (1922KB) ( 151 ) 　　　

• In order to study how FvMOB1 genes involved in auxin mediated woodland strawberry growth and regulate cell proliferation,this experiment using woodland strawberry（Fragraria vesca）‘Hawaii 4’material,cloned and analyzed coding sequence of homologous gene FvMOB1A and FvMOB1B based on bioinformatics. Fluorescence quantitative PCR was applied to analysis FvMOB1’s relative expression quantity in different organs of woodland strawberry,different development periods of fruit and different days during IAA treatment. Carried out subcellular localization of FvMOB1 and yeast two-hybrid interaction. The results show that FvMOB1A and FvMOB1B encode 215 and 216 amino acids respectively with open reading frame of 648 and 651 bp. In woodland strawberry,the expression level of FvMOB1A was much higher than that of FvMOB1B,the expression level of FvMOB1A is high in achene and root and lowest in stem,while the expression level of FvMOB1B is relatively highest in achene and lowest in leaves. The expression of both FvMOB1A and FvMOB1B are highest in the 30th day after flowering （post ripening stage）. The expression patterns of the two genes are the same after IAA treatment,both are up-regulated and reaching the peak value on the 7th day. The localization of FvMOB1A and FvMOB1B are in the cell nucleus and cell membrane,and yeast two-hybrid verified that both FvMOB1A and FvMOB1B can interact with mitogen-activated protein kinase FvM4K1.

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• High-throughput Screening of Transmission Rate for Ogura CMS Fertility Restorer Gene Rfo by HRM Technique in Cabbage
• REN Wenjing, YU Hailong, CHEN Li, ZHANG Bin, CHEN Wendi, FANG Zhiyuan, YANG Limei, ZHUANG Mu, LÜ Honghao, WANG Yong, JI Jialei, ZHANG Yangyong
• Acta Horticulturae Sinica. 2021, 48(11): 2197-2210. DOI:10.16420/j.issn.0513-353x.2020-1078
• Abstract ( 498 ) HTML ( 123 ) PDF (2075KB) ( 123 ) 　　　

• In order to create the cabbage Ogura CMS fertility restorer,backcrosses were conducted after distant hybridization between Brassica oleracea L. var. alboglabra and Brassica napus. BC₄ and BC₅ generations were developed. In this study,a Rfo-specific InDel molecular marker Rfo-11F/Rfo-11R suitable for high-resolution melting curve（HRM）analysis was designed and developed based on the Rfo gene coding sequence and promoter sequence. This marker was used for Rfo genotyping of BC₄ and BC₅ generations of the distant hybridization. A total of 41 progeny in BC₄ generation with Rfo gene were successfully selected with the average Rfo transmission rate of 0.51% and pollen viability of 81%. Five key Rfo-positive individuals were selected for further backcross. Cytological observation showed that the average proportion of normal pairing and segregating of pollen mother cells in BC₄ generation were 84% and 69%,respectively. After further backcrossing,117 Rfo-positive individuals were obtained from 15 408 BC₅ backcrossing progeny,and the Rfo gene transmission rate was 0.75%. The mean value of pollen viability was 83%,and the proportion of pollen mother cells with normal pairing and segregating chromosomes were 81% and 84%,respectively. After five successive generations of backcrossing,all the fertility-restored cabbage individuals returned to normal diploid level and exhibited fertility-restored,which was consistent with the molecular marker identification results. This indicated that the fast,accurate and efficient high-throughput genotyping system for Ogura CMS fertility restorer gene Rfo,which was constructed based on the developed InDel marker Rfo-11F/Rfo-11R,can be used for further screen of backcrossing progeny and great improvement of the breeding efficiency.

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• Establishment and Application of a Tomato KASP Genotyping System Based on Five Disease Resistance Genes
• WANG Peng, TIAN Zhejuan, KANG Chen, LI Yadong, WANG Hongle, YANG Chaosha, MANG Guangwei, KANG Liang, FAN Qingjie, WU Zhiming
• Acta Horticulturae Sinica. 2021, 48(11): 2211-2226. DOI:10.16420/j.issn.0513-353x.2020-0913
• Abstract ( 1180 ) HTML ( 276 ) PDF (2738KB) ( 276 ) 　　　

• Kompetitive allele specific PCR（KASP）is a novel genotyping tool based on single nucleotide polymorphism（SNP）. An efficient and economical resistance gene KASP genotyping method is very useful in tomato breeding program. In this study,KASP primer pairs of five tomato disease resistance genes were used to establish a KASP genotyping system,among them the primer sets for tomato yellow leaf curl virus（TYLCV）resistance gene Ty-1 and root-knot nematode（RKN）resistance gene Mi-1 were designed in this study,and KASP primers of tomato mosaic virus（ToMV）resistance gene Tm-2²,tomato spotted wilt virus（TSWV）resistance gene Sw-5 and fusarium crown and root rot（FCRR）resistance gene Frl were from previous publications. By using tomato germplasms containing different disease resistance genes,the KASP genotyping system was optimized for its template reaction volume,DNA concentration,primer concentration and the number of PCR cycles. Detection results using the optimized KASP method were consistent with the PCR detection results of molecular markers of five disease resistance genes. The KASP genotyping system developed in this study not only can save cost,but also possesses high accuracy and stability. Therefore,it can be widely used in identification of tomato disease resistance genes,genetic diversity analysis and gene mapping,which provides technical supports and theoretical basis for the tomato molecular marker-assisted disease resistance identification,rapid screening and utilization of resistance germplasms for tomato breeding.

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• Identification and Expression Analysis of miR156/157-SPL Pathway Genes in Cucumber
• WANG Shuwen, YANG Aiyi, WANG Huasen, XU Yunmin
• Acta Horticulturae Sinica. 2021, 48(11): 2227-2238. DOI:10.16420/j.issn.0513-353x.2020-0952
• Abstract ( 659 ) HTML ( 194 ) PDF (2404KB) ( 194 ) 　　　

• In this study,Cucumis sativus‘9930’was used as the material. The cucumber phenotype during different stages,the annotation of miR156/157-SPL,the structure and expression of genes were analyzed. The results showed cucumber exhibited an age-dependent developmental pattern,the leaf 1/2,leaf 3/4 and leaf 5 stages were classified as the juvenile stage,transition stage and adult stage,respectively. In cucumber genome,seven Csa-MIR156 loci,three Csa-MIR157 loci and 14 Csa-SPL were identified and distributed on chromosome 1,2,3,4 and 6,respectively. Exon number of Csa-SPL span is from 2 to 10,and their SBP domains are coded by exon 1 and 2. SBP domains contain two zinc finger domains （Zn_1 and Zn_2）and a nuclear localization signal. In addition,the large molecular weight of Csa-SPL8 and Csa-SPL11 contain several additional domains. Csa-SPL were clustered into 5 sub-family by phylogenetic tree analysis. Eleven Csa-SPL were predicted as target of Csa-miR156/157,and three of them （Csa-SPL5,10 and 14）hold the Csa-miR156/157 binding sites within the 3′UTR. Csa-SPL7,as a miR156 target,holds a specific mutation in 11th position. Interesting,this mutation is conserved among Cucurbitaceae plants. Gene detection results showed Csa-MIR156B and C functioned as the major loci,the expression of Csa-miR156 decreased and its Csa-SPL targets increased during age development. Specifically,Csa-SPL7 was highly expressed in cotyledon stage and its abundance showed no change during plant development. The expression pattern of Csa-SPL7 was consisted with the mutation within Csa-miR156 binding site,which suggested negative regulation by Csa-miR156 was relieved in Csa-SPL7. In summary,this study suggests miR156/157-SPL pathway plays a role in regulating cucumber vegetative traits（leaf shape,internode length and tendril formation）,moreover,the releasing of SPL7 may play an unknown role during early vegetative stage in Cucurbitaceae plants.

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• Screening for Genetic Variation in Photosynthesis and High Photosynthetic Efficiency Germplasm in Potato
• XU Guochun, LUO Wenbin, LI Huawei, XU Yongqing, JI Rongchang, ZHANG Hong, QIU Sixin, TANG Hao
• Acta Horticulturae Sinica. 2021, 48(11): 2239-2250. DOI:10.16420/j.issn.0513-353x.2020-0904
• Abstract ( 411 ) HTML ( 159 ) PDF (1157KB) ( 159 ) 　　　

• Twenty-four potato germplasms from different geographical regions were used to measure leaf gas exchange,instantaneous carboxylation efficiency（CE）,stomatal limitation value（L_s）,intrinsic water use efficiency（iWUE）and chlorophyll content（SPAD）of potato. Correlation analysis,principal component analysis and cluster analysis were combined to evaluate the genetic variation and screen high photosynthetic efficiency germplasm of tested materials. The results showed that,significant variation in all photosynthetic traits were observed among 24 germplasms,the coefficient of variation ranging from 8.42% to 25.21%,and more obviously variation in stomatal conductance（G_s）,transpiration rate（T_r）,L_s and iWUE were found,suggesting a promising opportunity for selection of greater photosynthetic efficiency in potato. Analysis of broad-sense heritability（h²）showed that,the h² of photosynthetic traits varied from 11.95% to 83.69%,six traits had a high level of heritability,whose h² were exceeded 60%,and the highest heritability was observed in SPAD（83.69%）. Principal component and cluster analysis revealed that,twenty-four germplasms were divided into three photosynthetic efficiency groups,and screened out eight germplasm with relatively higher photosynthetic efficiency,including‘Minshu 4’,‘Minshu 7’,‘Yunshu 108’,‘Yunshu 109’,‘Tianshu 10’,‘Longshu 7’,‘N210’and‘Longshu 9’. These germplasms can be used as genetic resources for the photosynthetic mechanism research and high photosynthetic efficiency breeding. In addition,the SPAD was significantly and positively correlated with comprehensive evaluation value of photosynthetic efficiency,so SPAD could be used as an early screening indicators of photosynthetic efficiency in potato germplasms.

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• Reference Genes Selection and Validation in Begonia masoniana Leaves of Different Developmental Stages
• YANG Ting, XUE Zhenzhen, LI Na, LANG Xiaoan, LI Lingfei, ZHONG Chunmei
• Acta Horticulturae Sinica. 2021, 48(11): 2251-2261. DOI:10.16420/j.issn.0513-353x.2021-0397
• Abstract ( 417 ) HTML ( 291 ) PDF (1386KB) ( 291 ) 　　　

• In order to research the suitable reference genes and the expression of the anthocyanin biosynthesis genes in the leaves of Begonia masoniana at different developmental stages,the expression stability of 11 genes（PP2A,EF1α,GADPH,CYP,elF4A,ACT2,18S,UBQ10,ACT7,PPR and HDH） was evaluated by real-time PCR,GeNorm,NormFinder and BestKeeper. The results showed that ACT7 and PP2A can be used as the suitable reference genes for gene expression analysis in B. masoniana. The expression levels of key genes involved in anthocyanin biosynthesis such as CHS,F3H,F3’H,FLS,DFR and UFGT were measured in leaves using the selected reference genes. The expression of the six anthocyanin pathway genes was higher in younger leaves and then declined during the later development stages,which was consistent with the change in the anthocyanin content in variegated leaves.

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• Study on the Fragrance Metabolic Genes of Rosa odorata Based on Transcriptome Sequencing
• ZHUANG Yueying, ZHOU Lijun, CHENG Bixuan, YU Chao, LUO Le, PAN Huitang, ZHANG Qixiang
• Acta Horticulturae Sinica. 2021, 48(11): 2262-2274. DOI:10.16420/j.issn.0513-353x.2020-0944
• Abstract ( 491 ) HTML ( 249 ) PDF (2612KB) ( 249 ) 　　　

• By using the technique of transcriptome sequencing,floral fragrance metabolic pathways and genes related to the unique floral fragrance of Rosa odorata var. gigantea and R. odorata var. odorata were investigated. The results showed that 8 339,8 849,and 7 572 differentially expressed genes were detected in these two plant species at the flower budding stage,early flowering stage,and blooming stage, including 3 762 differentially expressed genes that were detected in all three stages. Cluster analysis of GO and KEGG showed that the differentially expressed genes were mainly involved in the terms of metabolic process,cell process,single organism process,catalytic activity,and other biological processes. They were also largely enriched in the metabolic pathway,secondary metabolites biosynthesis,carbon metabolism,and other pathways. A total of 27 differentially expressed genes were predicted to be associated with six important floral fragrance biosynthesis pathways（terpenoid backbone biosynthesis,phenylpropanoid biosynthesis,fatty acid biosynthesis,monoterpenoid biosynthesis,diterpenoid biosynthesis,sesquiterpene,and triterpene biosynthesis）. The results showed that these 27 genes had a significant effect on the difference of floral fragrance emission between the two species,and the difference was consistent in the three stages. Furthermore,the expression of Rc_0128091 and Rc_0119291,which are the characteristic floral substance synthetase genes,were investigated. It was found that the expression of Rc_0128091 and Rc_0119291 in the transcriptional data was consistent with the emission of 3,5-dimethoxybenzene and 1,3,5-trimethoxybenzene,suggesting that they are decisive for the synthesis of the characteristic aroma compounds. By randomly selecting 10 differentially expressed genes,the correlation between qRT-PCR and RNA-seq results was verified. The highly correlated results indicate that the RNA-seq results are of high accuracy.

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• High-density Genetic Linkage Map Reconstruction in Jujube Using SNP Markers
• TANG Haixia, GAO Rui, WANG Zhongtang, ZHANG Qiong
• Acta Horticulturae Sinica. 2021, 48(11): 2275-2285. DOI:10.16420/j.issn.0513-353x.2020-0933
• Abstract ( 447 ) HTML ( 159 ) PDF (3356KB) ( 159 ) 　　　

• The genetic linkage map was reconstructed referred to the whole genome sequencing data of‘Dongzao’jujube,based on the 103 F₁ population of‘Dongzao’בJinsi 4’that have been published and SNP（38.45 Gb） developed from the population by our team. The new linkage map consisted a total of 3 678 SNP markers,spanning 939.23 cM,with an average marker distance of 0.26 cM. The genetic map anchored 324 Mb（74.17%）of scaffolds to the sequenced‘Dongzao’genome.

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• Effects of Cold Plasma Seed Treatment on Tomato Seedling Growth and Light Energy Utilization Under Daytime Sub-high Temperature Environment
• LI Kai, ZHANG Lili, SHAO Changyong, ZHONG Chongshan, CAO Bili, SHI Qinghua, GONG Biao
• Acta Horticulturae Sinica. 2021, 48(11): 2286-2298. DOI:10.16420/j.issn.0513-353x.2020-0698
• Abstract ( 451 ) HTML ( 157 ) PDF (886KB) ( 157 ) 　　　

• In view of the problem that the seedling and production of protected tomato often suffer from high daytime temperature in summer,this paper aimed to study the simple and effective technology and regulation mechanism of high temperature resistance of tomato seedlings. Tomato seeds were treated with cold plasma（CP）of 25,50,75,100,125,150,175 and 200 W respectively for 10 s,the seeds without CP treatment were used as control,these seeds were cultured in a controllable temperature glass greenhouse in summer. When the temperature was lower than 35 ℃,there was no ventilation to reduce the temperature. When the temperature was higher than 35 ℃,the temperature was controlled by ventilation or wet curtain. The temperature is controlled between 32 ℃ to 35 ℃ to create a daytime sub-high temperature environment for seedling growth. The growth indexes of seedlings were analyzed,and the diurnal variations of water and gas exchange parameters and chlorophyll fluorescence parameters were measured under control and optimal CP treatment（75 W）. The results showed that the plant height,stem diameter,shoot dry weight,root dry weight,root-shoot ratio and seedling index of the seedlings were firstly increased and then decreased with the increase of CP treatment power,and reached the highest values in CP treatments from 25 to 75 W. The growth quality of tomato seedlings showed the best level at 75 W CP treatment. In control,excepting the intercellular CO₂ concentration（C_i）,the net photosynthetic rate（P_n）,transpiration rate（T_r）,stomatal conductance（G_s）,stomatal limiting value（L_s）and water use efficiency（WUE）were firstly decreased and then increased in daytime,which arrived at the highest（lowest）values in the sub-high temperature（34.9-35.3 ℃）at noon（12:00 to 14:00）in summer. When compared with control,CP treatment increased midday P_n,T_r,G_s,L_s,and decreased C_i,and showed a higher WUE in daytime. Meanwhile,CP treatment significantly increased the maximum fluorescence（F_m）,potential photochemical activity（F_v/F_o）,maximum photochemical efficiency（F_v/F_m）,excitation energy capture efficiency（F_v′/F_m′）,actual photochemical efficiency（Φ_PSⅡ）,photochemical quenching coefficient（q_P）,chlorophyll fluorescence decay rate（R_fd）,excitation energy distribution coefficient of PSⅠ（α）and the share（P）of absorbed light energy used for photochemical reactions when compared with control treatment. The minimum fluorescence（F_o）,non photochemical quenching coefficient（NPQ）,relative limiting value of photosynthetic function（L_PFD）,excitation energy pressure of PSⅡ（1-q_P）,excitation energy distribution coefficient of PSⅡ（β）,imbalance of excitation energy distribution between PSⅠand PSⅡ（β/α-1）,share of thermal dissipation of antenna（D）and the share of non photochemical dissipation（E_x）were decreased. The results showed that CP treatment could reasonably regulate leaf water and air exchange and light energy utilization,and promote the healthy growth of tomato seedlings under daytime sub-high temperature environment in summer.

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• Molecular Identification of Four Viruses that Cause Mixed Infection of Pumpkin in Chengdu,Sichuan Province of China
• LIN Xiaomin, PENG Meifang, FAN Xiaoli, CHEN Kegui
• Acta Horticulturae Sinica. 2021, 48(11): 2299-2310. DOI:10.16420/j.issn.0513-353x.2020-0770
• Abstract ( 452 ) HTML ( 106 ) PDF (1466KB) ( 106 ) 　　　

• In recent years the disease caused by virus has become more and more serious issue in pumpkin field production. In this study,samples from the field in Chengdu,Sichuan Province of China were collected in May,2020. Deep sequencing of small RNA（sRNA）from the pumpkin sample revealed that there were four viruses of cucurbit aphid-borne yellows virus（CABYV）,watermelon mosaic virus（WMV）,papaya ringspot virus（PRSV）and zucchini yellow mosaic virus（ZYMV）. All the viruses were further confirmed by reverse transcriptional PCR（RT-PCR）and Sanger sequencing of the RT-PCR fragments. Alignments and phylogenetic analyses with sequences of the viruses in GenBank showed that CABYV and ZYMV were more similar with the viruses recently reported in China,whereas WMV and PRSV were similar with the other viruses in China and abroad,as well. Besides,the sequence alignments and phylogenetics further suggested that two isolates for both CABYV and PRSV might be currently infecting pumpkin in Sichuan Province. Discovery of the complicated mixed virus-infection in pumpkin might be of potential significance for the virus disease control in pumpkin production.

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• Research Progress of MYB Transcription Factors in Orchidaceae
• KE Yujie, CHEN Mingkun, MA Shanhu, OU Yue, WANG Yi, ZHENG Qingdong, LIU Zhongjian, AI Ye
• Acta Horticulturae Sinica. 2021, 48(11): 2311-2320. DOI:10.16420/j.issn.0513-353x.2020-0843
• Abstract ( 640 ) HTML ( 345 ) PDF (741KB) ( 345 ) 　　　

• This article systematically reviewed the structure and classification of MYB transcription factors,summarized their functions in flavonoid synthesis,floral aroma regulation,floral organ morphogenesis and environmental stress responses in orchids,as well as provided fundamental insights into future research of MYB molecular mechanism and the new varieties breeding of orchids.

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• A New Watermelon Cultivar‘Huazhixiu Bingtang’with Multicolour Flesh
• YUAN Shengkai, MA Cong, YAN Yuemin, LI Guangliang, MA Qiang, ZHU Shuncheng, JIA Zhen, WU Jiang, WANG Xuefen, LI Hongchen, MA Shiyuan, ZHAO Mingqin, MA Changsheng
• Acta Horticulturae Sinica. 2021, 48(11): 2321-2322. DOI:10.16420/j.issn.0513-353x.2019-0984
• Abstract ( 642 ) HTML ( 224 ) PDF (1467KB) ( 224 ) 　　　

• ‘Huazhixiu Bingtang’with small fruit is a new watermelon hybrid developped from YY-15B（female parent）and YYXZ048（male parent）. Its whole growth period is 98-105 days with 30 days for fruit growth,easily to fruit setting. The fruit owns elliptical type,with green fruit skin and covered by dark green strips. With 3.0 kg per fruit and 0.6 cm of pericarp thickness,the fruits are durable for storage and transportation. Surprisingly,the flesh is crisp,showing a chimera flesh with yellow and red colors. The average soluble solids content is about 12.8% in the center and 10.8% in the edge. It’s suitable for planting in small arch shed,open field and interplanting cultivation in Huanghuai Rivers Basin（including tobacco planting area）,Yangtze River Basin,and Hainan Province,etc.

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• A New Phalaenopsis Cultivar‘Ruyu’
• LÜ Fubing, CHEN Heming, LI Zuo, XIAO Wenfang, You Yi
• Acta Horticulturae Sinica. 2021, 48(11): 2323-2324. DOI:10.16420/j.issn.0513-353x.2020-0053
• Abstract ( 521 ) HTML ( 222 ) PDF (1216KB) ( 222 ) 　　　

• The Phalaenopsis cultivar‘Ruyu’of rich flowers is selected from the self-crossing offspring of‘Sogo Vivien’. The number of pedicels per plant is 2.6,and there are 8.8 flowers in the main inflorescence and 15.1 flowers on the whole. The length of flower branches is 30.0 cm,and the diameter of flower was 3.8 cm. The flower is light purple with round and good design,and the petals are purple with veinlets.

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