Research Papers

• Function Analysis of the Stilbene Synthase VqSTS12 and VqSTS25 Genes of the Resistance to Powdery Mildew in Vitis quinquangularis
• WU Fengying，LIU Mengqi，and WANG Yuejin
• Acta Horticulturae Sinica. 2020, 47(2): 205-219. DOI:10.16420/j.issn.0513-353x.2019-0329
• Abstract ( 354 ) HTML ( 722 ) PDF (4704KB) ( 722 ) 　　　
• Vitis quinquangularis‘Danfeng-2’is an important research material with high resistance to powdery mildew due to its high resveratrol content. In the present study，two stilbene synthase genes VqSTS12 and VqSTS25 were obtained from‘Danfeng-2’leaves using homologous sequence cloning. The overexpression vector was constructed and the transgenic seedlings were obtained by Agrobacteriummediated transformation with meristematic bulks of Vitis vinifera‘Thompson Seedless’was used as the receptor material. Through genetic transformation，we finally obtained 7 and 5 transgenic seedlings of VqSTS12 and VqSTS25 respectively，which were confirmed by PCR at DNA level and Western Blot at protein level. Afterwards，the expression of genes related to resveratrol synthesis in transgenic‘Thompson Seedless’seedlings was analyzed by real-time quantitative PCR，which revealed that the expression of stilbene synthase（STS）gene and downstream resveratrol glycosyltransferase（RSGT）gene were up-regulated，while that of chalcone synthase（CHS）gene was down-regulated due to the substrate competition with STS. Meanwhile，the content of stilbene components was higher in transgenic‘Thompson Seedless’seedlings compared to that in wild-type seedlings by HPLC，mainly existing in the form of trans-piceid. The transgenic plants with high content of stilbene components were subsequently selected for the functional study. As a result，the transgenic‘Thompson Seedless’seedlings were obviously less sensitive to powdery mildew than wild-type seedlings. The occurrence of powdery mildew on the transgenic‘Thompson Seedless’seedlings was later and milder compared with non-transgenic seedlings. In detail，a number of powdery mildew spore germination were inhibited，with slow mycelial growth. Moreover，the expression level of VqSTS12 and VqSTS25 genes in transgenic seedlings were significantly increased after induction by powdery mildew. The expression level of STS genes increased rapidly at 1–3 day after inoculation，then decreased，but still remaining at a high level. Finally，the expression level of STS genes rose again at 6–7 day after inoculation. Additionally，we also detected the high content and high activity of resveratrol，piceid，pterostilbene and ε-viniferin in transgenic‘Thompson Seedless’seedlings after inoculation by powdery mildew. In conclusion，these present findings suggested that the stilbene synthetase genes VqSTS12 and VqSTS25 from the Vitis quinquangularis‘Danfeng-2’and their expressed stilbene components exerted certain effects on inhibiting powdery mildew.
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• Cloning，Subcellular Localization and Expression Analysis of the EjSPL5 Gene in Triploid Loquat
• SUN Weixiong，SHI Min，XUE Baogui，XIA Yan，GUO Qigao，WANG Shuming，WU Di，JING
• Acta Horticulturae Sinica. 2020, 47(2): 220-232. DOI:10.16420/j.issn.0513-353x. 2019-0555
• Abstract ( 325 ) HTML ( 621 ) PDF (3598KB) ( 621 ) 　　　
• In this study，SQUMOSA PROMOTER BINDING PROTEIN LIKE5（EjSPL5）was isolated by homologous cloning and rapid amplification of cDNA ends（RACE）techniques from the triploid loquat‘Q27’. Full length cDNA sequence of EjSPL5 was 778 base pairs（bp），including a 24 bp 5′UTR and a 214 bp 3′UTR. Open reading frame（ORF）of EjSPL5 was 549 bp and encodes 182 amino acids. Sequence alignment analysis showed that EjSPL5 is highly similar to SPL proteins of Malus × domestica（Md），Arabidopsis thaliana（At）and Antirrhinum majus（Am），and has a conserved SBP domain and nuclear localization signal（NLS）. There were high homology of amino acid sequences in EjSPL5 and MdSPL5 of Malus × domestica. Subcellular localization of EjSPL5 was detected to be localized to nucleus. Real-time quantitative PCR analysis suggested that EjSPL5 was highly expressed in sepal and young fruit. There was a significant difference in the expression levels of EjSPL5 in the early and late flowering cultivars of diploid and triploid loquat. The expression of EjSPL5 was mainly concentrated in the first six stages of flower development，while the expression level of EjSPL5 was lower in the stages of white corollas and full bloom. However，the expression level of EjSPL5 was the highest in the morphological differentiation of flower bud in triploid loquat and the rapid elongation of lateral inflorescence branches in diploid loquat. Furthermore，the expression level of EjSPL5 in early-flowering cultivars was higher than that in lateflowering ones.
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• Studies on the Amino Acid Metabolism and Carbohydrate Metabolism Variation During Flower Development in Eriobotrya japonica
• XU Hongxia，LI Xiaoying，and CHEN Junwei
• Acta Horticulturae Sinica. 2020, 47(2): 233-241. DOI:10.16420/j.issn.0513-353x.2019-0271
• Abstract ( 358 ) HTML ( 591 ) PDF (2682KB) ( 591 ) 　　　
• In order to study the metabolic mechanism related to flower development in Eriobotrya japonica，GC–MS was used as the detection technique. The metabolites in five different developmental processes were detected at physiological differentiation stage，morphological differentiation stage，inflorescence emergence and expansion stage，single flower development stage and blossoming stage. Multivariate statistical analysis was carried out for all the samples，and then the metabolites were statistically classified and the most relevant metabolic pathways were screened out. In this research，the metabolic phenotypes of different flower developmental stages were summarized and analyzed. The soluble sugar，soluble proteins and starch content as well as C/N ratio variation during the five stages were also detected. A total of 430 metabolites were obtained. Amino acid and carbohydrate metabolism were the two most significant metabolic pathways related to flower development，and the metabolism was more vigorous in single flower development stage than the other stages. The soluble sugar，soluble proteins，starch content and C/N ratio were consistent with the phenotypic results of the metabolome. C/N ratio is one of the important factors determining thedevelopment process of flowers.
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• Physiological Reasons for Inhibiting Photosynthesis of Mango Leaves by Enhanced UV-B Radiation
• WANG Hong，YUE Kun，YANG Chengkun，GUO Yujian，WANG Peixuan，and ZHOU Kaibing
• Acta Horticulturae Sinica. 2020, 47(2): 242-252. DOI:10.16420/j.issn.0513-353x.2019-0381
• Abstract ( 211 ) HTML ( 424 ) PDF (835KB) ( 424 ) 　　　
• In order to investigate the characteristics of photosynthesis changes of mango leaves under enhanced UV-B Radiation，the treatment of artificial simulation of enhanced UV-B radiation（24 and 96 kJ ·m-2 ·d-1） were conducted with the adult trees of‘Tainong 1’in the field，and the photochemical reactions， activities of key enzymes in carbon assimilation and the expression of gene were observed. The results showed that，compared to the control（natural lighting），there was a decrease of tree yield and soluble sugar and sugar-acid ratio of fruits under the 96 kJ ·m-2 ·d-1 treatment and no significant changes with 24 kJ · m-2 · d-1 tratment except that vitamin C was significantly higher than the control. Chlorophyll a/b value，net photosynthetic rate，stomatal conductance，transpiration rate and intercellular CO2concentration in leaves treated by 96 kJ · m-2 · d-1 were significantly lower than the control and treated by 24 kJ · m-2 · d-1，The content of photosynthetic pigment，the vitality of Hill reaction，the quenching coefficient of photochemistry the activities of Rubisco were significantly higher than the control. The Hill activity and Rubisco activity treated by 24 kJ · m-2 · d-1 were significantly higher than the control，net photosynthetic rate，stomatal conductance，transpiration rate，intercellular CO2 concentration and the content of photosynthetic pigment showed no significant difference compared to the control. The expression of coding gene of Rubisco big subunit（RbcL）could be inhibited by the 96 kJ · m-2 · d-1treatment 5th March and 22nd April. It is clear that stomatal limitation could be induced by 96 kJ · m-2 · d-1treatment directly，and then photosynthesis would be inhibited and then result in the reduction of yield and the deterioration of quality
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• Impact of Grafting on Soil Microbial Properties and Bacterial Community Structure in Tomato Rhizosphere
• PANG Shichan1，GUO Shuang1，REN Kuiyu1，WANG Shuaishuai1，and YANG Shangdong1.2
• Acta Horticulturae Sinica. 2020, 47(2): 253-263. DOI:10.16420/j.issn.0513-353x.2019-0444
• Abstract ( 503 ) HTML ( 799 ) PDF (1409KB) ( 799 ) 　　　
• Grafting was found effective in enhancing plant disease resistance. Rhizosphere microbial communities play a crucial role in plant resistance to soil-borne diseases. Eggplants and tomato were used as rootstocks and scions，respectively，to investigate the impact of grafting on soil biochemical properties and bacterial community composition in tomato rhizosphere. We found that grafting significantly increased cultivable bacteria，actinomycetes，microbial biomass-C，N and P，and enzyme activities in tomato rhizosphere. Higher bacterial richness，evenness and diversity indices were also observed in the rhizosphere of grafted plants compare to self-rooted plants. High-throughput sequencing revealed that norank_c_Acidobacteria，Nitrospira，Bacillus，norank_f_Gemmatimonadaceae，norank_o_Gaiellales，norank_f_Xanthobacteraceae，norank_o_SC-I-84，norank_f_Anaerolineaceae，norank_f_Nitrosomonadaceae and Sphingomonas were dominant bacterial genera，which were found common in rhizosphere of grafted and self-rooted plants. The g_unclassified_o_Ignavibacteriales，g_Acetobacter，g_norank_f_ Longimicrobiaceae，g_unclassified_f_Verrucomicrobiaceae，g_norank_p_FBP，g_norank_p，and Aminicenantes were specific dominant bacterial genera found only in the rhizosphere of grafted plants. Our results indicated that tomato grafted on eggplant promoted soil nutrition availability by increasing culturable microorganisms，microbial biomass and related enzyme，activities in tomato rhizosphere. At the same time，it has different dominant proportions of the common bacterial genus,especially greater number of bacterial total OTU and endemic OTU，which is the main reason for the increased resistance of grafted plants.
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• Inheritance and QTL Analysis of Long-style Trait in Tomato
• MA Yalin and LIANG Yan
• Acta Horticulturae Sinica. 2020, 47(2): 264-274. DOI:10.16420/j.issn.0513-353x.2019-0458
• Abstract ( 312 ) HTML ( 542 ) PDF (1087KB) ( 542 ) 　　　
• In this study，the temperature sensitivity，inheritance and QTL（quantitative trait locus）analysis of long-style trait were performed using a tomato（Solanum lycopersicum）material，J59，which shows a long style phenotype. The main results were as follows：when the seedlings at two-leaf stage were treated with different temperature conditions，including 18/10 ℃，25/18 ℃，and 35/25 ℃ in day/night，respectively，the lengths of pistil，stamen，style，and stigma exsrtion were not significantly changed，implying that the tomato J59 is not a temperature-sensitive material. Furthermore，the six generations of genetic groups，namely，P1，P2，F1，BC1P1，BC1P2，and F2，were constructed using the J59 and M82（short style）tomatoes as parental materials. Genetic analysis indicated that the long style trait conforms to the MX2-ADI-AD model and is mainly controlled by major genes. The inheritabilities of major genes in BC1P1，BC1P2 and F2 populations are 65.51%，90.76% and 89.10%，respectively. Moreover，using 121 polymorphic SSR markers，a genetic linkage map was constructed，which consists of 12 linkage groups，and covers a total length of 2 108.71 cM in the genome with an average of 17.43 cM between the adjacent markers. The QTL analysis was performed based on the inclusive composite interval mapping method. 10 QTLs associated with long-style trait，which distribute in Chr1，Chr2，Chr3，Chr4，Chr5，and Chr12，were detected. LOD scores are ranged from 2.53 to 26.85. These QTLs can explain the phenotypic variability of 1.28%–20.22%，in which，the variabilities of 3 QTLs are higher than 10%，accounting for 30% of the total QTL.
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• Fine Mapping of Fruit Cracking-resistant Gene Cr3a in Tomato
• ZHU Yu，FAN Lina，HUANG Zejun，DU Yongchen，GUO Yanmei，LI Junming，LIU Lei，SHU Jinshuai，
• Acta Horticulturae Sinica. 2020, 47(2): 275-286. DOI:10.16420/j.issn.0513-353x.2019-0260
• Abstract ( 329 ) HTML ( 507 ) PDF (2704KB) ( 507 ) 　　　
• The introgression line 14h616 was derived from cultivated tomato inbred line 1052（Solanum lycopersicum 1052）and contained a 2.66 Mb fragment on chromosome 3 from S. pennellii LA0716，which contained a fruit cracking-resistance gene Cr3a. A sub-introgression population of tomato Cr3a resistance gene was constructed using 14h616 and 1052 as parents. Making paraffin sections and measuring the water content of fruits from the crackable fruits and cracking-resistant fruits containing the Cr3a gene in introgression population F5 generation. Histological examination suggested that fruit cracking- resistant Cr3a did not significantly affect the thickness of the cuticle and the number of epidermal cells of fruits. Water content analysis showed that the fruits from the sub-introgression line embodying Cr3a contained less water than that from cultivated tomato inbred line 1052 in mature green stage. Genetic analysis and phenotypic identification of sub-introgression populations showed that tomato cracking-resistant gene Cr3a was incompletely dominant，and its genetic contribution rate is 27.41%. Cr3a was narrowed down to a 349 kb interval between molecular markers 3-ZY75 and 3-ZY43，which encoded 47 putative genes. Using molecular markers，the F2 population constructed with the cracking-resistant material 182h640 as the maternal and the crackable material 182h680 as the paternal，and 200 high-generation materials with different genetic backgrounds were analyzed. The conformity is good and the accuracy of assistant selection was 96%. The study results laid a solid foundation for the map-based cloning of Cr3a and the molecular improvement of tomato cultivars resistant to fruit cracking.
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• Effect of Exogenous Hydrogen on Photosynthetic Carbon Assimilation and Nitrogen Metabolism of Cucumber Seedlings Under Low Temperature
• LIU Fengjiao，ZHANG Xiaowei，LI Fude，ZHAI Jiang，BI Huangai，and AI Xizhen
• Acta Horticulturae Sinica. 2020, 47(2): 287-300. DOI:10.16420/j.issn.0513-353x.2019-0353
• Abstract ( 258 ) HTML ( 463 ) PDF (977KB) ( 463 ) 　　　
• The purpose of this paper is to investigate the effect of exogenous hydrogen（H2）on photosynthetic carbon assimilation and nitrogen metabolism of cucumber（Cucumis sativus L.）under low temperature. The‘Jinyou 35’cucumber seedlings subjected to low temperature stress（day/night temperature was 8 ℃/5 ℃）were presoaked with hydrogen-rich water（HRW，the donor of H2）or the deionized water（Control）for 8 h. The results illustrated that the chilling stress restrained the seedling growth，and decreased the pigment contents，net photosynthetic rate（Pn），stomatal conductance（Gs），transpiration rate（Tr），actual photochemical efficiency of PSⅡ（ΦPSΠ），maximum photochemical efficiency of PSII in darkness（Fv/Fm），antenna efficiency of PSⅡ（Fv′/Fm′），the activity of ribulose bisphosphate carboxylicase（RuBPCase）and root activity，while increased the intercellular CO2 concentration（Ci）and initial fluorescence（F0）. Further studies revealed that chilling stress induced enhancement of sucrose synthetase（SS）and sucrose phosphate synthetase（SPS）activities and the total sugar，sucrose content，but reduced the starch content. Meanwhile，the total nitrogen content，ammonia nitrogen content and the activities of reduced nitrate reductase（NR），glutaminase（GS），glutamate synthase（GOGAT）and glutamate dehydrogenase（GDH）increased in the early days of chilling stress but subsequently decreased under low temperature stress. The nitrate nitrogen content increased gradually. These change tendencies of HRW treatment were almost the same as those of control. In addition to low Ci and F0，most of the remaining indicators in HRW treatment were significantly higher than control，which indicated that exogenous H2 could enhance the tolerance of cucumber seedlings to lower temperature stress by increasing the activities of key photosynthetic enzymes，reducing photoinhibition and maintaining a high level of carbon and nitrogen metabolism，thus promoting the cucumber seedlings growth finally.
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• Establishment of an Efficient Regeneration System in Hippeastrum vittatum with Plantlet Leaves
• WANG Chunxia，ZHANG Mengdi，WANG Jinxia，WANG Zhiping，and SUN Hongmei
• Acta Horticulturae Sinica. 2020, 47(2): 301-309. DOI:10.16420/j.issn.0513-353x.2020-0195
• Abstract ( 563 ) HTML ( 489 ) PDF (1498KB) ( 489 ) 　　　
• Using the leaves as explants in vitro culture，it has the advantages of convenient materials，abundant test materials，and low cost. However，the induced regeneration rate of leaves is extremely low，which is a major problem in vitro culture of Hippeastrum vittatum. Effects about different plant growth regulators and different parts of materials on adventitious bud induction and subculture were studied with the leaves of‘Blossom Peacock’and‘Royal Velvet’plantlet. The results showed that the best explants were the base of young leaves（0.5 cm）formed by culturing in MS medium for 10 days. The photoperoid is 16 h · d-1（light intensity 36 μmol · m-2· s-1）. The best medium for adventitious buds induction of Hippeastrum vittatum was MS + 2 mg · L-1 6-BA + 1 mg · L-1 NAA + 2 mg · L-1 TDZ. The adventitious buds of both varieties occurred in an indirect way，and the‘Blossom Peacock’formed callus after 40 days of culture，adventitious buds formed on 55 days，the induction rate reached 69.44%；‘Royal Velvet’formed callus after 45 days of culture，and adventitious buds formed on 65 days，the induction rate reached 66.67%. The optimal adventitious bud proliferation medium was MS + 2 mg · L-1 6-BA + 1 mg · L-1 NAA + 1 mg · L-1 TDZ，and the proliferation coefficients of‘Blossom Peacock’and‘Royal Velvet’reached 4.67 and 3.46，respectively. The optimal somatic embryo induction medium was MS + 2 mg · L-1 6-BA + 1 mg · L-1 PIC，and the induction rate of‘Blossom Peacock’and‘Royal Velvet’reached 66.67% and 63.89%，respectively. Rooting culture was carried out in MS medium without added hormones，and the rooting rate of both varieties reached 100% after 30 days. The Hippeastrum vittatum plantlets after 30 days of rooting culture were moved to room temperature for 3 days. Then remove the sealing film domestication for 3 days. They were transplanted to the high temperature sterilized charcoal︰vermiculite（volume ratio） 1︰1 matrix，and then the survival rate reached 100%.
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• Molecular Cloning and Functional Characterization of Linalool Synthase Gene OfTPS5 in Osmanthus fragrans‘Lianzi Dangui’Flowers
• LIU Cai1,4,*，XI Wan1,2,*，YUAN Jinmei1,2，ZHU Linlin1,2，CHEN Hongguo3，ZOU Jingjing3，ZHENG
• Acta Horticulturae Sinica. 2020, 47(2): 310-320. DOI:10.16420/j.issn.0513-353x.2019-0721
• Abstract ( 300 ) HTML ( 543 ) PDF (4859KB) ( 543 ) 　　　
• This study was conducted to isolate a linalool synthase gene from Osmanthus fragrans Lour.‘Lianzi Dangui’based on genome sequences. Functional identification，expression analysis and the relation with aroma compound formation were investigated. The gene was designated as OfTPS5（GenBank accession No. MN366471）. Sequence analysis demonstrated that the open reading frame（ORF）was 1 770 bp，and putatively encoded 589 amino acids. The OfTPS5 contained conserved domains and belonged to TPS-g subfamily. Multiple sequence alignment analysis demonstrated that it has approximate 50% homology with other plant TPSs. The transcript expression of OfTPS5 reached high level at the full bloom stage with a significant circadian rhythm，which also showed positive correlation with the aroma compound formation. Further transient expression in tobacco leaves proved that OfTPS5 was capable of producing linalool. Thus，OfTPS5 might play an important role in terpenoid biosynthesis in O. fragrans flowers.
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• Preliminary Study on the Regulation Mechanism of GA3 and IAA Combination in Paris polyphylla var. chinensis Seed Germination
• CHEN Yao1,2，ZHOU Hanmei1，HE Bing1,*，and LI Wei1
• Acta Horticulturae Sinica. 2020, 47(2): 321-333. DOI:10.16420/j.issn.0513-353x.2019-0263
• Abstract ( 318 ) HTML ( 469 ) PDF (2855KB) ( 469 ) 　　　
• The experiment used transcriptome sequencing to analyze differentially expressed genes（DEGs）in hormone synthesis and hormone signal transduction pathways. The mechanism of the combination of GA3 and IAA on the germination of seeds of Paris polyphylla var. chinensis was preliminarily revealed. The results found that the germination rate of seeds of P. polyphylla var. chinensisreached 87.33% after 8 months of treatment with 600 mg · L-1 GA3 + 40 mg · L-1 IAA. Comparing the DEGs from transcriptome sequencing with the KEGG database. We found that treating P. polyphylla var. chinensis seeds with exogenous GA3 and IAA of could down-regulated the GA2ox and up-regulate the GA20ox. In the GA signal transduction pathway，the GID1 was down-regulated and the PIF4 was up-regulated. It was speculated that the GA signal transduction was enhanced by the combined increase action of the exogenous GA3 and the endogenous GA. In the IAA synthesis pathway，the exogenous IAA up-regulated the YUCCA and ALDH. In the IAA signal transduction pathway，the auxin influx carrier gene AUX1，AUX/IAA，and SAUR et al were up-regulated. It was speculated that the IAA signal transduction was enhanced by the combined increase of the exogenous IAA and the endogenous IAA. Thus，the seed germination promoted by the combination of GA3 and IAA was associated with the GA and IAA synthesis and the signal transduction.
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Research Notes

• Identification and Expression Analysis of Sucrose-phosphate Synthase（SPS）Genes in Citrus
• WEI Qingjiang，MA Zhangzheng，LE Si，LEI Changyu，MA Qiaoli，and GU Qingqing
• Acta Horticulturae Sinica. 2020, 47(2): 334-344. DOI:10.16420/j.issn.0513-353x.2019-0612
• Abstract ( 338 ) HTML ( 535 ) PDF (2433KB) ( 535 ) 　　　
• In order to explore the characteristics of citrus sucrose-phosphate synthase（SPS）genes and their expression patterns during fruit development and ripening，four SPS genes（CsSPS1–CsSPS4）were identified in sweet orange genome. CsSPSs are distributed on different chromosomes and can be classified into three subfamilies，which also contain functional domains common in SPS family. Quantitative PCR revealed that CsSPSs were expressed in all tested tissues，and CsSPS4 preferentially expressed in fruit. Further study found that the expression levels of CsSPS3 and CsCSPS4 in‘Rongan’and‘Huapi’kumquat were higher than those of CsSPS1 and CsCSPS2 during the fruit development. In addition，the expression levels of CsSPS4 in the peel and pulp of two kumquats increased sharply with fruit development，suggesting its key functions in regulating sucrose synthesis and accumulation in kumquat fruit.
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• Genetic Background Analysis of Seedless Sour Orange‘Paoju’
• WEI Zhuangmin1,*，LI Mengmeng1,*，YANG Xiaoming2，YUAN Xiaohui3，YE Junli1，XIE Zongzhou1，DENG Xiuxin1，and CHAI Lijun1,**
• Acta Horticulturae Sinica. 2020, 47(2): 345-354. DOI:10.16420/j.issn.0513-353x.2019-0512
• Abstract ( 291 ) HTML ( 431 ) PDF (2554KB) ( 431 ) 　　　
• The objective of this study was to analyze the genetic background of a seedless sour orange species called‘Paoju’that is cultivated in Fujian Province using cpSSR, nSSR and genomic resequencing. We found that seven pairs of cpSSR primers could amplify 22 bands with an average of 3.14 bands per locus. The average expected heterozygosity（He）and Shannon information index（I）were 0.47 and 0.81, respectively. Thirteen pairs of nSSR primers amplified 65 bands with an average of 5 bands per locus. The average He and I were 0.66 and 1.27，respectively. A UPGMA analysis that used the data from the cpSSR and nSSR experiments demonstrated that‘Paoju’is a hybrid derived from a Citrus maxima × C. aurantium and that‘Paoju’is closely related to Daidai Sour Orange. A resequencing analysis with sweet orange as reference genome showed that the similarity rate between‘Paoju’and sour orange was more than 85%. Based on these data，we speculate that‘Paoju’may be a type of sour orange.
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• Cloning and Analysis of LTR Reverse Transcriptase from Chinese Cherry （Prunus pseudocerasus Lindl.）
• LIU Houyu1,2,3，WU Minfang1，and WEN Xiaopeng 1,*
• Acta Horticulturae Sinica. 2020, 47(2): 355-369. DOI:10.16420/j.issn.0513-353x.2019-0418
• Abstract ( 276 ) HTML ( 380 ) PDF (2126KB) ( 380 ) 　　　
• In order to provide fundamental clue for genetic evolution and variation mechanism，the reverse transcriptase gene fragments of Ty1-copia and Ty3-gypsy were isolated and sequenced using degenerate oligonucleotide primers from genomic DNA of Chinese cherry（Prunus pseudocerasus Lindl.）. And the transcriptional activity of retrotransposon were detected by reverse transcription polymerase chain reaction（RT-PCR）. The results showed that a total of 44 unique clones from Ty1-copia and 13 unique clones from Ty3-gypsy were obtained. Nucleotide sequence of Ty1-copia and Ty3-gypsy ranged in length from 262 to 269 bp and 414 to 435 bp，respectively. Alignment of nucleotide and amino acid sequences showed the high heterogeneity in LTR retrotransposon. Both Ty1-copia and Ty3-gypsy groups displayed mutation including premature stop codons，frameshift mutation and deletion. Phylogenetic analysis showed there were two lineages（TAR and Ale）in Ty1-copia group，and three lineages（Tat，Tekay，Reina）in Ty3-gypsy group. Furthermore，ratios of non-synonymous to synonymous（dN/dS）of Ty1-copia and Ty3-gypsy were less than 1，and Ty3-gypsy were greater than those of Ty1-copia，suggesting that they were evolving under a subfunctionalization model driven by purifying selection. Transcriptional activity was detected in 13 Ty1-copia and 7 Ty3-gypsy RT sequences and didn’t change as exposure to eight types of abiotic stresses. A Ty1-copia RT sequence named PpRT7 was highly transcriptionally activated by high temperature（42 ℃），and showed tissue specific expression.
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• Identification and Expression Analysis of the KCS Gene Family in Pepper
• YI Ting1，ZHANG Zhishuo2，TANG Bingqian1，XIE Lingling2,*，and ZOU Xuexiao1,3,*
• Acta Horticulturae Sinica. 2020, 47(2): 370-382. DOI:10.16420/j.issn.0513-353x.2019-0574
• Abstract ( 338 ) HTML ( 495 ) PDF (2512KB) ( 495 ) 　　　
• In order to understand the characteristics of the β-ketoacyl-CoA synthase（KCS）gene family in the Capsicum annuum genome deeply，all KCS gene family members were identified by using the bioinformatics methods，hereafter，the genes chromosomal location，phylogenetic relationship，gene structure，protein conserved motifs，tissue expression pattern and response to high temperature，low temperature and NaCl stress were analyzed. The results showed that a total of 22 KCS genes were identified and distributed on 9 chromosomes. Phylogenetic analysis indicated that the CaKCS were divided into 4 groups，and each of them included different numbers of genes which contained 0–3 introns and 6–14 conserved motifs. Each gene in the KCS family has different expression patterns，and the CaKCS could be repressed or activated by high temperature，low temperature and NaCl treatment.
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• Overexpression of SbRFP1 Gene Improves Salt Tolerance of in Vitro Potato Plantlets
• ZHAO Xijuan1,2，ZHANG Huiling1,*，HOU Juan2,3，ZHANG Juping1，CHEN Sudan1，and SONG Botao2
• Acta Horticulturae Sinica. 2020, 47(2): 381-389. DOI:10.16420/j.issn.0513-353x.2019-0769
• Abstract ( 251 ) HTML ( 463 ) PDF (1483KB) ( 463 ) 　　　
• The in vitro plantlets of transgenic lines overexpressed SbRFP1 and control were treated with NaCl at different concentrations. Results showed that the plant height，root length and fresh weight of transgenic lines were significantly higher than those of control under 5 g · L-1 or 8 g · L-1 NaCl stress. Transcriptome sequencing of transgenic lines and non-transgenic control tubers displayed that the expression levels of F-box gene（PGSC0003DMG400013116）and GDSL（Gly-Asp-Ser-Leu）gene（PGSC0003DMG400007815）in transgenic lines were significantly higher than those in control，as well as up-regulated by NaCl. The in vitro plantlets of E3（non-transgenic）were treated with exogenous substances and the expression of differentially expressed genes were detected. Results showed that the differentially expressed genes were induced by SA and other hormones，as well as NaCl. It is suggested that SbRFP1 may improve the salt tolerance of potato by regulating the expression of stress-related genes such as F-box gene and GDSL gene.
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New Technologies and New Methods

• A Method for the Detection of cherry virus A（CVA）Based on Recombinase Polymerase Amplification（RPA）Technique
• CHEN Ling，DUAN Xuwei，ZHANG Kaichun*，ZHANG Xiaoming，WANG Jing，YAN Guohua，and ZHOU Yu*
• Acta Horticulturae Sinica. 2020, 47(2): 390-398. DOI:10.16420/j.issn.0513-353x.2019-0566
• Abstract ( 283 ) HTML ( 422 ) PDF (1825KB) ( 422 ) 　　　
• In this study，recombinase polymerase amplification（RPA）method was developed using the specific primers and probe designed based on the conserved gene sequences of cherry virus A（CVA）coat protein to detect CVA in cherry. The RPA method could be conducted under thermostotic condition at 38 ℃ and was completed within 40 min. The sensitivity test showed that the RPA was about 10-fold more sensitive than PCR and no cross-reactivity was detected with other 6 cherry-infected viruses and 1 viroid in China. Moreover，the terminally labeled amplicons could be visually inspected with lateral flow strip. This method was verified effectively by testing field-collected samples.
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New Cultivars

• A New Red Flower Alpinia Cultivar‘Hongfengshou’
• WANG Yongqi1，ZHAO Yangyang1，TAN Guangwen1，HUANG Banghai3，HU Zhenyang1，LIU Ruimin1，LIU Xiaozhou1，LUO Shuai1，and LIU Nian2,*
• Acta Horticulturae Sinica. 2020, 47(2): 399-400. DOI:10.16420/j.issn.0513-353x.2018-0846
• Abstract ( 213 ) HTML ( 335 ) PDF (1264KB) ( 335 ) 　　　
• ‘Hongfengshou’is a new Alpinia hybrid which was selected from Alpinia zerumbet and A. henryi. This new hybrid is 1.1–1.7 m in height，which has leathery，lanceolate and dark green or bright green leaves with irregular radial dark markings. And it also has gorgeous flower，pink bractlet，milky white corolla with pink apex and bright yellow lips with red-orange pattern. Flowing across from April toOctober，the fruit is capsule without edge on the peel and it would become orange red when mature. It is suitable for cultivation in Guangdong area.
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• A New Mini Rose Cultivar‘Juyue’
• GAO Shumin1，ZHOU Yan1,2,*，FAN Lijuan1,2，and CHAO Yang2
• Acta Horticulturae Sinica. 2020, 47(2): 401-402. DOI:10.16420/j.issn.0513-353x.2018-0921
• Abstract ( 427 ) HTML ( 459 ) PDF (1161KB) ( 459 ) 　　　
• A new mini rose cultivar‘Juyue’was selected from the offspring of‘Orange Fire’（4x）× ‘Old Blush’（2x）.‘Juyue’is a triploid without prickle plant.‘Juyue’has an apricot pink color flower，fruity and thousands of double flowers. The plant height is from 20.0 to 30.0 cm，and the flower average diameter is from 7.0 to 10.0 cm. The first spring flowering period of the open field in Beijing was mid-April, and it continued to bloom until mid-late November.‘Juyue’has a strong cold resistance and environment adaptablity. It is suitable to be cultivated in North China，Northwest China，Northeast China and Central China.
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• A New Lagerstroemia indica Cultiviar‘Caixia’
• CAI Neng，QIAO Zhongquan*，WANG Xiaoming*，ZENG Huijie，LI Yongxin，and WANG Xiangying
• Acta Horticulturae Sinica. 2020, 47(2): 403-404. DOI:10.16420/j.issn.0513-353x.2018-0788
• Abstract ( 350 ) HTML ( 269 ) PDF (1711KB) ( 269 ) 　　　
• ‘Caixia’is a new cultivar selected from the seedlings of Lagerstroemia indica. It is a small tree，with new fuchsia leaves and dark grayish green mature leaves. The branchlets have wavy wings. The flower buds are conical with obvious protrusions at the top. The flowers are strong purplish red.
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• A New Cultivar of Landscaping Xanthoceras sorbifolium‘Senmiao Jinziguan’
• WANG Yali1,2,*，YUE Shaoli3，LI Ruifang1,2，ZHAI Hongxia4，and SONG Qin1
• Acta Horticulturae Sinica. 2020, 47(2): 405-406. DOI:10.16420/j.issn.0513-353x.2018-0853
• Abstract ( 493 ) HTML ( 332 ) PDF (1469KB) ( 332 ) 　　　
• Xanthoceras sorbifolium‘Senmiao Jinziguan’is a new yellowhorn cultivar by single-plant selection from seedlings. Leaflet is ovate，deeply lobed and edge curl outward. Young twig is purplish red.Flower is luxuriant. The petal color constantly changed with the prolongation of blossom，it was yellow in early blossom，then gradually change to red，and in late blossom it became purple slowly. At full-bloom stage，there were yellow，red and purple florets in the same plant. Usually the fruit is columnar and low yield. The average seeds number in each capsule is 10.52. The mature seeds are brown，and the average weight of 1 000 seeds is 1 033.95 g. The suitable cultivation area are Ningxia，Inner Mongolia，Shaanxi，Gansu and other main planting area of yellowhorn for landscaping and ornamental.
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