Research Papers

• Transcriptome Analysis of the Molecular Mechanism of Saline-alkali Stress Response in Malus halliana Leaves
• ZHANG Rui, ZHANG Xiayi, ZHAO Ting, WANG Shuangcheng, ZHANG Zhongxing, LIU Bo, ZHANG De, WANG Yanxiu
• Acta Horticulturae Sinica. 2022, 49(2): 237-251. DOI:10.16420/j.issn.0513-353x.2021-0077
• Abstract ( 849 ) HTML ( 610 ) PDF (3536KB) ( 610 ) 　　　

• Malus halliana is a highly saline-alkali-resistant apple rootstock in north-western China. The genes and main pathways which respond to saline-alkali stress were identified by RNA-Seq. This study revealed the mechanism of the response to salt damage and provided theoretical basis for the salt tolerance mechanism of apple rootstocks. Normal water（Hoagland nutrient solution）（Control）supply and mixed saline-alkali stress（Hoagland nutrient solution + 100 mmol · L^-1 NaCl + NaHCO₃）（Treatment）were set up to screen the saline-alkali resistance of each treatment in the growth period. These two samples before and after saline-alkali treatment were analyzed by RNA-seq. The function and pathway enrichment of differentially expressed genes（DEG）were also performed by GO and KEGG analysis. Twenty DEG were randomly selected for further qRT-PCR analysis to verify the RNA-seq data. A total of 16 246 DEGs were determined,7 268 genes were up-regulated and 8 978 genes down-regulated under saline-alkali stress. GO analysis fund that the DEGs were considerably differenct in the biological processes,cell components and molecular functions. KEGG analysis indicated that most enriched saline-alkali-responsive genes were mainly involved in signal transduction,carbon metabolism,biosynthesis of amino acids,and other secondary metabolites. DEG mainly focused on calcium signaling pathway,plant hormone signal transduction,phenylalanine metabolism,and carotenoid biosynthesis. qRT-PCR detection results of 20 DEG expression patterns were similar to those of RNA-seq. Among them,aspartate aminotransferase（GOT1）,monodehydroascorbate reductase（NADH）,chalcone isomerase（CHI,E5.5.1.6）,β-carotene 3-hydroxylase（CrtZ）genes were highly expressed during saline-alkali stress. The results indicated that they might play a role in the leaf response to saline-alkali stress. M. halliana is mainly regulated by calcium signal pathway,plant hormone signal transduction,biosynthesis of amino acids, carotenoid biosynthesis and other secondary metabolites to respond to saline-alkali stress.

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• Identification and Expression Analysis of Sugar Transporter Family Genes in‘Furongli’（Prunus salicina）
• JIANG Cuicui, FANG Zhizhen, ZHOU Danrong, LIN Yanjuan, YE Xinfu
• Acta Horticulturae Sinica. 2022, 49(2): 252-264. DOI:10.16420/j.issn.0513-353x.2020-0724
• Abstract ( 570 ) HTML ( 258 ) PDF (3152KB) ( 258 ) 　　　

• A comprehensive analysis was carried out to identify sugar transporter（ST）genes and dissect their phylogenetic relationships,and to investigate their expression patterns during fruit development in‘Furongli’（Prunus salicina Lindl.）based on its genome data. A total of 49 ST genes were identified in the‘Furongli’genome and they were divided into seven subfamilies according to conserved domains and phylogenetic analysis. Bioinformatics analysis results showed that the length of PsSTs ranged from 313 to 948 aa,and all of them were predicted to locate in membrane. All the PsSTs contained the conserved sugar transporter domain（PF00083）,and the majority of them contained 12 transmembrane helices（TMHs）. Expression profiles of the 49 PsST genes during fruit development derived from RNA-Seq data indicated that 15 PsST genes were differentially expressed at different developmental stages. qRT-PCR analysis showed that nine of the 15 differentially expressed genes were significantly correlated with glucose and sucrose content in‘Furongli’fruit. Among them,one inositol transporter gene（PsINT4）,one sugar transporter protein gene（PsSTP11）,one sugar facilitator protein gene（PsSFP5）and one tonoplast monosaccharide transporter gene（PsTMT1）were identified as candidate genes,which may play important roles in sugar accumulation during the development and ripening of‘Furongli’fruit.

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• Identification of TGA Gene Family in Peach and Analysis of Expression Mode Involved in a BABA-Induced Disease Resistance
• LI Chunhong, WANG Kaituo, LEI Changyi, XU Feng, JI Nana, JIANG Yongbo
• Acta Horticulturae Sinica. 2022, 49(2): 265-280. DOI:10.16420/j.issn.0513-353x.2020-1000
• Abstract ( 562 ) HTML ( 306 ) PDF (4089KB) ( 306 ) 　　　

• The highly conserved amino acid sequences of BRLZ（PF07716）and DOG1（PF14144）domains were used to identify the TGA family members,and the results showed that 15 members of the TGA family from the peach genome could be identified through bioinformatics analysis. The TGAs were unevenly distributed on the 1st,2rd,6th and 7th Prunus persica chromosomes. The protein parameters of the determined TGA TFs listed as follows：the sizes ranging from 333 to 546 aa,molecular weights ranging from 37.07 to 61.47 kD,the isoelectric points ranging from 6.01 to 8.59,respectively. And all members of the TGA family were located in the nucleus. According to the phylogenetic relationship, the TGA family of Arabidopsis thaliana,Glycine max,Solanum lycopersicum,Oryza sativa and Prunus persica was divided into five subfamilies,among which the peach TGA family members were mainly distributed inⅠ,Ⅱ and Ⅳ clades. Moreover,the promoter regions of the TGA members contained at least one plant hormone or stress response-related elements. In addition,the RNA-sequencing data exhibited that the expressions of the 15 TGA family members were potentiated by BABA treatment and/or Rhizopus stolonifer infection,and PpTGA1-1 expression was rapidly up-regulated within 12 h after stimulation. Further investigation indicated that the physical interaction between PpTGA1-1 and PpNPR1 provided the DNA binding capacity required by PpNPR1 for its activation of pathogenesis-related genes（PR）and consequently induced the priming resistance in harvested peaches. Collectively,a distinct member of TGA gene family in Prunus persica,particularly in PpTGA1-1,directly modified the PpNPR1 and thus exerted a crucial regulatory function for defensive response.

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• Cloning and Function Analysis of Mycorrhizal Signaling Receptor Protein Lysin Motif Receptor-like Kinases 2 Gene（LYK2）in Citrus
• SONG Fang, LI Zixuan, WANG Ce, WANG Zhijing, HE Ligang, JIANG Yingchun, WU Liming, BAI Fuxi
• Acta Horticulturae Sinica. 2022, 49(2): 281-292. DOI:10.16420/j.issn.0513-353x.2021-0045
• Abstract ( 503 ) HTML ( 182 ) PDF (3677KB) ( 182 ) 　　　

• Twelve CsLYK genes were annotated from Citrus sinensis genome,which were unevenly distributed on six chromosomes,including chr1,chr2,chr6,chr7,chr8 and chr9. The conserved domain analysis showed that seven conserved motifs were detected at 3′ terminator of CsLYKs,and the constructions of these seven motifs were highly conserved. However,only three conserved motifs were detected at 5′ terminator of CsLYKs,and the constructions of these three motifs were highly variable. Gene structure analysis showed that CsLYK2,CsLYK3,CsLYK6,CsLYK10 and CsLYK12 had no introns,while other seven CsLYK family members had one to nineteen introns. Phylogenetic analysis revealed that twelve CsLYKs could be divided into three groups and CsLYK2 was clustered together with PaNFP and SlLYK10 in a small brunch. The expression analysis revealed that all PtrLYK genes were expressed in the root,stem and leaf of P. trifoliata. In details,the expression of PtrLYK10 was more abundant in the roots than leaf and stem,and the expression of PtrLYK3,PtrLYK7,PtrLYK8,PtrLYK9 and PtrLYK12 were more abundant in the leaf. Additionally,the expression of PtrLYK2 was induced in the roots of poncirus during different mycorrhizal infection periods,and the highest expression level was observed at two weeks post inoculation. The subcellular localization vector,35S-PtrLYK2-CFP,was transiently expressed in the protoplast of Arabidopsis thaliana. The result of laser scanning Confocal microscope indicated that PtrLYK2 was expressed on the plasma membrane. The promoter expression vector,proPtrLYK2::GUS, was transiently expressed in M. truncatula hair root,and the positive roots were screened with Ds-Red report gene and inoculated with AM fungi. After GUS histochemical staining and WGA-488 mycorrhizal staining,the expression of proPtrLYK2 was observed in the cells around arbuscules and the root tip cells. Taken together,these results indicated that PtrLYK2 played a significant role in symbiotic signaling recognition at early stage between citrus and AM fungi.

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• Histological Observation of Eye Formation in Pineapple
• WU Jing, HE Yehua, ZHANG Wei, LIU Chaoyang, GONG Xue, XUE Biao, LIU Jiarou, LUAN Aiping, LIN Wenqiu, GAN Jichang, ZHONG Yizhong, LIAO Zhichan, QIU Mengqing, LI Jingjing
• Acta Horticulturae Sinica. 2022, 49(2): 293-303. DOI:10.16420/j.issn.0513-353x.2020-1093
• Abstract ( 1190 ) HTML ( 268 ) PDF (8255KB) ( 268 ) 　　　

• The formation and development of fruit eyes were observed,the dynamic changes of tissues and organs related to fruit eyes were measured and analyzed by histological section and anatomy,using the crown,flower and fruit from different pineapple germplasm as the research materials. Three stages for the developmental of pineapple fruit eye,including antrum differentiation,antrum development and fruit eye development were divided,according to the formation processes.The flower cavity is the early morphology of fruit eye,and its differentiation and development lead to the formation of fruit eye,which takes about 70 days（d）,and the fruit setting is the sign for the beginning of fruit eye development stage. The morphological differentiation of flower cavity begins with calyx differentiation and ends with disk（receptacle and ovary）differentiation. 14 days after the flower induction,the calyx primordium differentiation is firstly observed in the bractus axils at the base of flower buds,from bottom to top. All the antrum differentiation in the inflorescence was finished until 35 days after the flower induction,while the antrum morphological differentiation of the florets at the top of inflorescence was about 7 d later than that at the base. The size,morphology and structure of the flower cavity are changed by the growth and development of flower organs during the flowering process. The peak period of the flower cavity enlargement is the first week after the completion of the morphological differentiation（36 to 42 d after flower induction）. At this time,significant differences for the depth of the flower cavity were found between the pineapple varieties with deep and shallow fruit eyes,and then the expansion slows down gradually. There was no significant difference in the absolute growth of flower disc among different cultivars,so the deepening of flower cavity mainly depended on the growth of calyx. The fruit eyes start to develop after the fruit setting. With the rapid expansion of fruit,the growth of the dorsal and ventral sides of calyx tube is unbalanced,and the persistent calyx curves inward. However,the bending speed and growth stop time are associated with the variety types. The mass growth of calyx for ‘MD-2’was few and internal bending was rapid,while for ‘Jintong’was large and slow. The eye deepened mainly within 14 days after fruit setting,and the shape and size of the eye no longer changed about 70 d after fruit setting. According to the depth of eye in the middle of ripe fruit,pineapple germplasm could be divided into three types：shallow eye depth < 0.9 cm,medium eye depth 0.9-1.2 cm,and deep eye depth > 1.2 cm. There was no significant difference in disc depth（about 0.29 cm）among different types of cultivars. The difference in fruit eye depth was mainly associated with the height of calyx,and the bending degree and growth of calyx were the main reasons for the difference in height of calyx and protrusion of small fruit. Therefore,the formation of fruit eyes begins with the differentiation of flower buds,in which calyx growth and development have a significant impact on the morphology and depth of fruit eyes. The morphological differences of fruit eyes among cultivars are mainly caused by the unbalanced growth of the dorsal and ventral sides of calyx tube within 14 d after the fruit setting,while the differences of fruit eye depth mainly occur in the first week of calyx development（36-42 d after flower induction）.

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• Identification of LEA Family and Expression Analysis of Some Members Under Low-temperature Stress in Chinese Cabbage
• WANG Guangpeng, LIU Tongkun, XU Xinfeng, LI Zhubo, GAO Zhanyuan, HOU Xilin
• Acta Horticulturae Sinica. 2022, 49(2): 304-318. DOI:10.16420/j.issn.0513-353x.2021-0044
• Abstract ( 540 ) HTML ( 394 ) PDF (5662KB) ( 394 ) 　　　

• This study was based on the whole genome data of Chinese cabbage to identify and bioinformatics the late embryogenesis abundant protein（LEA）family genes. The sequence characteristics,gene structure,promoter cis-acting elements,chromosome localization,evolutionary relationships,and expression patterns in different tissues and under low temperature stress were investigated. The results showed that 65 family members were identified from the Chinese cabbage genome and could be divided into eight groups according to phylogenetic and conserved motif analysis. Fewer introns are prevalent and unevenly distributed on ten chromosomes,with three other members located on the Scaffold. The promoter cis-acting element analysis showed that 29 members（44.6%）had low temperature response elements. In addition,the proportion of light response elements and hormone response elements was the highest. The collinearity analysis showed that BrLEAs and AtLEAs had higher homology and were conservative in evolution. Analysis of transcriptome data of different tissues of Chinese cabbage found that the expression of BrLEA genes in different tissues was different and had tissue specificity. The expression of 13 family members under low temperature stress family members showed that the expression of low temperature stress increased.

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• The Jasmonic Acid Synthesis Gene LoxD Participates in the Regulation of Tomato Drought Resistance
• PENG Yi, LI Yuanhui, YANG Rui, ZHANG Ziyi, LI Yanan, HAN Yunhao, ZHAO Wenchao, WANG Shaohui
• Acta Horticulturae Sinica. 2022, 49(2): 319-331. DOI:10.16420/j.issn.0513-353x.2021-0025
• Abstract ( 516 ) HTML ( 225 ) PDF (1858KB) ( 225 ) 　　　

• To study the drought resistance mechanism regulated by JA,using tomato variety‘Castlemart’jasmonic acid synthesis gene LoxD-overexpression transgenic plants（LoxD-oe）and LoxD mutant（spr8）and their corresponding wild type（WT）as material. Under the drought stress,the relative water content,soluble sugar,malondialdehyde content,stomatal aperture,H₂O₂ level in guard cells,and the expressions of the ABA signaling and related ion channel genes were determined. It was found that LoxD gene was induced by drought stress. The overexpression of LoxD gene gave rise to the increases of the relative water content and soluble sugar content and the decline of MDA production in leaves. Moreover,under drought stress,overexpressing LoxD gene induced the expressions of SnRK2-like,SLAC1,AtrbohD and CPK1,inhibited the expressions of ABI2 and KAT1,and activated the H₂O₂ signal in guard cells,which probably arrested the stomatal opening and then reduced the water loss. The results showed that LoxD gene participates in regulating drought resistance.

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• Genome-wide Association Studies for Flower Color in Common Bean
• LU Tiantian, LIU Zhiyuan, XU Zhaosheng, ZHANG Helong, LI Guoliang, SHE Hongbing, QIAN Wei
• Acta Horticulturae Sinica. 2022, 49(2): 332-340. DOI:10.16420/j.issn.0513-353x.2021-0056
• Abstract ( 420 ) HTML ( 159 ) PDF (1589KB) ( 159 ) 　　　

• Flower color of 124 common beans investigated in 2019 and 2020 was used to identify its controlling genes by Genome-wide association study（GWAS）. The phenotypic data showed that the flower color between the two years had a relatively high similarity besides one individual. We obtained 517.58 Gb（~10×）of raw data by resequencing 124 common bean individuals. A total of 5 130 030 SNP were generated against the common bean reference genome,and 3 701 584 SNP were retained by filtering. GWAS analysis based on these high-quality SNPs with compress mixed linear model（cMLM）located flower color regulatory gene in the 322.67 kb region on chromosome 6. Within the region,eight genes were annotated based on the common bean reference genome. Particularly,Phvul.006G020200 was the MYB transcription factor of anthocyanin regulation and had differential expression in flower color. Thus,we assume that Phvul.006G020200 is a key candidate gene for regulating bean flower color.

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• Cytological Observation of Fruit Peduncle Abscission Zone and Preliminary Mapping of Mature Fruit Abscission AL3 gene in Melon
• SHENG Yunyan, YANG Limin, DAI Dongyang, ZHANG Jiaxin, WANG Ling, WANG Di, CAI Yi, TIAN Limei
• Acta Horticulturae Sinica. 2022, 49(2): 341-351. DOI:10.16420/j.issn.0513-353x.2020-1041
• Abstract ( 526 ) HTML ( 112 ) PDF (3254KB) ( 112 ) 　　　

• The F₂,F₃,F₄ and backcross populations derived from a cross between M2-10 （none-mature fruit abscission,NMFA）and ZT091（mature fruit abscission,MFA）was used to study the cytological observation of abscission zone and gene mapping of one of mature fruit abscission（MFA）gene（AL3）.The analysis of genetic inheritance indicated that the MFA was controlled by two genes. Paraffin section and scanning electron microscopy observation of the parent fruit at the maturity stage showed that the cells in the abscission zone of peduncle of ZT091 were larger in size,loosen arrangement and larger spaces between cells,there were significant difference between parental peduncle abscission zone. AL3 was primary mapped into a 0.355 Mb region（from 10 686 821 to 11 042 074 bp）on chromosome 8 with the strategy of SLAF-BSA using 83-F₃ family only segregated with AL3. F₄ family and CAPs markers were used for narrowing down the mapping region. Finally, AL3 was fined mapped into a 64.7 kb（from 10 774 778 to 10 839 486 bp）region with 10 annotated candidate genes.

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• Genome-wide Identification and Expression Analyses of Long-chain Acyl-CoA Synthetases Under Abiotic Stresses in Helianthus annuus
• ZHOU Zhiming, YANG Jiabao, ZHANG Cheng, ZENG Linglu, MENG Wanqiu, SUN Li
• Acta Horticulturae Sinica. 2022, 49(2): 352-364. DOI:10.16420/j.issn.0513-353x.2020-1013
• Abstract ( 573 ) HTML ( 193 ) PDF (6035KB) ( 193 ) 　　　

• Based on bioinformatics analyses,13 long-chain acyl-CoA synthetases（LACSs）putative genes from LACS gene family were identified from the genome of sunflower（Helianthus annuus）and mapped to eight chromosomes. The phylogenetic analysis showed that HaLACSs clustered into six subgroups and HaLACS proteins within each subgroup share the similar structures and conserved motifs. The main factors for HaLACS family amplification in sunflower were segmental duplication. Bioinformatic analysis of HaLACS genes promoter regions showed multiple cis-elements related to environmental stresses and plant hormone response. Tissue expression profile analysis showed that the HaLACS genes exhibited differential expression profiles in various tissues. The comparison of gene expression profiles between two sunflower cultivars（high/low linoleic acid）found that HaLACSs showed differential expression at different seed development stages. The qRT-PCR analysis showed that seven HaLACS up-regulated significantly in sunflower stem treated with 200 mmol · L^-1 NaCl for 24 h compared with control. After three hours treatment with 100 μmol · L^-1 ABA,eight HaLACS synchronized especially in roots,and most HaLACS colud be induced by drought stress（15% PEG 6000）. The above results indicate that the HaLACS play essential roles in dealing with different abiotic stresses and lipid biosynthesis.

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• Transcriptome Analysis Revealed the Formation Mechanism of Floral Color of Lotus‘Dasajin’with Bicolor Petal
• DENG Jiao, SU Mengyue, LIU Xuelian, OU Kefang, HU Zhengrong, YANG Pingfang
• Acta Horticulturae Sinica. 2022, 49(2): 365-377. DOI:10.16420/j.issn.0513-353x.2021-0574
• Abstract ( 405 ) HTML ( 274 ) PDF (2233KB) ( 274 ) 　　　

• ‘Dasajin’lotus with red and white flower was used as the research material,it’s red color of petals was caused by anthocyanins accumulation,which was related to acidification of petal cells. A total of 91 differentially expressed genes（DEGs）were identified between red and white petals by transcriptomics analysis and these DEGs can be divided into molecular function,cellular component and biological process categories base on gene ontology（GO）analysis,among which more genes were related to redox activity,thylakoid and photosynthesis. KEGG metabolic pathway analysis indicated that genes enriched in metabolic pathway,photosynthesis and galactose metabolic branches were more abundant. Fourteen DEGs related to chloroplast and photosynthesis were down regulated in the red petals region,one of which was thylakoid morphogenetic protein 1 gene（THF1）,whose low expression level was consistent with structure abnormality of thylakoid. Several transcription factors,including YABBY and bHLH,which were related to petal development,were predicted to bind the promoter of THF1 gene. In addition,several genes involved in biosynthesis of auxin and gibberellin as well as cell development were differentially expressed in red and white petal regions,leading to the formation of concave-like bowl shape of petal. Therefore,it was speculated that anthocyanins selectively accumulated in petal edge region with red color was related to petal development,that is,these genes regulating petal development may also regulate anthocyanins accumulation,which may be involved in thylakoid development,pH regulation and cell development.

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• Effects of Exogenous Spermidine on Photosynthetic Characteristics and Gene Expression of Key Enzymes Under Salt Stress in Tea Plant
• YANG Ni, WAN Qiwen, LI Yimin, HAN Miaohua, TENG Ruimin, LIU Jiexia, ZHUANG Jing
• Acta Horticulturae Sinica. 2022, 49(2): 378-394. DOI:10.16420/j.issn.0513-353x.2020-0946
• Abstract ( 389 ) HTML ( 157 ) PDF (2380KB) ( 157 ) 　　　

• In order to explore the regulatory effects of exogenous spermidine（Spd）on the photosynthetic characteristics under salt stress of tea plant,tea variety‘Zhongcha 108’was used as the experimental material in this study. Through different concentrations（0,0.5,1.0,1.5 mmol · L^-1）Spd spray treatments,the effects of exogenous Spd on tea photosynthetic parameters,chlorophyll content,stomatal aperture and the expression levels of key enzyme genes under salt stress（200 mmol · L^-1 NaCl）were detected and analyzed. The results showed that the net photosynthetic rate（P_n）,transpiration rate（T_r）,and chlorophyll content were significantly reduced,and the intercellular CO₂ concentration（C_i）was increased under salt stress. Stomatal aperture was promoted the initial treatment（1,3 d）,and inhibited gradually in the later period（5,9 d）. After spraying exogenous Spd,P_n,T_r,stomatal conductance（G_s）,chlorophyll a,chlorophyll b and Chlorophyll（a + b）contents were significantly increased under salt stress. Exogenous Spd can induce the up-regulation of CsRbcL,CsTK,CsFBPase,CsPRK and other photosynthetic carbon assimilation genes to varying degrees,and alleviate the influence of salt stress on the inhibition most chlorophyll synthesis genes. The study demonstrated that spraying exogenous Spd can effectively alleviate the degradation of chlorophyll,promote photosynthesis,and improve the salt tolerance of tea plant,of which 0.5 mmol · L^-1 Spd was the most effective.

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Research Notes

• Effects of Different Material Protein Fermentation Products on Apple Replanted Soil Microbial Environment and the Growth of Malus hupehensis Seedlings
• PAN Fengbing, CHEN Ran, JIANG Weitao, WANG Haiyan, LÜ Yi, SHEN Xiang, CHEN Xuesen, YIN Chengmiao, MAO Zhiquan
• Acta Horticulturae Sinica. 2022, 49(2): 395-406. DOI:10.16420/j.issn.0513-353x.2021-0066
• Abstract ( 360 ) HTML ( 161 ) PDF (1081KB) ( 161 ) 　　　

• This study aims to explore the feasibility of different material protein fermentation products to alleviate apple replant disease. A pot experiment was conducted using Malus hupehensis seedlings as the test material,and five treatments（replanted orchard soil（control）,sterilized replanted orchard soil,earthworm fermentation product,soybean meal fermentation product,waste fish fermentation product）were set up. The total amount of soil microorganisms,the number of harmful fungi,soil enzyme activities,the content of soil phenolic acids,the biomass of Malus hupehensis seedlings and the related indexes of plant roots were determined. The results showed that protein fermentation products of three different materials could effectively increase the number of bacteria,reduce the number of fungi and changed the fungal community structure in replanted soil. Among them,earthworm fermentation product had the best effect on reducing harmful fungi,Fusarium oxysporum,F. proliferatum,F. solani and F. moniliforme decreased by 59.2%,52.0%,64.9% and 67.1%,respectively,compared with replanted orchard soil（control）. Three different fermentation products also increased soil enzyme activity and decreased the content of phenolic acids in replanted soil. The plant biomass of earthworm fermentation product treatment was significantly higher than that of replanted orchard soil（control）treatment,and the plant dry weight increased by 90.22%. The fermentation products also promoted the growth of plant roots,the root antioxidant enzymes and the root respiration rate. Among them,earthworm fermentation product had the most significant effect. The total fine root length,total fine root surface area,root volume and root tip number of earthworm fermentation product were increased by 147.21%,225.87%,299.85% and 291.03% compared with replanted orchard soil（control）,respectively. SOD,POD,CAT and the root respiration rate were increased by 46.90%,133.94%,197.69% and 113.23% compared with replanted orchard soil（control）,respectively. In summary,the fermentation products of different protein materials can alleviate the damage of replant disease to young apple trees in varying degrees by adjusting the microbial community structure,improving the replanted soil environment,and promoting plant growth. Comprehensive consideration of various indicators,the effect of earthworm fermentation products is the most significant.

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• Genetic Evolution and Taxonomic Status Analysis of Wild Citrus Resources Based on Resequencing in Guposhan Mountain in Guangxi Province
• WU Xiaoxiao, CHEN Chuanwu, LIU Ping, TANG Yan, DENG Chongling
• Acta Horticulturae Sinica. 2022, 49(2): 407-415. DOI:10.16420/j.issn.0513-353x.2021-0058
• Abstract ( 409 ) HTML ( 82 ) PDF (1300KB) ( 82 ) 　　　

• Analyzing the genetic evolution and taxonomic status of wild citrus resources in Guposhan Mountain in Guangxi Province,provides a theoretical basis for citrus germplasm innovation and genetic improvement,and also provides a basis for in-depth exploration of genes related to excellent traits in the future. Whole genome sequencing was performed on four wild citrus varieties from Guposhan Mountain in Guangxi,one Poncirus trifoliata,one kumquat,and 14 other citrus. The amount of sequencing data for each sample was about 16 Gb,and the average sequencing depth was 54×. Through short read mapping,SNP detection,PCA principal component analysis,and neighbor joining method to construct a phylogenetic tree,reveal its genetic diversity and population genetic structure. From 20 samples,6 782 158 high-quality SNP loci were detected. Based on these SNP sites,and according to the PCA principal component analysis and phylogenetic tree analysis results,20 samples can be divided into three categories： wild citrus in Guposhan and C. mangshanensis are clustered together,and kumquat and other citrus are clustered together. Poncirus trifoliata is a separate category. The study analyzed the genetic diversity and population evolution of wild citrus resources in Guposhan Mountain from the whole genome level,and showed that wild citrus resources in Guposhan Mountain are primitive and unique like C. mangshanensis. They are supposed to be an independent and true species within the genus citrus,or it is a separate genus other than Poncirus,Fortunella Swing and Citrus L.

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• Genetic Analysis of Fruit Traits in F₁ Progenies of ‘Chinhuang’בRenong 1’Mango
• WU Hongxia, LI Xing, XU Wentian, ZHENG Bin, MA Xiaowei, SU Muqing, LIANG Qingzhi, YAO Quansheng, WANG Songbiao
• Acta Horticulturae Sinica. 2022, 49(2): 416-426. DOI:10.16420/j.issn.0513-353x.2021-0148
• Abstract ( 418 ) HTML ( 142 ) PDF (725KB) ( 142 ) 　　　

• Fifty-four individuals of F₁ population from a cross‘Chinhuang’（female）בRenong 1’（male）were chosen as materials and 30 fruit traits were evaluated in mango. The genetic analysis were studied for nine quantitative traits including fruit weight,fruit length,width,thickness,fruit shape index, soluble solids,editable rate,stone length and stone weight. The Shannon-Weaver diversity index and principal component analysis of nine quantitative traits and 21 descriptive traits were carried out by SPSS19.0 software. The results showed that the phenotypic diversity of nine quantitative traits in the evaluated progenies were normal distribution or partial normal distribution,and its coefficient of variation ranged from 7.98% to 41.73%,the Shannon-Weaver diversity index（H’）of nine quantitative characters ranged from 1.65 to 2.04 indicating that the fruit of progenies was rich in diversity of quantitative characters,its heritability ranged from 84.74% to 117.00%,eight traits including fruit weight showed a trend of medium variation,while total soluble solids showed a trend of super parent inheritance. The diversity index of 21 descriptive characters ranged from 0.16 to 1.48. Principal component analysis showed that 75.19% of cumulative contribution rate was explained by the first 10 principal components,and fruit weight,resistance,fruit shape index,skin smoothness,length of fiber in pulp,veins on stone,fruit flavor,total soluble solids,type of embryony and pulp color were selected as the main traits. A comprehensive evaluation model for fruit traits of progenies was also established,based on this method,combined with field and practical observation results,eight outstanding individuals were selected.

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• Isolation and Identification of Melon Black Spot in Gansu Province
• SHI Zhaorong, ZHANG Guangrong, SUN Shujun, JIN Mengjun, CUI Lingxiao, LIU Yanchao, WEI Lijuan, MEI Dahai, YANG Chengde
• Acta Horticulturae Sinica. 2022, 49(2): 427-436. DOI:10.16420/j.issn.0513-353x.2020-0929
• Abstract ( 529 ) HTML ( 202 ) PDF (1675KB) ( 202 ) 　　　

• This experiment was conducted to isolate,identify and determine the biological characteristics of black spot pathogen on melon in Baiyin City,Gansu Province. The results showed that the colony of isolate 98BYT2-1 was green-brown,round,conidia solitary or clustered,inverted rod-shaped or oval,with a vertical and horizontal septum. The size of conidia was（21.94-52.10）μm ×（7.01-13.93）μm,combining ITS,CAL and gpd gene sequence analysis showed that the strain 98BYT2-1 had 100% homology with Alternaria tenuissima and they were clustered together on the phylogenetic tree. Together,the isolate was identified as A. tenuissima. Starch,lactose and glucose were the most appropriate carbon sources for mycelia growth,spore formation and spore germination,respectively. Yeast extract and beef extract were the most suitable nitrogen sources for mycelia growth,but peptone was the most suitable source of nitrogen for sporulation and spore germination. In addition,PDA facilitated the mycelia growth of pathogen,and PCA was suitable for sporulation and spore germination. The optimum pH for mycelia growth and spore germination was 7 and the value for sporulation was 6. The optimum temperature for the growth and spore germination of mycelia was 30 ℃,and the sporulation was 15 ℃. The dark held up the growth of mycelium but benefited to sporulation and spore germination. The results obtained will provide a basis for the diagnosis and comprehensive control of melon black spot in Gansu Province.

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• Comparative Analysis of Photosynthetic and Physiological Characteristics of Red-leafed‘Quanhong’and‘Xuanhong’Poplar Cultivars
• CHEN Xinghao, LIU Hanqi, ZHANG Xinjian, CHENG Xiangjun, YANG Minsheng, ZHANG Jun
• Acta Horticulturae Sinica. 2022, 49(2): 437-447. DOI:10.16420/j.issn.0513-353x.2020-0759
• Abstract ( 573 ) HTML ( 103 ) PDF (2339KB) ( 103 ) 　　　

• One-year-old seedlings of green-leafed Populus deltoides‘Zhonglin 2025’and its red leaf of bud mutation variety‘Quanhong’and‘Xuanhong’were used as experimental materials to determine their phenotypic characters,photosynthesis parameters and chlorophyll fluorescence parameters. The results showed that the plant height,ground diameter,leaf area and leaf number of‘Quanhong’and ‘Xuanhong’were significantly lower than those of‘Zhonglin 2025’,indicating that the growth and development of‘Quanhong’and‘Xuanhong’were significantly inhibited. The anthocyanin content in the leaves of‘Quanhong’and‘Xuanhong’was higher than that of‘Zhonglin 2025’,and the ratio of anthocyanin to chlorophyll content increased significantly. In different months,the net photosynthetic（P_n）,stomatal conductance（G_s）and transpiration rate（T_r）of‘Zhonglin 2025’were higher,and the intercellular CO₂ concentration（C_i）of the three poplar varieties were similar. The non-photochemical quenching coefficient（NPQ）of‘Quanhong’was higher and the actual photosynthetic efficiency of PSⅡ[Y(Ⅱ)]was lower,leading to more energy dissipation,lower actual light energy conversion efficiency and lower photosynthetic capacity of PSⅡ in the photosynthetic system of‘Quanhong’. The values of F_o,F_m and NPQ of‘Quanhong’were the lowest among the three poplar cultivars,while the actual photosynthetic efficiency of PSⅡ[Y(Ⅱ)]was the higher.

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Review

• Research Advances and Prospects on Phalaenopsis Polyploid Breeding
• WU Ting, JIA Ruidong, YANG Shuhua, ZHAO Xin, YU Xiaonan, GUO Yuan, GE Hong
• Acta Horticulturae Sinica. 2022, 49(2): 448-462. DOI:10.16420/j.issn.0513-353x.2020-0916
• Abstract ( 745 ) HTML ( 363 ) PDF (858KB) ( 363 ) 　　　

• This paper reviews the polyploid induction pathways such as in vitro doubling induction,2n-gametes induction,sexual hybridization,and separation of endopolyploidy,as well as polyploid identification methods including morphology,cytology,and chromosome counting in Phalaenopsis polyploid breeding,and the recent achievements in Phalaenopsis polyploid breeding were summarized. Furthermore,the perspectives were proposed as follows: testing different chemical reagents and plant materials,strengthening the research and utilization of 2n gametes,strengthening the combination of sexual hybridization,cell fusion,and polyploid induction techniques,and enhancing the research and application of induced plants.

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New Cultivar

• A New Eggplant Cultivar‘Fuqie 8’
• LIN Hui, XUE Zhuzheng, HUANG Jiandu, CHEN Jibing, WEN Qingfang
• Acta Horticulturae Sinica. 2022, 49(2): 463-464. DOI:10.16420/j.issn.0513-353x.2020-0099
• Abstract ( 293 ) HTML ( 106 ) PDF (2624KB) ( 106 ) 　　　

• ‘Fuqie 8’is a new early ripening eggplant cultivar developed by crossing inbred line HLB107-2-3-1 with inbred line 06-10-2-1. The shape of fruit is slender. Its calyx is green and purple. Its flesh is white and green. The average fruit length is 35 cm,the fruit width is about 3.5 cm,and the fruit weight is about 170 g. The peel is purple and smooth. The cultivar has high yield and quality. It has resistance to low temperature and weak light,bacterial wilt,wilt and other diseases. It is suitable for protected cultivation in autumn and winter in Fujian Province.

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• A New Watermelon Cultivar‘Suchuang 5’
• XU Binghua, ZHANG Chaoyang, GU Yan, SUN Yudong
• Acta Horticulturae Sinica. 2022, 49(2): 465-466. DOI:10.16420/j.issn.0513-353x.2020-0073
• Abstract ( 330 ) HTML ( 79 ) PDF (1060KB) ( 79 ) 　　　

• ‘Suchuang 5’is a new watermelon hybrid cultivar crossing inbred line‘G21’as female parent with‘G12’as male parent. It is early-maturing,easy to bear fruits. The plant has strong growth vigor and the first female flower node of main vine is 7-8. The whole growth period is 115 d and the fruit development period is about 33 d. The shape of fruit is spherical,and the pericarp is green with dark green stripes on the surface. The flesh is deep red. The center soluble solids content is 11.5%. The average single fruit weight is 5.1 kg,and the yield is 42 000-66 000 kg · hm^-2. It is resistance to long distance transportation because of the 1.1 cm pericarp thickness. It is suitable for protected cultivation in most regions of China.

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• A New Melon Cultivar‘Jinmi 1’
• CAO Yanyan, DIAO Qiannan, CHEN Youyuan, ZHANG Yongping
• Acta Horticulturae Sinica. 2022, 49(2): 467-468. DOI:10.16420/j.issn.0513-353x.2020-0148
• Abstract ( 429 ) HTML ( 110 ) PDF (1103KB) ( 110 ) 　　　

• Hami melon type‘Jinmi 1’is a new melon cultivar bred by crossing wm-17 as female parent with 13-5A as male parent. The fruit is oval shaped with milky-white peel and dense and netty streaks. The flesh is orange,crisp and juicy,and the central soluble solids content is above 16%. The fruit is resistant to storage and fermentation. The plant showed resistance to powdery mildew and downy mildew. The single fruit weight is above 1.5 kg,and the output is 34 800-37 500 kg · hm^-2.

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• A New Magnolia Cultivar‘Rujuan’
• LI Renna, WANG Yaling, YAN Huiling, YE Wei, FENG Shengli
• Acta Horticulturae Sinica. 2022, 49(2): 469-470. DOI:10.16420/j.issn.0513-353x.2020-0038
• Abstract ( 538 ) HTML ( 79 ) PDF (1478KB) ( 79 ) 　　　

• ‘Rujuan’is a new Magnolia cultivar,deciduous shrub,which has a compact plant type. The plant height is 2.5-3.5 m.‘Rujuan’is formed by hybridization of‘Yellow Bird’magnolia（female parent）and‘Red Ingot’purple magnolia（male parent）. The leaf shape is inverted oval-shaped. The buds are terminal,clustered and axillary. The dorsal surface of the perianth piece is orange and the ventral surface is light red. Flowering period：late March to late April,June to August.

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• A New Magnolia Cultivar ‘Zichen’
• XIE Bin, WANG Yaling, DING Fangbing, YE Wei
• Acta Horticulturae Sinica. 2022, 49(2): 471-472. DOI:10.16420/j.issn.0513-353x.2020-0022
• Abstract ( 329 ) HTML ( 66 ) PDF (1339KB) ( 66 ) 　　　

• ‘Zichen’is a new Magnolia cultivar which is selected from the wild individuals of Magnolia sprengeri Pamp. discovered in Baoya Mountain,Gangou,Wufeng,Hubei Province. The perianths of flowers are long and thin which are slightly twisted. The cup-shaped flowers have bright colors with strong fragrance which appear to be pink. The flowering period of the cultivar is in March,and it has a large number of flowers and high ornamental value. It can be popularized and applied in the climate zone of the Yellow River basin and its south.

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