Research Papers

• Effects and Regulating Mechanism of Exogenous Brassinosteroids on the Growth of Malus hupehensis Under Saline-alkali Stress
• ZHENG Xiaodong, XI Xiangli, LI Yuqi, SUN Zhijuan, MA Changqing, HAN Mingsan, LI Shaoxuan, TIAN Yike, WANG Caihong
• Acta Horticulturae Sinica. 2022, 49(7): 1401-1414. DOI:10.16420/j.issn.0513-353x.2021-0499
• Abstract ( 883 ) HTML ( 476 ) PDF (2736KB) ( 476 ) 　　　

• In order to explore the effect of brassinosteroids on the growth of apple plants under saline-alkali stress,apple rootstock Malus hupehensis with apomixis characteristics were used as experimental materials. The study investigated the effects of exogenous EBL（brassinosteroids analogs）on ion homeostasis,osmotic regulation,antioxidant system and pH balance of M. hupehensis under saline-alkali stress. The results showed that application of 0.2 mg · L^-1 exogenous EBL could significantly enhance the tolerance of M. hupehensis to saline-alkali stress. The main mechanisms were as follows:exogenous EBL could regulate the expression of Na⁺/K⁺ transporter genes and enhance the ratio of potassium to sodium to maintain ion homeostasis. Moreover,exogenous EBL could accumulate proline and soluble sugar to modulate osmotic stress,and enhance the activities of POD and CAT to alleviate oxidative damage under saline-alkali stress. Furthermore,exogenous EBL could decrease root pH by improving root secretion of organic acids and enhancing the expression of MhAHA2 and MhAHA8 genes. Exogenous EBL could also cooperate with auxin,gibberellin and dihydrozeatin responding to saline-alkali stress.

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• Identification and Analysis of Apple Viruses Diseases Based on Virome Sequencing Technology
• XIA Yan, HUANG Song, WU Xueli, LIU Yiqi, WANG Miaomiao, SONG Chunhui, BAI Tuanhui, SONG Shangwei, PANG Hongguang, JIAO Jian, ZHENG Xianbo
• Acta Horticulturae Sinica. 2022, 49(7): 1415-1428. DOI:10.16420/j.issn.0513-353x.2021-0450
• Abstract ( 541 ) HTML ( 210 ) PDF (2755KB) ( 210 ) 　　　

• Virome Sequencing Technology was used for virus detection and analysis of virus-infected apple trees in Henan Province,a total of 13 viruses were detected from apple leaves in the sequenced database,including five apple viruses:apple stem grooving virus（ASGV）,apple stem pitting virus（ASPV）,apple chlorotic leaf spot virus（ACLSV）,apple necrotic mosaic virus（ApNMV）and apple green crinkle associated virus（AGCaV）. RT-PCR was used to verify the detection results of five apple viruses,and objective bands were obtained after amplification,it was consistent with virome sequencing results,indicating that the virome sequencing detection results were accurate and reliable. Based on the sequencing results,specific primers were designed to amplify the full length of ASPV,a length of 9 246 nt ASPV-HN isolate genome was obtained and shared sequence identities 75.48% to 79.85% with complete genome of 19 ASPV isolates published in NCBI database;the two assembly sequences of ASGV genomes ASGV-HN1 and ASGV-HN2 based on virome sequencing results were both 6 475 nt in length and shared sequence identities 79.98% to 98.08% with complete genome of 18 ASGV isolates published in NCBI database. Detection of apple mosaic virus（ApMV）and ApNMVwere carried out in 53 apple leaf samples collected from different apple producing areas in Henan Province. ApNMV was detected in all samples with mosaic disease,while ApMV was not detected in 53 samples. It indicated that ApNMV may be the main pathogen which can cause apple mosaic disease in Henan Province.

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• Fructokinase Gene PpyFRK5 Plays an Important Role in Sucrose Accumulation of Pear Fruit
• TAO Xin, ZHU Rongxiang, GONG Xin, WU Lei, ZHANG Shaoling, ZHAO Jianrong, ZHANG Huping
• Acta Horticulturae Sinica. 2022, 49(7): 1429-1440. DOI:10.16420/j.issn.0513-353x.2021-0445
• Abstract ( 444 ) HTML ( 205 ) PDF (5256KB) ( 205 ) 　　　

• As one of the important members of fructokinase gene family,the gene of PpyFRK5 was cloned utilizing‘Hosui’pear（Pyrus pyrifolia Nakai）fruit as the experimental material in the study. Simultaneously,its expression patterns and biological functions were studied. The results indicated that the protein encoded by PpyFRK5 belongs to the phosphofructokinase B subfamily（pfkB）,and contains the highly conserved pfkB characteristic domain and the ATP binding domain and sugar binding domain unique to fructokinase. The expression level of PpyFRK5 exhibited significant distinctions in different pear organs and fruit development stages,and reached the highest in fruits and seeds at the mature stage. PpyFRK5 was localized in the plasma membrane and cytoplasm. During the whole development of the pear fruit,there was a significant positive correlation between the expression level of PpyFRK5 and the sucrose content,and the sucrose content of pear fruits with transient overexpression of PpyFRK5 was significantly increased,while that of pear fruits with transient silencing of PpyFRK5 was significantly decreased;the promoter region of PpyFRK5 contained multiple cis-acting elements involved in light response,hormone induction,and stress response.

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• Gene Cloning and Expression Analysis of NAC Gene in Citrus in Response to Huanglongbing
• ZHENG Lin, WANG Shuai, LIU Yunuo, DU Meixia, PENG Aihong, HE Yongrui, CHEN Shanchun, ZOU Xiuping
• Acta Horticulturae Sinica. 2022, 49(7): 1441-1457. DOI:10.16420/j.issn.0513-353x.2021-0553
• Abstract ( 771 ) HTML ( 233 ) PDF (4699KB) ( 233 ) 　　　

• Citrus Huanglongbing（HLB）has become a major disease and limiting factor of production in citrus areas that have become infected. It can cause production extinction when the damage to citrus industry is serious,and there is no effective prevention and treatment method for this disease. The key to solve this problem is to excavate citrus resistance genes for disease resistance breeding. Therefor,in this study,based on the transcriptome data of Candidatus Liberibacter asiaticus（CLas）in the root and midrib in the early stage of infection（2 months）,nine NAC（NAM,ATAF1/2,CUC2）genes were screened in response to HLB infection,and three genes with high differential expression were cloned,named as CsNAC21/22,CsNAC68 and CsNAC78,respectively. Bioinformatics analysis showed that CsNAC21/22,CsNAC68 and CsNAC78 encoded 306,503 and 152 amino acids respectively,and the isoelectric point（pI） was 5.43,6.59 and 8.39,respectively. The conserved domain analysis showed that CsNAC21/22,CsNAC68 and CsNAC78 contained five subdomains of the conserved domain A-E,and the A,C and D parts were relatively conserved,which was consistent with the characteristics of the NAC gene family. Phylogenetic tree analysis showed that CsNAC21/22 was closely related to Glycine max and Populus trichocarpa,and CsNAC68 and CsNAC78 were closely related to Arabidopsis thaliana and Populus trichocarpa. Subcellular localization analysis showed that CsNAC68 located in the nucleus,and CsNAC21/22 and CsNAC78 located in the nucleus and cytoplasm. Real-time fluorescent quantitative PCR（qRT-PCR）analysis showed that the three candidate genes showed significantly different tissue and pathogen induced expression characteristics in HLB susceptible Jincheng（Citrus sinensis）and HLB resistant Mafenggan（C. hystrix）and Jiulixiang（Murraya exotica）. With healthy plants as the control,the expression levels of CsNAC68 and CsNAC78 were significantly up-regulated in the Jincheng root in response to CLas infection,while CsNAC68 was in response to CLas infection in the mesophyll of Jiulixiang and the root of Mafenggan significantly up-regulated expression. The expression of CsNAC21/22 was significantly down-regulated in the root of Jincheng and the mesophyll of Mafenggan. Using Jincheng leaves as the test material,the expression characteristics of candidate genes in response to plant hormone induction were analyzed by qRT-PCR. The results showed that the three genes may be involved in the signal transduction pathway of abscisic acid（ABA）,and CsNAC68 may be involved in the signal transduction pathway of salicylic acid（SA）and jasmonic acid（JA）,and CsNAC78 may be involved in the signal transduction pathway of ethylene（ETH）.

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• Expression Characteristics and Functional Analysis of FvYABBY5.1 in Strawberry
• CAI Jianfa, MO Xuelian, GUAN Sicong, CHEN Xu, XUE Cheng
• Acta Horticulturae Sinica. 2022, 49(7): 1458-1472. DOI:10.16420/j.issn.0513-353x.2021-0351
• Abstract ( 461 ) HTML ( 167 ) PDF (9219KB) ( 167 ) 　　　

• A total of five YABBY genes were identified from woodland strawberry（Fragaria vesca‘Hawaii 4’）. Based on phylogenetic tree analysis of YABBY gene in rosaceous plant,those YABBY genes were divided into five subfamilies:INO,YAB2,YAB3,CRC and YAB5. Gene structure analysis showed that exon and intron number of YABBY genes were different in the five sub-family,but were insignificantly different in the same subfamily. And the dispersion of protein motifs was little difference among all YABBY members. These results suggest that the function of YABBY genes were conservative in strawberry. Expression profile analysis showed that the expression level of FvYAB5.1 gene in dormant buds and non-dormant buds of strawberry runner was significantly different. In transgenic Arabidopsis thaliana,we found that overexpression FvYAB5.1 leaded to curly leaf shape,dwarf phenotype and delayed flowering time. The expression levels of SHOOT MERISTEMLESS（STM）and KNAT2,which regulate shoot apical meristem（SAM）development,were significantly inhibited. Meanwhile,the transcriptional expression levels of auxin and cytokinin-related genes AtARF5,AtARR4 and AtIPT7 were significantly increased,while the transcriptional expression levels of AtARR7 and AtARR15 were significantly repressed. In summary,we speculate that FvYAB5.1 gene may be involved in the development of SAM in strawberry runner by regulating the antagonistic relationship between cytokinin and auxin,leading to the alternating growth of dormant and non-dormant buds in the runner.

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• Analysis on Fruit Morphological Diversity of Persimmon Germplasm Resources
• ZHANG Yue, SUO Yujing, SUN Peng, HAN Weijuan, DIAO Songfeng, LI Huawei, ZHANG Jiajia, FU Jianmin, LI Fangdong
• Acta Horticulturae Sinica. 2022, 49(7): 1473-1490. DOI:10.16420/j.issn.0513-353x.2021-0520
• Abstract ( 725 ) HTML ( 282 ) PDF (3969KB) ( 282 ) 　　　

• In order to evaluate fruit morphological diversity of persimmon（Diospyros kaki Thunb.）,nine fruit quantitative traits,including longitudinal diameter,transverse diameter,lateral diameter,fruit shape index,stalk length,stalk diameter,pedicle length,pedicle width and fresh weight per fruit of 260 persimmon germplasm resources were determined. Subsequently,genetic diversity,correlation,cluster and principal component analysis were conducted on these traits. The results demonstrated high genetic diversities of the morphological traits. Variation coefficients of the nine morphological traits ranged from 16.98%（fruit shape index）to 50.57%（fresh weight per fruit）. Principal component analysis exhibited that the first three principal components with a cumulative contribution rate of 78.85% could represent all the nine morphological traits well. Based on the first and third principal components,the samples in this study were divided into five groups. Group Ⅰ and Ⅳ were suitable for breeding oblate spherical varieties;group Ⅱ and Ⅲ were suitable for breeding spherical varieties;group Ⅴ was suitable for breeding long spherical varieties;group Ⅳ was suitable for breeding large fruit varieties,and group Ⅱ was suitable for breeding small fruit size varieties.

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• The Effect of Water-nitrogen Coupling on Potato Photosynthesis,Tuber Formation and Quality
• YAN Wenyuan, QIN Junhong, DUAN Shaoguang, XU Jianfei, JIAN Yinqiao, JIN Liping, LI Guangcun
• Acta Horticulturae Sinica. 2022, 49(7): 1491-1504. DOI:10.16420/j.issn.0513-353x.2021-0436
• Abstract ( 382 ) HTML ( 139 ) PDF (2080KB) ( 139 ) 　　　

• A pot experiment was conducted in the rain shelter to investigate the effects of irrigation regimes and nitrogen fertilizer application on the potato and develop the optimal water and nitrogen application pattern. Three irrigation regimes（insufficient irrigation amount,normal irrigation amount,excessive irrigation amount）and three nitrogen applications（insufficient nitrogen application,normal nitrogen application,excessive nitrogen application）were set in the experiment to study the effects of the potato（Zhongshu 18,Zhongshu 28）on plant height,tuber formation,photosynthetic characteristics of leaves,tuber weight and quality. The result proved that the deficient nitrogen treatment can make the subapical stolon swelled,the tuber formation period advanced,but fail to obtain high yield ultimately,in The increase of nitrogen amount made the fresh weight of underground stem,underground root,stem and leaf improved,in the irrigation treatments. The increase of nitrogen amount could raise leaf stomatal conductance,net photosynthetic rate,relative chlorophyll content and plant height,in the treatments of normal and excessive irrigation amount. In the treatment of normal irrigation amount and excessive nitrogen application,the tuber weight per plant of Zhongshu 18 and Zhongshu 28 were 711.1 g and 637.2 g;moreover,the net photosynthetic rate,the yield water use efficiency,the tuber starch and the crude protein content of both were at the highest level among all the treatments. Therefore,it is suggested that the normal irrigation amount and excessive nitrogen application should be adopted for potato growth.

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• Identification and Expression Analysis of MYB Transcription Factors Regulating the Anthocyanin Biosynthesis in Zinnia elegans and Function Research of ZeMYB9
• QIAN Jieyu, JIANG Lingli, ZHENG Gang, CHEN Jiahong, LAI Wuhao, XU Menghan, FU Jianxin, ZHANG Chao
• Acta Horticulturae Sinica. 2022, 49(7): 1505-1518. DOI:10.16420/j.issn.0513-353x.2021-0474
• Abstract ( 513 ) HTML ( 202 ) PDF (4422KB) ( 202 ) 　　　

• In this study,Zinnia elegans‘Dreamland Red’was employed as plant materials,and 33 MYB transcription factors were screened based on the transcriptome data of Z. elegans. Furthermore,phylogenetic tree analysis revealed that ten R2R3-MYB transcription factors probably related to anthocyanin synthesis were identified in Z. elegans. Among them,five MYB proteins of Z. elegans belonged to subgroup 4（S4）,three MYB proteins were clustered in S6,and two MYB proteins were included in S7. According to combined analysis on gene expression levels of ten MYB genes and anthocyanidin content in Z. elegans‘Dreamland Red’,it was suggested that ZeMYB32 of S4 probably negatively regulated anthocyanin synthesis in Z. elegans,while ZeMYB3 and ZeMYB16 promoted the accumulation of anthocyanin. What’s more,ZeMYB9 and ZeMYB10 of S6 probably positively regulated anthocyanin synthesis. Further research found that ZeMYB9 is located in the nucleus. Overexpression of ZeMYB9 gene in tobacco enhanced the marked accumulation of anthocyanins in leaves,and dramatically up-regulated the expression levels of all detected genes related with anthocyanin synthesis,revealing that ZeMYB9 plays a positive role in anthocyanin biosynthesis.

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• Study on Antibacterial Activity of Dark Septate Endophytes Against Fusarium oxysporum in Chinese Wolfberry
• CHEN Sijie, ZHANG Tao, JIA Baosen, DU Juan, YAN Siyuan, GU Peiwen
• Acta Horticulturae Sinica. 2022, 49(7): 1519-1531. DOI:10.16420/j.issn.0513-353x.2021-0438
• Abstract ( 456 ) HTML ( 178 ) PDF (4171KB) ( 178 ) 　　　

• By tissue isolation method of the local isolate of Dark septate endophytes（DSE）strains from healthy roots of Lycium barbarum‘Ningqi 5’in order to further provide potential resources bacteria for the biological control of Fusarium oxysporum. The confrontation method,mycelium growth rate method,spore germination method,and pot experiments were conducted to evaluate the antibacterial activities of DSE against F. oxysporum in L. barbarum. The results showed that eight DSE strains could effectively colonize the roots of L. barbarum and form a typical DSE structure. In the meanwhile,all eight DES strains showed a significant inhibitory effect against F. oxysporum,the Cladosporium cladosporioides strain S12 had the highest inhibition rate of 81.47% on the mycelial growth of F. oxysporum;The fermentation filtrate and volatile substances of the eight DSE strains exhibited certain inhibitory effects on the growth of F. oxysporum,and the fermentation filtrate of strain S12 with a concentration of 10% showed the highest inhibitory effect on F. oxysporum mycelial growth,reached up to 78.43%;The fermentation filtrate of the Alternaria alternata strain M1 with a concentration of 50% showed the highest inhibition of conidial germination with 91.48%. Meanwhile,the volatile material produced by strain M1 exhibited the highest inhibition of mycelial growth with 94.10%. In the greenhouse pot experiment,inoculation with strains M1 and S12 provided a good biological control effect,with efficacy up to 89.54% and 83.17%,respectively,better than a treatment of 500× dilution 50% carbendazim wettable powder. These results demonstrate that DSE strains M1 and S12 can effectively control the root rot of disease L. barbarum,while having good potential for biological control and application.

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• CRISPR/Cas9 Technology for RcPDS1 Gene Editing in Rehmannia chingii
• ZUO Xin, LI Mingming, LI Xinrong, MIAO Chunyan, LI Yanfang, YANG Xu, ZHANG Zhongyi, WANG Fengqing
• Acta Horticulturae Sinica. 2022, 49(7): 1532-1544. DOI:10.16420/j.issn.0513-353x.2021-0475
• Abstract ( 336 ) HTML ( 104 ) PDF (9660KB) ( 104 ) 　　　

• To study the application of CRISPR/Cas9 technology in Rehmannia chingii,the phytoene desaturase gene（RcPDS1）of R. chingii was cloned,and its cDNA sequence and genomic DNA sequence were amplified by polymerase chain reaction（PCR）. The constructed single-target CRISPR/Cas9 plasmid was transformed into R. chingii genome using Agrobacterium-mediated genetic transformation method,and the types of gene editing were analyzed by TA clone sequencing. The results showed that the full-length cDNA sequence of RcPDS1 was obtained. The cDNA sequence of RcPDS1 with a length of 1 743 bp contains a single open reading frame,which encoding 580 amino acid residues. The length of genomic DNA sequence of RcPDS1 gene is 8 041 bp,which contains 14 introns and 15 exons. A total of 57 transgenic lines were obtained through A. tumefaciens-mediated genetic transformation,of which 20 lines（35.09%）had the obvious albino phenotype. The results of sequence analysis showed that the target sites mutation modes of RcPDS1 were mainly deletions,substitutions and insertions. It showed that the CRISPR/Cas9 system is a powerful tool to achieve targeted knockout of target genes in R. chingii genome.

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Research Notes

• Effects of Fertilizer Hole Application Sites on Fine Root Growth,¹⁵N Absorption and Utilization,Yield and Quality of Apple Trees
• LIU Zhaoxia, ZHANG Xin, WANG Lu, MA Yuting, CHEN Qian, ZHU Zhanling, GE Shunfeng, JIANG Yuanmao
• Acta Horticulturae Sinica. 2022, 49(7): 1545-1556. DOI:10.16420/j.issn.0513-353x.2021-0280
• Abstract ( 349 ) HTML ( 159 ) PDF (1365KB) ( 159 ) 　　　

• In order to clarify the reasonable fertilizer application site in apple production,realize the efficient utilization of nitrogen fertilizer. In 2018 and 2019,we studied the effects of hole application sites of organic and inorganic fertilizers in root zone（control without organic fertilizer application,strip furrow application and 1-4 hole application）on the root growth,¹⁵N uptake,utilization and loss,and fruit yield and quality of the 6-year-old‘Yanfu 3’/SH6/Malus robusta by using ¹⁵N isotope labeling technology. The results showed that among the treatments with increasing organic fertilizer,the chlorophyll content,leaf area and total dry weight of fine roots were the hightest in 3 and 4 hole fertilization treatments,and the lowest in strip furrow fertilization treatments. In the fruit ripening period,the Ndff values of leaves,fine roots,large roots and fruits were significantly increased by 3 and 4 hole fertilization compared with strip furrow fertilization. The utilization rate of ¹⁵N in trees was 3 holes > 4 holes > 2 holes > 1 hole > strip furrow > control. The loss rate of ¹⁵N showed an opposite trend to the utilization rate of ¹⁵N,fertilization in 3 and 4 holes was lower. Compared with the control and strip furrow fertilization treatments,the fruit yield,fruit weight and soluble sugar content of 3 and 4 hole fertilization treatments were significantly increased. It can be seen that under a certain condition of the amount of organic fertilizer（5 kg）combined with inorganic fertilizer,3 and 4 hole fertilization promoted the growth of fine roots,improved the uptake of ¹⁵N by trees,reduced nitrogen loss,and also had a positive effect on improving fruit yield and quality.

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• Screening of Reference Genes for Differentially Expressed Genes in Pyrus betulaefolia Plant Under Salt Stress by qRT-PCR
• ZHANG Qiuyue, LIU Changlai, YU Xiaojing, YANG Jiading, FENG Chaonian
• Acta Horticulturae Sinica. 2022, 49(7): 1557-1570. DOI:10.16420/j.issn.0513-353x.2021-0376
• Abstract ( 447 ) HTML ( 134 ) PDF (2486KB) ( 134 ) 　　　

• Screening the appropriate reference genes for qRT-PCR analysis on different progenies of Pyrus betulaefolia Bunge. under salt stress,in order to accurately evaluate expression of target genes. In this study,eight reference genes including Actin2（Chr15.g01351）,EF1α-1（Chr3.g19898）,EF1α-2（Chr4.g38173）,EF2（Chr5.g06899）,GAPDH-1（Chr16.g30426）,GAPDH 2（Chr13.g23532）,TUBB（Chr5.g06472）,UBQ（Chr4.g40121）were selected as candidates based on the whole genome and transcriptome sequencing data of P. betulaefolia Bunge. Ten pairs of qRT-PCR primers including Actin2,EF1α-1,EF1α-2A,EF1α-2B,EF2,GAPDH-1,GAPDH-2,TUBB-A,TUBB-B,UBQE were designed or cited from previous publications,and the amplification efficiency of the primer pairs was determined. Two families（Yancheng and Lianyungang）of P. betulaefolia Bunge. were treated with 200 mmol · L^-1 NaCl for 0,24,48,and 72 h respectively and leaf samples were collected. Total RNAs were extracted from 24 leaf samples and cDNAs were synthesized by reverse transcription as templates. The stability of amplification products by 10 primer pairs was analyzed by delta Ct,BestKeeper,geNorm and NormFinder respectively,and then analyzed comprehensively using RefFinder software based on four evaluation results to determine the most stable reference gene and the reference gene primers. The TUBB-A and GAPDH-1 have good stability and applicability. Finally,the expression of a HKT（Chr16.g29024）that may be involved in P. betulaefolia response to salt stress was measured by using those two selected primer pairs. The result showed that:the FPKM values（Fragments Per Kilobase Million）of the eight candidate reference genes were all greater than 30 and the FPKM variation coefficients under salt treatment at different times were 0.087-0.260;the amplification efficiency of 10 qRT-PCR primer pairs was between 91.82% and 112.99%,with primer pairs TUBB-A and GAPDH-1 being closest to 100%;The stability of 10 pairs of primer amplification products are ranked as GΑPDH-1,TUBB-Α,EF1α-1,TUBB-B,EF1α-2Α,EF2,UBQE,GAPDH-2,Actin2,EF1α-2B;Two genes（GΑPDH and TUBB）and primer pairs（GΑPDH-1 and TUBB-Α）were determined as the most suitable reference genes and the most stable primer pairs in this study. It was also found that the stability of the amplified products of different primer pairs of the same gene（such as TUBB-A and TUBB-B,EF1α-2A and EF1α-2B）is also significantly different. GAPDH-1 and TUBB-Α primer pairs are suitable for qRT-PCR analysis in P. betulaefolia under salt stress.

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• Genetic Diversity Analysis of Phenotypic Traits for Kiwifruit Germplasm Resources
• LÜ Zhengxin, HE Yanqun, JIA Dongfeng, HUANG Chunhui, ZHONG Min, LIAO Guanglian, ZHU Yi, YUAN Kaichang, LIU Chuanhao, XU Xiaobiao
• Acta Horticulturae Sinica. 2022, 49(7): 1571-1581. DOI:10.16420/j.issn.0513-353x.2021-0248
• Abstract ( 577 ) HTML ( 186 ) PDF (1636KB) ( 186 ) 　　　

• Sixty-six kiwifruit germplasm resources were used,and 19 phenotypic traits of branches,leaves and fruits were observed,and factor analysis and cluster analysis were applied to analyze the variation coefficient of distribution frequency of phenotypic traits of these kiwifruit germplasm resources. The results showed:the average variation of the 10 characters was 4.9,and the most abundant one was fruit shape（9）,among the nine quantitative traits,the coefficient of variation of stalk length was the largest （41.04%）,and that for fruit longitudinal diameter was the smallest（12.14%）. Q cluster analysis divided the 66 kiwifruit resources into four groups,and the germplasm resources in the same groups were clustered by color of one-year-old twig,mass of single fruit and fruit shape index,etc.

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• Creation of Novel Germplasm of Purple-orange Heading Chinese Cabbage
• ZHANG Lugang, LU Qianqian, HE Qiong, XUE Yihua, MA Xiaomin, MA Shuai, NIE Shanshan, YANG Wenjing
• Acta Horticulturae Sinica. 2022, 49(7): 1582-1588. DOI:10.16420/j.issn.0513-353x.2021-0597
• Abstract ( 517 ) HTML ( 329 ) PDF (11525KB) ( 329 ) 　　　

• In order to enrich the germplasm resources of Chinese cabbage and improve the functional composition,and create a new purple-orange heading Chinese cabbage germplasm riched in anthocyanins and carotenoids simultaneously. A purple heading Chinese cabbage pure line 14S838 and an orange heading Chinese cabbage pure line 14S125 were hybridized,and their F₂ was produced by single F₁ plant selfing. Then the excellent heading plants carrying purple heading gene and orange heading gene in the F₂ population were selected by molecular markers combining field horticultural traits observation,lately,the selected plants was self-crossed and selected for three generations continuously. Finally,four new Chinese cabbage germplasm with the green outer leaves and purple-orange heading leaves,such as 19ZS40-1,19ZS17-1,19ZS94 and 19SF19-4,were bred. This study first successfully aggregated the purple heading gene and orange heading gene in one plant of Chinese cabbage together,promote these two gene normal expression,and created the novel germplasms of Chinese cabbage simultaneously accumulated both carotenoids and anthocyanins,which has greatly improved the nutritional value,enrich the color heading Chinese cabbage breeding materials,laid a new foundation for the nutritional quality breeding of Chinese cabbage.

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• Studies on the Relationship Between Pigment Composition and Fruit Coloration of 63 Peppers
• LI Pingping, ZHANG Xiang, LIU Yuting, XIE Zhihe, ZHANG Ruihao, ZHAO Kai, LÜ Junheng, WANG Ziran, WEN Jinfen, ZOU Xuexiao, DENG Minghua
• Acta Horticulturae Sinica. 2022, 49(7): 1589-1601. DOI:10.16420/j.issn.0513-353x.2021-0449
• Abstract ( 649 ) HTML ( 192 ) PDF (2643KB) ( 192 ) 　　　

• In order to explore the relationship between pigment composition and fruit coloration of pepper（Capsicum spp.）,the International Commission on Illumination color space（CIE L^*a^*b^*）value and chlorophyll a/b of pepper fruit was measured using a colorimeter and spectrophotometer respectively;capsanthin,zeaxanthin,β-carotene and six anthocyanidins（delphinidin,cyanidin,malvidin,peonidin, pelargonidin,petunidin）of pepper fruit was measured using HPLC method. Basing on Python language to visualize pepper fruit color,the relationship between pigment composition and fruit coloration of pepper were analysed with principal component analysis（PCA）,orthogonal partial least squares（OPLS）,cluster analysis and aggregated boosted tree（ABT）. The results showed that 63 peppers were divided into two color groups（A and B）,where A was yellow-green and B was purple-black. There is a correlation between the CIE L^*a^*b^* value of pepper fruit and pigment composition. Zeaxanthin,chlorophyll a,and delphinidin contribute more to the CIE L^*a^*b^* value of pepper fruit. Under the same carotenoid content,when the content of chlorophyll and delphinidin is low,the fruit is yellow-green,and when the content of delphinidin is high,the fruit is purple-black.

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Reviews

• Research Progress on the Epigenetic Mechanisms of Sex Determination in Horticultural Plants
• YANG Linlin, HUANG Yuntong, FU Zeyuan, XU Qijiang
• Acta Horticulturae Sinica. 2022, 49(7): 1602-1610. DOI:10.16420/j.issn.0513-353x.2021-0447
• Abstract ( 515 ) HTML ( 283 ) PDF (1206KB) ( 283 ) 　　　

• The flowers of angiosperm plants are classified into hermaphroditic and unisexual flowers. Some species having both male and female flowers on the same plant（monoecious）,and some species having only one type of unisexual flower per plant（dioecious）. Flowering plants initiate sex differentiation during the transition from vegetative growth to reproductive growth. During sex differentiation of unisexual flowers plants,many studies have demonstrated a variety of mechanisms that determine whether an inflorescence develops as male or female flower. Recently,multiple epigenetic mechanisms,such as DNA methylation,histone modification and microRNA,etc. have been shown function in regulating plant sex determination. In this review,how epigenetic mechanisms—including DNA methylation,histone modification,and diverse microRNAs—function in sex determination of flowers were described in horticultural plants,and they regulates plant sex and floral organ development via plant hormones. At last,the epigenetic mechanism of sex determination was discussed in horticultural crops.

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New Cultivars

• A New Citrus Cultivar‘Yungui Cui Cheng’
• YANG Haijian, ZHANG Yungui, ZHOU Xinzhi
• Acta Horticulturae Sinica. 2022, 49(7): 1611-1612. DOI:10.16420/j.issn.0513-353x.2020-0386
• Abstract ( 410 ) HTML ( 108 ) PDF (1190KB) ( 108 ) 　　　

• ‘Yungui Cui Cheng’,a new few-seed sweet orange cultivar with an orange-yellow thin rind,was selected from‘Xiangshui Cheng’strain. It grows strongly. The fruit is nearly round in shape,and the fruit shape index is 0.94. After ripening,the average fruit weight is 120.5 g. The pulp is orange-yellow,fibreless and crisp,with good flavor and aroma. The juice cells are elongated,containing total soluble solids（TSS）of 12.0%,total acid of 0.41%,and vitamin C of 418.0 mg · L^-1. Its full bloom occurs in early April,and the fruits mature in mid-November in Jiangjin,Chongqing City.

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• A New Castanea henryi Cultivar‘Huali 3’
• ZHU Zhoujun, YUAN Deyi, XIAO Shixin, ZHAO Junru, ZOU Feng, FAN Xiaoming
• Acta Horticulturae Sinica. 2022, 49(7): 1613-1614. DOI:10.16420/j.issn.0513-353x.2020-0777
• Abstract ( 523 ) HTML ( 44 ) PDF (1298KB) ( 44 ) 　　　

• ‘Huali 3’is a new Castanea henryi cultivar selected from the natural C. henryi seedlings. The nuts are oblong,reddish brown,oily and beautiful in appearance. The average nut weight is 8.41 g. Sugar content is 7.07%,starch content is 36.56%,protein content is 3.72%,fat content is 1.04%,vitamin C content is 313.5 mg · kg^-1,calcium content is 364 mg · kg^-1,iron content is 9.15 mg · kg^-1,and zinc content is 4.43 mg · kg^-1. It begins to bear fruit in the second year after grafting. The yield is up to 4 250 kg · hm^-2.

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• A New Mini Pumpkin Cultivar‘Miniju’
• MA Jianxiang, WEI Chunhua, LI Hao, WANG Enyu, LI Wanru, CHENG Yongan, ZHANG Yong, Xu Zhongmin, ZHANG Xian
• Acta Horticulturae Sinica. 2022, 49(7): 1615-1616. DOI:10.16420/j.issn.0513-353x.2020-0420
• Abstract ( 486 ) HTML ( 75 ) PDF (1094KB) ( 75 ) 　　　

• ‘Miniju’is a new pumpkin cultivar which was selected from the cross-combination of GS01-3-11 and R03-6-5. The plant is trailing. The average single fruit weight is 300 g. The fruit is oblate shape. The good quality pulp was sweet and fragrant after taste. The fruit skin is yellow with orange stripes. The yield is 24 180 kg · hm^-2. This cultivar has high resistance to disease and other adverse stimuli. It is suitable for protected cultivation in Shaanxi Province in spring. It can be edible vegetable and ornamental.

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• A New Early Maturing Oriental Melon Cultivar‘Xitian 5’
• DOU Hongtao, LU Yurong, WU Yunxia, YANG Xiaozhen, LIU Minqiang, ZHOU Ling, ZHAN Tao
• Acta Horticulturae Sinica. 2022, 49(7): 1617-1618. DOI:10.16420/j.issn.0513-353x.2020-0328
• Abstract ( 604 ) HTML ( 73 ) PDF (1789KB) ( 73 ) 　　　

• ‘Xitian 5’is a new early maturing oriental melon hybrid. The average single fruit weight is 450-550 g. The fruit is long pear shaped whose skin is white-bright,covered with yellowish halo on the surface,and the skin is thin and tough. The flesh is white,1.7 cm thick,crisp,sweet and fragrant. The soluble solids content in central part is 13%-15%. The whole fruit growth period is 80-85 days,and fruit development period is 26-29 days. The yield is up to 45 000 kg · hm^-2. It has a good resistance to powdery mildew,gummy stem blight and tolerant storage-transportation.

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• A New Michelia platypetala Cultivar‘Fenyun’
• HU Xijun, JIN Xiaoling, XING Wen, ZHANG Zhe, LI Weidong, HUANG Guolin
• Acta Horticulturae Sinica. 2022, 49(7): 1619-1620. DOI:10.16420/j.issn.0513-353x.2020-0363
• Abstract ( 350 ) HTML ( 60 ) PDF (1006KB) ( 60 ) 　　　

• ‘Fenyun’is a new cultivar bred from the seedling of Michelia platypetala. It is evergreen tree and the crown of the tree is nearly spherical. Outer surface of tepals are white distally,lower 1/3 is reddish. The inner surface of tepals are white with a reddish halo at the base. This cultivar has loaded flowers,one bud contains 1-3 flowers with short internodes. It is early flowering（late January or early February）,and the tree has strong cold tolerance.‘Fenyun' can be planted in the south of the Yangtze River hills and plains,mainly for urban street trees and courtyard greening.

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