Reviews

• Functions and Mechanisms of Protein Post-Translational Modifications During Fruit Ripening
• DUAN Chengyuan, WEI Wei, SHAN Wei, CHEN Jianye, LU Wangjin, KUANG Jianfei, YANG Yingying
• Acta Horticulturae Sinica. 2026, 53(7): 1853-1870. DOI:10.16420/j.issn.0513-353x.2026-0158
• Abstract ( 26 ) HTML ( 10 ) PDF (3409KB) ( 10 ) 　　　

• Fruit ripening is a complex biological process that is precisely regulated by multi-level molecular networks，in which protein post-translational modifications（PTMs）act as central regulatory hubs. This review systematically summarizes the functions and mechanisms of classical PTMs，including phosphorylation，ubiquitination，acetylation and glycosylation，as well as emerging PTMs such as methylation，crotonylation，persulfidation，redox-related modifications and S-nitrosylation during fruit ripening. Different PTMs differentially regulate the ripening of climacteric and non-climacteric fruits by modulating hormone signaling pathways，such as ethylene and abscisic acid（ABA），as well as kinase cascades including MAPK，CDPK and SnRK2，and epigenetic modifications such as histone acetylation and methylation. Crosstalk mechanisms，such as phosphorylation-ubiquitination coupling，also occur among PTMs，coordinately regulating the activity，stability and subcellular localization of transcription factors and metabolic enzymes. These processes further mediate pigment biosynthesis，cell wall degradation，sugar-acid metabolism，volatile compound synthesis and nutrient accumulation，ultimately determining fruit color，texture，taste，aroma and nutritional quality. In addition，environmental factors such as low temperature and light，as well as exogenous signals including ethylene，nitric oxide（NO）and hydrogen sulfide（H₂S），can dynamically remodel PTMs to finely regulate fruit ripening，quality formation and postharvest preservation. A deeper understanding of the regulatory networks and molecular mechanisms of PTMs will not only improve the theoretical framework of fruit ripening regulation，but also provide a foundation for PTM-targeted gene editing breeding and precision postharvest regulation strategies，thereby promoting fruit quality improvement and extending storage life.

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• Advances in Chilling Injury and Associated Quality Deterioration in Postharvest Fruits
• LIU Mengfei, LI Junduo, HU Ruoqian, SHI Yanna, XU Changjie, CHEN Kunsong
• Acta Horticulturae Sinica. 2026, 53(7): 1871-1890. DOI:10.16420/j.issn.0513-353x.2026-0388
• Abstract ( 35 ) HTML ( 16 ) PDF (2834KB) ( 16 ) 　　　

• Chilling injury constitutes a major constraint on quality maintainance of chilling sensitive fruit during cold storage. This review focuses on chilling injury-induced quality deterioration in fruits，specifically addressing the associated biological manifestations，including color deterioration，aroma loss，flavor imbalance，and textural disorders. The underlying molecular regulatory networks are systematically examined from the perspectives of cellular changes，metabolic remodelling，transcriptional cascades，epigenetic modifications，post-translational regulation and signal transduction pathways. Based on recent advances in cold tolerance mechanisms from model plants，strategies for dissecting chilling resistance in postharvest fruits and developing targeted preservation technologies are further discussed. This review provides a theoretical basis for mitigating chilling injury and achieving precision regulation of fruit quality.

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• Research Progress on the Synergistic Regulation of Sugar and Acid in Fresh Fruits
• JIAO Tiantian, DANG Suqing, ZHU Lingcheng, LI Mingjun
• Acta Horticulturae Sinica. 2026, 53(7): 1891-1909. DOI:10.16420/j.issn.0513-353x.2026-0447
• Abstract ( 33 ) HTML ( 14 ) PDF (1899KB) ( 14 ) 　　　

• The synergistic regulation of sugar and acid is a popular themes in fruit quality. At present，the synergistic regulation of sugar and acid in fruit encompasses multiple levels，ranging from metabolic enzyme activity and transmembrane transport to hormonal signal transduction and epigenetic modification，collectively shaping fruit sugar-acid balance through a complex regulatory network. This review focuses on the coupling mechanisms between sugars and organic acids metabolism and transport in fruit，and provides an in-depth summary of recent advances in the synergistic regulation of fruit sugar and acid，with particular emphasis on the regulatory mechanisms of metabolic enzymes，phytohormones，transcription factors，and epigenetic modifications underlying this process. The aim is to provide a theoretical basis for further elucidation of the synergistic regulatory mechanism of sugar and acid in fresh fruits and improvement of fruit quality.

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• Research Progress on Carotenoid Metabolism and its Role in Stress Tolerance in Apple
• GUO Xudong, WANG Huimin, WANG Xinyuan, LI Chunyu, MO Meihua, XU Yishu, HAN Xiaoya, YUAN Yongbing, JIA Dongjie
• Acta Horticulturae Sinica. 2026, 53(7): 1910-1928. DOI:10.16420/j.issn.0513-353x.2026-0307
• Abstract ( 28 ) HTML ( 7 ) PDF (1329KB) ( 7 ) 　　　

• Apple（Malus × domestica Borkh.）is an important fruit tree resource in the world，and the synergistic improvement of fruit quality and stress resistance is the key to the sustainable development of the industry. Carotenoids are crucial metabolites that determine fruit color，nutritional quality，and stress resistance，and their metabolic regulatory mechanisms are a research hotspot. In this paper，the main metabolic pathways of apple carotenoids and the functional identification of their key enzymes are systematically reviewed. The multi-level regulatory network underlying its biosynthesis is reviewed from the aspects of transcription factors，hormone signals，and epigenetics. The molecular mechanisms of carotenoids mediated stress response through antioxidant properties and abscisic acid（ABA）signaling pathway are discussed. The genetic improvement of key genes and the application progress of multi-gene co-transformation technology in apple astaxanthin synthesis are summarized. Future research focuses on the integrated analysis of multi-omics，the construction of efficient gene-editing system，and the synergistic improvement of fruit quality and stress resistance. These efforts will provide a theoretical basis for elucidating the regulatory mechanisms underlying fruit quality formation and facilitate molecular breeding in apple.

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• Advances in the Research on Salt Tolerance of Malus Plants
• LIU Zhao, GAO Yuan, SUN Simiao, WANG Kun, GUO Hanxin, SHANG Wei, WANG Lin, TIAN Wen, LI Zichen, SUN Yanming, LI Lianwen, WANG Dajiang
• Acta Horticulturae Sinica. 2026, 53(7): 1929-1954. DOI:10.16420/j.issn.0513-353x.2025-0738
• Abstract ( 23 ) HTML ( 21 ) PDF (2016KB) ( 21 ) 　　　

• In-depth research on the response mechanisms and defense strategies of Malus plants to salt stress is of great theoretical significance for the development of salt tolerant cultivation techniques for apples and the breeding of salt tolerant varieties. This review comprehensively analyzed the advanced results on the effects of salt stress in Malus plants，the identification，evaluation and screening of Malus plants under salt stress，the physiological processes and molecular mechanisms of salt tolerance，and the identification of salt-tolerant functional genes，aiming to obtain a comprehensive understanding of salt tolerance in Malus plants and identify the current situation and existing problems in the research，and propose the main research directions. It will provide selection and reference for the practical application of salt-tolerant Malus and the selection and breeding of salt-tolerant apple rootstocks.

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• Research Progress of Drought Stress Response in Pear
• LIU Xiaomin, XU Liangliang, LIU Yaling, WU Jun
• Acta Horticulturae Sinica. 2026, 53(7): 1955-1976. DOI:10.16420/j.issn.0513-353x.2026-0453
• Abstract ( 49 ) HTML ( 16 ) PDF (2454KB) ( 16 ) 　　　

• Drought is an important abiotic stress that limits the development of the global pear industry and has an important impact on the growth and development of pear trees and the formation of fruit quality. In this paper，the physiological mechanism of pear in response to drought stress was summarized from the aspects of osmotic regulation，antioxidant defense and water balance，and the molecular regulation mechanisms such as drought signal perception，transcriptional regulation pathway and post-translational modification were expounded. Combined with the screening of cultivar resources and the breeding of new cultivars，the progress of drought-resistant breeding of pear was summarized. The current drought-resistant regulation measures of pear were listed，the existing problems in the existing research were analyzed，and the future research hotspots were prospected，in order to provide theoretical basis and guidance for drought-resistant cultivation and breeding of pear.

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Genetic & Breeding · Germplasm Resources · Molecular Biology

• Evaluation and Validation of Molecular Markers for Fruit Color and Firmness in Multiple Apple Hybrid Progenies
• ZHANG Xiaoke, WANG Jinhong, YANG Yazhou, LI Chao, LI Linguang, HAN Zhenhai, WU Ting
• Acta Horticulturae Sinica. 2026, 53(7): 1977-1990. DOI:10.16420/j.issn.0513-353x.2026-0240
• Abstract ( 21 ) HTML ( 3 ) PDF (1576KB) ( 3 ) 　　　

• In six apple hybrid progenies（‘Honeycrisp’בRuiyang’，‘Mato 1’בGala’，‘Fuji’בPink Lady’，‘Ruiyang’בEnvy’，‘Fuji’בMalus sieversii’，and‘Qinguan’בHoneycrisp’），six molecular markers（ERF17，MYB1，ERF4，ACS1，ACO1 and ACS3a866）were validated. The correlation between markers and traits was analyzed by associating genotypes with fruit phenotypes（including peel chlorophyll content，coloration degree，and fruit firmness）. The results showed that the ERF17 marker accurately predicted chlorophyll content in most progenies，but it was not significant in the ‘Mato 1’בGala’progeny. The MYB1 marker achieved a high prediction accuracy of 92.05% for whether the peel is red. ERF4，ACS1，and ACS3a866 showed high accuracy in predicting fruit firmness，but there were interactions among the markers.

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• MdWRKY33 and MdWRKY127 Regulate Sugar and Organic Acid Metabolism to Improve the Sugar-Acid Ratio in Apple Fruit
• SU Anqi, ZHUANG Yingyu, DU Lianda, PEI Feifei, CHEN Ze, ZHAO Tingting, HU Dagang
• Acta Horticulturae Sinica. 2026, 53(7): 1991-2003. DOI:10.16420/j.issn.0513-353x.2026-0120
• Abstract ( 11 ) HTML ( 1 ) PDF (6918KB) ( 1 ) 　　　

• Transcriptome analysis of‘Greensleeves’apple（Malus × domestica Borkh.）fruit during developmental stages identified two WRKY transcription factors，MdWRKY33 and MdWRKY127，which were specifically highly expressed at the ripening stage. To clarify the biological functions of these two WRKY transcription factors，they were cloned and subjected to bioinformatics analysis. Phylogenetic

  analysis revealed that the MdWRKY33 protein shares close phylogenetic relationships with its homologous proteins from wild apple relative Siberian crabapple（Malus baccatavar. baccata）and pear（Pyrus× bretschneideri），while the MdWRKY127 protein is closely related to an incompletely annotated protein in apple. Subcellular localization analysis indicated that both MdWRKY33 and MdWRKY127 proteins are located in the nucleus，exhibiting the typical subcellular localization characteristics of WRKY transcription factors. To verify their functions，overexpression experiments were carried out using apple calli as the material. The results showed that overexpressing either MdWRKY33or MdWRKY127gene significantly reduced the content of malic acid and citric acid in the calli，while increasing the accumulation levels of fructose and sucrose，resulting in a higher sugar-acid ratio in the calli. Further transient injection experiments in apple fruits showed that the overexpression results were consistent with those in the calli，whereas silencing either gene led to a decrease in the sugar-acid ratio in the fruit. These results indicate that both MdWRKY33 and MdWRKY127 are involved in regulating sugar and acid metabolism in apple fruit，thereby effectively improving the flavor of apple fruit.

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• Assessment of Gummosis Pathogens Resistance in Four Peach Rootstocks
• ZHUO Siting, LIANG Xin, SHEN Xingyi, HUANG Xue, LIU Junwei, ZHAO Shili, HE Huaping, LI Guohuai, ZHU Wei, ZHU Kaijie
• Acta Horticulturae Sinica. 2026, 53(7): 2004-2018. DOI:10.16420/j.issn.0513-353x.2025-1161
• Abstract ( 24 ) HTML ( 6 ) PDF (1940KB) ( 6 ) 　　　

• Four peach rootstock resources（Taobadan，Tsukuba，Zhezhen 1，and Prunus persica）and two peach cultivars（Dahongpao and Spring Snow）with varying resistance to gummosis were used as experimental materials，disease resistance evaluation was conducted after inoculating with gummosis pathogens Lasiodiplodia theobromae JMB-122 and Botryosphaeria dothidea XNHG-241 using the detached shoot inoculation method. Antioxidant enzyme activities，hormone content and related genes expression were measured to assess the resistance of these peach germplasms to gummosis. The results showed that Taobadan exhibited the highest level of resistance，followed sequentially by Tsukuba，Zhezhen 1，Dahongpao，and Spring Snow. In contrast，P. persica identified was the most susceptible. Following inoculation with gummosis pathogens，Taobadan exhibited a significantly reduced lesion expansion rate and gummosis incidence compared to other germplasms. Additionally，there was a rapid increase in its antioxidant enzyme activities，alongside a swift elevation in the levels of salicylic acid and jasmonic acid. The expression of salicylic acid biosynthesis gene PpICS2 and jasmonic acid biosynthesis gene PpLOX2 were significantly up-regulated，and Taobadan is a promising resistant rootstock for peach gummosis.

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• Genome-Wide Identification of Grapevine SWEET Protein Family Reveals the Potential Function of VvSWEET15 in Sugar Accumulation
• YAN Yun, XIAO Yang, YAO Yaqi, NONG Yuying, GUO Dejun, SHAO Jianhui, MA Chunhua, SU Jing
• Acta Horticulturae Sinica. 2026, 53(7): 2019-2033. DOI:10.16420/j.issn.0513-353x.2025-0792
• Abstract ( 18 ) HTML ( 8 ) PDF (5073KB) ( 8 ) 　　　

• SWEET is a newly discovered class of sugar transporters that regulate the unloading and accumulation of sugar in plants and participate in plant senescence，nectar secretion，hormone signaling，pathogenesis，and abiotic stress response. The study systematically identifies the VvSWEETs protein family in grapevine（Vitis vinifera L.）and analyses its expression patterns across different stages of berry development to explore genes related to sugar accumulation in grape berries，which is crucial for improving fruit quality. The physicochemical properties，phylogenetic relationships，gene structure，and cis-regulatory elements of VvSWEETs were analyzed using grape whole-genome data. Integrating these analyses with transcriptome data from‘Red Globe’at different developmental stages，VvSWEET15 was identified as a key candidate. Its function in fruit sugar accumulation was elucidated through gene cloning，subcellular localization，and gene silencing. The grape genome contains 16 VvSWEET genes，distributed on 10 chromosomes and categorized into four evolutionary clades（CladesⅠ，Ⅱ，Ⅲ and Ⅳ）. Genes within each clade share similar structural characteristics. The promoter region is enriched in cis-acting elements responsive to light, phytohormones, development, and stress. Transcriptome analysis revealed increased VvSWEET15 expression from 40 to 120 days after flowering，positively correlating with hexose accumulation in ripe berries. VvSWEET15 is a protein localized to the plasma membrane，and transient silencing of its expression significantly reduced the fructose and glucose concentrations in fruits，indicating that VvSWEET15 plays an important role in the accumulation of sugar concentration in grape fruits.

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• Identification of the DGK Family Genes in Vitis vinifera and Functional Study of VvDGK1 Under Salt Stress
• TAN Yanxiao, HAN Shuang, LENG Songning, CHEN Xiaole, LIU Bailin, SHI Hongmei, HE Weihua, ZHANG Yu
• Acta Horticulturae Sinica. 2026, 53(7): 2034-2052. DOI:10.16420/j.issn.0513-353x.2025-0766
• Abstract ( 20 ) HTML ( 4 ) PDF (3501KB) ( 4 ) 　　　

• Diacylglycerol kinase（DGK）is a key signaling enzyme that induces the synthesis of phosphatidic acid（PA）under adverse stress and plays an important regulatory role in the process of cellular signal transduction. To systematically analyze the DGK family gene members in grapes and conduct biological function research，based on the grape genome database，searched for and identified the DGK gene family members in grapes，and conducted analyses on their phylogenetic evolution，physicochemical properties，gene structure，protein and promoter sequences，and gene expression levels. In addition，VvDGK1 was genetically transformed into Arabidopsis thaliana and subjected to salt stress treatment，and the interacting proteins of VvDGK1 were screened and identified. The results showed that a total of five DGK family members were identified in the grape genome database. Among them，VvDGK1 and VvDGK2 belong to ClusterⅠ，VvDGK3 to ClusterⅡ，and VvDGK4 and VvDGK5 to Cluster Ⅲ. Systematic evolution and collinearity analysis revealed that the five VvDGKs in grapes have a relatively high homology with the DGK genes in apples，and the collinearity relationship between VvDGK1 and MdDGK3，MdDGK7，and AtDGK1 is the strongest. The promoter region of the VvDGKs gene contains a large number of cis-acting elements related to growth and development，plant hormones，and responses to adverse stress. The VvDGK gene has a relatively high expression level in stems and leaves，but a relatively low expression level in roots，flowers and fruits，showing obvious tissue specificity. The VvDGK gene shows different expression patterns under stress treatments such as drought，salt，and abscisic acid. Among them，VvDGK1 gene expression was significantly induced under different stress treatments. Overexpression of VvDGK1 in Arabidopsis revealed that the transformed strain enhanced resistance to salt stress，slowed the decline of the maximum photochemical efficiency of leaf photosystemⅡ（F_v/F_m）and the degradation of chlorophyll under stress，reduced the accumulation of reactive oxygen species under stress，and increased the activity of antioxidant enzymes（such as CAT，POD and APX）. The yeast two-hybrid system screened out VvFd and VvRCA，which can interact with VvDGK1. The bimolecular fluorescent complimentary（BiFC）further verified the in vivo interaction between VvDGK1 and VvFd. It is speculated that VvDGK1 participates in signal transduction under salt stress by influencing photosynthesis through interaction with VvFd and VvRCA.

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• Genome-Wide Identification of the HSP20 Gene Family in Strawberry and its Functional Analysis in Fruit Response to High-Temperature Stress and Ripening Regulation
• ZHAO Yanxia, SUN Jiabo, Wu Yiqing, LI Qian, LIANG Hongmin, LI Bingbing
• Acta Horticulturae Sinica. 2026, 53(7): 2053-2074. DOI:10.16420/j.issn.0513-353x.2026-0341
• Abstract ( 25 ) HTML ( 13 ) PDF (10578KB) ( 13 ) 　　　

• Small heat shock protein 20（HSP20）are pivotal regulators involved in plant high-temperature stress response as well as growth and development. To dissect the high-temperature response mechanism of the strawberry HSP20 gene family and its regulatory function in fruit ripening，diploid woodland strawberry（Fragaria vesca）was used as material in this study. A genome-wide identification of the FvHSP20 gene family was carried out using bioinformatics methods，and the gene structure，phylogeny，chromosomal localization，and cis-acting elements were systematically analyzed. Furthermore，combined with transcriptome and qRT-PCR technologies，the expression patterns of this family at different fruit developmental stages and under high-temperature stress in both woodland strawberry and cultivated strawberry（Fragaria × ananassa）were resolved，and the biological function of key gene was further validated in cultivated strawberry. The results showed that a total of 33 FvHSP20 genes were identified from the F. vesca genome. The encoded HSP20 proteins contained 78 to 399 amino acids with stable physicochemical properties，and were targeted to cytoplasm，chloroplasts，mitochondria and other organelles，exhibiting obvious subcellular compartmentalization. Phylogenetic analysis categorized these genes into 13 subfamilies，among which a novel clade designated CXⅡ subfamily was newly classified in this study. Notably，strawberry HSP20 family lacked endoplasmic reticulum subfamily members，reflecting unique evolutionary characteristics of this species. The 33 FvHSP20 genes were unevenly mapped onto seven strawberry chromosomes，most family members possessed compact gene structures with zero or one intron. Promoter sequence of various genes analysis revealed numerous stress-responsive and hormone-responsive cis-elements，among which light-responsive，abscisic acid（ABA）-responsive and methyl jasmonate（MeJA）-responsive elements were the most abundant. Transcriptomic results indicated that both FvHSP20 and FaHSP20 genes displayed fruit developmental stage-specific expression patterns. Fruits at the white stage were most susceptible to high-temperature stress，and core genes including HSP20-13，HSP20-14 and HSP20-20 were significantly upregulated upon heat treatment. Distinct transcriptional responses to heat stress were detected between two cultivated strawberry cultivars：the heat-tolerant cultivar‘Kaorino’exhibited milder and more stable gene expression fluctuations. Transient overexpression assays verified that FaHSP20-13 accelerated fruit coloration，enhanced sugar enrichment under normal temperature conditions. Furthermore，FaHSP20-13 maintained ABA signaling homeostasis to relieve heat-induced growth inhibition in strawberry fruits，performing dual functions in promoting maturation and heat resistance. In this study，the basic characteristics and high-temperature response patterns of the strawberry HSP20 family were clarified，and key candidate genes for heat tolerance and ripening regulation were identified，which provided theoretical basis and genetic resources for molecular breeding of heat tolerance and high-quality improvement in strawberry.

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• CsBBX20 Regulates Anthocyanin Biosynthesis in Citrus
• FU Jialing, WEI Yurong, SUN Juan, WEI Xing, DU Linzhu, HOU Jianqi, LIU Yuqi, XU Qiang
• Acta Horticulturae Sinica. 2026, 53(7): 2075-2091. DOI:10.16420/j.issn.0513-353x.2026-0253
• Abstract ( 34 ) HTML ( 9 ) PDF (5897KB) ( 9 ) 　　　

• Anthocyanins are important secondary metabolites responsible for citrus fruit coloration，and their accumulation is regulated by environmental signals and multilayered regulatory networks. In this study，CsBBX20 was cloned from blood orange fruit. The open reading frame of CsBBX20 is 609 bp，encoding a protein of 202 amino acids. Sequence analysis showed that CsBBX20 contains two highly conserved B-box domains. Functional analysis revealed that anthocyanin accumulation was significantly increased in CsBBX20-overexpressing apple calli under light conditions，whereas only trace amounts of anthocyanins accumulated in wild-type calli. However，under dark conditions，neither CsBBX20-overexpressing lines nor wild-type calli accumulated anthocyanins. Further biochemical analyses demonstrated that CsBBX20 can directly bind to the promoters of CsF3’H，CsDFR，CsRuby1，and CsHY5，and significantly activate their expression. Moreover，CsBBX20 physically interacts with the light signaling regulator CsHY5，and their co-expression markedly enhances the activation of CsRuby1. Taken together，CsBBX20 directly activates key genes involved in anthocyanin biosynthesis and forms a complex with CsHY5 to coordinately regulate the expression of target genes，thereby promoting anthocyanin accumulation in citrus fruit under light conditions.

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Cultivation · Physiology & Biochemistry

• Effects of Exogenous Melatonin and Dopamine on Nutrient Absorption and Drought Resistance Evaluation of Apple Plants Under Drought Stress
• SUN Nan, LIU Huaite, CAO Yang, DU Peihua, ZHANG Xueying, LIANG Bowen
• Acta Horticulturae Sinica. 2026, 53(7): 2092-2106. DOI:10.16420/j.issn.0513-353x.2026-0281
• Abstract ( 20 ) HTML ( 7 ) PDF (1893KB) ( 7 ) 　　　

• Using grafted seedlings of‘Tianhong 2’/Malus hupehensis as experimental materials，a pot experiment was conducted with two water regimes（moderate drought and normal water supply）combined with three exogenous treatments：no exogenous substance application，melatonin application （100 μmol · L^-1），and dopamine application（100 μmol · L^-1），resulting in six treatments in total. After 60 days of treatment，the dry weight of each plant part，mineral element contents，uptake flux，translocation rate，and accumulation amount were measured. The regulatory effects of exogenous melatonin and dopamine on nutrient uptake and utilization in apple plants under drought stress were analyzed. Meanwhile，principal component analysis and the membership function method were used to comprehensively evaluate drought resistance. The results showed that drought stress significantly decreased the dry weight of roots，stems，and leaves，reduced mineral element uptake and their accumulation in roots，and significantly inhibited the translocation rates of mineral elements to leaves and stems. Exogenous application of melatonin and dopamine significantly increased the dry weight of each plant part and the uptake of mineral elements under drought stress，and simultaneously enhanced the translocation rates of mineral elements to leaves and stems as well as their accumulation in roots. Mineral element contents were significantly or highly significantly correlated with organ dry weight and nitrogen，phosphorus，and potassium content. The drought resistance of plants treated with melatonin was higher than that of plants treated with dopamine. In conclusion，melatonin and dopamine can promote apple plant growth and improve drought resistance by regulating nutrient uptake and utilization，with melatonin being more effective than dopamine.

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• Study on Effect of Apple Rootstocks on Cold Resistance of Annual Branches Through Regulating Leaf Nutrient Reflux
• LIU Qian, WANG Jingyi, XIA Mingran, LIU Dawei, LIU Yi, LIANG Bowen, ZHOU Shasha, YIN Baoying, ZHANG Xueying, LI Zhongyong
• Acta Horticulturae Sinica. 2026, 53(7): 2107-2118. DOI:10.16420/j.issn.0513-353x.2025-1156
• Abstract ( 15 ) HTML ( 3 ) PDF (1082KB) ( 3 ) 　　　

• Apple cultivars‘Yanfu 8’and‘Tianhong 2’grafted onto different rootstocks（‘Jizhen 2’，9-3，ZC9-3，53，24-5，and SH40）were used to compare and analyze the leaf nutrient reflux rates of nitrogen（N），phosphorus（P），and potassium（K），the semilethal temperature（LT₅₀）of one-year-old shoots，and physiological indicators related to cold resistance. The objective was to explore the physiological mechanism by which leaf nutrient reflux affects the cold resistance of one-year-old shoots. The results showed that rootstocks could influence the cold resistance of one-year-old shoots by increasing leaf nutrient reflux in the scions. The combinations of‘Yanfu 8’and‘Tianhong 2’grafted onto rootstock 9-3 exhibited higher leaf N，P，and K resistance rates，lower LT₅₀，higher proline（PRO）content，higher superoxide dismutase（SOD）and peroxidase（POD）activities，and lower malondialdehyde（MDA）content and superoxide anion radical（ ）production rate in one-year-old shoots. Collectively，these findings suggest that rootstock 9-3 enhances the nutrient storage and cold resistance of scion cultivars during the overwintering period by increasing leaf nutrient reflux rate，making it a promising cold-hardy dwarfing apple rootstock for practical application.

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• Effects of Apple Mosaic Disease on Leaves Photosynthesis and Fruit Quality of‘Hirosaki Fuji’Apple
• LUO Zhangji, LI Haojian, LI Lianzhen, HOU Xiangting, DONG Wen, SUN Ping, XUE Xiaomin, YOU Chunxiang, ZHANG Zhenlu
• Acta Horticulturae Sinica. 2026, 53(7): 2119-2128. DOI:10.16420/j.issn.0513-353x.2026-0123
• Abstract ( 10 ) HTML ( 4 ) PDF (1983KB) ( 4 ) 　　　

• In a seven-year-old‘Hirosaki Fuji’apple orchard，apple trees without mosaic symptoms（control）and those with obvious mosaic symptoms were selected to investigate the effects of apple mosaic disease（AMD）on leaf photosynthetic efficiency and key quality during fruit growth and development. The results showed that the net photosynthetic rate（P_n）of leaves exhibiting mosaic symptoms was significantly reduced compared with that of asymptomatic control leaves，accompanied by a significant increase in intercellular CO₂ concentration（C_i）. From 40 to 200 days after full bloom，measurements were taken every 30 days for indicators including single fruit mass，fruit longitudinal and transverse diameters，peel and flesh firmness，peel color difference and glossiness，soluble solids content，and titratable acidity. The occurrence of mosaic disease significantly inhibited the increase in single fruit mass and the expansion of fruit longitudinal and transverse diameters，accelerated the decline in peel firmness，and suppressed the degradation of titratable acidity，resulting in a reduced solid-to-acid ratio. However，no significant differences were observed between the diseased and control fruits in terms of soluble solids content，peel color difference，or glossiness.

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• The Effects of Aged Walnut and Grape Orchards Soil on the Growth of Malus hupehensis Seedlings
• QIN Lei, LU Lei, TANG Jin, YU Yajing, YIN Chengmiao, JIANG Weitao, MAO Zhiquan
• Acta Horticulturae Sinica. 2026, 53(7): 2129-2143. DOI:10.16420/j.issn.0513-353x.2026-0255
• Abstract ( 17 ) HTML ( 1 ) PDF (6838KB) ( 1 ) 　　　

• To investigate the impact of aged walnut and grape orchards soil on the growth of Malus hupehensis seedlings，this study used M. hupehensis seedlings as test materials and set up four groups of treatments：aged walnut orchard soil，aged grape orchard soil，and their sterilized soil. The growth and development of the seedlings，soil allelopathic substances，and pathogenic bacteria types were measured to analyze the impact of aged orchard soils on the growth of M. hupehensis seedlings. The results showed that the untreated old walnut orchard soil and old grape orchard soil inhibited the growth of M. hupehensis seedlings，which was manifested by the decrease of biomass，root activity and the activity of root protective enzymes（SOD，POD，CAT），the increase of malondialdehyde（MDA）content，the decrease of soil bacteria/fungi ratio. The content of allelopathic substances and microbial community structure in two kinds of aged orchard soils were determined and analyzed. The results showed that the soil was enriched with allelopathic substances such as p-hydroxybenzoic acid，phenylpropionic acid，quercus quinone，ferulic acid and gallic acid，and potential pathogenic bacteria genus such as Fusarium，Aspergillus and Alternaria alternata. Further validation was conducted through exogenous addition allelopathic substances and inoculation pathogenic bacteria. The above mentioned allelopathic substances and pathogenic bacteria could significantly inhibit the growth of M. hupehensis seedlings. In conclusion，the main reason for the growth inhibition of the next crop seedings is the accumulation of phytochemicals and harmful microorganisms in the soil of aged vineyards and walnut orchards，neither is suitable for direct crop rotation planting of apple seedlings.

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• Effects of Different Regulated Deficit Irrigation Treatments on Growth and Fruit Quality of‘Ruidu Kemei’Grape
• WANG Xiaoyue, REN Jiancheng, ZHANG Congying, LIU Zhenhua, LU Haocheng, YAN Ailing, ZHANG Lixia, WANG Huiling, SUN Lei
• Acta Horticulturae Sinica. 2026, 53(7): 2144-2168. DOI:10.16420/j.issn.0513-353x.2025-1318
• Abstract ( 23 ) HTML ( 25 ) PDF (3328KB) ( 25 ) 　　　

• The Muscat-flavored table grape cultivar‘Ruidu Kemei’was used as the experimental material. Plants were grown in a plastic greenhouse with drip irrigation. Three irrigation levels were applied at the fruit set and veraison stages：full irrigation（65%-75% of field capacity，FC），mild water deficit（50%-60% FC），and moderate water deficit（35%-45% FC），resulting in a total of nine treatments. The effects of regulated deficit irrigation（RDI）on photosynthetic characteristics，shoot growth，fruit physicochemical quality，and the composition and content of monoterpenes were systematically measured. Principal component analysis（PCA）was used for comprehensive evaluation. The results indicated that water deficit applied at fruit set effectively suppressed excessive shoot growth while maintaining a stable net photosynthetic rate，but it reduced single berry weight. Veraison was identified as a critical stage for enhancing berry flavor and aroma accumulation. Moderate water deficit during this stage significantly increased the total soluble solids to titratable acidity ratio and promoted the accumulation of monoterpene compounds. Cluster analysis and variable importance in projection（VIP）analysis showed that deficit irrigation over two years notably enhanced monoterpene accumulation，with β-myrcene，cis-rose oxide and geraniol being the key signature monoterpene components in response to water deficit. The OAV analysis indicated that cis-rose oxide，linalool，and geraniol were the main contributing compounds to the characteristic aroma of the fruit. Based on the two-year PCA evaluation，full irrigation at fruit set followed by mild deficit irrigation at veraison achieved the best overall performance. This irrigation strategy synergistically optimizes growth regulation and fruit quality improvement，providing a feasible approach for water-saving and high-efficiency cultivation of Muscat-flavored table grapes.

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• Physiological and Ecological Mechanisms of Trichoderma asperellum in Enhancing Drought Resistance of Banana Plants
• ZHANG Miaoyi, YAN Kun, WANG Wei, ZHAO Yankun, LI Kai, CHEN Yufeng, FENG Junting, XIE Jianghui
• Acta Horticulturae Sinica. 2026, 53(7): 2169-2184. DOI:10.16420/j.issn.0513-353x.2026-0251
• Abstract ( 13 ) HTML ( 1 ) PDF (6405KB) ( 1 ) 　　　

• This study investigated the physiological and microecological mechanisms by which Trichoderma asperellum M7 enhances drought tolerance in banana using physiological and biochemical assays，gene expression analysis，and microbiome technology. The results showed that M7 inoculation significantly increased the activities of superoxide dismutase（SOD），peroxidase（POD），and catalase（CAT）in leaf. The strain treatment also elevated proline and soluble sugar contents，reduced malondialdehyde（MDA）accumulation，and promoted the synthesis of abscisic acid（ABA）and auxin（IAA）in roots，thereby effectively alleviating the inhibitory effects of drought on seedling growth. Gene expression analysis revealed that the M7 significantly up-regulated transcript levels of ABA biosynthesis genes（MaAO，MaNCED2），a signal transduction gene（MaSnRK2-11），and an aquaporin gene（MaPIP1;1）. Furthermore，compared with the sterilized soil treated with M7，the natural soil significantly enriched beneficial microorganisms such as Pseudomonas，Nitrosococcus，and Streptomyces. Through core microbe isolation and reconnection verification experiments，it was found that the composite microbial community could effectively enhance the drought-resistant phenotype of plants，and some of the microorganisms alone also had certain effects. In conclusion，M7 inoculation was associated with enhanced drought tolerance in banana，which correlated with direct modulation of host physiological responses and drought-responsive gene expression，as well as indirect reshaping of the beneficial rhizosphere microbial community，suggesting a synergistic effect.

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• Study on the Integrative Effect of UV-B and Low Temperature on Litchi Flowering Regulatory Mechanism
• LIU Jingjing, XIE Haoyang, HUANG Xiao, HU Zhengxiao, ZENG Wanqi, ZHANG Huiyun, LUO Xinping, SHEN Jiyuan
• Acta Horticulturae Sinica. 2026, 53(7): 2185-2199. DOI:10.16420/j.issn.0513-353x.2026-0361
• Abstract ( 24 ) HTML ( 5 ) PDF (4043KB) ( 5 ) 　　　

• Litchi flowering requires sufficient low-temperature induction，but the “warm winters” that frequently occur in southern China often lead to inadequate flowering in litchi. In this study，five-year-old air layered potted‘Feizixiao’litchi plants were placed in a climate chamber at 15 ℃，and two intensities of UV-B radiation（1.75 and 3.75 kJ · m^-2 · d^-1，respectively）were applied to investigate the integrative effects of UV-B radiation and low temperature on the growth，development，antioxidant capacity，and flowering of litchi. The results showed that the combination of high-intensity UV-B radiation （3.75 kJ · m^-2 · d^-1） and low temperature increased the flowering plant rate and the pure panicle rate in comparison to the control. The combination of UV-B radiation and low temperature enhanced the accumulation of H₂O₂，but significantly reduced the total phenolic content and SOD activity in leaves. The accumulation of sucrose and glucose in leaves was induced by short-term low temperature，but decreased in the late stage of low temperature indcution. Low temperature induced the expression of LcUVR8-1，LcUVR8-2，LcCOP1，LcCO1，LcCO2，LcFT1，and LcFT2；the combination of high-intensity UV-B radiation and low temperature induced the expression of LcFT1 but inhibited the expression of LcFT2. These findings indicate that the accumulation of H₂O₂ by high-intensity UV-B radiation treatment resulting in an up-regulation of LcFT1，may enhance the flowering ability of litchi in the presence of low temperature.

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Plant Protection

• Identification of Pathogen Causing Loquat Root Rot in Zhejiang and Characteristics of Host Endogenous Hormone Response
• GOU Xiuhong, WEI Yue, QIN Yi, CHEN Junwei, GUO Qigao, LIANG Guolu, ZHOU Can, WU Di
• Acta Horticulturae Sinica. 2026, 53(7): 2200-2212. DOI:10.16420/j.issn.0513-353x.2026-0323
• Abstract ( 11 ) HTML ( 2 ) PDF (4028KB) ( 2 ) 　　　

• The pathogens causing loquat root rot exhibit high diversity and regional specificity，making the identification and pathogenicity characterization essential for precise disease management. Through tissue isolation，morphological observation，molecular identification，and pathogenicity assays，Fusarium oxysporum was identified as an important pathogen causing loquat root rot in Zhejiang Province. Biological characterization of the representative isolate（R1）revealed that the optimal culture conditions for mycelial growth of F. oxysporum were 30 ℃ and pH 7-8，with soluble starch as the optimal carbon source，and yeast extract and potassium nitrate as the optimal nitrogen sources. To elucidate the host-pathogen interaction，the spatiotemporal dynamics of endogenous hormones in loquat following F. oxysporum infection were profiled using liquid chromatography-tandem mass spectrometry（LC-MS/MS）and real-time quantitative PCR（qRT-PCR）. The results showed that during the early stage of infection（1 day post-inoculation，1 dpi），the jasmonic acid（JA）content in roots decreased，followed by an increase in the middle（7 dpi）and late（14 dpi）stages. Correspondingly，the expression of jasmonic acid carboxyl methyltransferase 5（JMT5）was initially up-regulated and subsequently down-regulated. Conversely，salicylic acid（SA）and its inactive glucoside form，SA 2-O-β-D-glucoside（SAG），accumulated significantly during the middle stage before declining rapidly in the late stage. In the stems，the SA content showed no significant change，whereas SAG and JA accumulated substantially in the late stage. The expression of defense-related genes，such as chitinase（CHI）and pathogenesis-related 1（PR1），was up-regulated initially；however，PR1 was suppressed in the late stage. In contrast，the JA synthesis-related lipoxygenase 22（Lox22）was up-regulated during the late stage. In conclusion，F. oxysporum facilitates colonization by regulating loquat endogenous hormone signaling networks. In the early stage，it disrupts JA metabolic homeostasis to weaken local defense；in the middle stage，it induces SA accumulation to antagonize JA signaling；and in the late stage，it further facilitates infection by suppressing SA-mediated systemic acquired resistance（SAR）.

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