Genetic & Breeding·Germplasm Resources·Molecular Biology

• Evaluation of Fruit Segmental Membrane Development and Mastication in Two Citrus Triploids
• CAO Huixiang, LUO Xin, LIU Wanrong, GUAN Shuping, WANG Tingting, WU Xiaomeng, GUO Wenwu, XIE Kaidong
• Acta Horticulturae Sinica. 2024, 51(6): 1179-1188. DOI:10.16420/j.issn.0513-353x.2023-0493
• Abstract ( 328 ) HTML ( 260 ) PDF (2881KB) ( 260 ) 　　　

• To investigate the reason for the fruit mastication difference between citrus triploid progeny with their diploid parents，two triploid hybrids derived from the crosses with Bendizao tangerine and Red tangerine as female parent were selected as materials to investigate the effect of segmental membrane structure and its components on the mastication of triploid fruits comparing with their diploid parents. In this study，using the two diploid parents as the control，the fruit mastication of the two triploid hybrids was firstly determined with texture analyzer at mature stage. It showed that the hardness and shear force of the segmental membrane of the two triploid progenies were significantly higher than that of their diploid parents，indicating that the segmental membranes of the two triploid hybrids might thicker than that of their corresponding diploid parents. It showed that the thickness and cell layer number of the segmental membranes of the two triploid hybrids were significantly higher than that of their corresponding diploid parents at the same developmental stage started from 120 days after flowering（DAF）. The ultrastructure of the segmental membrane showed that the cell walls in the two triploid hybrids were thicker and the cellulose microfibrils were denser than those of their diploid parents. The content of water-soluble pectin，protopectin，cellulose and hemicellulose in the segment membrane of the two triploid hybrids were significantly higher than that of their diploid parents，while the lignin content was significantly lower at some developmental stage. In conclusion，segmental membrane thickness，water-soluble pectin，protopectin，cellulose and hemicellulose contents are important factors affecting the mastication of some citrus triploid hybrids，providing some useful evaluation indexes to screen superior triploid lines with good fruit mastication quickly from a large-scale triploid population.

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• Quantitative Trait Locus Mapping and Analysis of Traits Related to Flower，Fruit，and Leaf in Loquat
• ZHAO Chongbin, ZHANG Weiyin, LI Shuqing, GUO Yihan, XU Hongxia, CHEN Junwei, YANG Xianghui, PENG Ze
• Acta Horticulturae Sinica. 2024, 51(6): 1189-1200. DOI:10.16420/j.issn.0513-353x.2023-0500
• Abstract ( 184 ) HTML ( 154 ) PDF (2103KB) ( 154 ) 　　　

• The study focused on an F₁ population of 130 individuals from the cross between‘Ninghaibai’בOobusa’loquat cultivars. Based on a well-constructed high-density genetic map of loquat，QTL mapping was performed for 17 fruit-，leaf- and floral-related traits，and candidate genes were screened from the key QTL intervals. The results showed significant correlations exceeding the significance level among multiple traits. A total of 153 QTLs were identified for the 17 traits. Nine traits，including transverse diameter，flesh thickness，seed number，seed weight，fruit shape index，width of leaf blade，length of leaf blade，width of leaf blade，and shape of leaf base，had QTLs with phenotypic variance explained rates of above 25%. Notably，six QTL intervals on LG4（13.500-14.276 cM and 23.646-24.804 cM），LG8（0-8.851 cM），LG12（41.198-45.852 cM and 65.246-66.407 cM），and LG15（92.921-95.244 cM），were shared among six or more traits，with phenotypic variance explained rates above 35% for multiple traits. Furthermore，a total of 13 candidate genes related to plant growth and development，cell division，cell expansion，and plant hormone regulation were obtained from the overlapping intervals of LG12（41.198-45.852 cM）and LG15（92.921-95.244 cM）.

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• Genetic Tendency Analysis and Comprehensive Evaluation of the Fruit Traits in Loquat F₁ Generation
• ZHU Qixuan, LI Xiaoying, WU Junkai, GE Hang, CHEN Junwei, XU Hongxia
• Acta Horticulturae Sinica. 2024, 51(6): 1201-1215. DOI:10.16420/j.issn.0513-353x.2023-0427
• Abstract ( 213 ) HTML ( 113 ) PDF (2522KB) ( 113 ) 　　　

• In order to explore the variation and genetic tendency of multiple traits of loquat fruit in the hybrid offspring，the F₁ loquat lines of‘Ninghaibai’（white pulp，female parent）and‘Oobusa’（yellow pulp，male parent）were used as materials，a total of 14 traits，including quality，color，secondary metabolic functional components，and cell wall components were studied in the mature fruits of 100 lines and their parents. The comprehensive quality of hybrid offspring fruit was evaluated by principal component analysis. The results showed that the 10 traits，including fruit weight，total soluble solids（TSS），gloss brightness（L^*）and color saturation（C^*），total phenolic，flavonoids，pectin，cellulose，total hemicellulose and total lignin were widely separated in the F₁ generation with a normal distribution. Four traits，including titrable acid（TA），ratio of TSS to TA，hue angle（H^*），and carotenoid content showed a skewed distribution in F₁ generation. TSS and TA showed a tendency of higher genetic variation，L^*，C^*，H^*，carotenoid content，pectin content and cell wall cellulose content showed a tendency of intermediate genetic variation，while fruit quality，solid acid ratio，total phenol content，flavonoids content，total hemicellulose content and total lignin content showed a trend of small genetic variation. Correlation analysis showed that fruit quality was positively correlated with L^*，C^*，carotenoid content，total phenol content and total hemicellulose content，and negatively correlated with TSS，H^*，flavonoids content and pectin content. According to the principal component analysis，five principal components with eigenvalues greater than 1 were obtained，and the cumulative contribution rate was 70.424%，which were mainly summarized into three aspects：fruit color，fruit flavor and fruit texture，and 26 excellent quality lines were successfully screened out according to the comprehensive quality score.

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• Mechanism of miR408-MnBBP Module Regulating Anthocyanin Biosynthesis in Mulberry
• SUN Zhichao, GUO Xinmiao, WANG Hui, XIE Yan, GAO Yanxia, LI Jisheng, GAO Yujun
• Acta Horticulturae Sinica. 2024, 51(6): 1216-1226. DOI:10.16420/j.issn.0513-353x.2023-0571
• Abstract ( 127 ) HTML ( 116 ) PDF (2450KB) ( 116 ) 　　　

• To elucidate the molecular mechanisms by which mulberry miR408 targets the MnBBP gene to modulate anthocyanin biosynthesis，the effect of mulberry miR408 on anthocyanin metabolism was analyzed by quantitative real-time PCR（qRT-PCR），bioinformatics analysis，5′-rapid amplification of cDNA ends（5′-RACE），and transgenic methodologies. Sequence alignment revealed that the miR408 sequence is identical to that of dicotyledonous plants，while featuring a single nucleotide polymorphism （SNP）at the first nucleotide position in monocotyledons. Expression profiling via qRT-PCR demonstrated differential expression patterns of miR408 across various mulberry tissues，with high expression levels observed in leaves and fruits. Through predictive analysis using the Omicstudio online platform，the mulberry blue-copper binding protein gene（MnBBP）was identified as a target gene of miR408. Degradome sequencing further corroborated that MnBBR is subject to specific cleavage by miR408. 5′-RACE analysis pinpointed the cleavage site between the 9th and 10th bases of the sequence complementary to miR408. Overexpression of mulberry miR408 in Arabidopsis thaliana led to elevated anthocyanin levels in the leaves. Transcriptomic analysis identified differentially expressed genes（DEGs）between the transgenic and wild-type plants，with a notable enrichment of DEGs in the anthocyanin biosynthetic pathway. The up-regulation of five key genes within this pathway was subsequently validated by qRT-PCR. Collectively，this study not only identifies MnBBP as a target gene of miR408 in mulberry，but also elucidates the regulatory roles of miR408 and MnBBP in anthocyanin biosynthesis.

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• Using the Fluorescent Labeled SSR Markers to Establish Molecular Identity of Hawthorn
• QIN Yu, GUO Rongkun, NONG Huilan, WANG Yan, CUI Kai, DONG Ningguang
• Acta Horticulturae Sinica. 2024, 51(6): 1227-1240. DOI:10.16420/j.issn.0513-353x.2023-0444
• Abstract ( 195 ) HTML ( 120 ) PDF (1274KB) ( 120 ) 　　　

• In present research，simple sequence repeats（SSR）markers were employed to analyze the genetic diversity and to establish the molecular identity of 91 hawthorn accessions. Ninety-six pairs of SSR primers were developed from the hawthorn genome database，and 12 pairs with good polymorphism were selected. The screened primers were labeled with four kinds of fluorescence and used for PCR amplification. The PCR products of the 91 samples were analyzed by capillary electrophoresis. The GeneMarker analysis software was used to determine the sizes of the amplified fragments and the genotypes. The individual digits and uppercase English letters were used to mark each band to encode a fingerprint. According to the polymorphic information content（PIC）of 12 primers，the order of these primer pairs were sorted from high to low，and molecular identities of 91 hawthorn accessions were established. Cluster analysis of 91 hawthorn accessions were performed using the Unweighted pair-group method with arithmetic means（UPGMA）. The results showed that a total of 67 alleles were detected from 12 pairs of SSR primers，with an average of 5.583 alleles per each primers and an average of 2.730 effective alleles. The mean values of observed heterozygosity（H_o），expected heterozygosity（H_e），Shannon’s information index（I），and polymorphic information content（PIC）were 0.490，0.593，1.195，and 0.551（range 0.300-0.715），respectively. The genetic similarity coefficient of 91 hawthorn accessions ranged from 0.25 to 0.98 with an average of 0.529，and the samples could be classified into five groups at the genetic similarity coefficient of 0.46. The molecular identities of the 91 hawthorn accessions were constructed through the selection of primers according to its PIC，these accessions could be distinguished by the least specific primers. This study could provide reliable basis for the identification，evaluation，utilization，and genetic relationship analysis of hawthorn germplasm resources.

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• Preliminary Study on the Mechanism of DXR Regulating Chloroplast Development Flower Color and Fruit Coloring in Tomato
• MA Xingyun, FAN Bingli, TANG Guangcai, JIA Zhiqi, LI Ying, XUE Dongqi, ZHANG Shiwen
• Acta Horticulturae Sinica. 2024, 51(6): 1241-1255. DOI:10.16420/j.issn.0513-353x.2023-0774
• Abstract ( 152 ) HTML ( 107 ) PDF (3386KB) ( 107 ) 　　　

• In the growth and development of plants，carotenoids play a crucial role in leaf，flower，and fruit pigmentation，serving as the primary pigment compounds during fruit maturation. The 1-deoxyd-D-xylose-5-phosphate reduction isomerase gene（DXR）is involved in the synthesis of carotenoids. The SlDXR gene editing and overexpression lines of tomato were constructed. It was found that gene editing lines exhibited yellow or even white leaves，the chlorophyll content and maximum photoenergy conversion efficiency of PSⅡ decreased significantly，the chloroplast development was affected，and the number of thylakoids was reduced. Meanwhile，the petal edge of gene editing lines turned white and the fruit color changed to orange or even yellow in the red ripening stage. The content of lycopene，flavonoid and other pigments in these fruits decreased to different degrees. There was no significant difference between the overexpression linesand the wild type（the control），however，the soluble solids content was significantly increased. Transcriptome sequencing showed that SlDXR was related to flavonoid biosynthesis，carotenoid biosynthesis and other pathways. These findings suggested that SlDXR could affect the coloring of tomato by regulating the synthesis of terpenoids.

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• Cloning and Functional Analysis of PqDFR and PqANS Genes and Its Promoters from Paeonia qiui
• LI Qinqin, DONG Shanrong, LUO Jianrang, ZHANG Yanlong
• Acta Horticulturae Sinica. 2024, 51(6): 1256-1272. DOI:10.16420/j.issn.0513-353x.2023-0336
• Abstract ( 253 ) HTML ( 142 ) PDF (3994KB) ( 142 ) 　　　

• To explore the causes of the spring leaves of Paeonia qiui with purple-red color，PqDFR and PqANS genes were selected as key genes for anthocyanin synthesis based on the leaf transcriptional data. The two genes were cloned，analyzed for expression patterns，functional characterization and analyzed for promoter activity. The open reading frame of PqDFR was 1 095 bp，encoding 364 amino acids，containing the NADPH conserved domain and a substract-binding binding site. The open reading frame of PqANS was 1 065 bp，encoding 354 amino acids，including 2OG-FeⅡ_Oxy and conserved amino acids binding ferrous ion. The results of real-time quantitative PCR showed that the expression of PqDFR and PqANS genes showed a trend of increasing first，then decreasing during leaf development，which was consistent with the accumulation of anthocyanin. The anthocyanin content of leaf disks was decreased after silencing of PqDFR and PqANS genes in Paeonia qiui. Stable overexpression assays showed that transgenic Arabidopsis seedlings all showed significant anthocyanin accumulation compared to wild-type. Both PqDFR and PqANS gene promoters contain MYB binding sequence，light response elements（G-box），abscisic acid response element（ABRE）and growth factor response element（TGA-element）. GUS staining and quantitative results showed that both PqDFR and PqANS gene promoters had good activity. This research suggests PqDFR and PqANS can promote anthocyanin synthesis in Paeonia qiui leaves.

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• Cloning and Functional Verification of Linalool Synthase Gene PsTPS14 in Tree Peony‘High Noon’
• WANG Peiyun, LI Ziang, BAI Yang, YANG Ping, YIN Chengpeng, LI Chuanrong, ZHANG Xinwen, SONG Xiuhua
• Acta Horticulturae Sinica. 2024, 51(6): 1273-1283. DOI:10.16420/j.issn.0513-353x.2023-0383
• Abstract ( 122 ) HTML ( 106 ) PDF (1766KB) ( 106 ) 　　　

• The linalool synthase gene PsTPS14 was cloned from the aromatic tree peony‘High Noon’based on the transcriptome sequencing. The complete CDS sequence of this gene was 903 bp in length encoding 300 amino acids. The analysis of the amino acids sequence showed that the protein has one conservative domain（Terpene_cyclase_plant_C1）. The expression level of PsTPS14 was the highest in half opening stage of petals in tree peony‘High Noon’，consistent with the release pattern of floral volatiles. Subcellular localization analysis showed that PsTPS14 was mainly localized in the chloroplast. The overexpression vector of PsTPS14 was injected into tobacco leaves and the petals of cut flowers of ‘Fengdan’，a light scent tree peony cultivar，by using the transient expression method. The release of linalool in tobacco leaves and‘Fengdan’petals could be detected by GC-MS method. At the same time，the expression level of PsTPS14 was higher in tobacco leaves and‘Fengdan’petals，and the content and activity of linalool synthase were significantly increased. This study showed that PsTPS14 regulated the synthesis of linalool in plants.

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• The Mechanism of Heat Stress Response and the Exploration of Functional Genes in Rosa chinensis‘Angela’
• YANG Binan, LI Bowen, YANG Zhenyu, XU Yipeng, YAN Yunqing, LOU Yuxia, FENG Shucheng, MING Feng
• Acta Horticulturae Sinica. 2024, 51(6): 1284-1296. DOI:10.16420/j.issn.0513-353x.2023-0417
• Abstract ( 149 ) HTML ( 153 ) PDF (6195KB) ( 153 ) 　　　

• In this study，high temperature experiment was conducted and phylogenetic index were analyzed using Rosa chinensis‘Angela’‘Renyue’and‘Xianjing’as test materials. The results showed that‘Angela’exhibited the highest heat resistance among the three varieties. Comparative transcriptome analysis，co-expression network analysis，protein-protein interaction network analysis and phylogenetic analysis revealed that the improvement of heat tolerance in‘Angela’is associated with the overexpression of heat shock transcription factors（HSFs）and heat shock proteins（HSPs）. Notably，the expression level of HSP gene RcHSP18.1 significantly increased with prolonged heat stress duration. Furthermore，by silencing the homologous gene NtHSP18.1 in tobacco，the heat resistance of tobacco was significantly reduced，confirming the essential role of HSP18.1 in heat stress tolerance. Overexpressing of RcHSP18.1 through gene bombardment and silencing RcHSP18.1 gene by virus induced gene silencing technique have both confirmed the significant role the gene RcHSP18.1 in enhancing heat stress resistance in‘Angela’.

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• Analysis of Differential Genes in Response to Sucrose Feeding in Disc Florets of Chrysanthemum nankingense
• WANG Wen, ZHANG Peng, WANG Zhimin, LIU Genzhong, BAO Zhilong, MA Fangfang
• Acta Horticulturae Sinica. 2024, 51(6): 1297-1310. DOI:10.16420/j.issn.0513-353x.2023-0321
• Abstract ( 175 ) HTML ( 54 ) PDF (4943KB) ( 54 ) 　　　

• To explore effects of sucrose feeding on the accumulation of total flavonoids in Chrysanthemum nankingense capitula and the underlying mechanism，Chrysanthemum nankingense，a unique wild diploid species of chrysanthemum in China，was used as the test material，and its detached capitula were fed with sucrose. The dynamic changes of total flavonoids and total phenols in disc and ray florets were determined at 0，12，36 and 60 h after sucrose feeding，and transcriptome sequencing of disc florets was performed. The results confirmed that sucrose feeding could increase the content of flavonoids and total phenols in disc florets within 24 h. However，in ray florets，these compounds changed slightly. A total of 9 135 differentially expressed genes（DEGs），which was also the maximum number of DEGs identified between treatments，were obtained by transcriptome analysis of disc florets sucrose-fed for 60 h and 0 h，while only 3 423 differentially expressed genes were obtained by transcriptome analysis of disc florets sucrose-fed for 60 h and no sucrose-fed for 60 h. These data indicate that the response degree of disc florets to sucrose increased with the increase of feeding time on the biochemistry level. KEGG analysis indicated that the flavonoid biosynthesis pathway was significantly enrichedand 32 flavonoid biosynthetic structural genes were differentially expressed. Correlation analysis showed that transcription factors MYBs，WRKYs and MADS-boxes had a strong co-expression relationship with flavonoid biosynthetic structural gene expression in disc florets in response to sucrose feeding. Nine DEGs were randomly selected for qRT-PCR，indicating that the transcriptome data were accurate. Spatio-temporal expression and subcellular localization of the encoding genes of two transcription factors were further analyzed to confirm the findings. Genes screened out from this study can offer potential targets for further efforts of metabolic engineering aiming to probe secondary metabolism in Chrysanthemum nankingense.

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• Functional Analysis of OfbHLH89 Gene in Regulating Flower Opening in Osmanthus fragrans
• LI Xiang, ZHONG Shiwei, WANG Yiguang, DENG Jinping, FANG Qiu, ZHAO Hongbo
• Acta Horticulturae Sinica. 2024, 51(6): 1311-1320. DOI:10.16420/j.issn.0513-353x.2023-0299
• Abstract ( 115 ) HTML ( 106 ) PDF (1772KB) ( 106 ) 　　　

• The flower opening process was investigated by screening and cloning gene OfbHLH89 from the Osmanthus fragrans transcriptome database. This gene has a coding frame（ORF）that is 744 bp long and encodes for 247 amino acids. Sequence alignment and phylogenetic tree analysis revealed that OfbHLH89 shared similarities of 54.1% and 52.74% with Vigna angularis VaBPE and Capsicum baccatum CbBPE，respectively. The subcellular localization results showed that OfbHLH89 was localized on the nucleus. Spatiotemporal expression analysis showed that OfbHLH89 was highly expressed in the flower，and its expression gradually increased from ball-shaped stage to full flowering stage，reaching a peak at the full flowering stage. Further analysis revealed that under low temperature induction，the relative expression level of OfbHLH89 in the flower buds was significantly higher than that of the control. In Petunia hybrida，overexpression of OfbHLH89 resulted in the enlargement of petals，suggesting that OfbHLH89 may be involved in petal expansion during flower opening in O. fragrans. Additionally，the expression of PhEXPA1，PhXTH24，and PhXTH25 were significantly up-regulated. Quantitative analysis of downstream cell expansion related genes by transient transformation of OfbHLH89 into O. fragrans flower buds revealed that the expression of OfXTH5，OfXTH21，OfXTH32，OfXTH34，OfEXPA4 and OfEXPA13 were significantly upregulated compared with empty vector. It is suggested that OfbHLH89 can impact the flower opening of O. fragrans by activating the transcription of genes related to cell expansion，leading to increase in petal size.

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• Principal Component Analysis and Genetic Relationship Research on Cultivars of Schlumbergera truncata Based on Morphological Characteristics for DUS Testing
• ZHAO Tianrong, LING Jiangang, REN Xiliang
• Acta Horticulturae Sinica. 2024, 51(6): 1321-1331. DOI:10.16420/j.issn.0513-353x.2023-0788
• Abstract ( 127 ) HTML ( 89 ) PDF (3396KB) ( 89 ) 　　　

• Sixteen morphological characteristics，often used for DUS（Distinctness，Uniformity and Stability）testing，of 58 cultivars of Schlumbergera truncata were recorded for statistical analysis in order to reveal the variation of each characteristic and the principal component analysis and cluster analysis were performed by using the DPS software. The results showed that the maximum coefficient of variation of receptacle color was 62.74%，and the minimum coefficient of variation of inner perianth width was 10.35%. According to the cumulative contribution rate of variance 86.8%，10 principal components were extracted，and the characters leafy stem width，leafy stem length，the beginning of flowering，leafy stem type of margin notch，leafy stem depth of margin notch，flower length，inner perianth segments width，inner perianth segments color of marginal zone，flower width，receptacle color and pistil length above tube were screened out by the scores of each trait in principal component. Based on the results of cluster analysis，58 cultivars were divided into three groups according to the differences of 16 characteristics，and were further subdivided into six groups. Nine of the 10 cultivars clustered into class C had type of margin notch with obtuse serrated or dense serrated type，which indicated that the cultivars clustered into class C had genes of Schlumbergera bridgesii，so it is far away from class A and class B. The results showed that there was a wide range of polymorphisms among S. truncata cultivars in the DUS-test. The distance between classes could accurately reflect the relationship between cultivars.

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Cultivation·Physiology & Biochemistry

• Effects of UV-B on Chlorophyll Biosynthesis in Greenhouse Nectarine Leaves
• TIAN Ge, LIU Jianting, GAO Chuancai, ZHAO Xuehui, FAN Yongxin, LI Sen, ZHANG Hanxiao, CHEN Xiude, LI Ling, LI Dongmei
• Acta Horticulturae Sinica. 2024, 51(6): 1332-1344. DOI:10.16420/j.issn.0513-353x.2023-0482
• Abstract ( 155 ) HTML ( 112 ) PDF (1068KB) ( 112 ) 　　　

• In order to clarify the key steps in the response of chlorophyll（Chl）biosynthesis to ultraviolet B（UV-B）irradiation in greenhouse nectarine leaves，the 7-year-old nectarine‘Zhongyou 5’was used as the test material，which was cultivated in greenhouse from 7 days after flowering. The appropriate dose of UV-B（about 1.44 kJ · m^-2 · d^-1 screened by previous experiments）was supplemented at 8：30—9：30 every morning until the fruit was harvested. The dynamic changes of precursor substances，intermediate product content，Chl content and key enzyme activity in the process of Chl biosynthesis in leaves during the growth and development period were investigated with normal growth and unsupplemented UV-B irradiated plants as the control. The results showed that in the first stage of Chl synthesis，UV-B irradiation increased the accumulation of δ-aminolevulinic acid（ALA）by increasing the activity of glutamate-1-semialdehyde-2,1-aminomutase（GSA-AM），a key enzyme in the synthesis of precursor ALA，which laid a good material foundation for the beginning of biosynthesis. In the second stage，UV-B increased the activity of bile pigment deaminase（PBGD），promoted the synthesis of hydroxymethyl bile pigment，and provided sufficient substrates for the synthesis of subsequent products uroporphyrinogen Ⅲ（Urogen Ⅲ），so that the content of Coprogen Ⅲ and Proto Ⅸ in leaves increased significantly during the whole growth period. After UV-B irradiation，the activities of key enzymes such as Mg-chelating enzyme（MgCH）and Mg-protoporphyrin Ⅸ monomethyl ester cyclase（MgPEC）in the third stage were significantly increased，and the content of intermediate products Mg-protoporphyrin Ⅸ（MgPⅨ），Mg-protoporphyrin Ⅸ methyl ester（MgPME），bivinyl protochlorophyllate，protochlorophyllate（Pchlide），chlorophyllate a（Chlide a）and chlorophyllate b（Chlide b）were all increased，the chlorophyll content of the product was also significantly higher than that of the control. It can be seen that the main key steps of UV-B irradiation affecting Chl biosynthesis are the synthesis of precursor ALA，the synthesis of hydroxymethylcholanogen，the conversion of Urogen Ⅲ to Coprogen Ⅲ，the insertion of Mg^{2 +} into Proto Ⅲ and the following four steps，and the effect of UV-B on Chl biosynthesis has a long-term accumulation.

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• Leaf Nutrient Diagnosis of‘Xuxiang’Kiwifruit at Different Growth Stages for Achieving High and Stable Yield and High Quality
• DONG Xiaoke, CHEN Yuanlei, NIU Youyi, LIU Zhande, WANG Nannan
• Acta Horticulturae Sinica. 2024, 51(6): 1345-1360. DOI:10.16420/j.issn.0513-353x.2023-0521
• Abstract ( 173 ) HTML ( 81 ) PDF (897KB) ( 81 ) 　　　

• A total of 114 leaf samples from 20‘Xuxiang’kiwifruit orchards in central Shaanxi Province were analyzed for element concentration at the late fruit development stage in 2020，and at three stages of the leaf expansion，fruit enlargement and late fruit development in 2021. Based on the leaf norm values developed by high and stable yield and high quality，the leaf nutrient status was diagnosed using three methods：diagnosis and recommendation integrated system （DRIS），deviation from optimum percentage（DOP），and compositional nutrient diagnosis（CND）. Additionally，probability grading method，one derivative method of sufficiency range method，was used to determine the sufficient range of leaf elements for‘Xuxiang’kiwifruit. This study provides a scientific basis for annual nutrient resource management in‘Xuxiang’kiwifruit production. The results indicated that leaf element concentration was significantly different between various growth stages，and there were significant correlations between leaf element concentration and fruit yield，fruit quality as well as vine growth performance. Fourteen samples were selected as high-productivity populations from 114 samples，based on the functional relationships between leaf element analytic parameter and fruit yield，comprehensive fruit quality score as well as vine growth performance，established by CND cutoff method. The results from DRIS，DOP and CND indicated that，the remaining 100 leaf samples of low-productivity populations were deficient in Ca and Fe but excessive in Mn，Cl and P during the leaf expansion stage，deficient in N and Ca but excessive in Mg and Cl at the fruit enlargement stage，and deficient in Ca but excessive in Cl，Mn and N at the late fruit development stage. The sufficient ranges of leaf elements in ‘Xuxiang’kiwifruit were developed using probability grading method：at the leaf expansion stage，N 35-40 g · kg^-1，P 3.0-3.8 g · kg^-1，K 21-26 g · kg^-1，Ca 15-20 g · kg^-1，Mg 2.5-3.0 g · kg^-1，Cl 3.0-4.5 g · kg^-1，Fe 100-180 mg · kg^-1，Mn 50-80 mg · kg^-1，Cu 14-20 mg · kg^-1，Zn 21-30 mg · kg^-1 and B 32-45 mg · kg^-1；at the fruit enlargement stage，N 29-35 g · kg^-1，P 1.4-1.8 g · kg^-1，K 9-16 g · kg^-1，Ca 37-44 g · kg^-1，Mg 6.0-7.8 g · kg^-1，Cl 3.5-5.5 g · kg^-1，Fe 175-250 mg · kg^-1，Mn 85-200 mg · kg^-1，Cu 8.5-15.0 mg · kg^-1，Zn 15-30 mg · kg^-1 and B 55-85 mg · kg^-1；at the late fruit development stage，N 20-24 g · kg^-1，P 1.3-1.7 g · kg^-1，K 7-14 g · kg^-1，Ca 42-51 g · kg^-1，Mg 7-9 g · kg^-1，Cl 3-5 g · kg^-1，Fe 180-250 mg · kg^-1，Mn 80-160 mg · kg^-1，Cu 7-12 mg · kg^-1，Zn 20-45 mg · kg^-1 and B 52-67 mg · kg^-1.

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• Comprehensive Evaluation of the Edible Coating on Postharvest Quality of Blueberry
• HUANG Peng, DING Jie, LIU Chunyan, LI Hongying, LI Xinyu, LIU Yaowen, QIN Wen
• Acta Horticulturae Sinica. 2024, 51(6): 1361-1376. DOI:10.16420/j.issn.0513-353x.2023-0393
• Abstract ( 99 ) HTML ( 82 ) PDF (5471KB) ( 82 ) 　　　

• The objective was to comprehensively evaluate the edible coating of thymol microcapsules/ konjac glucomannan/low acyl gellan gum（TKL）on preservation of blueberry fruit. The‘Bluegold’ blueberry cultivar was used as experimental material. The efficacy of TKL preharvest coating on blueberry quality was comprehensively evaluated by entropy weigtht method（EWM），entropy-technique for order preference by similarity to an ideal solution（Entropy-TOPSIS）and cluster analysis from the parameters of texture，color，malondialdehyde，sugar and acid and total phenols. The experimental results showed that the TKL coating treatment slowed down the decrease of sensory，hardness，L^*，b^*，fruit shape index，chewiness and springing，decreased the increase of water weight loss，decay index，MDA，reducing sugar，and suppressed the changes of titratable acid，total sugar，a^*，C^*. The Entropy-TOPSIS model demonstrated that the comprehensive quality was more consistent with the sensory quality analysis after different coating treatments. Cluster analysis revealed that the blueberry quality of the TKL coating treatment at 14-42 d was clustered in the same category as the control at 7-21 d. The TKL coating treatment extended the shelf life of blueberries from 28 d to 42 d.

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• Effects of Irrigation Lower Limits on Early-Spring Cucumber Grown Under Different Soil Textures in the Solar Greenhouse
• YUAN Quan, LU Wei, WANG Jun, CHEN Ru, LI Yansu, YU Xianchang, HE Chaoxing, SUN Mintao, YAN Yan
• Acta Horticulturae Sinica. 2024, 51(6): 1377-1385. DOI:10.16420/j.issn.0513-353x.2023-0162
• Abstract ( 121 ) HTML ( 120 ) PDF (807KB) ( 120 ) 　　　

• In order to optimize irrigation parameters for high-yield or high-quality cucumber production in protected facilities under different soil textures，the effects of irrigation lower limits on growth，yield，and quality of early-spring cucumber were investigated. Cucumber‘Zhongnong 26’was used as experimental material. Three typical soil textures（loam，clay loam，and sandy loam）in major vegetable producing areas were adopted. Three irrigation lower limits for each soil texture were performed from fruiting period，including 60%，70%，and 80% of filed capacity. When soil water content dropped to irrigation lower limit，corresponding irrigation system initiated. The irrigation amount was the calculated variation of soil water content from irrigation lower limit to 90% of field capacity. Results showed that for loam，clay loam，and sandy loam，70%，60%，and 80% of field capacity were the optimal irrigation limits for high-yield cucumber cultivation，which could reach up to 110 800，130 300，and 125 000 kg · hm^-2，respectively，together with high irrigation water use efficiency，which could reach up to 45.1，42.3，and 45.3 kg · m^-3，respectively. For loam，clay loam，and sandy loam，60%，80%，and 60% of field capacity were the recommended irrigation limits to obtain high contents of soluble sugar and vitamin C，respectively.

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Plant Protection

• Degradation Behaviors and Dietary Risk Assessment of Flonicamid and Spirotetramat in Kiwifruit Plantations
• QIAO Chengkui, ZHUANG Ming, TIAN Fajun, WANG Caixia, PANG Tao, CHEN Ruxia, LI Xiaoguang, CHENG Xin, XIE Hanzhong
• Acta Horticulturae Sinica. 2024, 51(6): 1386-1402. DOI:10.16420/j.issn.0513-353x.2023-0416
• Abstract ( 223 ) HTML ( 51 ) PDF (2577KB) ( 51 ) 　　　

• A high performance liquid chromatography-triple quadrupole tandem mass spectrometry （HPLC-MS/MS）method was established for the simultaneous determination of residues of flonicamid and its three metabolites，as well as spirotetramat and its four metabolites in kiwifruits and soil. The cleanup sorbents was optimized. The samples were extracted by acetonitrile with 1% acetic acid，cleaned-up by octadecyl bonded silica gel（C18），and detected in multiple reaction monitoring（MRM）mode. The good linear relationships were obtained for the nine target compounds within the mass concentration range of 0.005-1.000 mg · L^-1，and the determination coefficients were 0.9921 to 0.9999. The matrix effects in kiwifruits and soil were 0.04-1.04，and the matrix-matched calibration curves were used for quantification. At the spiking levels of 0.005-0.500 mg · kg^-1，the average recoveries were 71%-117%，and the relative standard deviations were 0.3%-10.5%. The method was suitable for rapid detection of flonicamid and its three metabolites，as well as spirotetramat and its four metabolites residues in kiwifruits and soil. The results of the residue tests showed that the degradation dynamics of flonicamid and spirotetramat in kiwifruits and soil followed the first-order kinetic equations. Compared to individual applications，mixed applications had an impact on the half-lives of flonicamid in both kiwifruits and soil，while it had no significant effect on spirotetramat. The residual amount of the metabolites of spirotetramat，especially the metabolite S-enol，significantly increased or even exceeded that of the parent in the soil under the mixed application condition. The final residue results showed that the residues of flonicamid and its metabolite TFNG，as well as spirotetramat and its metabolites S-mono，S-keto and S-enol were detected in kiwifruit samples，and the residues ranged from 0.005 to 3.445 mg · kg^-1. However，only residues of two metabolites of spirotetramat，S-keto and S-enol，were detected in the soil，and no other compounds were detected. Correlation analysis showed that the residual amounts of flonicamid，spirotetramat and their metabolites in kiwifruits and soil were positively correlated with the dosage and frequency of application，and were negatively correlated with the harvest interval. The results of dietary risk assessment indicated that the short-term dietary intake risk of flonicamid and spirotetramat was acceptable. The residues of spirotetramat had no long-term dietary risk to the general population，while flonicamid might pose a long-term dietary risk to the general population.

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• Antagonistic Activity of Volatile Organic Compounds of Bacillus cereus Strain G3-17 Against Apple Ring Rot
• QIN Genhong, YUAN Hongbo, WANG Zhuoni, SHI Bingke, FAN Yangyang, WANG Li, ZHANG Meng, TU Hongtao, XU Chao, HOU Hui
• Acta Horticulturae Sinica. 2024, 51(6): 1403-1412. DOI:10.16420/j.issn.0513-353x.2023-0453
• Abstract ( 86 ) HTML ( 57 ) PDF (2432KB) ( 57 ) 　　　

• The purpose of this study is to analyze the antagonistic activity of volatile organic compounds（VOCs）of Bacillus cereus strain G3-17 against Botryosphaeria dothidea，and to explore the biological control methods of apple ring rot. The plate-to-plate experiment showed that the volatiles of Bacillus cereus strain G3-17 at different concentrations could significantly inhibit the growth of Botryosphaeria dothidea. Headspace solid-phase microextraction-gas chromatography-mass spectrometry analysis showed that the strain G3-17 mainly secreted six VOCs. Among them，benzaldehyde had the best inhibitory effect on Botryosphaeria dothidea，with an inhibition rate of 57.24%-100.00% in the concentration range of 125-625 μL · L^-1. Further results also showed that benzaldehyde treatment also destroyed the integrity of the cell membrane of Botryosphaeria dothidea. In addition，benzaldehyde treatment could induce the expression of apple fruit pathogenesis-related protein genes（MdPR1 and MdPR5）. Benzaldehyde treatment also could effectively control apple ring rot caused by Botryosphaeria dothidea，and the control effects were 39.80%，84.77% and 90.67% at the concentrations of 125，250 and 500 μL · L^-1，respectively. In summary，the volatiles of Bacillus cereus strain G3-17 and its main VOCs have good control potential against apple ring rot.

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• Genome Analysis of Bacillus velezensis XDY66，an Antagonist of Tomato Botrytis cinerea
• ZHANG Wenjing, XU Dayong, WU Qianlin, YANG Fo, XIN Bingyue, ZENG Xin, LI Feng
• Acta Horticulturae Sinica. 2024, 51(6): 1413-1425. DOI:10.16420/j.issn.0513-353x.2023-0597
• Abstract ( 97 ) HTML ( 86 ) PDF (5103KB) ( 86 ) 　　　

• Bacillus velezensis XDY66 was isolated and screened from rhizosphere soil from tomato，which showed strong inhibition to Botrytis cinerea. The antagonistic activity of Bacillus velezensis XDY66 against Botrytis cinerea was evaluated in vitro and in vivo. The results showed that the total length of Bacillus velezensis XDY66 genome is 3.964 552 Mb，which contained a circular chromosome（3.956 418 Mb，GC content 46.53%，NCBI accession number CP130608）and a plasmid（8 134 bp，GC content was 40.31%，NCBI accession number CP130609）. Comparative genomic analysis showed that Bacillus velezensis XDY66 contained 176 unique genes. In addition，Bacillus velezensis XDY66 was closely related to Bacillus velezensis SQR9，next is Bacillus velezensis FZB42. AntiSMASH analysis showed that the Bacillus velezensis XDY66 genome contained 13 gene clusters for secondary metabolites synthesis，including lipopeptides（surfactin，fengycin），siderophore（bacillibactin），polyketides（bacillaene，macrolactin，difficidin），and dipeptide compound（bacilysin）etc. These results showed that Bacillus velezensis XDY66 could be potentially applied in bio-controlling of crop pathogenic fungi，such as tomato Botrytis cinerea.

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New Technology and New Method

• Establishment of Tissue Culture and Virus Eliminating Technology for Shallot
• ZHANG Chunyu, WANG Chen, LIU Jianqing, ZHAN Xiaolei, LI Xiaoyu, WANG Yongzhi
• Acta Horticulturae Sinica. 2024, 51(6): 1426-1434. DOI:10.16420/j.issn.0513-353x.2023-0351
• Abstract ( 88 ) HTML ( 62 ) PDF (2067KB) ( 62 ) 　　　

• The bulb tip of shallot was used as explants to obtain tissue culture seedlings by direct induced clustered shoots and callus-induced differentiation. The disinfection treatment，plant growth regulator ratio of medium and the size of bulb tip were optimized，and the virus-free effect of shallot latent virus（SLV）and onion yellow dwarf virus（OYDV） in tissue culture seedlings was tested by ELISA. The results showed that the bulb tip explants were soaked in 75% ethanol for 30 s and 2% sodium hypochlorite solution for 15 min. The pollution rate was 6.7% and the survival rate was 93.3%. The optimal bulb tip induction medium was MS + 0.5 mg · L^-1 NAA + 1.0 mg · L^-1 6-BA，with the bud induction rate of 85.6% and the average number of differentiated buds was 3.3. The optimal callus medium was MS + 0.4 mg · L^-1 NAA + 0.5 mg · L^-1 2,4-D and the callus rate was 71.7%. The optimal bud-forming medium was MS + 0.4 mg · L^-1 NAA + 1.0 mg · L^-1 6-BA，with the bud-forming rate was 82.2% and the average number of seedlings was 9.23. The rooting requirement could be satisfied in 1/2MS medium without plant growth regulator ratio，and the rooting rate could reach 100%. The shallot virus-free seedlings were obtained by stripping the bulb tips of 0.3-0.4 mm，with the virus-free rate of 92%. The survival rate of tissue culture seedlings was 90% after transplanting.

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New Cultivarse

• A New Tomato Hybrid Cultivar‘Yuanhong 212’
• WANG Yongzhen, ZHANG Jianguo, LIU Caihong, LI Sibei, LÜ Tiantian
• Acta Horticulturae Sinica. 2024, 51(6): 1435-1436. DOI:10.16420/j.issn.0513-353x.2021-0931
• Abstract ( 112 ) HTML ( 121 ) PDF (1100KB) ( 121 ) 　　　

• ‘Yuanhong 212’is a new tomato hybrid which was developed by crossing‘B69-29’as a female parent with‘S70-42’as a male parent. It is middle ripening and indeterminate growth type with strong growing vigor，dark green leaves，middle leaf volume，7th to 8th segments with first inflorescence，mainly single cluster inflorescence，medium internode. Its fruit in mature is oblate，bright red，shape index is 077 and small navel，single fruit weight ranges from 165 to 270 g，high hardness，long storability，soluble solids content of 5.1%. Its marketable yield is more than 97 500 kg · hm^-2. It is resistant to ToMV，CMV，leafmol and some other diseases. It can be well cultivated in greenhouse in Beijing，Shanghai，Liaoning，Shandong，Shanxi，Inner Mongolia，Henan，Hunan，Sichuan，Guangdong，etc.

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New Cultivars

• A New Cerasus campanulata Cultivar‘Tianshi’
• ZENG Jin, RAO Xianlong, HU Xiaomin, YE Xiaoling, ZHU Jun, GAO Shan, YANG Zibin, QIU Xiaoping
• Acta Horticulturae Sinica. 2024, 51(6): 1437-1438. DOI:10.16420/j.issn.0513-353x.2021-0748
• Abstract ( 85 ) HTML ( 82 ) PDF (1158KB) ( 82 ) 　　　

• Cerasus campanulata‘Tianshi’is a new cultivar selected from the seedlings of C. campanulata. The flowers are dense and open in a flat disc shape，with large diameter and 5 purplish red ovate petals. The sepals are reflexed and glabrous. The stigma comes out before the flower blooms. The flowering period is in February.

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