Flavonols and phenolic acids are key determinants of loquat nutritional quality, yet their inheritance remains unclear. In this study, high-performance liquid chromatography-photodiode array detector (HPLC-PDA) profiling of mature fruits from 95 F1 individuals derived from 'Tangkebaisha' & times; 'Algerie' identified seven flavonol glycosides and two phenolic acids. Among these, quercetin 3-O-galactoside (Q3Gal) and kaempferol 3-O-rhamnoside (K3Rha) were the most abundant flavonols, whereas neochlorogenic acid (5-CQA) dominated the phenolic acid fraction in both peel and flesh. All the traits exhibited wide transgressive segregation (coefficient of variation (CV), 39.86%-81.48%). Notably, K3Rha, kaempferol 3-O-glucoside (K3Glc), quercetin 3-O-rutinoside, and chlorogenic acid in fruit pulp showed high transmission ability (>110%) and significantly better-parent heterosis (8.86%-88.56%), indicating strong potential for phenolic enrichment. Within the F1 population, line J-TAL-029 accumulated 746.79 mu g/g fresh weight (FW) of total flavonols, and J-TAL-087 reached 3100.76 mu g/g FW of total phenolic acids, both substantially exceeding parental levels. Significant positive correlations were observed among flavonol glycosides sharing the same aglycone (e.g. K3Rha vs. K3Glc), indicating the feasibility of indirect selection for superior individuals. These findings elucidate the genetic basis of key phenolic compounds in loquat and provide a foundation for biofortification through breeding.

[Objective]Loquat(Eriobotrya japonica),a significant economic fruit tree in southern China,is highly susceptible to sunburn injury during its ripening stage,which typically coincides with periods of high temperature and intense light.Sunburn manifests as fruit peel browning,tissue necrosis,and flavor deterioration,severely undermining both the marketability and economic value of the fruit.WRKY transcription factors,as plant-specific regulators of stress responses,play pivotal roles in abiotic stresses such as high temperature and drought.This study aims to analyze the function and regulatory mechanism of EjWRKY15 under sunburn stress,providing a theoretical foundation and candidate gene resources for elucidating the sunburn response pathways in loquat and developing sunburn-resistant germplasms.[Method]Centering on the transcription factor EjWRKY15,its interacting proteins were screened and validated to systematically characterize its expression profiles and molecular interaction networks under sunburn stress.A sunburn-induced yeast two-hybrid(Y2H)cDNA library of loquat fruit was constructed using SMART technology.The library capacity,titer,and recombination rate were evaluated through plating selection and sequence analysis.Using EjWRKY15 as the bait protein,potential interactors were screened from the library via the Y2H system.Functional annotation of the screened proteins was performed using NCBI,Swiss-Prot,and other databases,focusing on factors related to heat and stress responses.The physical interaction between EjWRKY15 and the candidate protein EjLHP1.2(Like Heterochromatin Protein 1)was validated both in vitro and in vivo through one-on-one Y2H assays and bimolecular fluorescence complementation(BiFC).Based on transcriptome data and correlation analysis,a molecular interaction network for loquat sunburn response was constructed with EjWRKY15 as the core node.[Result]A high-quality cDNA library of loquat fruit with a large capacity and high recombination rate was successfully constructed.After excluding background interference via bait self-activation assays,12 candidate proteins interacting with EjWRKY15 were obtained,with functions involving epigenetic regulation,stress signaling,and substance metabolism.Notably,EjLHP1.2,which is closely associated with sunburn response,was identified as a key interactor.One-on-one Y2H and BiFC assays confirmed that EjWRKY15 and EjLHP1.2 interact physically both in vivo and in vitro.Expression analysis revealed that EjWRKY15 and its 12 candidate interactor genes exhibited significant differential expression patterns under sunburn stress.Based on the interaction data and expression correlations,an EjWRKY15-mediated sunburn response network was preliminarily established.The network suggests that EjWRKY15 may precisely regulate downstream heat-responsive genes by recruiting EjLHP1.2 and other factors.[Conclusion]This study identified the interacting proteins of EjWRKY15 and revealed its expression patterns and molecular interaction network in the sunburn response of loquat.The results elucidate the molecular mechanism by which the core transcription factor EjWRKY15 mediates the sunburn response of loquat fruit through its protein interaction with the epigenetic regulator EjLHP1.2 and the precise modulation of the associated interaction network.These findings reveal a novel stress-regulatory pathway involving the synergetic mode of transcription factor-chromatin remodeling protein in loquat under high temperature and strong light,providing critical theoretical support and gene resources for the molecular breeding of sunburn-resistant loquat varieties.

Manshanhong is a new high-quality loquat cultivar with medium maturing and yellow flesh, obtained from a cross between the female parent Ninghaibai and the male parent Jiefangzhong. Hybridization was carried out in December 2011, hybrid fruits were harvested in late May 2012, and seeds were collected and germinated in nutrient pots. In spring 2013,450 hybrid seedlings were transplanted to the same base for field evaluation. The offspring of the hybrid began to blossom in 2016 and initiated fruiting in 2017. After 3 years of continuous analysis and evaluation, a superior genotype(temporarily numbered A207)was finally selected from the 450 hybrids, exhibiting delayed flowering, strong stress resistance, uniform fruit appearance, high fruit-setting rate, and superior fruit quality. From 2017 to 2019, three consecutive years of phenotypic evaluations confirmed the stability of its botanical and agronomic traits. It was provisionally named Zhehong 1, and in 2020, it was granted national plant variety rights under the official denomination Manshanhong. To validate its adaptability and commercial potential,200 grafted seedlings were propagated in 2018 and introduced to demonstration orchards, including Yuhang District and Lanxi City, through a technology transfer agreement. These trial plantings began fruiting in 2022, with consistent trait performance observed over three consecutive years, confirming its stability across diverse environments. Manshanhong is a vigorous, semi-spherical, open-canopy tree with a distinct central leader. The trunk exhibits a grayish-white hue, sparse lenticels, and moderate pubescence. Mature one-year-old branches are brown, with an average length of 57.0 cm and a diameter of 1.4 cm for central branches, while lateral branches measure 44.5 cm in length and 1.3 cm in diameter. The tree produces five lateral branches per central branch on average, with medium branching capacity. Leaves on one-year-old spring shoots are dark green, thick, and rigid, with an elliptic in shape(32.9 cm × 12.1 cm, and length-to-width ratio 2.7). The leaf is slightly wrinkled, with a tapered apex, cuneate base, and flat margins. Leaf thickness averages 0.43 mm, with a concave cross-sectional profile. The adaxial surface is light green and pubescent, while the abaxial surface is gray-yellow with moderate pubescence and prominent reticulate venation. Leaf margins bear shallow, medium-density serrations covering half of the edge, with 16-18 pairs of lateral veins. Petioles are short(1.1 cm)and thick (5.5 mm), with deciduous stipules averaging 13.5 mm in length. Manshanhong flowers in late autumn to winter, with a delayed phenology: initial flowering occurs in early December, full bloom from late December to early January, and terminal flowering in late January to early February. Inflorescences are conical, averaging 9.5 cm in length and 10.5 cm in width, with eight horizontally spreading rachises per cluster. Each inflorescence bears approximately 106 flowers, characterized by yellow-white petals (26.6 mm in diameter), five pistils, and 22-24 stamens per flower. Fruits ripen around May 25 in Haining City, Zhejiang province, and a near-spherical shape with closed calyx cavities. Post-thinning fruits average 48.9 g in weight. The peel is orange-yellow, resilient, and easy to separate from the flesh. The orange-yellow pulp has medium firmness, tender texture, high juiciness, and excellent melts in the mouth. Biochemical analysis reveals soluble solids content(SSC)of 14.9%, titratable acidity(TA)content of 0.31%, and an edible rate of 75.8%. Each fruit contains 5.8 seeds on average. This variety exhibits strong resistance to fruit cracking and sunscald, coupled with excellent fruit quality. Under openfield cultivation, the average yield reaches 979.9 kg per 666.7 m2for six-year-old trees. Manshanhong represents a significant advancement in yellow-fleshed loquat breeding, combined with delayed phenology, robust adaptability, and superior fruit traits, marking it apromising leading cultivar for commercial loquat production.

Flavonol glycosides are secondary metabolites important for plant development and stress defense such as UV-B irradiation. UDP-glycosyltransferase (UGT) catalyzes the last step in the biosynthesis of flavonol glycosides. Eriobotrya japonica is abundant in flavonol glycosides, but UGTs responsible for accumulation of flavonol glycosides remain unknown. Here, 13 flavonol glycosides including monoglycosides and diglycosides were characterized in different tissues of loquat by LC-MS/MS. UV-B irradiation significantly increased the accumulation of four quercetin glycosides and two kaempferol glycosides in loquat fruit. Based on UGT gene family analysis, transcriptome analysis, enzyme assays of recombinant proteins as well as transient overexpression assays in Nicotiana benthamiana, three UGTs were identified, i.e. EjUGT78T4 as flavonol 3-O-galactosyltransferase, EjUGT78S3 as flavonol 3-O-glucosyltransferase, and EjUGT91AK7 as flavonol 1 -> 6 rhamnosyltransferase. This work elucidates the formation of flavonol glycosides in loquat through UGT-mediated glycosylation.

Loquat leaves, flowers, and other organs contain abundant antioxidant substances, which have wide applications in medicine, health, and food industries. This study aims to provide theoretical guidance for loquat hybrid parent and combination selection and a basis for high-quality loquat strain screening and development. For comprehensive antioxidant profiling, we used “Ninghaibai” and “Oobusa” loquat and their F1 generation as experimental materials to determine the total phenol, flavonoid, DPPH, ABTS, and FRAP content in the leaves and flowers of 56 strains. Five traits, including total phenols, flavonoids, DPPH, ABTS, and FRAP, were widely separated and normally distributed in the flowers of 56 F1 loquat strains, exhibiting the genetic basis of these quantitative traits. However, these traits displayed widely separated and slightly skewed distribution in the leaves of the F1 generation. The total phenols, flavonoids, DPPH, and FRAP showed a trend of small inheritance in the leaves. However, the ABTS showed a trend of medium and high inheritance in leaves and flowers, respectively. Through cluster and principal component analyses, a comprehensive antioxidant activity evaluation was conducted. Ten strains with comprehensive scores greater than 1 for antioxidant activity in leaves and flowers were selected. Among them, the top three strains with high antioxidant capacity were ND107, “Oobusa”, and ND128. These results suggest that hybrid breeding guided by the genetic characteristics of each trait can improve the possibility of cultivating new varieties with high antioxidant activity.

Loquat (Eriobotrya japonica) is rich in flavonols with health-promoting functions. However, regulatory mechanisms of flavonol biosynthesis in loquat are unclear. This study functionally characterized an R2R3-MYB, EjMYBF1 from loquat. Expression level of EjMYBF1 is positively correlated with flavonol content at different stages of fruit development and in ten accessions with differential flavonol accumulation. Dual-luciferase assays and EMSA indicated that EjMYBF1 transactivated the promoters of structural genes involved in flavonol biosynthesis by binding to promoter regions containing MYBCORE elements. Transient overexpression and virus-induced gene silencing assays of EjMYBF1 in loquat fruit peels and leaves, as well as heterologous constitutive expression of EjMYBF1 in Nicotiana tabacum confirmed that EjMYBF1 is a positive regulator of flavonol biosynthesis in loquat. These results demonstrate that EjMYBF1 is a functional flavonol-specific activator in loquat and explain one reason for its high flavonol content from the perspective of transcriptional regulation. This work provides a potential target for improving loquat nutrition and for applications in secondary metabolic engineering.

A novel ionic liquid/inorganic salt system, [C14mim][PF6]/Na2CO3, was developed for the simultaneous extraction and purification of polysaccharides from medicinal loquat leaves in a single-step procedure. The system forms a homogeneous phase upon heating in water for the polysaccharide extraction and transitions to a solid-liquid two-phase system upon cooling centrifugation for the polysaccharide separation, enabling polysaccharides to partition into the supernatant while proteins and other impurities gather in the sediment. This innovative approach demonstrated superior deproteinization efficiency, achieving a protein removal rate exceeding 99%, significantly outperforming the traditional Sevag method. Crude polysaccharides were further separated into alkali-extracted and water-soluble fractions, followed by purification using DEAE cellulose and Sephadex G-100 chromatography, yielding two homologous polysaccharides, EJp1-1 and EJp2-1. Based on the complementary information, mainly the NMR data, of these two homologous polysaccharides, a new strategy for rapid structure analysis was established. Both EJp1-1 and EJp2-1 were rhamnogalacturonan-I (RG-I) type pectins. EJp1-1 was primarily composed of the RG-I backbone, while EJp2-1 was dominated by the side chains. The side chains of EJp1-1 and EJp2-1 consisted primarily of alpha-1,5-linked arabinan and beta-1,4-linked galactan, which were alternately attached to the O-4-position of rhamnose residues of the repeat RG unit of the main chain. To sum up, this work integrates the efficient extraction, purification and rapid structure analysis of homologous polysaccharides, potentially promoting the sustainable utilization of plant-derived resources.

Loquat (Eriobotrya japonica) is an important subtropical evergreen fruit tree of the Rosaceae family that possesses significant edible and economic value. The NAC transcription factor family, as plant-specific regulatory factors, not only participated in plant growth and development but also played crucial roles in fruit quality formation. Through genome-wide analysis, this study identified 117 NAC family members in loquat, which were phylogenetically classified into 14 distinct subfamilies. Chromosomal localization revealed that 114 genes were unevenly distributed across 17 chromosomes, while the remaining 3 were located in genomic scaffold regions. Collinearity analysis indicated that loquat NAC genes primarily underwent purifying selection and showed high homology with NAC genes from other Rosaceae species. Cis-acting element prediction analysis suggested these genes were extensively involved in various biological processes, including abiotic stress responses, hormone signal transduction, and growth regulation. Expression pattern analysis based on transcriptome data further uncovered differential expression characteristics of NAC genes across different loquat cultivars and fruit developmental stages. Notably, correlation analysis identified several NAC candidate genes that were significantly associated with fruit sugar-acid content. This study provided the first comprehensive and systematic characterization of the NAC gene family in loquat, establishing an important foundation for elucidating the molecular mechanisms by which NAC transcription factors regulate loquat fruit flavor quality.

Loquat (Eriobotrya japonica) is a subtropical evergreen fruit tree with high economic benefits and nutritional value. AP2/ERF (APETALA2/ethylene responsive factor) are a wide range of transcription factors found in plants, which play an important role in regulating plant development and biological processes. However, the systematic identification and characterization of AP2/ERF genes in loquat remains unclear. In the present research, a total of 189 loquat AP2/ERF members were identified. According to the phylogenetic tree, these members were divided into three subfamilies, including AP2 (42), ERF (96), and DREB (51). Except for three genes located on the skeleton, most of the loquat AP2/ERF genes were unevenly distributed across all chromosomes. The collinearity results showed that 175 duplicate gene pairs were found in the AP2/ERF gene family of loquat. Ka/Ks results indicated that these genes underwent purification selection pressure. The syntenic analysis of AP2/ERF genes between Arabidopsis, pomegranate, peach, and loquat provided valuable clues for the potential evolution of AP2/ERF family in loquat. Cis-element analysis showed that most of the AP2/ERF genes in loquat had multiple cis-elements related to stress response, plant hormone signal transduction, and plant growth and development. Transcriptomic data indicated that the expression patterns of AP2/ERF genes exhibited diversity in different loquat cultivars during fruit development and ripening. The results of this study displayed the first comprehensive analysis of AP2/ERF genes in loquat, which provides a solid foundation for future research on the function of AP2/ERF genes in loquat.

The effect of artificial lighting with different light spectra and photoperiods/daily light integrals (DLIs) on the yield, bioactive compounds and antioxidant capacity of the common ice plant (Mesembryanthemum crystallinum) was studied. Four-week-old seedlings were selected and subjected to four different light spectra made up of different combinations of blue (400–500 nm), green (500–600 nm) and red light (600–700 nm), with a total photosynthetic photon flux density (PPFD) of 180 µmol.m−2.s−1. Concurrently, the effect of the daily light integral (DLI) was also studied, with the light treatment photoperiod set at 18 h and 21 h. Biometric parameters such as fresh mass weight, leaf area, leaf width, and dry mass, together with plant metabolite contents such as total antioxidant capacity (TAC), vitamin C, chlorophyll a and b content, and total carotenoids and nitrates, were investigated. It was found that the plants grew better when exposed to light with a higher proportion of the red and blue spectrum, with the highest fresh mass of 68 g observed at a photoperiod of 18 h. On the other hand, green spectrum light was not found to yield any significant improvement in shoot weight, leaf area, or leaf size. It was also found that dry mass, chlorophyll b and nitrates were not influenced by the light spectrum but were influenced by the photoperiod duration. While both the dry mass and nitrate content increase as the photoperiod increases, a longer photoperiod had a negative effect on chlorophyll a, chlorophyll b and total carotenoids, with their content decreasing by as much 29% for chlorophyll a, 59% for chlorophyll b and 29% for total carotenoids. TAC content was seen to increase by more than 24% under the influence of 66% more green light, and 38% more under the 21 h photoperiod.

为了解枇杷(Eriobotrya japonica)叶片性状和单果质量的遗传多样性及其相关性,对'宁海白'与'大房'杂交组合的F1群体(123株)的7个叶片性状与单果质量进行相关分析.结果表明,叶片的长度、宽度、厚度和叶柄长度及单果质量5个性状在后代中均呈现连续性较好的正态分布,其中单果质量、叶片的长度、宽度和厚度呈趋小遗传趋势,叶柄长度呈趋中变异趋势.F1杂交群体叶面形态主要以"稍皱"为主,叶片形状以"椭圆形"为主,叶基形状以"楔形"为主.单果质量与叶柄长度、叶片长度、叶片宽度、叶片厚度均表现出极显著的正相关性.因此,叶柄长度可考虑作为早期筛选大果优株的参考指标之一.

Introduction:Lignification of fruit flesh is a common physiological disorder that occurs during post-harvest storage, resulting in the deterioration of fruit quality. Lignin deposition in loquat fruit flesh occurs due to chilling injury or senescence, at temperatures around 0°C or 20°C, respectively. Despite extensive research on the molecular mechanisms underlying chilling-induced lignification, the key genes responsible for the lignification process during senescence in loquat fruit remain unknown. MADS-box genes, an evolutionarily conserved transcription factor family, have been suggested to play a role in regulating senescence. However, it is still unclear whether MADS-box genes can regulate the lignin deposition that arises from fruit senescence.Methods:Both senescence- and chilling-induced flesh lignification were simulated by applying temperature treatments on loquat fruits. The flesh lignin content during the storage was measured. Transcriptomic, quantitative reverse transcription PCR and correlation analysis were employed to identify key MADS-box genes that may be involved in flesh lignification. The Dual-luciferase assay was utilized to identify the potential interactions between MADS-box members and genes in phenylpropanoid pathway.Results and Discussion:The lignin content of the flesh samples treated at 20°C or 0°C increased during storage, but at different rates. Results from transcriptome analysis, quantitative reverse transcription PCR, and correlation analysis led us to identify a senescence-specific MADS-box gene, EjAGL15, which correlated positively with the variation in lignin content of loquat fruit. Luciferase assay results confirmed that EjAGL15 activated multiple lignin biosynthesis-related genes. Our findings suggest that EjAGL15 functions as a positive regulator of senescence-induced flesh lignification in loquat fruit.

Sorbitol is an important signaling molecule in fruit trees. Here, we observed that sorbitol increased during flower bud differentiation (FBD) in loquat (Eriobotrya japonica Lindl.). Transcriptomic analysis suggested that bud formation was associated with the expression of the MADS-box transcription factor (TF) family gene, EjCAL. RNA fluorescence in situ hybridization showed that EjCAL was enriched in flower primordia but hardly detected in the shoot apical meristem. Heterologous expression of EjCAL in Nicotiana benthamiana plants resulted in early FBD. Yeast-one-hybrid analysis identified the ERF12 TF as a binding partner of the EjCAL promoter. Chromatin immunoprecipitation-PCR confirmed that EjERF12 binds to the EjCAL promoter, and β-glucuronidase activity assays indicated that EjERF12 regulates EjCAL expression. Spraying loquat trees with sorbitol promoted flower bud formation and was associated with increased expression of EjERF12 and EjCAL. Furthermore, we identified EjUF3GaT1 as a target gene of EjCAL and its expression was activated by EjCAL. Function characterization via overexpression and RNAi reveals that EjUF3GaT1 is a biosynthetic gene of flavonoid hyperoside. The concentration of the flavonoid hyperoside mirrored that of sorbitol during FBD and exogenous hyperoside treatment also promoted loquat bud formation. We identified a mechanism whereby EjCAL might regulate hyperoside biosynthesis and confirmed the involvement of EjCAL in flower bud formation in planta. Together, these results provide insight into bud formation in loquat and may be used in efforts to increase yield.

"迎雪"是由"宁海白" × "解放钟"杂交选育出的晚熟白肉枇杷新品种. 2022 年 5 月通过浙江省林业品种审认定委员会审定,良种编号:浙S-SV-EJ-008-2022.

Loquat is a high-value fruit tree with medicine and fruit homology. Loquat flowers with special fragrance, strong cold resistance and rich in various bioactive components, are valuable agri-cultural auxiliary products and have been widely used for making floral teas and beverages in recent years. In this study, we found the concentration of active components increased from the floral buds to initial flowers along with flower development, the bioactives of initial flowers were the richest in four flowering stages, and loquat flowers contained major volatile components such as alcohols, aldehydes and esters, which are the source of fragrance. When extract with hot water, the most efficient method was 80 degrees C for 30 min or boiling water within 2 h. For Baijiu (56% Vol), the best solid-to-liquid ratio was 3:100 (Dry flower: Baijiu) in 6-12 h. Baijiu achieved higher bioactive content than water extraction, the amygdalin concentration in Baijiu reached 0.3 mg/ mL.

Fruit weight is an integral part of fruit quality and directly influences the commodity value and economic return of fruit crops. Despite the importance of fruit weight, its underlying molecular mechanisms remain understudied, especially for perennial fruit tree crops such as cultivated loquat (Eriobotrya japonica Lindl.). Auxin is known to regulate fruit development, but its role and metabolism during the development of loquat fruit remain obscure. In this study, we used a multi-omics approach, integrating whole-genome resequencing-based quantitative trait locus (QTL) mapping with an F1 population, population genomics analysis using germplasm accessions, transcriptome analysis, and metabolic profiling to identify genomic regions potentially associated with fruit weight in loquat. We identified three major loci associated with fruit weight, supported by both QTL mapping and comparative genomic analysis between small- and large-fruited loquat cultivars. Comparison between two genotypes with contrasting fruit weight performance by transcriptomic and metabolic profiling revealed an important role for auxin in the regulation of fruit development, especially at the fruit enlargement stage. The multi-omics approach identified homologs of ETHYLENE INSENSITIVE 4 (EjEIN4) and TORNADO 1 (EjTRN1) as promising candidates for the control of fruit weight. Three single nucleotide polymorphism (SNP) markers were also closely associated with fruit weight. Results from this study provide insights into the genetic and metabolic controls of fruit weight in loquat from multiple perspectives. The candidate genomic regions, genes, and sequence variants will facilitate our understanding of the molecular basis of fruit weight and lay a foundation for future breeding and manipulation of fruit weight in loquat.

利用SLAF-seq测序技术,开发一批特异性强、稳定性高的单核苷酸多态性(SNP)位点,为枇杷遗传图谱构建、分子辅助育种和物种进化等研究提供理论依据.本研究共收集294份枇杷属资源,利用SLAF-seq测序技术进行测序.以梨基因组为参考基因组进行电子酶切预测,确定使用HaeⅢ+Hpy166Ⅱ进行酶切,构建SLAF-seq文库,而后筛选314～364 bp长度的DNA片段定义为SLAF标签,预测可得到116 171个SLAF标签.共获得526.63 Mreads数据,各样品所获得的读长数目在119893～9305 152范围内,平均读长为1 787581;测序质量值Q30的范围在88.26％～95.67％,平均为93.61％;GC含量分布在38.79％～42.92％范围内,平均值为40.35％.本实验以水稻测序获得0.16 M reads的数据量为Control,双端比对效率在91.28％,说明SLAF建库基本正常.生物信息学分析结果显示本研究共获得623 356个SLAF标签,且有123 498个多态性的标签,多态性为19.81％.在多态性SLAF标签上开发得到1 604 434个群体SNP标记.根据完整度＞0.8,MAF＞0.05过滤,共得到95 960个高一致性的群体SNP.

以浙江省淳安县主栽白沙枇杷品种"软条白沙"和"宁海白"为试材,调查白沙枇杷田间皱果因素,并试验套袋、覆盖遮阳网遮阳布、树冠喷水、树盘覆盖反光膜等措施的皱果预防效果.结果表明,白沙枇杷皱果与品种、果实位置、果园土壤肥力水平、果实负载量、果实成熟度等因素有关."宁海白"果实抗皱性强于"软条白沙";树冠南面的果实比东、西、北面的果实易皱果,树体外围果实比树冠内膛果实易皱果;重施基肥的果园果实抗皱性强于肥力低的果园;叶果比大的植株果实抗皱性强于叶果比小的植株.幼果套袋、转色期覆盖遮阳网遮阳布、树冠喷水、树盘覆盖反光膜等措施对预防皱果都有效果,其中,幼果早期套袋是预防白沙枇杷皱果最为实用的方法.

研究比较了枇杷(Eriobotrya japonica Lindl.)不同发育阶段花果的低温响应机制.以花蕾、完全开放的花和花后2周左右的幼果为试验材料,-3℃低温处理12h,以未经低温处理样品为对照,测定生理生化指标并进行转录组测序分析.低温胁迫导致细胞膜破坏,超氧阴离子产生速率、丙二醛和脯氨酸含量、抗氧化酶活性明显升高.总体上抗低温能力为花蕾＞花＞幼果.转录组测序分析共获得6987个差异表达基因(DEG),对这些基因进行通路注释分析,发现大量与低温胁迫相关的代谢途径,其中碳水化合物代谢中的糖酵解/糖异生、乙醛酸和二羧酸代谢及磷酸肌醇代谢途径,氨基酸代谢中的色氨酸代谢和酪氨酸代谢途径,酯类代谢中的甘油磷脂代谢、α-亚麻酸代谢和甘油酯代谢途径,次生代谢中的异喹啉生物碱生物合成途径以及能量代谢中的硫代谢途径在3个花果发育时期低温与对照的比较组中显著富集,说明这几个途径都是枇杷花果响应低温胁迫的重要代谢途径."苯丙烷类生物合成"途径在前两个时期比较组中富集水平较高,氨基酸代谢相关途径在幼果比较组中富集更多.另外,从低温处理相关差异表达基因中筛选到了53个AP2-EREBP基因,14个WRKY基因和15个NAC基因,并对其中12个低温响应相关转录因子基因进行了qRT-PCR表达分析,进一步证实了转录组数据的准确性.

The sugar alcohol sorbitol plays an important signaling role in fruit trees. Here, we found that sorbitol significantly increased during flower bud differentiation (FBD) in loquat (Eriobotrya japonica Lindl.) from the physiological FBD stage (EjS1) to the morphological FBD stage (EjS2), and it then decreased in the panicle development stage (EjS3) compared to in EjS2, and in subsequent stages. Spraying sorbitol increased the sorbitol content and thereby promoted early FBD and increased the proportion of flower buds that completed FBD. A transcriptomics analysis showed that the expression of a MADS-box transcription factor (TF) family gene, EjCAL, was highly correlated with the FBD phenotypic data. EjCAL-overexpressing transgenic tobacco exhibited the early FBD phenotype. Using the EjCAL promoter as bait in a yeast-one hybrid (Y1H) assay, the TF ERF12 was identified. Chromatin immunoprecipitation (ChIP)-PCR confirmed that EjERF12 can bind to the EjCAL promoter, and β-glucuronidase (GUS) activity assays demonstrated that EjERF12 can regulate EjCAL expression. Spraying loquat with sorbitol confirmed that EjERF12 and EjCAL expression were regulated by sorbitol. We also identified downstream functional genes (EjUF3GaT1, EjGEF2, and EjADF1) that might be involved in FBD. Finally, we found that the change in the level of hyperoside (a reproduction-related flavonoid) was consistent with that of sorbitol during FBD in loquat, and EjCAL can bind to the EjUF3GaT1 promoter and might thereby regulate hyperoside biosynthesis. Two early- and late-flowering varieties of loquat and EjCAL-overexpressing transgenic tobacco plants were used to confirm this hypothesis. One-sentence summary Sorbitol promotes bud differentiation via EjCAL.