Table_3_Integrative Morphological, Physiological, Proteomics Analyses of Jujube Fruit Development Provide Insights Into Fruit Quality Domestication From Wild Jujube to Cultivated Jujube.XLSX

Jujube (Ziziphus jujuba) was domesticated from wild jujube (Z. jujuba var. spinosa). Here, integrative physiological, metabolomic, and comparative proteomic analyses were performed to investigate the fruit expansion and fruit taste components in a jujube cultivar ‘Junzao’ and a wild jujube ‘Qingjiansuanzao’ with contrasting fruit size and taste. We revealed that the duration of cell division and expansion largely determined the final fruit size, while the intercellular space in the mesocarp dictated the ratio of mesocarp volume in mature fruits. The high levels of endogenous gibbereline3 (GA) and zeatin in the growing fruit of ‘Junzao’ were associated with their increased fruit expansion. Compared with ‘Junzao,’ wild jujube accumulated lower sugars and higher organic acids. Furthermore, several protein co-expression modules and important member proteins correlated with fruit expansion, sugar synthesis, and ascorbic acid metabolism were identified. Among them, GA20OX involved in GA biosynthesis was identified as a key protein regulating fruit expansion, whereas sucrose-6-phosphate synthase (SPS) and neutral invertase (NINV) were considered as key enzymes promoting sugar accumulation and as major factors regulating the ratio of sucrose to hexose in jujube fruits, respectively. Moreover, the increase of Nicotinamide adenine dinucleotide-Malate dehydrogenase (NAD-MDH) activity and protein abundance were associated with the malic acid accumulation, and the high accumulation of ascorbic acid in wild jujube was correlated with the elevated abundance of GalDH, ZjAPXs, and MDHAR1, which are involved in the ascorbic acid biosynthesis and recycling pathways. Overall, these results deepened the understanding of mechanisms regulating fruit expansion and sugar/acids metabolisms in jujube fruit.

枣（Ziziphus jujuba）由酸枣（Z. jujuba var. spinosa）驯化而来。本研究以果实大小与风味特征存在显著差异的栽培枣品种‘俊枣’（‘Junzao’）及野生酸枣‘青涧酸枣’（‘Qingjiansuanzao’）为材料，通过整合生理、代谢组学（metabolomic）与比较蛋白质组学分析，探究二者的果实膨大过程及风味组分差异。研究发现，细胞分裂与伸长的持续时间在很大程度上决定了果实最终大小，而中果皮的细胞间隙则决定了成熟果实的中果皮体积占比。‘俊枣’发育中果实内高水平的内源赤霉素3（gibbereline3, GA）与玉米素（zeatin），与其果实膨大增强显著相关。相较于‘俊枣’，野生酸枣的糖分积累量更低，而有机酸含量更高。此外，本研究还鉴定出多个与果实膨大、糖分合成及抗坏血酸（ascorbic acid）代谢相关的蛋白质共表达模块及关键功能蛋白。其中，参与赤霉素生物合成的GA20氧化酶（GA20OX）被鉴定为调控果实膨大的关键蛋白；蔗糖-6-磷酸合酶（sucrose-6-phosphate synthase, SPS）与中性转化酶（neutral invertase, NINV）则分别被认定为促进糖分积累的关键酶，以及调控枣果中蔗糖与己糖比例的核心因素。此外，烟酰胺腺嘌呤二核苷酸-苹果酸脱氢酶（Nicotinamide adenine dinucleotide-Malate dehydrogenase, NAD-MDH）的活性及蛋白丰度提升与苹果酸积累密切相关；野生酸枣中较高的抗坏血酸积累，则与GalDH、ZjAPXs及MDHAR1的蛋白丰度上调相关，上述蛋白均参与抗坏血酸的生物合成与循环代谢途径。综上，本研究结果加深了对枣果果实膨大及糖酸代谢调控机制的认知。