枣糖酸代谢及其驯化的分子机制研究

发布时间：2018-07-07 08:58

本文选题：枣 + 糖　；参考：《西北农林科技大学》2016年博士论文

【摘要】：枣(Ziziphus jujuba Mill.)是鼠李科最重要的经济树种,其果实营养丰富,含糖量高,素有“木本粮食”之称。果实糖酸含量影响品质及商品价值。本研究通过测定糖、酸和抗坏血酸等生理指标,结合基因组数据,利用转录组测序和荧光实时定量PCR分析,从分子水平上阐明了枣和酸枣糖、酸、抗坏血酸形成与积累的遗传与生理本质,深化了对枣和酸枣糖酸积累差异的理解。同时,利用全基因组重测序技术研究了酸枣到枣的糖酸驯化,明确糖酸驯化关键基因。本研究为枣果实品质形成和新品种选育提供分子理论基础。主要研究结论如下:1.蔗糖是枣果实糖积累的最主要形式,积累时期始于白熟期。研究鉴定了5个枣蔗糖合成关键基因(ZjSPS1、ZjSPS2、ZjSS1、ZjSS2和ZjSS3)。糖代谢关键基因中,转化酶类基因(vINV、nINV和cINV)在枣果实的低表达是其蔗糖含量高于果糖和葡萄糖含量的重要原因;而转化酶基因及己糖基因(HK3和HK6)在酸枣的高表达降低了其糖分积累。本研究鉴定了枣果实发育过程中糖分积累的关键基因,揭示了果实糖分以蔗糖为主的重要原因,为果实糖分积累期的管理及提高含糖量提供生产指导。2.本研究共鉴定得到83个糖转运蛋白基因,其中两个参与山梨醇的运输。ZjSWEET2和ZjSWEET15在花和果实中特异表达。基因的表达模式揭示ZjSUC2和ZjSWEE2促进了果实的蔗糖积累;单糖转运蛋白ZjSTP12,ZjSTP16,ZjpGlcT3,SWEET15,ZjSWEET20和ZjTMT2基因也对果实糖分积累起到重要作用。与其直系同源基因(葡萄和番茄)相比,ZjSTP12,ZjSTP16,ZjSUC2和ZjSWEET2特异在枣果实中高表达,这可能是枣果实含糖量高于其他果实的重要原因。另外,糖转运蛋白基因在果实发育不同阶段的叶片表达水平也具有差异性。本研究深化了糖转运蛋白生物学功能的理解,明确了枣果实糖转运机理,为红枣优质栽培和新品种选育提供了理论基础。3.枣果实的有机酸类型主要为苹果酸,酸枣的为苹果酸和柠檬酸;本研究鉴定的9个枣和酸枣表达显著差异的酸代谢关键基因是酸枣果实含酸量高于枣的重要原因。此外,ZjCS3促进了枣和酸枣柠檬酸的积累,果实中特异表达的苹果酸合酶ZjMS及苹果酸脱氢酶ZjMDH12促进枣和酸枣的苹果酸合成,ZjMT3和ZjMT11促进了苹果酸的运输。本研究揭示了野生型酸枣味道极酸的重要原因,探究了导致有机酸积累的关键基因,为定向选育过程中淘汰酸性口味的种质提供分子基础。4.基于32个样品的全基因组重测序,找到了4个酸代谢关键基因、13个糖转运蛋白及3个糖代谢相关基因。驯化关键基因的选择,揭示了枣在栽培化过程中,糖代谢基因尤其是糖转运蛋白的受选择,对枣果实高含糖量的积累具有重要作用;酸代谢基因的选择效应对驯化过程中酸积累的抑制具有重要贡献。酸枣到枣糖酸驯化机制的解析,对于优化种质、提升含糖量及利用酸枣多样性选育新品种提供了分子依据,为其他果树的风味驯化研究提供理论模型。5.枣抗坏血酸(AsA)主要在果实发育早期合成,成熟期已趋于稳定,且果实的含量远高于其他组织。研究深化了枣果实中的两条AsA合成途径—半乳糖途径和肌醇途径:在果实发育早期半乳糖途径对AsA的合成起决定作用,并且GMP1、GME1、GGP、GPP和GaLDH是合成AsA的关键基因;肌醇通路及半乳糖通路中的GMP2和GME2基因在枣果实成熟期AsA含量的维持起重要作用。AsA再循环通路中,MDHAR和DHAR对维持枣AsA含量起协同作用。本研究阐明了枣果实AsA合成关键基因和关键通路。AsA代谢机制的研究对提高果实抗坏血酸含量、改善果实品质具有重要指导意义。
[Abstract]:Ziziphus jujuba Mill. is the most important economic tree of rhamnarifamily. Its fruit is rich in nutrition and high in sugar content. It is known as "woody grain". The content of fruit sugar and acid affects the quality and commodity value. In this study, the physiological indexes such as sugar, acid and ascorbic acid were measured, combined with genomic data, the transcriptional sequence and fluorescence real-time quantitative P were used. CR analysis, from the molecular level, clarified the genetic and physiological nature of jujube and jujube sugar, acid, ascorbic acid formation and accumulation, and deepened understanding of the accumulation difference between jujube and Zizyphus jujube. At the same time, the whole genome re sequencing technology was used to study the acclimatization of sour jujube to jujube and the key genes of acclimation of sugar and acid. This study was the quality of jujube fruit. The main conclusions are as follows: 1. sucrose is the main form of sugar accumulation in jujube fruit, and the accumulation period begins in the white ripening period. 5 key genes of sucrose synthesis (ZjSPS1, ZjSPS2, ZjSS1, ZjSS2 and ZjSS3) are identified. In sugar metabolism key genes, the invertase genes (vINV, nINV and cINV) are in jujube fruit. The actual low expression is the important reason for the sugar content higher than the fructose and glucose content, and the high expression of the invertase gene and hexose gene (HK3 and HK6) in the sour jujube decreased the sugar accumulation. This study identified the key genes of sugar accumulation during the development of jujube fruit, and revealed the important reason for the fruit sugar to be mainly sucrose. The management of solid sugar accumulation period and the improvement of sugar content provided production guidance.2., 83 sugar transporter genes were identified. Two of them were specifically expressed in the flower and fruit of.ZjSWEET2 and ZjSWEET15. The gene expression pattern revealed that ZjSUC2 and ZjSWEE2 promoted the accumulation of sucrose in fruit; monosaccharide transporter Zj STP12, ZjSTP16, ZjpGlcT3, SWEET15, ZjSWEET20 and ZjTMT2 genes also play an important role in the accumulation of fruit sugar. Compared to their direct homologous genes (grapes and tomatoes), ZjSTP12, ZjSTP16, ZjSUC2 and ZjSWEET2 are highly expressed in jujube fruit, which may be an important reason for the sugar content of jujube fruit higher than that of other fruits. This study deepened the understanding of the biological function of sugar transporter and clarified the mechanism of sugar transport in jujube fruit, and provided a theoretical basis for high quality and new varieties of jujube fruit. The organic acid type of jujube fruit, malic acid and lime, was the main organic acid type of jujube fruit,.3. and lime. Citric acid; the important acid metabolism key gene of the 9 jujube and Zizyphus jujube expressed in this study was the important reason for the acid content of jujube fruit higher than that of jujube. In addition, ZjCS3 promoted the accumulation of citric acid in jujube and Zizyphus jujube, and the specific expression of malic acid synthase ZjMS and malate dehydrogenase ZjMDH12 in fruit to promote the synthesis of malic acid in jujube and Zizyphus jujube, ZjMT3 And ZjMT11 promoted the transport of malic acid. This study revealed the important cause of the wild sour jujube flavor acid, and explored the key genes that lead to the accumulation of organic acids, providing a molecular basis for the elimination of acid flavors in the directional selection process,.4. based on the whole genome re sequencing based on 32 samples, and found 4 key genes for acid metabolism, 13 The selection of key genes, sugar transporter and 3 glycometabolism related genes, reveals that the selection of sugar metabolism genes, especially sugar transporters, plays an important role in the accumulation of high sugar content in jujube fruit, and the selection effect of acid metabolism gene has an important contribution to the inhibition of acid accumulation during the domestication process. The analysis of the acclimatization mechanism of jujube to jujube acid has provided a molecular basis for optimizing the germplasm, raising the sugar content and using the variety of Zizyphus jujuba, and providing a theoretical model for the study of the flavor domestication of other fruit trees,.5. ascorbic acid (AsA), which is mainly synthesized at the early stage of fruit development, and is stable at maturity, and the content of fruit is much higher than that of its fruit. The study deepened two AsA synthesis pathways in jujube fruit - galactose pathway and inositol pathway: in the early stage of fruit development, galactose pathway plays a decisive role in the synthesis of AsA, and GMP1, GME1, GGP, GPP and GaLDH are the key genes for AsA, and the GMP2 and GME2 genes in the inositol pathway and galactose pathway are AsA in date fruit maturity. The maintenance of content plays an important role in the.AsA recirculation pathway. MDHAR and DHAR play a synergistic role in maintaining the AsA content of jujube. This study illustrates that the key genes of AsA synthesis and the mechanism of.AsA metabolism in the key pathway of jujube fruit are of great importance to improve the content of ascorbic acid and improve the quality of fruit.
【学位授予单位】：西北农林科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S665.1

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