枣果实成熟软化的细胞壁物质代谢及其基因表达研究

发布时间：2018-07-10 20:26

本文选题：枣 + 成熟　；参考：《西北农林科技大学》2017年硕士论文

【摘要】：枣(Ziziphus jujuba Mill.)是原产于中国的传统果树,根据用途主要分为制干枣和鲜食枣两个类型,二者的成熟过程存在差异,研究其果实成熟软化过程中的质地变化、细胞壁代谢及其基因表达特性具有重要意义。本研究以鲜食枣‘冬枣’、制干枣‘木枣’和‘骏枣’为材料,测定了果实成熟和软化7个时期及采后常温条件下30d内的硬度、含水量、细胞壁物质(果胶和纤维素)含量及相关酶类(多聚半乳糖醛酸酶PG、果胶酯酶PE和纤维素酶Cx)活性;利用冬枣和骏枣基因组和转录组数据,筛选了不同成熟时期与细胞壁代谢相关的差异基因;并基于基因注释选择15个细胞壁代谢基因以实时荧光定量PCR验证其在枣果实各个发育时期的表达量。主要取得以下研究结果:(1)鲜食枣冬枣在成熟过程中,硬度和含水量无显著变化,PG、PE与果胶的降解和果实成熟相关性较强,PG和Cx酶对冬枣采后的非自然软化具有显著影响。木枣和骏枣作为制干枣,脆熟期之后具有一个自然软化的完熟过程。与冬枣相比,木枣在成熟过程中果胶(包含原果胶和可溶性果胶)和纤维素降解特性与冬枣不同,果胶和纤维素降解发生在完熟期(冬枣在脆熟期)。PG和PE对于木枣和冬枣各自成熟关键期作用显著,PE对于木枣的软化具有前导作用,Cx对木枣成熟期作用比冬枣更显著,对冬枣采后软化作用比木枣更显著。(2)筛选出与枣果实细胞壁物质和酶类代谢的差异表达基因共107个,包含果胶酶、纤维素酶和半纤维素酶类等3大类、11个基因家族,其中1个PG基因、6个PE基因、7个纤维素相关酶基因和8个半纤维素相关酶基因的表达水平与酶活性变化具有一致性。通过基因表达研究,骏枣果实细胞壁代谢物质与相关酶类及基因表达水平间具有较大相关性;PG基因为软化非关键因子,PE基因具有软化前导作用,纤维素酶各基因联合调控果实成熟软化,其中β-葡萄糖苷酶基因β-Glu40对于枣果实成熟后期的软化具有关键调控作用。本研究深化了对枣果实成熟和软化期细胞壁代谢机制的理解,揭示了鲜食枣与制干枣成熟过程的细胞壁物质及酶类生理和分子调控的不同机制,为深入探究枣果实成熟调控提供了理论基础,也为鲜食枣的成熟采收与保鲜、制干枣的成熟采收及其干制处理提供了理论依据。
[Abstract]:Ziziphus jujuba Mill. It is a traditional fruit tree native to China. According to its use, it can be divided into dry jujube and fresh jujube. There are differences in maturation process between them. The texture changes in the process of fruit ripening and softening are studied. Cell wall metabolism and its gene expression are of great significance. Using fresh jujube 'Dongzao', dried jujube 'Muzao' and 'Jun jujube' as materials, the hardness and water content of fruit in 7 periods of ripening and softening and 30 days after harvest were measured. Cell wall substances (pectin and cellulose) and the activities of related enzymes (polygalacturonase PGPE and cellulase CX); using genomic and transcriptional data of Dongzao and Junzao. Different genes related to cell wall metabolism in different maturation stages were screened, and 15 cell wall metabolic genes were selected based on gene annotation to verify their expression in jujube fruit at different stages of development by real-time fluorescent quantitative PCR. The main results were as follows: (1) there was no significant change in hardness and water content during the ripening of fresh jujube. PGPE had a strong correlation with pectin degradation and fruit ripening. PG and Cx enzymes had significant effects on the unnatural softening of winter jujube after harvest. Jujube and Jun jujube as dry jujube have a natural softening ripening process after brittleness. Compared with winter jujube, the degradation characteristics of pectin (including protopectin and soluble pectin) and cellulose were different from those of winter jujube. The degradation of pectin and cellulose occurred at the mature stage (winter jujube at brittle ripening stage) .PG and PE played a significant role in the critical maturation stage of wood jujube and winter jujube respectively. Pe had a leading effect on the softening of wood jujube and CX had more significant effect on the mature stage of wood jujube than that of winter jujube. (2) 107 differentially expressed genes including pectinase, cellulase and hemicellulase, and 11 gene families were screened out. The expression level of PG gene, 6 PE gene, 7 cellulose related enzyme gene and 8 hemicellulose related enzyme gene were consistent with the change of enzyme activity. Through the gene expression study, the metabolites of cell wall of Junzao fruit have a significant correlation with the related enzymes and gene expression level because the softening of non-key factor Pe gene has a leading role in softening, and there is a significant correlation between the metabolites and the related enzymes and gene expression level in jujube fruit. The 尾 -Glu40 gene of 尾 -glucosidase plays a key role in the softening of jujube fruit after maturation. This study deepened the understanding of cell wall metabolism mechanism of jujube fruit maturation and softening stage, and revealed the different mechanisms of cell wall substance, enzyme physiology and molecular regulation of fresh jujube and dried jujube maturation. It provides a theoretical basis for further study on the regulation of jujube fruit ripening, as well as for the mature harvesting and preservation of fresh jujube, the mature harvest of dried jujube and its dry treatment.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S665.1

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