成束状阿拉伯半乳糖蛋白（FLA）家族基因在桃果实采后贮藏期间的表达分析

发布时间：2018-06-21 20:58

本文选题：桃果实 + 冷害　；参考：《上海海洋大学》2017年硕士论文

【摘要】：桃果实因其浓郁的香味、柔软多汁的口感,以及丰富的营养深受消费者的喜爱。桃果实为典型的呼吸跃变型果实,采后在常温下迅速进入呼吸和乙烯高峰,从而加速衰老和软化,极易受到机械损伤和病原微生物侵染而导致大量腐烂。低温冷藏是抑制桃果实采后呼吸代谢进、延长货架期的有效手段。然而,桃果实又属于冷敏性果实,低温贮藏环境会导致果实冷害的发生,主要表现为出汁率下降、果肉絮败、果心褐变等不良性状。成束状阿拉伯半乳糖蛋白(FLA)作为一类与细胞壁结构相关的糖蛋白,与果实软化之间的联系及其作用还不清楚。为此,本研究以“湖景蜜露”桃果实为试材,鉴定了12个假定的FLA家族成员,并对它们进行了生物信息学分析,测定了这些成员在桃生长发育组织中的表达;分析了褪黑素处理后的桃果实细胞壁果胶中性糖的组成变化,从细胞壁代谢的层面揭示了褪黑素缓解冷害的机理;研究了外源乙烯和ABA处理对FLA成员在桃果实成熟期间的表达影响,以期为阐明果实软化的分子调控机制提供新的视角。研究结果如下:(1)成束状阿拉伯半乳糖蛋白(FLA)是阿拉伯半乳糖蛋白(AGP)大家族中的亚族,含有阿拉伯半乳糖糖基化区域和假定的成束域(FAS)。从桃基因组数据库筛选出了12个假定的FLA序列,对这12个FLA的蛋白结构进行分析,结果显示PpFLA7不具有特定的阿拉伯糖或半乳糖糖基化位点,不属于典型的FLA家族。PpFLA6的氨基酸组成和保守域的分布与其它成员相比差别较大。聚类分析结果表明PpFLAs家族可以分为CladeⅠ,CladeⅡ,CladeⅢ三类。利用荧光定量PCR(qPCR)对不同组织和成熟阶段桃果实进行表达分析,发现各个成员在不同时期的桃组织中差异化表达。其中,PpFLA4在桃果实成熟阶段显著上调表达,暗示了它可能在桃果实的成熟阶段扮演重要角色。(2)低温贮藏下的桃果实在经过褪黑素处理后质地特性发生了改变,其中包括果实硬度、内聚力和粘附力,出汁率得到了明显提升。中性糖(阿拉伯糖和半乳糖)的流失现象出现在贮藏第7天桃果实CDTA溶性和Na2CO3溶性的果胶组分中,分支程度明显下降,但在贮藏第21天这一现象得到了改善。原子力显微镜结果显示处理组桃果实果胶多糖的链宽集中在较小的区间,表明处理组中果胶的降解更为严重。FLA家族成员在褪黑素处理的桃果实贮藏后期呈现一致的上调表达,暗示它们响应了褪黑素诱导下的果实软化,可能起到保护细胞壁结构不被过快分解的作用。(3)外源乙烯和ABA处理上调了常温贮藏桃果实中PpFLA2、PpFLA4、PpFLA5、PpFLA6、PpFLA8的表达水平,表明FLA部分成员参与成熟阶段乙烯或ABA信号途径的调控网络,与果实的软化相关。其中,Pp FLA4和PpFLA6在外源乙烯和ABA处理下上调表达极为明显。结果表明,外源乙烯和ABA影响时会提升FLA家族成员的表达,调控细胞壁多糖网络的代谢,防止果实细胞在其他胞壁相关的水解酶作用下过快地溃散解体。
[Abstract]:Peach fruit is very popular because of its rich flavour, soft and juicy taste and rich nutrition. Peach fruit is a typical respiratory climacteric fruit. After harvest, it quickly enters the respiration and ethylene peak at the normal temperature, thus accelerating aging and softening. It is extremely vulnerable to mechanical damage and pathogenic microorganism infection, resulting in a large amount of decay. Cold storage is an effective means to inhibit respiration and prolong shelf life after peach fruit. However, peach fruit belongs to cold sensitive fruit, and cold storage environment will lead to the occurrence of cold damage. The main performance is the decline in juice rate, Pulp Flocculation, and browning of fruit. The bundle shaped Arabia semi lactose protein (FLA) is a kind of cells as a kind of cell. The relationship between wall structure related glycoproteins and fruit softening is not clear. In this study, 12 FLA family members were identified and bioinformatics were used to determine the expression of these members in the Peach Growth and development tissues. The changes in the composition of the neutral sugar of pectin in the peach fruit wall were revealed. The mechanism of melatonin to alleviate the cold injury was revealed from the cell wall metabolism. The effects of exogenous ethylene and ABA treatment on the expression of FLA members during peach fruit ripening were studied in order to provide a new perspective for elucidating the molecular regulation mechanism of fruit softening. The results are as follows: (1) the fascicular Arabia galactose protein (FLA) is a subfamily in the large family of Arabia's galactose protein (AGP), containing the Arabia galactoglycosylation region and the presumed bundle domain (FAS). 12 assumed FLA sequences are screened from the peach genome database, and the protein structure of the 12 FLA is analyzed. The results show that PpFLA7 is not specific. The distribution of carbohydrate or galactoglycosylation sites in Arabia, which does not belong to the typical FLA family.PpFLA6, is different from those of other members. The cluster analysis results show that the PpFLAs family can be classified into Clade I, Clade II, Clade III three. Using fluorescent quantitative PCR (qPCR) to make the peach fruit in different tissues and mature stages The expression analysis showed that each member was differential expression in peach tissues at different stages. Among them, PpFLA4 was significantly up-regulated in the ripening stage of peach fruit, suggesting that it may play an important role in the maturity stage of peach fruit. (2) the texture characteristics of peach fruit under melatonin treatment under low temperature storage were changed, including the changes in the properties of melatonin. The fruit firmness, cohesion and adhesion of fruit increased significantly. The loss of neutral sugar (Arabia sugar and galactose) appeared in the CDTA solubility and Na2CO3 soluble pectin components of peach fruit for seventh days, and the branch degree decreased obviously, but the phenomenon was improved at twenty-first days in storage. The chain width of pectin polysaccharides in the peach fruit was concentrated in the smaller interval, indicating that the degradation of pectin in the treatment group was more serious in the late storage of melatonin treated peach fruit, suggesting that they responded to melatonin induced fruit softening, which may protect the cell wall structure from excessive decomposition of the wall structure of the melatonin. (3) exogenous ethylene and ABA treatment up regulate the expression level of PpFLA2, PpFLA4, PpFLA5, PpFLA6, PpFLA8 in peach fruit at normal temperature, indicating that part of FLA members participate in the regulation network of ethylene or ABA signaling pathway in the mature stage, which is related to the softening of fruit. Among them, Pp FLA4 and PpFLA6 are highly expressed under exogenous ethylene and ABA treatment. The results show that exogenous ethylene and ABA affect the expression of FLA family members, regulate the metabolism of cell wall polysaccharide network, and prevent the fruit cells from collapsing and disintegrating over the other cell wall related hydrolases.
【学位授予单位】：上海海洋大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TS255.1

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