葡萄NCED基因家族进化及表达分析

9-顺式-环氧类胡萝卜素双加氧酶(NCED)是植物体内ABA生物合成的关键限速酶, 参与植物对干旱、外源ABA和高盐的响应过程, 降低环境胁迫对植株的危害。基于全基因组鉴定分析葡萄(Vitis vinifera) NCED基因家族成员, 探讨各成员的物种进化关系及各个基因成员在不同组织中的时空表达模式及对干旱、ABA和高盐(NaCl)胁迫的响应, 为进一步揭示该基因家族成员的生物学功能奠定基础。在葡萄基因组中共发现12个NCED基因。其推测的编码蛋白质长度在510 (VvNCED2)-625 aa (VvNCED10)之间。VvNCED蛋白的分子量最大值是70.53 kDa (VvNCED10), 最小值是57.85 kDa (VvNCED2)。在从祖先基因分化之后, 葡萄NCED基因发生了5次复制事件, 同时有2次丢失事件。NCED1/2、NCED3/4、NCED6/7和NCED9/10基因对被认为是通过片段复制产生。上述4对复制基因复制时间分布在3.08-120.0百万年前, 晚于单双子叶植物分化的时间。与对照相比, VvNCED1在ABA处理48小时后显著上调(72.1%), 而VvNCED2显著下调(84.0%)。VvNCED6只在干旱处理14、21和28天的根系中表达量高于对照, 分别为对照的2.49、1.05和1.09倍。VvNCED7只在干旱处理14天的根系中表达量高于对照, 为对照的1.07倍。在ABA处理72小时后, VvNCED3表达量较对照显著下调(59.5%), 而VvNCED4较对照显著上调(169.9%)。VvNCED3/VvNCED4分别在NaCl处理24和48小时出现显著性峰值, 较对照分别上调219.2%和114.4%。保守结构域不同组成和不同胁迫处理下差异表达模式是NCED蛋白发生功能分化的基础。推测NCED在进化过程中发生的功能分化有利于复制事件的发生。

Evolution and Expression of NCED Family Genes in Vitis vinifera

9-cis-epoxycarotenoid dioxygenase (NCED), a key rate-limiting enzyme in ABA biosynthesis in plants, is involved in plant drought, exogenous abscisic acid (ABA) and high salt response, and can reduce the damage of environmental stress on plants. With genome-wide identification and analysis of the grape NCED gene family, we aimed to understand the species evolution relationship and study the expression patterns of various genes in different tissues and under drought, ABA and high salt (NaCl) stress treatment, to lay the foundation for further study of the biological functions of NCED genes. A total of 12 NCED genes were found in the grape genome. The amino acid residues encoded by the genes are distributed between 510 aa (VvNCED2) and 625 aa (VvNCED10). The maximum molecular weight of the VvNCED protein was 70.53 kDa (VvNCED10) and the minimum was 57.85 kDa (VvNCED2). After differentiation from the ancestral gene, the grape NCED genes had five replication events with two loss events. The NCED1/2, NCED3/4, NCED6/7 and NCED9/10 gene pairs are thought to be produced by segmental duplication. The replication time of segmental duplication ranged from 3.08 to 120.0 million years ago, which is later than the differentiation of monocotyledons. As compared with the control, VvNCED1 was significantly upregulated by 72.1% after 48 h of ABA treatment, whereas VvNCED2 was significantly downregulated by 84.0%. The expression of VvNCED6 was higher in only roots under drought treatment for 14, 21 and 28 days than in the control: 2.49, 1.05 and 1.09 times of control values, respectively. The expression of VvNCED7 was only 1.07 times higher than the control value in roots under drought treatment for 14 days. After 72 h of ABA treatment, the expression of VvNCED3 was significantly downregulated by 59.5% as compared with the control, whereas VvNCED4 was significantly upregulated by 169.9% as compared with the control. The significant peaks in expression of VvNCED3/VvNCED4 after NaCl treatment were 24 and 48 h, respectively, up by 219.2% and 114.4%. The differential conserved-domain expression patterns with different stress treatments are the basis for the functional differentiation of NCED proteins. The functional differentiation of NCED during evolution may be conducive to the occurrence of replication events.