桃4CL基因家族鉴定及其在果实色泽发育和采后贮藏冷害中的表达分析

Identification of 4CL gene family in peach and its expression analysis in fruit coloration during development stage and chilling injury during post-harvest low temperature storage

4-香豆酸辅酶A连接酶(4-coumarate:CoA ligase,4CL)在类黄酮和木质素等化合物代谢中具有重要作用。本研究基于桃基因组数据库系统鉴定4 CL基因家族成员,从基因家族进化树的角度分析桃4 CL基因家族的结构与潜在功能,结合转录组数据和qRT-PCR技术分析其在果实发育阶段类黄酮合成及采后冷害木质化调控中的功能。结果表明,基于桃基因组数据库鉴定出21个4 CL基因家族成员,分布在8条染色体上;基因家族进化树分析表明,Pp4CL 1与Pp4CL 2属于第一亚家族,主要参与木质素合成,Pp4CL3-Pp4CL 21属于第二亚家族,主要参与类黄酮的合成;启动子顺式元件分析发现其含有大量的非生物胁迫以及茉莉酸甲酯(MeJA)等激素响应元件。发育阶段的基因表达结果表明,Pp4CL 8和Pp4CL 13的表达水平随发育阶段总体呈上升趋势,且在红肉品种中的表达量高于黄肉和白肉品种,猜测其可能参与花青素等类黄酮合成。采后低温贮藏阶段的基因表达结果表明,Pp4CL 2可能在果实采后冷害木质化中发挥作用,程序性降温(low temperature conditioning,LTC)处理后Pp4CL 8、Pp4CL 10和Pp4CL 14也可通过诱导类黄酮合成,减轻采后低温贮藏对果实造成的冷害。本研究将为桃果实色泽发育和采后保鲜提供理论依据。

4CL(4-coumarate:CoA ligase)plays an important role in the metabolism of phenylalanine compounds such as flavonoids and lignin.In this study,the peach 4CL gene family members were systematically identified based on the peach genome database,and the structure and possible functions of the peach 4CLs were analyzed using the genetic family evolutionary analysis,combing transcriptome data and qRT-PCR techniques to analyze their functions in flavonoids synthesis at the fruit development stage and chilling-induced lignification regulation at postharvest.The results showed that 21 members of the 4CL gene family,namely Pp4CL1-Pp4CL 21,were identified on 8 chromosomes based on the peach genome database.Phylogenetic analysis showed that Pp4CL1 and Pp4CL 2 belong to the first subfamily,mainly involved in the synthesis of lignin,and Pp4CL3-Pp4CL 21 belongs to the second subfamily,mainly involved in the synthesis of flavonoids.The cis-element analysis of the 4CL promoters found that it contains a large number of abiotic stress and MeJA-responsive and other hormone response elements.The gene expression of different peach varieties at the development stage showed that Pp4CL 8 and Pp4CL 13 increased generally,and higher expression was observed in blood-flesh varieties than in yellow-and milk-white-flesh varieties,suggesting that these genes may participate in the fruit flavonoids synthesis.The gene expression of peach fruit during post-harvest cold storage showed that Pp4CL 2 may play a role in the chilling-induced lignification of fruit flesh after harvest.After low temperature conditioning(LTC)treatment,Pp4CL8,Pp4CL 10 and Pp4CL 14 may reduce the chilling injury of peach fruit during post-harvest cold storage by improving flavonoids content.This study provides a theoretical basis for the coloration of peach fruit and its postharvest preservation.