西瓜SOD家族基因的鉴定及其对枯萎病菌的响应特征分析

Identification of Watermelon SOD Family Genes and Their Characteristics Analysis in Response to Fusarium wilt

西瓜作为一种重要的园艺作物,极易受到逆境尤其是各种病原菌的侵害,在生产上造成严重的损失。逆境胁迫会诱导植物细胞内活性氧自由基的积累,产生氧化胁迫,影响植物的生长发育。超氧化物歧化酶(superoxide dismutase,SOD)是抗氧化系统的第一道防线,能有效清除活性氧,减轻氧化胁迫从而提高植物对逆境的耐受能力,但还没有研究对西瓜SOD基因进行分离和鉴定。本研究采用生物信息学手段在西瓜基因组中共鉴定到8条ClSOD基因,并对它们基因结构、进化关系、蛋白结构、亚细胞定位、启动子顺式作用原件及表达模式等进行预测和分析。根据蛋白结构和进化分析表明,西瓜SOD蛋白可分为Cu/ZnSODs和Fe-MnSODs两类,进一步分为4个亚族。绝大多数西瓜SOD基因含有多个内含子。利用荧光定量PCR(qRT-PCR)分析发现,西瓜SOD基因具有不同的的时空表达模式。另外,我们从ClSOD基因的启动子上鉴定到许多激素和逆境相关的顺式作用元件。接种尖孢镰刀杆菌后,西瓜抗病品种中大部分SOD基因的表达上调而感病品种中则相反,初步鉴定到一些与枯萎病抗性相关的ClSOD基因。本研究将为西瓜抗病基因的功能鉴定及其调控机理的探究提供科学依据,也为西瓜抗病分子育种提供理论基础。

Watermelon,as an important horticultural crop,is vulnerable to all kinds of pathogens,which cause serious losses in production.Stress can induce the accumulation of reactive oxygen radicals in plant cells,produce oxidative stress and affect the growth and development of plants.Superoxide dismutase(SOD)is the first line of defense of the antioxidant system,which can effectively remove reactive oxygen species and reduce oxidative stress so as to improve the tolerance ability of plants to adversity.However,no studies have been conducted to isolate and identify the SOD gene in watermelon.In this study,a total of 8 ClSOD genes were identified in watermelon genome by means of bioinformatics,and their gene structure,evolutionary relationship,protein structure,subcellular localization,promoter cis-action elements and expression patterns were predicted and analyzed.According to the analysis of protein structure and evolution,watermelon SOD protein can be divided into Cu/ZnSODs and FE-MnSODS,and further divided into 4 subgroups.Most of the watermeion SOD gene contains multiple introns.Fluorescence quantitative PCR(QRT-PCR)analysis showed that watermelon SOD gene had different spatiotemporal expression patterns.In addition,we identified many hormone and stress-related cis-acting elements from the promoter of ClSOD gene.After inoculation with Fusarium oxysporum,the expression of SOD gene was up-regulated in most of the watermelon cultivars resistant to Fusarium oxysporum,while the expression of SOD gene was reversed in susceptible cultivars,and some ClSOD genes related to wilt resistance were preliminarily identified.This study will provide scientific basis for the functional identification of watermelon disease resistance genes and the exploration of their regulatory mechanism,as well as theoretical basis for watermelon disease resistance molecular breeding.