西瓜OSCA基因家族全基因组鉴定及胁迫响应分析

Genome-wide identification and stress response analysis of OSCA gene family in watermelon

【目的】对西瓜OSCA基因家族进行成员鉴定、系统发育分析以及胁迫响应分析,为揭示西瓜OSCA基因生物学功能和抗逆分子机制提供参考依据。【方法】运用生物信息学的方法从西瓜全基因组数据库中鉴定出西瓜OSCA基因家族成员,根据染色体定位信息进行命名。对基因家族成员染色体位置、基因结构、共线性、启动子、蛋白结构和系统发育等进行全面分析。利用转录组数据和qRT-PCR分析西瓜OSCA基因在胁迫条件下的表达情况。【结果】西瓜OSCA基因家族有10个成员,不均等地分布在6条染色体上。西瓜OSCA蛋白分子量变化范围为24.59~91.97 kD,氨基酸数量为214~809 aa,多数定位于质膜上。共线性分析结果表明,西瓜OSCA基因在进化过程中发生了片段复制事件。西瓜OSCA基因家族分为三大类群,同一类群成员的外显子一内含子的组成模式、蛋白保守基序排列、蛋白二级结构数量比例和蛋白三级结构模型均相似。西瓜、水稻、番茄和拟南芥的OSCA基因被分为6个亚族,每个亚族均有西瓜OSCA基因分布。西瓜OSCA基因启动子区域含有厌氧诱导、冷胁迫应答、光反应和干旱胁迫应答等多种非生物胁迫响应元件。在干旱、低温和盐胁迫下,西瓜OSCA基因家族各成员表达量均有不同程度变化,其中ClaOSCA3和ClaOSCA5在3种不同胁迫条件下表达量均有显著差异(P<0.05)。【结论】西瓜OSCA基因在进化过程中具有一定保守性,与拟南芥、水稻和番茄OSCA基因存在较近亲缘关系。西瓜OSCA基因家族内部存在功能分化,ClaOSCA3和ClaOSCA5可能是胁迫响应机制中的重要抗逆基因。

【Objective】The member identification,phylogenetic analysis and stress response analysis of watermelon OSCA gene family were carried out to provide reference for revealing the biological function and molecular mechanism of stress resistance of watermelon OSCA gene.【Method】The members of watermelon OSCA gene family were identified by bioinformatics method from watermelon genome database,and named according to chromosome location information.Chromosome position,gene structure,collinearity,promoter,protein structure and phylogeny of gene family members were analyzed comprehensively. Transcriptome data and qRT-PCR were used to analyze OSCA gene expression in watermelon under stress.【Result】Watermelon OSCA gene family had 10 members,which were unevenly distributed on 6 chromosomes. The molecular weight of watermelon OSCA protein varied from 24.59 to 91.97 kD,and the number of amino acids ranged from 214 to 809 aa,most of which were located in the plasma membrane. The results of collinearity analysis showed that the fragment replication event occurred during the evolution of watermelon OSCA gene. The watermelon OSCA gene family was divided into three groups,and the exon-intron composition pattern,conserved motif arrangement of protein,the number proportion of secondary structure and the tertiary structure model of the members of the same group were similar. The OSCA genes of watermelon,rice,tomato and Arabidopsis thaliana were divided into 6 subgroups,watermelon OSCA gene was distributed in each subgroup. The promoter region of OSCA gene in watermelon contained several abiotic stress response elements such as anaerobic induction,cold stress response,light response and drought stress response. Under drought,low temperature and salt stress,the expression levels of OSCA gene family members in watermelon all changed to different degrees,and the expression levels of ClaOSCA3 and ClaOSCA5 all changed significantly under three different stress conditions(P<0.05).【Conclusion】Watermelon OSCA gene is conserved in the evolutionary process,and is closely related to OSCA gene of A. thaliana,rice and tomato. Functional differentiation exists within the OSCA gene family in watermelon,and ClaOSCA3 and ClaOSCA5 may be important stress resistance genes in the stress response mechanism.