辣椒几丁质酶类基因家族的全基因组鉴定和表达特征分析

几丁质酶（chitinase, EC 3.2.1.14）是一种降解几丁质的糖苷酶,在植物应对非生物和生物胁迫中起重要作用。本研究对辣椒几丁质酶类（Capsicum annuum chitinase-like, CaCTL）基因家族成员进行了全基因组注释、进化分析和基因表达模式分析。从最新的辣椒基因组数据库中鉴定出31个CaCTL成员。根据系统发育进化树将这些成员分为GH18和GH19亚家族,并进一步分为5个亚类（Ⅰ~Ⅴ类）。保守基序分析结果表明,每个亚类中的成员存在功能相关性。对辣椒、矮牵牛以及番茄的CTL基因家族成员同源性分析表明,在矮牵牛和番茄中分别有7个和11个辣椒CaCTL的同源基因。通过qRT-PCR分析发现,在正常环境生长的辣椒植株中,64.2%的GH18亚家族的CaCTL成员表达水平很低,有64.7%的GH19亚家族成员在不同组织中存在差异表达。顺式作用元件分析表明,CaCTL成员启动子区域存在许多激素反应以及生物和非生物应激相关元件。当植物遭受不同的非生物胁迫时,qRT-PCR结果显示,多数CaCTL成员表达上调。当植物遭受高温干旱条件时,多个CaCTL成员的表达上调明显。上述结果丰富了CTL基因家族进化的研究,为探索CaCTL成员的功能提供了数据基础。

Genome-wide Identification and Expression Analysis of CTL Gene Family Memebers in Capsicum annuum L.

Chitinase (EC 3.2.1.14) is chitin-degrading glycosidase, which plays important roles in the abiotic and biotic defense of plants. In this study, we conducted whole-genome annotation, molecular evolution, and gene expression analyses on the Capsicum annuum chitinase-like (CaCTL) gene family members. Thirty-one CaCTL genes (CaCTLs) were identified from the latest Capsicum genome database. According to the phylogenetic analysis, the genes were divided into GH18 and GH19 subgroups and further subdivided into five classes (Class I to Class V). Conserved motif arrangements indicated the functional relevance within each group. Homology analysis of CTL gene family members in pepper, petunia and tomato indicated that there were 7 and 11 homologous genes of CaCTL members in petunia and tomato, respectively. By qRT-PCR analysis, in the normal growing plants, we found that 64.2% GH18 subgroup CaCTLs showed a very low expression level, 64.7% GH19 subgroup CaCTLs were differentially expressed in different tissues. Cis-acting element analysis showed that many hormone responses, as well as biotic and abiotic stress elements were found in the promoters of CaCTLs. Correspondingly, qRT-PCR showed that many CaCTLs had upre gulated expression profiles when the plants suffered different abiotic stress conditions, especially when plants are subjected to high temperature and drought conditions. The results would enrich the evolutionary process of the CTL gene family and provide a foundation for the exploration of the function of CaCTLs.