Genome-Wide Identification and Expression Analysis of in .

Chitinase (EC 3.2.1.14) is a kind of 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 () gene family members of . Thirty-three () were identified from the latest Petunia genome database. According to the phylogenetic analyses, these genes were divided into GH18 and GH19 subgroups and further subdivided into five classes (Class I to Class V). Conserved motif arrangements indicated their functional relevance within each group. The expansion and homeology analyses showed that gene replication events played an important role in the evolution of and the increase of the GH18 subgroup members was the main reason for the expansion of the gene family in the evolution progress. By qRT-PCR analysis, we found that most of the showed a very low expression level in the normal growing plants. But lots of showed upregulated expression profiles when the plants suffered different abiotic stress conditions. Among them, five responded to high temperature and exhibited significantly upregulate expression level. Correspondingly, many hormone responses, as well as biotic and abiotic stress elements were found in the promoters of by using cis-acting element analysis. These results provide a foundation for the exploration of ' function and enrich the evolutionary process of the gene family.