Genome-wide identification and expression analysis of CRK gene family in chili pepper (Capsicum annuum L.) in response to Colletotrichum truncatum infection

The cysteine-rich receptor-like kinases (CRKs) belong to the plant receptor-like kinases family and have multitudinous roles, including stress responses. However, information on CRKs in chili pepper (Capsicum annuum L.) plants is limited. In this study, a total of 22 C. annuum CRKs (CaCRKs) have been identified in the chili genome. All the identified CaCRKs were mapped onto different chili chromosomes. The gene duplication analysis revealed that five gene pairs had the Ka/Ks ratio greater than one, suggesting the positive selection of CaCRKs in chili. Phylogenetic analysis grouped the CaCRKs into four groups alongside other plant CRKs. The structural characterization of the CaCRKs revealed that all of them carry the signature domains and motifs. The gene ontology analysis predicted their major potential functions to be stress response and protein kinase activity. The expression analysis the CaCRKs in two contrasting chili varieties under Colletotrichum truncatum infection added valuable insights into their involvement in chili-C. truncatum interactions. The comparison of expression dynamics suggested that CaCRK13 could be a potential candidate gene in regulating chili defense against anthracnose pathogen. Moreover, the results of this study will help to get insights into the chili CRKs and their involvement in chili defense response against C. truncatum.