Genome-wide analysis of the calmodulin-binding transcription activator (CAMTA) gene family in Sesamum indicum L., and its role in abiotic stress tolerance traits

Abstract

Calmodulin-binding transcription activator (CAMTA) is one of the key transcription factor families possessing calcium receptors (calmodulins, CaM). It modulates the expression levels of genes associated with ontogeny and various biotic and abiotic stress factors. The CAMTA family genes were known to be involved in different abiotic stress in several crop species. However, their functional relevance in sesame remains unexplored. To understand the role of CAMTA in stress tolerance in sesame, we performed a genome-wide analysis to identify the members of the SiCAMTA gene family. We have identified and reported here the five SiCAMTA genes localized on four chromosomes within the sesame genome. In silico analysis of the putative 2-kilobase (kb) promoter regions for these five SiCAMTA genes showed that phytohormone and stress response-related cis-elements were predominated in SiCAMTA2 and SiCAMTA5. Also, we studied its modulated expression levels, with special reference to drought and waterlogging stress. It revealed that the SiCAMTA5 and SiCAMTA2 genes were the most responsive to the studied stress factors. The target prediction and network analysis suggested that SiCAMTAs could bind the CGCG cis element in the target gene promoters and predicted 1202 SiCAMTA target genes in the sesame genome, including abiotic stress-responsive genes viz. LEA, PIP1–2, PPO1, SAP, ARF17, and GA3OX1. These findings were validated using qPCR analysis for five CAMTA and 10 CAMTA target genes and establish a foundation for future functional research of SiCAMTA genes towards sesame stress tolerance.

Keywords

• Sesamum indicum
• SiCAMTA
• Drought
• Waterlogging
• Transcription factor