Comprehensive in-silico characterization and expression pattern of calmodulin genes under various abiotic and biotic stresses in Indian mustard (Brassica juncea).

Calcium (Ca²⁺) as a secondary messenger has a multidimensional role, including the growth and development of plants and the adaptive response to stress conditions. Calmodulin (CaM), a calcium-binding protein, uniquely binds with these Ca²⁺ ions and transmits Ca²⁺ signals. Calmodulin proteins have been well-reported in various plants for playing a role in abiotic and biotic stress signaling; however, a comprehensive analysis of the CaM genes of Indian mustard (Brassica juncea) has not been studied much. This study reports their chromosome placements, phylogenetic relations, the presence of protein motifs and cis-acting elements, and their expression patterns under stress due to salt, heat, cadmium, Xanthomonas campestris, and Alternaria brassicae. We identified 23 BjCaM genes coding for eight BjCaM proteins possessing the signature EF-hand domains. Chromosome locations, intron-exon structure, and in-silico protein characterization pointed toward genetic diversification. Phylogenetic analysis revealed a close relationship with previously characterized CaM proteins from Arabidopsis and rice. Cis-acting elements in the promoter regions suggested the potential role of BjCaM candidates in hormone signaling and various stress-responsive regulatory mechanisms. qRT-PCR analysis showed differential expression patterns, of which BjCaM17 and BjCaM19 showed higher expression under all stresses. The seven selected BjCaM genes were sensitive to cadmium stress. Interestingly, despite translating to same protein, BjCaM15, BjCaM17, and BjCaM19 showed differential expressions under the same stresses. This research represents the first genome-wide analysis of calmodulin genes in Indian mustard, providing a valuable reference for decoding calcium signaling via calmodulin and its potential exploitation to improve crop resistance to stress conditions.

Supplementary information: The online version contains supplementary material available at 10.1007/s12298-025-01561-x.