Comprehensively characterize the soybean CAM/CML gene family, as it provides resistance against both the Soybean Mosaic Virus and Cercospora sojina pathogens

Chunlei Zhang¹Yanbo Wang^1,2Ruiping Zhang¹Rongqiang Yuan¹Kezhen Zhao¹Xiulin Liu¹Xueyang Wang¹Fengyi Zhang¹Sobhi F Lamlom^1,3Bixian Zhang⁴Honglei Ren^1*

• ¹Soybean Research Institute, Heilongjiang Academy of Agricultural Sciences, Harbin, China
• ²Northeast Agricultural University, Harbin, China
• ³Alexandria University, Alexandria, Egypt
• ⁴Institute of Biotechnology of Heilongjiang Academy of Agricultural Sciences, harbin, China

Calmodulin (CAM) and calmodulin-like (CML) proteins are essential calcium sensors that mediate plant responses to biotic and abiotic stresses. In soybean these proteins play critical roles in resistance to multiple pathogens, yet a comprehensive characterization of this gene family and its connection to disease resistance has been lacking. This study identified and characterized 113 CAM/CML genes in the soybean genome, including 11 GmCAMs and 102 GmCMLs, through bioinformatic analysis using sequence homology, domain architecture, and phylogenetic approaches. Phylogenetic analysis revealed 14 distinct groups with evidence of both ancient and recent gene duplication events contributing to family expansion. Gene structure analysis demonstrated higher conservation among GmCAMs (with all but one containing introns) compared to GmCMLs (70% intron-less). Analysis of cis-acting elements indicated enrichment of hormone-responsive elements, particularly those associated with abscisic acid (31.2%) and methyl jasmonate (27.7%) responses, suggesting regulatory roles in stress signaling.Expression profiling revealed distinct CAM/CML gene expression patterns in response to two major soybean pathogens: Soybean Mosaic Virus (SMV) and Cercospora sojina (C. sojina ). We identified 15 GmCAM/CML genes that showed significant expression in response to both pathogens.Additionally, GmCML23, GmCML47, and GmCAM4 displayed expression patterns closely linked to resistance phenotypes. The expression of these genes was validated across various resistant and susceptible varieties, suggesting their potential role in responses to broad-spectrum pathogens. Our findings offer valuable insights into the evolutionary history and functional diversification of the soybean CAM/CML gene family, highlighting promising candidates for improving soybean resistance to multiple pathogens through molecular breeding strategies.