Genome-Wide Identification and Characterization of the LEA Gene Family in the Common Bean and the Role of the Dehydrin Gene Pvhdn3 in Enhancing Salt and Drought Tolerance in the Transgenic Tobacco Plant

Abstract

Global climate change exposes crops to numerous abiotic and biotic stress factors, significantly threatening their growth, development, and productivity. Among the various abiotic stresses, salt and drought are the most detrimental, severely impacting yield stability. Late embryogenesis abundant (LEA) proteins represent a broad and varied class of polypeptides that accumulate in response to cellular dehydration across diverse organisms. Nonetheless, there has been a scarcity of studies on this protein family in the common bean ( Phaseolus vulgaris L.) prior to this investigation. In this study, we identified 69 members of the LEA gene family in the common bean, characterized by conserved LEA and dehydrin domains and additional functional domains. Based on their phylogenetic relationships, these proteins are categorized into eight distinct subfamilies: LEA_1, LEA_2, LEA_3, LEA_4, LEA_5, LEA_6, dehydrin, and SMP. In this study, approximately 62% of the identified PvLEAs are classified within the LEA_2 group, characterized by their higher hydrophobicity. Notably, they are clustered on chromosomes 7 and 8, suggesting their evolutionary conservation within these chromosomal regions. Analysis of promoter regions uncovered a variety of elements, including those responsive to stress, including ARE, ABRA, WRKY, TCA element, and CGTCA motif, implying their potential role in stress response mechanisms. The PvHDN3 overexpressed transgenic lines exhibited enhanced physiological health, increased height, and better-developed roots and leaves than wild-type plants under salt and drought stresses. In addition, it was found that PvHDN3 expression in response to different abiotic stress (salt and drought) intensity was closely linked to several stress-related physiological parameters, including proline and malondialdehyde concentrations, ascorbate peroxidase, catalase, and peroxidase activity. The current study offers novel insights into the formation of LEA proteins in common beans and their roles in developmental processes under stress conditions, providing a valuable foundation for future research.