Abstract
BACKGROUND: S-adenosyl-L-methionine synthetase (SAMS) catalyzes the synthesis of S-adenosylmethionine (SAM), a universal methyl donor, and regulate plant growth, development, and stress responses. Although SAMS genes have been functionally characterized in several plant species, their roles in peanut (Arachis hypogaea L.) remain unclear. RESULTS: Here, we conducted a genome-wide identification and characterization of the SAMS gene family in peanut. Phylogenetic analysis clustered these genes into five groups, revealing close evolutionary relationships with soybean SAMS homologs. Conserved domain and motif analyses indicated that all AhSAMS proteins share highly conserved functional features. Expression profiling revealed tissue-specific patterns, AhFJ1AK4 was highly expressed, while AhRG5YED and AhPNM9T4 were preferentially expressed in reproductive organs. Promoter analysis identified abundant cis-regulatory elements related to stress and hormone responses. Upon Ralstonia solanacearum infection and treatments with salicylic acid (SA), abscisic acid (ABA), and methyl jasmonate (MeJA), AhRG5YED and Ah6Q1KS5 were significantly induced in the resistant cultivar H108. Functional validation demonstrated that overexpression of Ah6Q1KS5 in peanut and tobacco reduced cell death, and significantly inhibited bacterial growth, confirming its role in positively regulating bacterial wilt resistance responses. CONCLUSIONS: This study presents the first comprehensive genome-wide analysis of the AhSAMS gene family in peanut, providing insights into their functional diversification. In particular, Ah6Q1KS5 is highlighted as a candidate gene contributing to resistance responses, providing a genetic resource and theoretical foundation for future molecular breeding aimed at enhancing disease resistance in peanut.