Genome-wide analysis of AhCN genes reveals the AhCN34 involved in bacterial wilt resistance in peanut

Peanut (Arachis hypogaea L.) bacterial wilt (BW), caused by Ralstonia solanacearum (RS), is a devastating soil-borne disease that poses a significant threat to peanut yield and quality. Nucleotide-binding leucine-rich repeat (NBS-LRR) proteins are a class of plant-specific immune receptors that recognize pathogen-secreted effector molecules and activate immune responses to resist pathogen infections. However, the precise functions of AhCN genes (CN is a class of NLR genes lacking LRR structural domains) in peanut plants are not fully understood. In this study, a total of 150 AhCN genes were identified and classified into nine subfamilies based on a systematic phylogenetic analysis. The AhCN genes showed highly conserved structural features; promoter cis-elements indicated involvement in plant hormone signaling and defense responses. Following inoculation with RS, the highly resistant peanut variety 'H108' significantly outperformed the susceptible variety 'H107' in physiological indicators such as plant height, main stem diameter, and fresh weight, likely due to inhibition of bacterial proliferation and diffusion in the stem vascular bundle. AhCN34 was found to be significantly upregulated in H108 compared to H107 during plant infection and in response to treatment with each of three plant hormones. Importantly, AhCN34 overexpression in peanut leaves enhanced their resistance to BW. These findings demonstrate the great potential of AhCN34 for applications in peanut resistance breeding. Our identification and characterization of AhCN genes provide insights into the mechanisms underlying peanut BW resistance and inform future research into genetic methods of improving peanut BW resistance.