Ectopic Expression of AhDef1 Gene (Peanut Defensin Gene) Reveals Enhanced Fungal Resistance and Aflatoxin Suppression in Peanut (Arachis hypogaea L.)

Abstract

The aim of the present study is functional characterization of a native plant defensin gene (AhDef1) from Arachis hypogaea (peanut). Further its potential has been evaluated to enhance resistance against Aspergillus flavus infection and reduce aflatoxin accumulation through transgenic intervention. Transgenic peanut lines overexpressing the AhDef1 gene exhibited significantly improved resistance to A. flavus colonization and a marked reduction in aflatoxin B1 content compared to wild-type (WT) plants. Quantitative real-time PCR confirmed transgene expression, and aflatoxin accumulation was analyzed by a spectrophotometer which revealed a reduction in aflatoxin levels in the transgenic seeds. Alongside its direct antifungal activity, AhDef1 overexpression also triggered the upregulation of genes which are involved in the biosynthesis of secondary metabolites such as resveratrol, ferulic acid and butenedioic acid, myoinositol, octadecanoic acid, suggesting an amplified biochemical defense response. Multivariate analysis further suggested that accumulation of these defense-related metabolites was positively correlated with transgenic lines challenged by A. flavus. In conclusion, the AhDef1 gene functionally validated in this study emerges as a promising candidate for engineering fungal disease resistance and aflatoxin mitigation in peanut and potentially other susceptible crops.