The Wild Soybean C3HC4-Type RING Zinc-Finger Protein ZFP4 Enhances Resistance to Soybean Mosaic Virus

Soybean [Glycine max (L.) Merr.] is a globally important source of protein and edible oil, but is severely threatened by soybean mosaic virus (SMV). Wild soybean [Glycine soja Sieb. & Zucc.], the wild ancestor of cultivated soybean, exhibits high genetic diversity and strong resistance to pathogens. In this study, we identified a novel SMV resistance locus R_SC7-4 and its candidate gene ZFP4 from wild soybean, encoding a C3HC4-type RING zinc-finger protein. The knockout mutants of ZFP4 showed enhanced susceptibility to SMV strains SC7 and SC3, while its overexpressing lines conferred resistance without yield penalty; ZFP4 mediates resistance by inhibiting GSTT1 to increase glutathione and reduce excessive reactive oxygen species accumulation. Domestication analysis revealed reduced genetic diversity of ZFP4 in cultivated soybean, with the resistant ZFP4^Hap1 underutilized in breeding. In summary, this study provides not only excellent genetic resources for SMV-resistant soybean breeding but also new insights into the regulatory mechanisms of soybean resistance to SMV.