Enhanced expression and interaction of GmRDR1 and GmSGS3 proteins in resistant soybean cultivars synergistically regulate antiviral defense against mungbean yellow mosaic India virus.

Mungbean yellow mosaic India virus (MYMIV) causes significant losses to soybean productivity in India. Resistance to MYMIV is reported to be linked with two QTLs. It was hypothesized that within these QTLs, two RNA silencing-related genes, RNA-DEPENDENT RNA POLYMERASE-1 (GmRDR1) and SUPPRESSOR OF GENE SILENCING (GmSGS3), may have a role in governing resistance. In this study, coding regions of the above genes were sequenced from resistant (SL 1074) and susceptible (JS 335) soybean cultivars. While GmRDR1 had identical sequences in both cultivars, two synonymous SNPs in GmSGS3 were identified. Based on one of these SNPs, a CAPS marker was developed, which differentiates resistant and susceptible genotypes. In silico docking and yeast two-hybrid assays confirmed the interaction between GmRDR1 and GmSGS3. Gene expression analysis showed that resistant genotypes expressed higher levels of these transcripts after MYMIV inoculation. Additionally, reducing expression of either gene via RNA interference increased viral accumulation, indicating reduced resistance. This study highlights the critical role of GmRDR1 and GmSGS3 in soybean resistance to MYMIV, suggesting that their enhanced expression and interaction facilitate antiviral defense. Future research should explore molecular pathways involved, which could improve breeding strategies for MYMIV resistance in soybean.