Development of a Reproducible Agrobacterium-Mediated Transformation Platform in Mung Bean (Vigna radiata L. Wilczek)

Mung bean (Vigna radiata L. Wilczek) is an important short-duration grain legume; however, the development of reliable molecular approaches for studying Mungbean Yellow Mosaic Virus (MYMV) is limited for its recalcitrance to in vitro regeneration and inefficient transformation protocols. The present study aimed to optimize an Agrobacterium tumefaciens-mediated transformation and regeneration system for MYMV resistance and molecular assessment of viral transmission in mung bean cv. VBN 4. A hypocotyl-assisted wounding approach combined with pre-induced A. tumefaciens strain LBA4404 carrying MYMV infectious clones was optimized using 100 µM acetosyringone for 2 h. The optimized protocol resulted in 96.0% post-inoculation survival. Following 48 h of dark co-cultivation, MS medium supplemented with 4 mg L−1 BAP, 250 mg L−1 kanamycin and 200 mg L−1 cefotaxime resulted in rapid shoot regeneration, with the success rate of 95.2%. Root induction with 1 mg L−1 IBA resulted in 87.5% rooting, while primary and secondary acclimatization achieved 80.0% and 90.0% survival, respectively. Molecular analysis of regenerated plants confirmed MYMV infectious clones through amplification of coat protein (CP) and movement protein (MP) sequences in 88.88% of plants, while the nptII selectable marker was detected in 77.77% of regenerants. T1 progeny showed 100% seed germination, and MYMV-specific PCR amplification was detected in 72.2% of seedlings, indicating persistence of viral sequences across generations. Overall, the optimized hypocotyl-wounding and Agrobacterium-mediated system provides a reproducible platform for controlled MYMV transformation, plant regeneration, molecular screening and investigation of viral persistence and transmission in mung bean.