Development of Molecular Marker Linked with Cercospora Leaf Spot (CLS) Disease Resistance in Vigna radiata, Cloning, and Expression for Evaluating Antifungal Activity against Cercospora canescens

We developed a molecular marker for MAS of mungbean resistant varieties against CLS from the consensus sequence (MB-CLsRG) of identified RGAs (MB-ClsRCaG1 and MB-ClsRCaG2). The MB-CLsRG sequence-specific primer pair was used to screen Cercospora leaf spot (CLS) resistant varieties of mungbean in genomic analysis that showed congruency with phenotypic screening. Validation of molecular marker linkage with CLS resistance was performed using rtPCR in transcriptomic analysis. The sequenced PCR products showed 100% homology with MB-CLsRG sequence and putative disease resistance proteins that confirmed the linkage of molecular marker with CLS resistance in mungbean. The antifungal potential of MB-CLsRG gene encoding protein was assessed. The MB-CLsRG gene sequence was cloned in the E. coli expression vector for recombinant protein production. The recombinant protein was then investigated for its in vitro antifungal potential against Cercospora canescens. The in vitro investigation showed strong antifungal activity of recombinant protein as it restricted the growth of fungal mycelial mass. The results validated the linkage of developed marker with CLS-resistant mungbean varieties; therefore, it can be used to screen resistant varieties from a large population in MAS. Moreover, the recombinant protein of the MB-CLsRG gene sequence revealed antifungal potential, which proved the gene sequence could be suitable to use in transgenic plants technology to develop fungal-resistant transgenic crops.