Development of agro-infectious clones for screening resistance against recombinant mungbean yellow mosaic India virus causing golden mosaic disease in vegetable cowpea

Begomovirus associated with golden mosaic disease on vegetable cowpea has been characterized through rolling circle amplification. The genomic components (DNA A and DNA B) were cloned and sequenced. Nucleotide sequence analysis of DNA A (MT671430) and DNA B (MT671431) component had > 98% identity toward the mungbean yellow mosaic India virus (MYMIV) reported previously from India on various legumes. In phylogenetic analysis, study isolate shared common ancestry with MYMIV isolates of India, Pakistan and Nepal infecting legumes. Based on the recombination analysis, this cowpea isolate appears to be evolved through recombination of MYMIV sequences both at DNA A (Major parent: AF481855; Minor parent: AF416742) and DNA B (Major parent: AF416741; Minor parent: MN698281) level. Furthermore, Agrobacterium-based dimeric clone constructs were found highly infectious on cowpea host upon co-inoculation of DNA-A and DNA-B components by producing typical golden mosaic symptoms 42 days post-inoculation. Upon inoculation of these agro-infectious clones, vegetable cowpea germplasm lines were categorized as resistant, moderately resistant and susceptible to golden mosaic disease.