P-661 - A novel recombinant weed-infecting begomovirus forms a pseudorecombinant with bean golden yellow mosaic virus inducing severe symptoms in common bean

We identified and characterized a novel bipartite begomovirus infecting Macroptilium spp. in the Dominican Republic (DO), which we named macroptilium golden yellow mosaic virus (MacGYMV). Sequence and recombination analyses revealed that ~1.5 kb of the MacGYMV DNA-A component was derived from the DNA-A of an isolate of bean golden yellow mosaic virus (BGYMV) from the DO, indicating recombination between these viruses. Host range tests demonstrated that MacGYMV DNA-A and DNA-B has a narrow host range inducing yellow vein symptoms in macroptilium, mild leaf deformation in Nicotiana benthamiana and stunting, leaf distortion and mottling in common bean plants. Furthermore, pseudorecombination experiments between MacGYM showed that this recombinant DNA-A replicates BGYMV DNA-B in infiltrated leaves of N. benthamiana and common bean. However, systemic infection and severe symptoms of stunting, leaf distortion and mottling developed in common bean plants, whereas no symptoms developed in N. benthamiana. Rolling circle amplification and PCR analyses showed MacGYMV DNA-A and BGYMV DNA-B in symptomatic common bean plants, whereas MacGYMV DNA-A was detected in symptomless N. benthamianaplants. These findings suggest that host factors in common bean facilitate the systemic movement of BGYMV DNA-B. Notably, the MacGYMV DNA-A/BGYMV DNA-B seudorecombinant was more pathogenic in commonly grown bean cultivars in the DO than the MacGYMV DNA-A and DNA-B, highlighting how a weed-infecting begomovirus can become a greater thread to crop host by recombining with a crop-infecting virus.