Incidence and molecular diversity of poleroviruses infecting cucurbit crops and weed plants in Thailand

Construction of an Agrobacterium-mediated infectious cDNA clone of melon aphid-borne yellows virus

Melon aphid-borne yellows virus (MABYV), a member of the genus Polerovirus in the family Solemoviridae, has widely spread in recent years and cause yellowing disease on cucurbits. Here, we obtained the complete genome sequence of MABYV bottle guard (Lagenaria siceraria) isolate MABYV-KF, and constructed its infectious cDNA clone under the control of the cauliflower mosaic virus (CaMV) 35S promoter by Gibson assembly. The 5,677 nt of its genome shared more than 94.00% sequence identity with the two known MABYV isolates. The inoculation results showed that MABYV infectious cDNA clone could systemically infect bottle guard, cucumber and muskmelon plants, and cause typical yellowing symptom. The virus progeny from the infectious clone could be transmitted between bottle guard plants by aphid. Further analyses revealed that point mutations in the F-box-like motif (Pro57) and C-terminal conserved sequence (Phe211) of P0 cause low viral accumulations in systematic leaves and failed to induce symptom. The infectious clone will be potentially a tool in the investigation of viral pathogenesis, virus-virus interaction and virus-host/-vector interactions.