Evidence of recombination and genetic diversity in southern rice black-streaked dwarf virus.

Southern rice black-streaked dwarf virus (SRBSDV) causes one of the most serious viral diseases of rice in China and Vietnam. Sequence identities of S10, encoding the major capsid protein, were 98.0 %-100 % and 98.3 %-100 % at the nucleotide and amino acid level, respectively. Our results suggest that the codon at position 550 of S10 is under positive selection, while most of the other codons are under neutral evolution. Putative recombination events were identified in genomic RNA segments S1, 2, 4, 5, 6 and 10, which are rare in plant-infecting dsRNA viruses. This study reveals the current state of SRBSDV evolution.