Molecular characterization of a novel Conyza canadensis-infecting begomovirus in China

Abstract

AbstractA novel monopartite begomovirus was found in naturally infected Conyza canadensis plants exhibiting typical begomovirus-induced yellow vein symptoms in Yunnan Province of China. Analysis of two obtained full-length viral genome sequences showed that they shared 99.8% nucleotide (nt) sequence similarity, and both consisted of 2733 nts (GenBank accession no. OK120264 and OK120266, respectively). Further analysis showed that these two sequences shared the highest nt sequence similarity (78.9%) with tomato yellow leaf curl Vietnam virus (TYLCVV) (EU189150). In the assayed C. canadensis plants, a betasatellite of 1,341 nts (Accession no. OK120265 and OK120267, respectively) was also found, and it shared 98.1% sequence similarity with malvastrum yellow vein betasatellite (MaYVB) (JX679254). Based on the current classification criteria for begomoviruses, we consider that the two obtained viral isolates are a novel begomovirus, and named it as conyza yellow vein virus (CoYVV). Our further analysis result showed that CoYVV is likely originated from a recombination event between tomato yellow leaf curl Yunnan virus (TYLCYnV) and tomato yellow leaf curl China virus (TYLCCNV). To investigate the effect of CoYVV infection in plant, we constructed two infectious clones (i.e., pCoYVV and pMaYVB), and inoculated them individually or together to Nicotiana benthamiana plants through agro-infiltration. The result showed that the plants co-inoculated with CoYVV and MaYVB developed yellow vein and downward leaf-curling symptoms, whereas the plants inoculated with CoYVV alone showed no clear virus-like symptoms. Virus infection in the inoculated N. benthamiana plants was confirmed through polymerase chain reaction (PCR). The result of quantitative PCR (qPCR) showed that in the presence of MaYVB, the accumulation level of CoYVV DNA was significantly increased compared to that in the plants infected with CoYVV alone.