Prevalence and distribution of Grapevine leafroll‐associated virus 7 in China detected by an improved reverse transcription polymerase chain reaction assay
2014
Lyu, M. D. | Li, X. M. | Guo, R. | Li, M. J. | Liu, X. M. | Wang, Q. | Cheng, Y. Q.
To determine prevalence and distribution of Grapevine leafroll‐associated virus 7 (GLRaV‐7) in China, a total of 213 grapevine (Vitis spp.) samples (92 popular cultivars) from 13 Chinese provinces and regions were tested for the presence of GLRaV‐7 by reverse transcription polymerase chain reaction (RT‐PCR) assays and sequencing. GLRaV‐7 was found in 40·4% of the samples, and shown to be widely distributed in major grapevine growing areas in China. GLRaV‐7 was found in more than 50 grapevine cultivars. Some popular grape cultivars showed a high incidence of GLRaV‐7 infection, such as Manicure Finger (100%), Cabernet Sauvignon (83·3%), Merlot (60%), Fujimineri (60%) and Red Globe (50%). The genetic variability of GLRaV‐7 isolates was characterized based on partial nucleotide sequences (nucleotides 945–1329 and 97–598 of the ORF) of heat shock protein 70 homologue (HSP70h) and 61‐kDa protein (p61) (nucleotides 1073–1572 of the ORF) genes. The overall mean values of nucleotide diversity were low (ranging from 0·009 to 0·066), and phylogenetic analysis based on p61 showed that the GLRaV‐7 isolates segregated into three phylogenetic clusters. The results also showed that two previously described primer pairs failed to amplify a wide range of GLRaV‐7 isolates present in China. However, a new primer pair reported here, based on the p61 gene and its associated downstream intergenic region, detected more GLRaV‐7 Chinese isolates. This is the first report on the prevalence and distribution of GLRaV‐7 in China, and also provides an improved RT‐PCR assay for detecting the virus.
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