First Report of Grapevine Pinot gris virus in Grapevines in China.

Grapevine Pinot gris virus (GPGV) was first found in ‘Pinot gris’ grapevines displaying chlorotic mottling and leaf deformations in Italy (Giampetruzzi et al. 2012), and now has been reported in symptomatic and asymptomatic grapevines in other countries (Glasa et al. 2014; Saldarelli et al. 2015). A survey to assess the presence of GPGV in China in 2014 was performed by RT-PCR testing dormant canes of 36 grapevine samples, including 19 samples showing chlorotic mottling and 17 asymptomatic samples, collected from the Chinese provinces of Liaoning (29 samples), Beijing (5 samples), and Zhejiang (2 samples). These samples included 24 different cultivars, in which 14 cultivars showed chlorotic mottling. Because no commercial antibody for GPGV is available, RT-PCR assays were carried out to amplify the different gene fragments of GPGV. The 544-bp, 1041-bp, and 626-bp fragments were amplified using the primers GPGVCP1A/1B (5′-TGAGATCAACAGTCAGGAGAG-3′/5′-GAAGCCGTGATAGCATTAGTC-3′) based on the GPGV coat protein (CP) gene, GPGVMP1A/1B (5′-GGTTTCTGGGAGGATTGCAAC-3′/5′-RCTTYGCGATCAGCTCTCTCC-3′) based on the GPGV movement protein (MP) gene, and GPGVMPCP1A/1B (5′-GCTGTGCTGAAAATAGTGCTG-3′/5′-GAAGCCGTGATAGCATTAGTC-3′) based on the segmental fragment covering the MP and CP genes, respectively. The results showed that 15 of 36 samples tested positive for GPGV by PCR using all the above three primers, with 10 samples displaying chlorotic mottling. The obtained PCR product from ‘Red Globe’ (symptomless), ‘Merlot’ (symptomless), ‘Muscat Hamburg’ (symptomless), ‘Cabernet Franc’ (symptomatic), and ‘Moldova’ (symptomatic) were sequenced and submitted to GenBank (Accession No. KT345217-19, CP gene; KT345220, MP gene; KT345221-23, MP and CP gene), and were compared with seven previously reported GPGV genomes (GenBank Accession Nos. NC_015782, KF686810, KF134123 to KF134125, KM491305, and FR877530). The results showed that CP and MP gene sequences showed identities ranging from 96.67 to 100% and 81.03 to 97.40% at amino acid levels compared with the previously reported sequences, respectively. Additionally, we found that ‘Beta’ rootstock, used for the GPGV-infected diseased ‘Shine-Muscat’ grapevine, also displayed chlorotic mottling symptoms. Furthermore, five GPGV-infected samples (only one showing chlorotic mottling symptom) and one GPGV-free sample were grafted onto GPGV-free ‘Beta’ grapevines (three biological replicates for the same source bud) to test ‘Beta’ grapevine’s susceptibility to GPGV. The results showed that all of the grafted ‘Beta’ grapevines using the GPGV-infected scions showed serious chlorotic mottling and tested positive for GPGV using RT-PCR. Other nepoviruses, including Grapevine fanleaf virus, Arabis mosaic virus, Strawberry latent ringspot virus, Tomato black ring virus, Tomato ringspot virus, and Tobacco ringspot virus, were not found by ELISA assays and RT-PCR. The present study represents the first report of GPGV in China, and suggests that the ‘Beta’ grapevine, widely used as rootstock in China, may be susceptible to infection by GPGV. Considering the complexity of mixed infection by grapevine viruses, further study on the pathogenicity of GPGV and the mode of transmission is needed. © 2016 The American Phytopathological Society.