Complete genome sequencing and infectious cDNA clone construction of a Chinese isolate of grapevine Pinot gris virus (GPGV)

The complete nucleotide sequence of a Chinese isolate C12B1 of grapevine Pinot gris virus (GPGV) from a 'Beta' grapevine was determined by small RNA sequencing. The size of the C12B1 genome was 7259 nucleotides (nt) without the poly (A) tail. Sequence identities of C12B1 with other GPGV isolates ranged from 79.13 to 97.52%. Phylogenetic analysis based on complete genome sequences of the global GPGV isolates indicated GPGV isolates are divided into three major groups and five subgroups within group 3, with the C12B1 isolate felled within subgroup 3a of group 3. Moreover, an infectious cDNA clone of the GPGV isolate C12B1 was generated using the seamless assembly approach. The infectious clone was then inoculated to Nicotiana occidentalis 37B and grapevine plants. Inoculated Nicotiana plants showed leaf chlorotic mottling symptoms and RT-PCR and transmission electron microscopy analysis confirmed successful infection. Additionally, the inoculated Beta grapevine plants also exhibited mild chlorotic mottling and ring spot symptoms. This study represents the first complete genome sequence of GPGV in China and the successful production of an infectious cDNA clone of a divergent GPGV isolate. These findings are a foundation for further research on the interaction between GPGV and its plant hosts.