Molecular detection and identification of eight potato viruses in Gansu province of China

Potato (Solanum tuberosum), a major food crop in the world is commonly infected with viral diseases, causing a loss in both quality and quantity of this crop. To determine the prevalence of eight important potato viruses in Gansu province of China, tuber samples were collected from Weiheyuan potato seed industry development Co., Ltd., and nineteen different commercial potato production fields at different locations in October 2018. Viruses were identified by RT-PCR using coat protein (CP)-specific primers, and validated by cloning three PCR positive amplicons of each virus followed by sequencing of three positive clones from each plasmid. Sequences were deposited in the GenBank. RT-PCR results demonstrated that mixed infections were very common in the collected tuber samples. Mixed infection of Potato virus X (PVX) and Potato virus S (PVS) caused 12.5 %; PVX and Potato aucuba mosaic virus (PAMV) caused 20.83 %; PVX, PVS and PAMV caused 12.5 %; PVX, Potato virus H (PVH) and PAMV caused 8.33 %; Potato leafroll virus (PLRV), PVX, PVS and PAMV caused 8.33 %; PVX, PVS, PVH and PAMV caused 16.67 %; PLRV, PVX, PVS, PVH and PAMV caused 8.33 %; and PVX, PVS, PVH, PAMV and Potato virus M (PVM) caused 4.17 % tuber infection, respectively; whereas, Potato virus Y (PVY) and Potato virus A (PVA) were not detected. PVY and PVA requires further testing in the future, and the result for these two viruses in the current study cannot be validated due to the lack of positive controls. PVS and PVH were also confirmed by western blot analysis. Phylogenetic analysis further revealed that the PLRV from Gansu was closely related to a Guangdong isolate (GenBank accession no. MF062487), PVX was closely related to a Shandong isolate (GenBank accession no. AF628555), PVS was closely related to a Guangxi isolate (GenBank accession no. KF011279) and an Australi isolate (GenBank accession no. GU319949), PVH was closely related to a Yunnan isolate (GenBank accession no. JQ904630), PAMV was closely related to a Bangladeshi isolate (GenBank accession no. MF133526), and PVM was closely related to a Tanzania isolate (GenBank accession no. KC866622). These findings will provide a basis for control of potato viruses in this region in the future.