Differential occurrence and strain composition of potato viruses between two major seed potato production zones in China suggest the need for different management strategies for the zones

Abstract

Viral disease is one of the major reasons leading to yield and quality reduction of potato production. To gain better knowledge about seed potato quality in China, the occurrences of six common viruses, including potato leafroll virus (PLRV) and potato viruses A (PVA), M (PVM), S (PVS), X (PVX) and Y (PVY), were investigated in two of China’s four potato production zones (specifically, Zone I and Zone IV) from 2013 to 2016. A total of 1231 random tuber samples (Zone I, n = 571; Zone IV, n = 660) and 532 symptomatic leaf samples (Zone I, n = 375; Zone IV, n = 157) were collected in seed potato and commercial potato fields and tested for the viruses by reverse transcription (RT)-PCR (tuber samples) and/or enzyme-linked immunosorbent assay (ELISA; leaf samples). The results showed that virus-free tubers accounted for 79.7% and 52.0% in seed tuber samples from zones I and IV, respectively. All of the six viruses analysed were present in both zones I and IV, but occurred at different frequencies, with PVY and PVS being the predominant viruses in zones I and IV, respectively. Moreover, 44.0% and 39.8% of the virus-positive samples in zones I and IV, respectively, were found to be infected with more than one virus. Strain typing of PVS and PVY demonstrated the existence of similar strains of PVY (i.e. PVYO, PVYNTNb, PVYN:O, PVYN- Wi, PVY – (SYR-I and -II) and of PVS (i.e. PVSO and PVSA) in both zones. For PVY, recombinant strains were predominant, with SYR-II (27.7%) being the most abundant strain in Zone I and SYR-I (53.3%) being the predominant strain in Zone IV. PVSO was the predominant strain in Zone I whereas PVSA was the dominant strain in Zone IV. This study revealed not only the high incidence of viruses in both seed and commercial potatoes in China, but also the differential occurrence and strain composition of the viruses between two major production zones in China for the first time. In addition, the study suggests the need for different management strategies for different production zones to enhance the quality of seed potatoes in China.