Temperature‐dependent resistance to potato virus M in potato (Solanum tuberosum)

Abstract

AbstractPotato virus M (PVM) is present worldwide and the vast majority of potato cultivars are susceptible to PVM infection. The only source of PVM resistance intentionally introduced into potato cultivars is Solanum megistacrolobum, which is a donor of the Rm gene. However, differences in S. megistacrolobum‐derived resistance of potato clones have been observed. The aim of our study was to assess the influence of temperature on PVM infection of potato plants. The reaction of potato clones originating from S. megistacrolobum to inoculation with PVM and incubation at various temperature regimes (20 and 28°C) was evaluated. The presence of PVM in inoculated plants as well as in their tuber progeny was qualitatively detected by a double‐antibody sandwich (DAS)‐ELISA and quantitatively detected by quantitative reverse transcription PCR (RT‐qPCR). In the examined clones, three types of resistance reactions were observed: (a) Rm‐based resistance, (b) temperature‐dependent resistance, and (c) susceptibility. In potato clones with Rm‐based resistance, multiplication of PVM was completely inhibited regardless of incubation temperature. In the second group of clones, PVM resistance was dependent on temperature: in plants incubated at 20°C, the virus was present in inoculated plants as well as in tuber progeny plants, while in plants incubated at 28°C, complete inhibition of virus multiplication was observed. In the susceptible potato clones, PVM accumulated to a high level at both temperatures. We assume that S. megistacrolobum‐derived potato resistance to PVM infection is highly complex, and in addition to Rm‐based resistance, there are other resistance mechanisms, and resistance is at least partly based on temperature‐dependent reactions.