Temperature and CO(2) Level Influence Potato leafroll virus Infection in Solanum tuberosum

We determined the effects of atmospheric temperature (10–30 ± 2°C in 5°C increments) and carbon dioxide (CO(2)) levels (400 ± 50 ppm, 540 ± 50 ppm, and 940 ± 50 ppm) on the infection of Solanum tuberosum cv. Chubaek by Potato leafroll virus (PLRV). Below CO(2) levels of 400 ± 50 ppm, the PLRV infection rate and RNA content in plant tissues increased as the temperature increased to 20 ± 2°C, but declined at higher temperatures. At high CO(2) levels (940 ± 50 ppm), more plants were infected by PLRV at 30 ± 2°C than at 20 or 25 ± 2°C, whereas PLRV RNA content was unchanged in the 20–30 ± 2°C temperature range. The effects of atmospheric CO(2) concentration on the acquisition of PLRV by Myzus persicae and accumulation of PLRV RNA in plant tissues were investigated using a growth chamber at 20 ± 2°C. The M. persicae PLRV RNA content slightly increased at elevated CO(2) levels (940 ± 50 ppm), but this increase was not statistically significant. Transmission rates of PLRV by Physalis floridana increased as CO(2) concentration increased. More PLRV RNA accumulated in potato plants maintained at 540 or 940 ± 50 ppm CO(2), than in plants maintained at 400 ± 50 ppm. This is the first evidence of greater PLRV RNA accumulation and larger numbers of S. tuberosum plants infected by PLRV under conditions of combined high CO(2) levels (940 ± 50 ppm) and high temperature (30 ± 2°C).