Effect of temperature on symptom expression and viral spread of Melon yellow spot virus in resistant cucumber accessions

摘要

Melon yellow spot virus (MYSV), a member of the genus Tospovirus, is a devastating thrips-transmitted virus of cucurbits in Japan. Recently, we reported that cucumber accessions originating from South Asia, in particular Southeast Asia, had moderate resistance to MYSV. Here, we investigated the effect of three temperatures (20 degree C, 25 degree C, and 30 degree C) on symptom expression and viral spread of MYSV in plants of resistant cucumber accessions. No systemic infection developed in resistant cucumber plants after inoculation with melon isolate MYSV-S at low temperature (20 degree C); viral spread of MYSV-S and cucumber isolate MYSV-FuCu05P in inoculated cotyledons was suppressed. In contrast, higher incubation temperatures (25 degree C and 30 degree C) facilitated viral spread in inoculated cotyledons and systemic infection of MYSV-S. These data suggest that the resistance to MYSV of resistant cucumber accessions is temperature dependent.