HR-Mediated Defense Response is Overcome at High Temperatures in Species.

Resistance to isolated from paprika (TSWV-Pap) was overcome at high temperatures (30 ± 2°C) in both accessions of S3669 (Hana Seed Company) and PI15225 (AVRDC Vegetable Genetic Resources). S3669 and PI15225, which carrying the gene, were mechanically inoculated with TSWV-Pap, and then maintained in growth chambers at temperatures ranging from 15 ± 2°C to 30 ± 2°C (in 5°C increments). Seven days post inoculation (dpi), a hypersensitivity reaction (HR) was induced in inoculated leaves of PI152225 and S3669 plants maintained at 25°C ± 2°C. Meanwhile, necrotic spots were formed in upper leaves of 33% of PI15225 plants maintained at 30 ± 2°C, while systemic mottle symptoms developed in 50% of S3669 plants inoculated. By 15 dpi, 25% of S3669 plants had recovered from systemic mottling induced at 30 ± 2°C. These results demonstrated that resistance to TSWV-Pap can be overcome at higher temperatures in both and . This is the first study reporting the determination of temperatures at which TSWV resistance is overcome in a genetic resource expressing the gene. Our results indicated that TSWV resistance shown from pepper plants possess the gene could be overcome at high temperature. Thus, breeders should conduct evaluation of TSWV resistance in pepper cultivars at higher temperature than 30°C (constant temperature).