HIGH-TEMPERATURE EFFECTS ON HYPERSENSITIVE RESISTANCE TO TOMATO SPOTTED WILT TOSPOVIRUS (TSWV) IN PEPPER (CAPSICUM-CHINENSE JACQ.)

The tomato spotted wilt virus resistance in pepper conferred by the Ts w gene is less stable at 32 degrees C continuous temperature. Continuo us high temperatures for at least nine days lead to systemic spread an d necrotic symptoms in plants that are totally resistant at a lower te mperature (22 degrees C). We show that continuous high temperatures de stabilize this resistance in young plants, but older inoculated plants rarely develop systemic symptoms. Populations segregating for the Tsw gene showed that heterozygosity at the Tsw locus increased the chance of inoculated seedlings to develop systemic necrotic symptoms. Geneti c background was less significantly involved in the thermosensitivity of the resistant response. As a consequence, it would be preferable to grow cultivars homozygous at the Tsw locus in high temperature condit ions.