The coat protein gene of tobamovirus P 0 pathotype is a determinant for activation of temperature-insensitive L 1a-gene-mediated resistance in Capsicum plants.

Tobamovirus resistance in Capsicum plants, which is mediated by L genes (L 1 , L 2 , L 3 or L 4 ), is known to be temperature sensitive. However, the L 1a gene, a newly identified tobamovirus resistance gene that is mapped to the L locus, confers temperature-insensitive resistance against the tobamovirus P0 pathotype. To identify the viral elicitor that activates the L 1a -gene-mediated resistance, several chimeric viral genomes were constructed between tobacco mosaic virus-L (P0 pathotype), paprika mild mottle virus-J (P1 pathotype) and pepper mild mottle virus-J (P1,2 pathotype). Infection patterns of these chimeric viruses in L 1a -harboring plants revealed that the L 1a -gene-mediated resistance was activated by the CP of a particular pathotype of tobamovirus, like other L-gene-mediated resistances, but the L 1a -gene-mediated resistance differs from those conferred by other L genes in terms of temperature sensitivity.