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 P(0) 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 (P(0) pathotype), paprika mild mottle virus-J (P(1 )pathotype) and pepper mild mottle virus-J (P(1,2) 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.