Identification of new resistance sources for Cucumber mosaic virus new isolate-P1 (CMV-P1) in Capsicum spp.

Abstract

Cucumber mosaic virus is responsible for agronomic losses in many important crops worldwide. Capsicum annuum Bukang Commercial F1 hybrid shows resistance to CMV-P0 strains (CMV-Kor and CMV-Fny). And the single dominant resistance gene, Cmr1, is known to control CMV resistance in Bukang . Recently, a new isolate, CMV-P1, breaking the Cmr1-mediated resistance, was identified in Korea. To find out the resistance sources, about two thousands of Capsicum germplasm collections comprising cultivated and wild species were screened for resistance to CMV-P1. For the selection of resistance sources, two criteria were established: 1) CMV-P1 inoculated plants were evaluated once a week for a month, compared with susceptible controls (Jeju and Bukang) and one resistant control C. annuum LAM. Symptomless peppers were selected as potential resistance plants. 2) For these candidate plants, CMV accumulation levels were evaluated with a double antibody sandwich (DAS)-enzyme-linked immunosorbent assay (ELISA). Finally Kathmandu-1, Kathmandu-2a and Kathmandu-2b have been selected as resistant plants. Genetic analysis from all F1 hybrids, crossed with Jeju, showed that the new resistance sources were recessive gene. Moreover, the result of allelism test with all resistant lines x LAM F1 showed, the genes of three resistant lines are alleles of cmr2.