|Ben Chaim, Arnon|
Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/16/2000
Publication Date: 6/5/2001
Citation: N/A Interpretive Summary: A study was undertaken to determine the genomic locations of genes controlling resistance to cucumber mosaic virus (CMV) in the small-fruited hot pepper cultivar 'Perennial'. Three separate experiments were conducted using a single genetic population, in two locations, using two isolates of CMV, & two additional regions were associated with CMV resistance, when present in conjunction with one or more of the other four genes. the gene that acounted for the largest percentage of the observed variation in CMV resistance (16-33%) was identified in all three experiments. This gene is located near the gene L, which confers resistance to tobacco mosaic virus (TMV) resistance. A CMV-resistant pepper breeding line, '3990', was generated by the backcross method to incorporate CMV resistance from 'Perennial' into a bell pepper type. This line was evaluated for molecular markers spaced throughout the genome, which revealed that four of the six identified resistance genes from 'Perennial' were incorporated into '3990' & were therefore sufficient to confer resistance. Two of the genomic regions involved in determining CMV resistance also contain genes determining fruit weight, confirming observations in breeding programs of an association between CMV resistance and small fruit weight in 'Perennial'.
Technical Abstract: QTL analysis for resistance to cucumber mosaic virus (CMV) was performed in an intraspecific Capsicum annuum population. 180 F3 families were derived from a cross between the susceptible bell-type cultivar 'Maor' and the resistant small-fruited Indian line'Perennial' & inoculated with CMV in total of three experiments in USA & Israel using two virus isolates. Mostly yRFLP & AFLP markers were used to construct the genetic map & interval analysis was used for QTL detection. Four QTL were significantly associated with resistance to CMV. Two digenic interactions involving markers with and without an individual effect on CMV resistance were also detected. The QTL is linked to the L locus that confers resistance to tobacco mosaic virus (TMV), confirming earlier anecdotal observations of an association between resistance to CMV & susceptibility to TMV in 'Perennial'. An advanced backcross breeding line from an unrelated population, '3990', selected for resistance to CMV was analyzed for markers covering the genome, allowing the identification of genomic regions introgressed from 'Perennial'. Four of these introgressions included regions associated with QTL for CMV resistance. Markers in two genomic regions that were identified as linked to QTL for CMV resistance were also linked to QTL for fruit weight, confirming additional breeding observations of an association between resistance to CMV originating from 'Perennial' and small fruit weight.