C. Caranta et al., QTLS FOR A COMPONENT OF PARTIAL RESISTANCE TO CUCUMBER MOSAIC-VIRUS IN PEPPER - RESTRICTION OF VIRUS INSTALLATION IN HOST-CELLS, Theoretical and Applied Genetics, 94(3-4), 1997, pp. 431-438
Ninety four doubled-haploid (DH) lines obtained from the F-1 between P
erennial, a cucumber mosaic virus (CMV)-partially resistant Capsicum a
nnuum line, and Yolo Wonder, a CMV-susceptible C. annuum line, were an
alysed with 138 markers including mostly RFLPs and RAPDs. Clustering o
f RAPD markers was observed on five linkage groups of the intraspecifi
c linkage map. These clusters could correspond to the centromeric regi
ons of pepper chromosomes. The same progenies were evaluated for restr
iction of CMV installation in pepper cells in order to map quantitativ
e trait loci (QTLs) controlling CMV resistance. This component of part
ial resistance to CMV was quantitatively assessed using a CMV strain t
hat induced necrotic local lesions on the inoculated leaves. The numbe
r of local lesions gave an estimation of the density of the virus-infe
ction sites. Genotypic variance among the DH lines was highly signific
ant for the number of local lesions, and heritability was estimated to
be 0.94. Using both analysis of variance and non-parametric tests, th
ree genomic regions significantly affecting CMV resistance were detect
ed on chromosomes Noir, Pourpre and linkage group 3, together explaini
ng 57% of the phenotypic variation. A digenic epistasis between one lo
cus that controlled significant trait variation and a second locus tha
t by itself had no demonstrable effect on the trait was found to have
an effect on CMV resistance. For each QTL, the allele from Perennial w
as associated with an increased resistance. Implications of QTL mappin
g in marker-based breeding for CMV resistance are discussed.