June
2002
, Volume
15
, Number
6
Pages
587
-
597
Authors
Friederike
Trognitz
,
Patricia
Manosalva
,
Rene
Gysin
,
David
Niño-Liu
,
Reinhard
Simon
,
Ma.
del Rosario Herrera
,
Bodo
Trognitz
,
Marc
Ghislain
,
and
Rebecca
Nelson
Affiliations
International Potato Center, P.O. Box 1558, Lima 12, Peru
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RelatedArticle
Accepted 12 February 2002.
Abstract
Markers corresponding to 27 plant defense genes were tested for linkage disequilibrium with quantitative resistance to late blight in a diploid potato population that had been used for mapping quantitative trait loci (QTLs) for late blight resistance. Markers were detected by using (i) hybridization probes for plant defense genes, (ii) primer pairs amplifying conserved domains of resistance (R) genes, (iii) primers for defense genes and genes encoding transcriptional regulatory factors, and (iv) primers allowing amplification of sequences flanking plant defense genes by the ligation-mediated polymerase chain reaction. Markers were initially screened by using the most resistant and susceptible individuals of the population, and those markers showing different allele frequencies between the two groups were mapped. Among the 308 segregating bands detected, 24 loci (8%) corresponding to six defense gene families were associated with resistance at χ2 ≥ 13, the threshold established using the permutation test at P = 0.05. Loci corresponding to genes related to the phenylpropanoid pathway (phenylalanine ammonium lyase [PAL], chalcone isomerase [CHI], and chalcone synthase [CHS]), loci related to WRKY regulatory genes, and other defense genes (osmotin and a Phytophthora infestans-induced cytochrome P450) were significantly associated with quantitative disease resistance. A subset of markers was tested on the mapping population of 94 individuals. Ten defense-related markers were clustered at a QTL on chromosome III, and three defense-related markers were located at a broad QTL on chromosome XII. The association of candidate genes with QTLs is a step toward understanding the molecular basis of quantitative resistance to an important plant disease.
JnArticleKeywords
Additional keywords:
gene mapping
.
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ArticleCopyright
© 2002 The American Phytopathological Society