title: Plant defense genes associated with quantitative resistance to potato late blight in Solanum phureja x dihaploid S. tuberosum hybrids.
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 chi2 > or = 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.
authors.affiliation: International Potato Center, Lima, Peru.
authors.forename: Friederike
authors.initials: F
authors.lastname: Trognitz
authors.forename: Patricia
authors.initials: P
authors.lastname: Manosalva
authors.forename: Rene
authors.initials: R
authors.lastname: Gysin
authors.forename: David
authors.initials: D
authors.lastname: Niñio-Liu
authors.forename: Reinhard
authors.initials: R
authors.lastname: Simon
authors.forename: Ma Rosario
authors.initials: MR
authors.lastname: del Herrera
authors.forename: Bodo
authors.initials: B
authors.lastname: Trognitz
authors.forename: Marc
authors.initials: M
authors.lastname: Ghislain
authors.forename: Rebecca
authors.initials: R
authors.lastname: Nelson
mesh_terms: D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism; D002874:Chromosome Mapping; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D005819:Genetic Markers; D006823:Hybrid Vigor / Q000235:genetics; D006824:Hybridization, Genetic / Q000235:genetics*; D007113:Immunity, Innate / Q000235:genetics; D019753:Intramolecular Lyases / Q000235:genetics / Q000378:metabolism; D010650:Phenylalanine Ammonia-Lyase / Q000235:genetics / Q000378:metabolism; D010838:Phytophthora / Q000254:growth & development*; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics; D040641:Quantitative Trait Loci; D011198:Solanum tuberosum / Q000235:genetics* / Q000382:microbiology; D014157:Transcription Factors / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; D005819:Genetic Markers; D010940:Plant Proteins; D014157:Transcription Factors; D003577:Cytochrome P-450 Enzyme System; D000217:Acyltransferases; C020141:flavanone synthetase; D010650:Phenylalanine Ammonia-Lyase; D019753:Intramolecular Lyases; C019865:chalcone isomerase