title: Validation of quantitative trait loci for Ascochyta blight resistance in pea ( Pisum sativum L.), using populations from two crosses.
abstract: Resistance to Ascochyta blight of pea was genetically characterized by mapping quantitative trait loci (QTLs) using two crosses, 3147-A26 (A26, partially resistant) x cultivar Rovar (susceptible) and 3148-A88 (A88, partially resistant) x Rovar, with the aim of developing an increased understanding of the genetics of resistance and of identifying linked molecular markers that may be used to develop resistant germplasm. Molecular linkage maps for both crosses were aligned so that the results of QTL mapping could be compared. Ascochyta blight disease severity in response to natural epidemics was measured in field trials conducted in Western Australia and New Zealand. Eleven putative QTLs for Ascochyta blight resistance were identified from the A26 x Rovar population and 14 putative QTLs from the A88 x Rovar population. Six QTLs were associated with the same genomic regions in both populations. These QTLs reside on linkage groups II, III, IV, V, and VII (two QTLs). The severity of Ascochyta blight disease symptoms on pea increases during field epidemics as plants mature; therefore, QTLs for plant reproductive maturity were mapped. Six QTLs were detected for plant maturity in the A26 x Rovar population, while five plant maturity QTLs were mapped in the A88 x Rovar population. QTLs for plant maturity coincide with Ascochyta blight resistance QTLs in four genomic regions, on linkage groups II (two regions), III, and V. The plant maturity and Ascochyta blight resistance QTLs on III were linked in repulsion phase. Therefore, the coincidence of these QTLs may be explained by linkage of distinct loci for the two traits. The QTLs on linkage groups II and V were linked in coupling phase; therefore, linked QTLs for resistance and maturity may be present in these regions, or the Ascochyta blight resistance QTLs detected in these regions are the result of pleiotropic effects of plant-maturity genetic loci.
authors.affiliation: Crop and Food Research, P.O. Box 4704 Christchurch, New Zealand. timmermang@crop.cri.nz
authors.forename: Gail M
authors.initials: GM
authors.lastname: Timmerman-Vaughan
authors.forename: Tonya J
authors.initials: TJ
authors.lastname: Frew
authors.forename: Ruth
authors.initials: R
authors.lastname: Butler
authors.forename: Sarah
authors.initials: S
authors.lastname: Murray
authors.forename: Margy
authors.initials: M
authors.lastname: Gilpin
authors.forename: Karla
authors.initials: K
authors.lastname: Falloon
authors.forename: Paul
authors.initials: P
authors.lastname: Johnston
authors.forename: Michael B
authors.initials: MB
authors.lastname: Lakeman
authors.forename: Adrian
authors.initials: A
authors.lastname: Russell
authors.forename: Tanveer
authors.initials: T
authors.lastname: Khan
mesh_terms: D001203:Ascomycota; D002874:Chromosome Mapping; D018556:Crops, Agricultural / Q000235:genetics*; D003433:Crosses, Genetic; D017931:DNA Primers; D007113:Immunity, Innate / Q000235:genetics*; D009520:New Zealand; D021141:Nucleic Acid Amplification Techniques; D018532:Pisum sativum / Q000235:genetics*; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology*; D012150:Polymorphism, Restriction Fragment Length; D040641:Quantitative Trait Loci; D019105:Random Amplified Polymorphic DNA Technique; D012098:Reproduction / Q000235:genetics; D016324:Sequence Tagged Sites; D014904:Western Australia
chemical_list: D017931:DNA Primers