| The objective of the first part of this research was to determine the ability of molecular markers for alleles at the major vernalization (VRN) loci in wheat, Vrn-A1, Vrn-B1 and Vrn-D1, to predict growth habit and cold tolerance phenotypes of near isogenic lines (NILs) varying at the vernalization loci.;Two sets of 32 NILs each were developed with winter wheat cultivars Daws and Wanser as recurrent parents and Triple Dirk NILs as donor parents for the individual VRN alleles at the three orthologous Vrn loci. There were significant differences in cold tolerance between Daws spring and winter NILs at the Vrn-A1 locus but did not at the Vrn-B1 and Vrn-D1 loci. Wanser NILs for spring and winter habit differed significantly for cold tolerance at the Vrn-A1, Vrn-B1 and for one genotype at the Vrn-D1 locus, indicating that Vrn-B1 and Vrn-D1 loci are also important for regulating cold tolerance. Polymorphisms at the VA1-FNA1-R Cleavage Amplified Polymorphic Sequence (CAPS) marker were associated with the Vrn-A1 alleles and differences in growth habit and cold hardiness. The marker for Vrn-A1 can be used to screen germplasm for growth habit and cold tolerance. The markers specific for Vrn-B1 and Vrn-D1 alleles did not consistently show any relationship to the growth habit and cold tolerance and hence need further evaluation.;The second objective of the research was to map QTLs for cold temperature tolerance in two winter wheat crosses. This study is the first to report the use of winter x winter wheat crosses to identify QTLs for cold tolerance, which will eliminate the pleiotropic effect of major genes for vernalization and photoperiod on cold tolerance.;Stripe rust disease of wheat caused by the fungus Puccinia striiformis Westend f.sp.tritici Eriks is one of the most important biotic stresses affecting the U.S. Pacific Northwest. The third objective was to characterize stripe rust resistance of two soft white winter wheat populations WA7697 x A9622 and WA7697 x A96330. The parents and F1s were evaluated for all-stage resistance in the greenhouse using 21 races of stripe rust. The parent WA7697 was resistant to 16 of the 21 races, used to screen for seedling resistance. WA7697 was susceptible to only two races, PST-23 and PST-37, and had intermediate reaction to three races. The two other parents, A9622 and A96330, were resistant to 21 and 17 races, respectively.;Ninety three selections that are highly resistant to new races of stripe rust that have been prevalent in the US since 2001, have been identified in this study. After further characterization for agronomic qualities these progenies can be used as a source of stripe rust resistance. (Abstract shortened by UMI.)... |
