Inheritance of Stem Rust Resistance of Wheat Line Xing117 Selection.

Abstract

The wheat stem rust pathogen, Puccinia graminis f. sp. tritici (Pgt) can potentially devastate wheat (Triticum aestivum L.) crops and stem rust disease occurs in most wheat growing areas globally.  A new Pgt virulence genotype, Ug99, was identified in Uganda in 1999, and has been recognized as a major threat to wheat production. Resistant wheat cultivars have long been of primary importance to control disease epidemics. A stem rust resistant plant selection of the spring wheat line Xing117, from China, is moderately resistant to Indiana isolates of Pgt. The objectives of this research are to determine the inheritance of this novel source of stem rust resistance, determine the chromosomal location of the resistance and identify molecular markers that are closely linked to the stem rust resistance. A population of recombinant inbred lines (RIL) from the cross of Xing117 selection/OK3040 (susceptible) was developed and characterized for resistance to local isolates of Pgt in field tests in 2009 and 2010 at Lafayette, Indiana. Tests for resistance were carried out on the F_2:3 and F_5:6 families with Indiana isolates of Pgt. The Segregation ratio (resistant: segregating: susceptible) in both tests indicated that resistance of spring wheat line Xing117 selection is controlled by a single dominant gene. Several simple sequence repeat (SSR) markers, polymorphic on the resistant and susceptible parent lines, have been identified and identification of additional polymorphic markers is in progress. SSR markers that are polymorphic on the parent lines and resistant and susceptible bulks of, respectively, 8 RILs have been identified, and will be used to map the stem rust resistance of Xing117 selection.  Markers that co-segregate with the resistance will be useful for marker-assisted selection for this resistance in wheat improvement research.