Identification and Characterization Of Stem Rust Resistance In Wheat CV. Gage.

Wheat (Triticum spp.) stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), re-emerged as a devastating disease of wheat (Triticum aestivum L.) because of the virulent race Ug99 (TTKSK). Many modern wheat cultivars grown in Nebraska are susceptible to Ug99 or its derivative races with additional virulence. ‘Gage’, a USDA-University of Nebraska developed hard red winter wheat cultivar, was released in 1963 mainly for its excellent field resistance to leaf rust caused by Puccinia triticina and stem rust. However, its resistance has not been genetically characterized to be able to be used in breeding programs. For molecular marker and genetic analysis, we used F₂ generation and F_2:3 and F_4:5 families from crosses between Gage and the highly susceptible cultivar ’Bill Brown’. Inheritance of seedling and adult plant resistance to Pgt race QFCSC indicated that additional genes to Sr2 explain the stem rust resistance of Gage. Seedling and adult plant data confirmed that at least one dominant and one recessive gene are involved in Gage’s resistance.  Seedling resistance is acting independently of Sr2, which is effective only at the adult plant stage. We have identified potential molecular markers linked to seedling resistance.