Wheat (Triticum spp.) stem rust, caused by Puccinia graminis f. sp. tritici Eriks. and E. Henn. (Pgt), re-emerged as a devastating disease of wheat because of virulent race Ug99 (TTKSK). Many bread wheat (T. aestivum L.) cultivars grown in North America are susceptible to Ug99 or its derivative races that carry additional virulence. ‘Gage’ was released in 1963 mainly for its excellent field resistance to leaf rust (caused by Puccinia triticina Eriks) and stem rust. However, Gage's resistance has not been genetically characterized, which would facilitate its use in breeding programs. To better define the nature of the resistance in Gage, we created an F2 population and the corresponding F2:3 and F4:5 families from crosses between Gage and stem rust susceptible cultivar ‘Bill Brown’. Inheritance of resistance to Pgt race QFCSC and molecular marker analysis indicated that Sr2 and additional genes explain the stem rust resistance of Gage. Using seedling plant infection types from the F2, F2:3, and F4:5 families, we found that at least one dominant and, most likely, one recessive gene are involved in Gage's resistance. Seedling resistance genes acted independently of Sr2 since Sr2 is effective only at the adult plant stage.
Bibliographical noteFunding Information:
T. Kumssa was funded by a Monsanto Beachell-Borlaug International Scholarship. Partial funding for P.S. Baenziger is from Hatch project NEB-22-328, USDA, CSREES NRICAP grant number 2006-55606-16629, USDA OREI 2007-51300-03785, USDA-NIFA Triticeae Coordinated Agricultural Project, 2011-68002-30029, USDA under Agreement No. 59-0790-4-092 which is a cooperative project with the U.S. Wheat and Barley Scab Initiative, Nebraska Wheat Development, Utilization, and Marketing Board, and BASF Corporation. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the views of the USDA. Mention of trade names does not constituted endorsement by the USDA.