Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/14/2010
Publication Date: 3/1/2011
Citation: Kolmer, J.A., Garvin, D.F., Jin, Y. 2011. Expression of a Thatcher wheat adult plant stem rust resistance QTL on chromosome arm 2BL is enhanced by Lr34. Crop Science. 51(2):526-533.
Interpretive Summary: Wheat is attacked by a fungus called Puccinia graminis that causes the disease wheat stem rust. The wheat cultivar Thatcher, deveoloped at the University of Minnesota in the 1930s has had good resistance to stem rust for many years and has been used extensively in wheat breeding programs in the U.S. This research was done to determine the chromosome location of the stem rust resistance in Thatcher. The stem rust resistance in Thatcher was best expressed when plants of Thatcher also had the gene Lr34 that conditions resistance to the leaf rust pathogen Puccinia triticina. The Thatcher stem rust resistance was located on the long arm of chromosome 2B in wheat. This information will be useful for development of wheat cultivars with stem and leaf rust resistance.
Technical Abstract: An F6 recombinant inbred line (RIL) spring wheat population derived from RL6071, a stem rust susceptible line and RL6058, a backcross line of Thatcher wheat with Lr34 that is highly resistant to stem rust, was evaluated for adult plant stem rust resistance in North Dakota in 1999, and in Kenya in 2007 and 2008. In all three tests, most RILs that exhibited low stem rust severity had Lr34 and most lines that had high disease severity lacked Lr34. Molecular mapping with DArT and SSR markers detected a QTL for adult plant stem rust resistance on chromosome arm 2BL. RILs with both Lr34 and DArT marker wPt5044 on 2BL had significantly lower stem rust severites compared to lines that only had Lr34 in North Dakota 1999 and Kenya 2008. Marker wPt5044 alone did not significantly increase stem rust resistance. The QTL region on 2BL was not associated with any previously mapped Thatcher seedling stem rust resistance genes. The stem rust resistance in Thatcher enhanced by the presence of Lr34 is effective to different races in North America and Kenya and mapped to the same QTL.