Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/19/2005
Publication Date: 4/7/2005
Citation: Obert, D.E., Fritz, A., Moran, J., Sukhwinder, S., Rudd, J.C., Menz, M.A. 2005. The identification and molecular tagging of a gene from pi 289824 conferring resistance to leaf rust (puccinia triticina) in wheat. Journal of Theoretical and Applied Genetics (2005) 110:1439-1444.
Interpretive Summary: Economic losses due to leaf rust in wheat are significant in major portions of the US Great Plains on a regular basis. Although effective fungicides exist, the low yield potential of wheat in the Great Plains wheat production areas, combined with low grain prices, prevent their use from being economically viable. The best option available to producers is the use of resistant cultivars. Typically, new varieties are released and if grown on significant acreage, are soon very susceptible to disease as new races of leaf rust develop virulence to the resistance gene. One option in overcoming this cycle is to develop new varieties with multiple sources of resistance. This would allow the variety to have a more durable resistance to diseases than varieties containing only one resistance gene. Varieties with multiple resistance genes have been released, but typically, one or more of the resistance genes in the variety have already been defeated by the pathogen when they are released in the latest variety. This occurs because the variety was not developed specifically for disease resistance, but more so because of the superior combining ability of the parents. This research was undertaken to identify new sources of leaf rust resistance in wheat with the ultimate, long-term objective of developing varieties with multiple resistance genes. This research identified leaf rust resistance in plant introductions contained in the National Small Grains Collection. One specific population, PI 289824, was then characterized and shown to contain one major resistance gene. The resistance gene identified here was screened against all prevalent races of leaf rust in the Great Plains area and showed resistance to all races. This gene was then tagged with a molecular marker which allows for its selection in segregating populations. This molecular marker will be used in conjunction with other markers to pyramid multiple sources of resistance into a single line in order to develop a more durable leaf rust resistant variety.
Technical Abstract: Abstract Host-plant resistance is the most economically viable and environmentally responsible method of control for Puccinia triticina, causal agent of leaf rust in wheat (Triticum aestivum L.). The identification and utilization of new resistance sources is critical to the continued development of improved cultivars as shifts in pathogen races cause widely deployed genes to be short lived. The objectives of this research were to identify and tag new leaf rust resistance genes. We report the identification of a gene from PI 289284 conferring resistance to all prevalent races of leaf rust in the Great Plains area of the USA. AFLP analyses resulted in the identification of a marker (P39M48-367) linked to resistance and provided sequence information for the development of an STS marker (TXW200) linked to a major disease resistance gene at a distance of 1.4cM. Keywords Wheat, leaf rust, resistance genes,