Submitted to: Plant Disease
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/20/2003
Publication Date: 11/1/2003
Citation: Marshall, D.S., England, C.E. 2003. Effectiveness of new genes for resistance to wheat leaf rust.. Plant Disease. Interpretive Summary: Leaf rust is a widespread and highly damaging disease of wheat in the United States and worldwide. We studied the effectiveness of different forms of genetic resistance to the disease. We concluded that the resistance from one wheat ancestor (emmer wheat) was highly effective, yet the resistance from a different wheat ancestor (goat grass) caused the wheat plants to lose yield as a result of trying to resist infection. We also determined that resistance in the variety 'Sturdy' was effective in suppressing leaf rust, and that it became more effective as the plant became older.
Technical Abstract: The wheat leaf rust pathogen, Puccinia triticina, is a highly polymorphic fungus that typically adapts to cultivars possessing single gene resistance. New genes for resistance to leaf rust are needed for deployment into adapted wheat cultivars. We compared the adult-plant resistance present in 'Sturdy', the seedling and adult-plant resistance in 'TAM 302', and the leaf lesion mimic resistance in TX94D7206, to the newly discovered seedling gene resistance in TX97D6220 from Triticum monococcum, and that in TX97D6234 derived from T. cylindricum. The susceptible check cultivar was 'TAM 107'. Field experiments were conducted at four locations in 1999 and 3 locations in 2000. A split-plot design was used with fungicide treatment (tebuconazole) as whole plots and wheat genotype as sub-plots. The area under the disease progress curve was greatest for TAM 107, followed by TAM 302 and Sturdy. The lines TX94D7206, TX97D6220 and TX97D6234 remained immune to P. triticina over the two years of the study. However, the resistant reaction (heavy flecking) of TX94D7206 and TX97D6220 were significant enough to result in a grain yield reduction when fungicide treated and untreated plots were compared. These data indicate that the adult-plant resistance in Sturdy and the seedling resistance present in TX97D6234 were effective in reducing the level of leaf rust on the plants and in maintaining high grain yield levels.