Title: Development of Isogenic Lines for Resistance to Septoria Tritici Blotch in Wheat Authors
Submitted to: International Wheat Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: March 10, 2010
Publication Date: June 1, 2010
Citation: Goodwin, S.B., Thompson, I.A. 2010. Development of Isogenic Lines for Resistance to Septoria Tritici Blotch in Wheat . International Wheat Conference Proceedings. Technical Abstract: Septoria tritici blotch (STB), caused by Mycosphaerella graminicola (asexual stage: Septoria tritici), is one of the most economically important diseases of wheat worldwide. During the past decade 13 genes for resistance to STB have been identified and mapped in the wheat genome. Analysis of resistance gene expression and utility for plant improvement programs would be improved if the resistance genes were isolated in a common susceptible background. To address this problem, a program was begun to backcross resistance genes Stb1-8 into two susceptible wheat cultivars. The program was initiated with all eight resistance genes but problems with the markers and phenotypic testing slowed progress for some genes. One cultivar appears to have the gene Stb6 and the small size of its leaves can complicate testing. To address this problem, a new method of inoculation was developed that avoids the need for high humidity for infection and gives better results. Work with genes Stb2 and Stb3 has proceeded the farthest and is now at the BC3 or BC4 generations. Analyses with different isolates have shown that resistance gene Stb3 is dominant, while Stb2 may be recessive when tested with an Indiana isolate of the pathogen. If the Stb2 results are confirmed it will be the first report of recessive resistance to STB. The Stb3 resistance so far has remained strong in the backcross progeny. Effectiveness of some of the other resistance genes has eroded slightly in the backcross lines, indicating that modifier genes may be necessary for complete resistance of some wheat cultivars. After six or seven generations of backcrossing the lines will be self pollinated to develop homozygous isolines that can be used to analyze the mechanism of resistance to STB in wheat.