|Hu, Xueyi - USDA-ARS|
|Shaner, Gregory - PURDUE UNIVERSITY|
Submitted to: Wheat Genetics International Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: April 16, 1998
Publication Date: N/A
Interpretive Summary: Septoria tritici blotch, caused by the fungus Mycosphaerella graminicola, is one of the most important diseases of wheat in the midwestern United States, causing millions of dollars in losses every year. Attempts to control the disease using host resistance have had only limited success, primarily because of confusion about the number of genes controlling the resistance response and their locations on the genetic map of wheat. Breeding for increased resistance also is hampered because resistance testing is difficult, time consuming, and requires specialized knowledge of plant pathology. The purpose of this study was to find molecular markers linked to a gene for resistance to the disease. A population of wheat lines was developed from a cross between a resistant parent and a susceptible parent. Genetic analysis of 106 progeny lines indicated that septoria resistance is controlled by a single dominant gene. Analysis with molecular markers revealed many that potentially were linked to the resistance gene. These markers were then scored on the complete progeny population to determine the true linkage relationships. The analysis confirmed that one marker was linked to the resistance gene. Work is now in progress to convert this marker into a form that can be used more easily by others. Work also is under way to find additional markers linked to the resistance gene and to determine its location on the wheat genetic map. This marker will be useful to plant breeders as they attempt to move the resistance into other wheat breeding lines, and to plant pathologists studying the genetic basis of septoria tritici blotch resistance in wheat.
Technical Abstract: Septoria leaf blotch caused by Mycosphaerella graminicola (anamorph Septoria tritici) is one of the most important diseases of wheat in the midwestern United States. Some host resistance is available, but the number of genes involved and their map locations are not known. Furthermore, testing for resistance is difficult and time consuming. To determine the genetic basis of Septoria resistance and to identify molecular markers linked to a putative resistance gene, a population of recombinant inbred lines (RILs) was developed from a cross between the resistant line 72626E2-12-9-1 and the susceptible cultivar Arthur. Genetic analysis of 106 RILs at the F6 generation indicated that the resistance in line 72626E2-12-9-1 is controlled by a single dominant gene. Bulked segregant analysis of resistant and susceptible RILs was performed with amplified fragment length polymorphism (AFLP) analysis. In addition, a number of simple sequence repeat (SSR) or microsatellite markers was teste for potential linkage with the resistance locus. Potentially linked AFLP markers identified from the bulked segregant analysis were scored on the complete RIL population to determine the linkage relationships. One AFLP marker was loosely linked to the resistance gene at a map distance of approximately 10 cM. None of the SSR markers was linked. Conversion of this marker into a sequence tagged site, genetic mapping of the resistance gene, and bulked segregant analysis with additional primer combinations to find more markers linked to the resistance gene are currently in progress.