ARS | Publication request: Population genetic structure of Phaeosphaeria nodorum in the central United States

Submitted to: Septoria International Workshop Proceedings
Publication Type: Abstract
Publication Acceptance Date: June 7, 2008
Publication Date: August 18, 2008
Citation: Adhikari, T.B., Ali, S., Burlakoti, R.R., Singh, P.K., Mergoum, M., Goodwin, S.B. 2008. Population genetic structure of Phaeosphaeria nodorum in the central United States. Septoria International Workshop Proceedings. Available at: http://www.path.ethz.ch/news/conferences/Mycosphaerella_Ascona_2007/00024_posterabstract.pdf

Technical Abstract: Phaeosphaeria nodorum causes Stagonospora nodorum blotch (SNB) and occurs in most of the wheat-producing states in the United States. However, little is known of its population biology in the central United States. We determined the genetic structure of 12 populations of P. nodorum (five from hard red spring wheat cultivars in Minnesota and North Dakota and seven from soft red winter wheat in Indiana and Ohio) by analyzing polymorphisms at five microsatellite or simple-sequence repeat (SSR) loci and the mating type locus. Although a few clones were identified, most P. nodorum populations had high levels of gene (HS = 0.175 to 0.519) and genotype (D = 0.600 to 0.972) diversity. Gene diversity was higher among isolates collected from spring wheat cultivars in North Dakota and Minnesota (mean HS = 0.503) than in those from winter wheat cultivars in Indiana and Ohio (HS = 0.269). Clone-corrected data sets showed equal frequencies of each mating type in both regional and local populations, indicating that sexual recombination may occur regularly. However, significant gametic disequilibrium occurred in three of the four populations from North Dakota, and there was genetic differentiation both within and among locations. Genetic differentiation between the hard red spring and soft red winter wheat production regions was moderate (FST = 0.168). These results support the hypothesis that sexual reproduction occurs in P. nodorum populations in the major wheat-growing regions of the central United States, and that gene flow among regions is not sufficient to prevent genetic differentiation.