Submitted to: Fungal Genetics Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 1/7/2005
Publication Date: 3/15/2005
Citation: Goodwin, S.B., Cavaletto, J.R., Lee, T.V., Hekkert, B.T., Kema, G.H. 2005. Identification from an EST database and genetic mapping of microsatellites in Mycosphaerella graminicola. Fungal Genetics Newsletter. Fungal Genetics Conference Proceedings, March 15-19, 2005, Pacific Grove, CA. 51(S):154.
Technical Abstract: Mycosphaerella graminicola, the cause of septoria tritici blotch of wheat, is developing rapidly as a model for fungi in the order Dothideales. Further development of the genetics of this organism would be facilitated by the availability of microsatellite or simple-sequence repeat (SSR) markers. However, only nine SSR loci have been identified so far in M. graminicola, and none has been mapped. To identify additional SSR loci, an EST database from M. graminicola was scanned for di- and trinucleotides repeated six or more times. Among more than 30,000 EST sequences screened, 109 possible SSR loci were identified. Primers flanking 99 of these SSRs were developed and tested for amplification and polymorphism on the two Dutch parents of the standard M. graminicola mapping population, one isolate from North Africa, and two from North America. Seventy-seven of the 99 primer pairs generated an easily scored banding pattern and 51 were polymorphic among the five field isolates tested. Among these 51 loci, 23 were polymorphic between the parents of the mapping population; 21 of these plus two previously published microsatellites were integrated into the existing genetic map. These 23 SSR loci mapped to 12 of the 22 linkage groups, and reduced the number of linkage groups in the previous map by three. Most (66%) of the primer pairs also amplified bands in the closely related barley pathogen Septoria passerinii, but only six were polymorphic among the four field isolates tested. The EST database provided an excellent source of new SSRs, some of which also may be useful in closely related species. These markers are highly polymorphic (up to 4 alleles per locus) and can be multiplexed to facilitate integration of the different types of genetic analysis performed on this important plant pathogen.