|Goodwin, Stephen - Steve|
|Van Der Lee, T|
|De Weerdt, Marianne|
Submitted to: Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/16/2002
Publication Date: N/A
Interpretive Summary: Septoria tritici leaf blotch, caused by the fungal pathogen Mycosphaerella graminicola, is an economically important disease of wheat with a worldwide distribution. Finding an effective control for this disease has been hampered by a lack of genetic tools to analyze the pathogen. One tool that is needed greatly is a genetic map. So far, no genetic maps are available for M. graminicola, or even for related species in the same genus, family or order. To correct this deficiency, two types of molecular data were combined in a collaborative research project to produce a high-density genetic linkage map for M. graminicola. The map contains more than 280 markers organized into 23 groups that may correspond to chromosomes. This is the first genetic linkage map for any species in the genus Mycosphaerella or the family Mycosphaerellaceae. The utility of the map was demonstrated by finding molecular markers linked to two traits of biological interest, virulence and mating type. This map will be very useful to geneticists studying the biology of M. graminicola, and can be used to find molecular markers on the same segment of a chromosome containing almost any gene of biological interest. Molecular biologists can then use the map to help clone these genes. The increased understanding of the genetics of M. graminicola provided by the genetic map may help guide plant pathologists as they search for improved methods to suppress this economically important pathogen.
Technical Abstract: An F1 mapping population of the septoria tritici blotch pathogen of wheat, Mycosphaerella graminicola, was generated by crossing the two Dutch field isolates IPO323 and IPO94269. AFLP and RAPD marker data sets were combined to produce a high-density genetic linkage map. The final map contained 223 AFLP and 57 RAPD markers, plus the biological traits mating type and avirulence, in 23 linkage groups spanning 1216 cM. Many AFLPs and some RAPD markers were clustered. When markers were reduced to one per cluster, 229 unique positions were mapped, with an average distance of 5.3 cM between markers. This should correspond to an average physical distance of one marker every 136 kb throughout the genome. Because M. graminicola probably has 17-18 chromosomes, at least five of the 23 linkage groups probably will need to be combined with others once additional markers are added to the map. This was confirmed with pulsed-field gel analysis; probes derived from two of the smallest linkage groups hybridized to two of the largest chromosome-sized bands, revealing a discrepancy between physical and genetic distance. The utility of the map was demonstrated by identifying molecular markers tightly linked to two genes of biological interest, mating type and avirulence. Bulked segregant analysis was used to identify additional molecular markers closely linked to these traits. This is the first genetic linkage map for any species in the genus Mycosphaerella or the family Mycosphaerellaceae.