Molecular genetic variability, within a population of Mycosphaerella graminicola, cause of Septoria tritici leaf blotch of wheat
The pathogen Mycosphaerella graminicola (anamorph Septoria tritici), causes speckled leaf blotch of wheat and has worldwide distribution. Information about genetic variability of the pathogen population is useful for development of disease management strategies. In this study 90 isolates of M. graminicola were collected using a hierarchical sampling procedure from a single wheat field and the genomic DNA of isolates were extracted. RAPD analysis was conducted using 15 random primers, according to standard protocols. Forty molecular phenotypes were detected which phenotype 1 had the highest frequency within the population. The total genotypic diversity was estimated as 0.94.When it was partitioned into within and among location components, 91% of the genetic diversity occurred within locations and only 9% occurred among locations. Low degree of variability among locations and high degree of variability within locations, points that, most likely the source of primary inoculum was air-borne ascospores, which were dispersed evenly across the field. This finding suggests that, the sexual stage of M. graminicola, occurs in Saskatchewan, although it has not yet been reported from Canada. High degree of genetic variability implies that most likely the pathogen will adapt rapidly to single gene resistance sources, therefore, in breeding for disease resistance, emphasis should be given to non- race specific resistance.
genotypic diversity, RAPDs, molecular phenotypes, non-race specific resistance
Soils and Crops Workshop