Genetic Analysis Reveals Wheat- Phaeosphaeria nodorum Follows the Gene-for-Gene Hypothesis.

Stagonospora nodorum blotch (SNB), caused by Phaeosphaeria nodorum, is a major component of the leaf spotting disease complex of wheat in the Northern Great Plains of North America. This study was conducted, under controlled environmental conditions, to determine the inheritance of resistance to SNB in a diverse set of hexaploid and tetraploid wheat genotypes to two isolates of P. nodorum. Plants were inoculated at two to three-leaf stage with individual spore suspensions of isolates Kelvington-SK and Sn2000. Disease reaction was assessed  eight days after inoculation based on lesion-type scale. Tests of the F₁ and F₂ generations and F_2:3 or F_2:6 families indicate that a single recessive gene controlls resistance to isolate Kelvington-SK and this gene is likely to be located on chromosome 3A. Similarly, a single recessive gene located on chromosome 5B appears to control resistance to isolate Sn2000. Results of this study suggests that wheat-P. nodorum interaction may follow the toxin model of gene-for-gene hypothesis.