| Abstrakt: |
Fusarium head blight (FHB) caused mainly by Fusarium graminearum, is a devastating disease of wheat and other small grain cereals in humid and semi-humid areas. Understanding the host-pathogen interaction and realizing the relationship between the host and pathogen is an important issue in breeding programs. In this study, the interaction between F. graminearumisolates causing FHB and wheat genotypes was investigated by inoculating two representative isolates of the fungus from each of Canada, Iran, and CIMMYT, Mexico on five wheat genotypes with different levels of resistance to FHB from each of the mentioned origins. Results showed significant differences in aggressiveness of Fusariumisolates inoculated on wheat genotypes. While CIMMYT isolates produced the least disease severities on wheat genotypes tested (8.1–10.0%), the isolates from Canada and Iran severely infected the genotypes (43.2–59.3%). Significant differences were also observed in reaction of wheat genotypes to Fusariumisolates, and four genotypes including 93FHB37 (Canada), SHA3/CBRD (CIMMYT), N-83-6 (Iran), and NG8675/NING8645 (CIMMYT), with disease severities from 8.0 to 9.0%, were consistently among the most resistant ones. Our results also showed significant interactions (P< 0.0001) between Fusariumisolates and wheat genotypes used. Due to significant differences in disease rate caused by Fusariumisolates in wheat genotypes, it seems that all isolates, regardless of their rate of aggressiveness, will be able to differentiate wheat genotypes in terms of resistance/susceptibility. However, in wheat breeding programs, the criteria used for selecting resistant genotypes, have to be considered in appropriate to the rate of aggressiveness of the isolate used. |
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