Effects of genotype and genotype-enviromment interaction on deoxynivalenolaccumulation and resistance to Fusarium head blight in rye, triticale, andwheat

Fusarium culmorum is one of the most important Fusarium species causing hea d blight infections in wheat, rye, and triticale. It is known as a potent m ycotoxin producer with deoxynivalenol (DON), 3-acetyl deoxynivalenol (3-ADO N), and nivalenol (NIV) being the most prevalent toxins. In this study, the effect of winter cereal species, host genotype, and environment on DON acc umulation and Fusarium head blight (FHB) was analysed by inoculating 12 rye , eight wheat, and six triticale genotypes of different resistance levels w ith a DON-producing isolate at three locations in 2 years (six environments ). Seven resistance traits were assessed, including head blight rating and relative plot yield. In addition, ergosterol, DON and 3-ADON contents in th e grain were determined. A growth-chamber experiment with an artificially s ynchronized flowering date was also conducted with a subset of two rye, whe at and triticale genotypes. Although rye genotypes were, on average, affect ed by Fusarium infections much the same as wheat genotypes, wheat accumulat ed twice as much DON as rye. Triticale was least affected and the grain con tained slightly more DON than rye. In the growth-chamber experiment, wheat and rye again showed similar head blight ratings, but rye had a somewhat lo wer relative head weight and a DON content nine times lower than wheat (3.9 vs. 35.3 mg/kg). Triticale was least susceptible with a five times lower D ON content than wheat. Significant (P = 0.01) genotypic variation for DON a ccumulation existed in wheat and rye. The differences between and within ce real species in the held experiments were highly influenced by environment for resistance traits and mycotoxin contents. Nevertheless, mean mycotoxin content of the grain could not be associated with general weather condition s in the individual environments. Strong genotype-environment interactions were found for all cereal species. This was mainly due to three wheat varie ties and one rye genotype being environmentally extremely unstable. The mor e resistant entries, however, showed a higher environmental stability of FH B resistance and tolerance to DON accumulation. Correlations between resist ance traits and DON content were high in wheat (P = 0.01), with the most re sistant varieties also accumulating less DON, but with variability in rye. In conclusion, the medium to large genotypic variation in wheat and rye off ers good possibilities for reducing DON content in the grains by resistance selection. Large confounding effects caused by the environment will requir e multiple locations and/or years to evaluate FHB resistance and mycotoxin accumulation.