Genetics of deoxynivalenol (DON) contamination caused by Fusarium head blight in hybrid rye.

T. Miedaner

miedaner@uni-hohenheim.de
Univ. of Hohenheim, State Plant Breeding Inst., D-70593 Stuttgart, Germany (Germany)

H. Wortmann

Hybro GmbH & Co. KG, D-76669 Bad Schönborn, Germany (Germany)

H. H. Geiger

Univ. of Hohenheim, Inst. of Plant Breeding, Seed Science, and Population Genetics, D-70593 Stuttgart, Germany (Germany)

Abstract

Head blight caused by Fusarium culmorum or F. graminearum affects all cereals including winter rye (Secale cereale L.). Besides yield and quality losses, grain is contaminated with the mycotoxin deoxynivalenol (DON) that is harmful to animals and humans. We analysed 76 self-fertile S₂ lines and their corresponding testcrosses for head blight resistance and DON concentration in the grain by inoculating them with an aggressive isolate of F. culmorum at two locations in Southwestern Germany in 2000. Disease severity at both locations was low with mean ratings from 2.7 to 3.4 on a 1-9 scale (1=healthy), but still DON occurred in considerable amounts (11.4 - 15.0 mg kg^-1). Genotypic variance was significant (P=0.01) in all instances, genotype-location interaction and error variances were more important for DON concentration resulting in a lower heritability of this trait. No association between S₂ lines and their testcrosses was found for head blight rating or DON concentration (r = 0.33 and 0.19, respectively). The coefficient of correlation between head blight rating and DON concentration was low for the S₂ lines and medium for the testcrosses (r=0.24 and 0.60, P=0.05 and P=0.01, resp.). The hybrid rye breeder should select predominantly on testcross performance. Selection for low head blight ratings should result in lower DON concentrations in the grain also. In later generations, DON should be analysed additionally to exploit the maximum selection gain possible.

Keywords:

Fusarium culmorum, hybrid breeding, mycotoxins, population parameters, Secale cereale