AN OAT SPECIES LACKING AVENACIN IS SUSCEPTIBLE TO INFECTION BY GAEUMANNOMYCES-GRAMINIS VAR TRITICI

The saponin avenacin is a pre-formed inhibitor of fungal growth and occurs in the roots of Avena species. Gaeumannomyces graminis var. tritici (the causal agent of rake-all disease of wheat) is unable to attack oats, apparently because of the sensitivity of this fungus to avenacin. After screening a wide range of oat genotypes, one species, Avena longiglumis, was identified which lacked detectable levels of avenacin and was susceptible to infection by G. graminis var. tritici, supporting a role for avenacin as a determinant of resistance to fungal attack.