Identification of type I resistance to Fusarium head blight controlled by a major gene located on chromosome 4A of Triticum macha.

Using a set of 21 substitution lines of Triticum macha in a 'Hobbit Sib' background, it was previously demonstrated that chromosome 4A of T. macha carries significant resistance to Fusarium head blight. In the present study, the T. macha 4A resistance was further characterized in a 'Hobbit Sib' (T. macha 4A) single-recombinant chromosome doubled haploid (DH) population. Lines were phenotyped for disease resistance, yield components and deoxynivalenol (DON) mycotoxin content over two consecutive seasons. Both resistance to spread and resistance to initial infection were examined, and it was established that the resistance residing on T. macha 4A is predominantly of type I (resistance to initial infection). It was demonstrated that this type I resistance significantly lowered levels of DON accumulation in the grain and improved yield components under high disease pressure. Genotyping the DH lines using microsatellite genetic markers enabled the location of the gene(s) for resistance to be assigned to a region of the short arm of chromosome 4A, distal to microsatellite marker Xgwm601 and co-segregating with microsatellite marker Xgwm165 in this population.