Enhancing Fusarium crown rot resistance of durum wheat by introgressing chromosome segments from hexaploid wheat

Compared with hexaploid wheat, tetraploid durum is more susceptible to Fusarium crown rot (FCR) infection. The feasibility of enhancing FCR resistance in durum wheat by introgressing chromosome segments of hexaploid wheat was investigated by generating and analysing a backcross population derived from a susceptible durum wheat variety 'Bellaroi' (recurrent parent) and a resistant hexaploid genotype 'CSCR6' (donor parent). Together with a few scattered segments on various chromosomes, segments of a large section of the donor chromosome 6B showed a significant effect in enhancing FCR resistance in the durum background. However, a known major locus on the donor 3BL conferring high level of resistance to FCR in hexaploid wheat failed to provide any improvement in resistance than that of the genome average once it was introduced into the durum wheat. A small proportion of the backcross population gave similar resistance to the bread wheat variety 'Kennedy', a level of FCR resistance acceptable to durum growers. These lines share a 4B segment from the hexaploid donor, although the segment was not among those with the largest individual effect across the whole population. These results show that it is feasible to improve FCR resistance of durum wheat by exploiting hexaploid chromosome segments, although resistance loci of the hexaploid wheat may not function properly in durum backgrounds.