Additional genetic factors of resistance to stem rust , leaf rust and powdery mildew from Dasypyrum villosum

The gene diversity for rust and powdery mildew disease resistance is very narrow in durum wheat varieties. The chromosome 6V#4 from D. villosum contains genes for broad-spectrum resistance to diseases caused by Puccinia graminis f. sp. tritici (Pgt) (stem rust), Puccinia triticina Eriks. (Pt) (leaf rust), Puccinia striiformis f. sp. tritici Er ks. (Pst) (stripe rust), and Blumeria graminis f. sp. tritici (Bgt) (powdery mildew). Progenies from the cross of a durum wheat F7 line (derived from ‘Cappelli’ × ‘Peleo’) with CS-DA6V#4 (a disomic addition line of chromosome 6V#4 to the T. aestivum ‘Chinese Spring’ genomic background), were backcrossed to durum wheat lines in order to selected plants for resistance to airborne Bgt inoculum in the greenhouse as a marker for the presence of chromosme 6V#4. The chromosome number of the progenies of two of those plants, ‘46768.1’ and ‘491-50.2’, ranged from 28 to 36 with an average of 2n=31, and the presence of 6V#4 was revealed by GISH. The seedlings of the two progenies were tested for response to different races (isolates) of Pgt and Pt under controlled experiments at CAR-HAS in Hungary, and to Pgt and Bgt under controlled experiments at CRA-QCE in Italy. All the seedlings from the ‘467-68.1’ and ‘491-50.2’ progenies, were resistant to Pt and Bgt, and the ‘467-68.1’ progeny displayed resistance to Pgt. The NAU/Xibao15902 molecular marker linked to Pm21, a putative locus in 6V#4 with a gene determining resistance to Bgt, was detected in all the seedlings of the two progenies. Plants with chromosome number ranging from 28 to 30 are now ield tested and are being prepared for the inal round of backcross to the ‘4.5.1’ durum wheat recurrent parent.