Molecular cytological characterization of two novel durum--Thinopyrum intermedium partial amphiploids with resistance to leaf rust, stem rust and Fusarium head blight.

Thinopyrum intermedium, a wild relative of wheat, is an excellent source of disease resistance. Two novel partial amphiploids, 08-47-50 and 08-53-55 (2n = 6x = 42), were developed from wide crosses between durum wheat and Th. intermedium. Meiotic analysis showed that pollen mother cells of the two partial amphiploids formed an average 20.49 bivalents for 08-47-50 and 20.67 bivalents for 08-53-55, indicating that they are basically cytologically stable. GISH analysis revealed that the two partial amphiploids carried different chromosome compositions. 08-47-50 had fourteen chromosomes from Th. intermedium and its alien chromosomes included six St-, four E(e) - and four E(e)-St translocated chromosomes, whereas 08-53-55 had four St- and ten E(e)-St translocated chromosomes. Fungal disease evaluation indicated that both partial amphiploids had a high level of resistance to FHB, leaf rust and stem rust race Ug99. These two novel partial amphiploids with multiple disease resistance could be used as a new source of multiple disease resistance in bread wheat and durum wheat breeding programs.