Characterization of a potential source of barley yellow dwarf virus resistance for wheat

Resistance to barley yellow dwarf virus (BYDV) has been described in lines derived from crosses between wheat and Thinopyrum intermedium. The resistance in one such line, Zhong 4, originating in China, was expressed against two different serotypes of BYDV as measured by accumulation of virus in infected seedlings. F 1 hybrids between wheat (2n = 42) and Zhong 4 (2n = 56) had 49 chromosomes and intermediate levels of virus when compared to the parent lines. Cytological and molecular hybridization studies suggested that the BYDV resistance in Zhong 4 is carried on a set of seven pairs of nonwheat chromosomes that derived from a combination of the E and X genomes present in Th. intermedium.Key words: Barley yellow dwarf virus, wheat, ribosomal DNA, Agropyron intermedium, Thinopyrum intermedium, virus resistance.