Characterization of wheat-Thinopyrum partial amphiploids for resistance tobarley yellow dwarf virus

Resistance to viruses such as wheat streak mosaic virus (WSMV) and barley y ellow dwarf virus (BYDV) is lacking in the primary gene pool of wheat, and therefore resistance is being introgressed from wild relatives such as Thin opyrum species. Resistance to BYDV was found in partial amphiploids (2n = 8 x = 56, consisting of 42 wheat and 14 alien chromosomes) obtained in hybrid s between wheat and both Th. intermedium and Th. ponticum. GISH analysis re vealed that the alien genomes of all but one resistant partial amphiploid w ere heterogeneous consisting of different ratios of St, J(s) and J genome c hromosomes obtained from the Thinopyrum parent. Translocated chromosomes co nsisting of Robertsonian, interstitial and terminal translocations between the different genomes were also detected. The tissue blot immunoassay showe d that partial amphiploids having resistance could be inoculated with the v irus but both virus multiplication and spread were completely blocked.