MOLECULAR VERIFICATION AND CHARACTERIZATION OF BYDV-RESISTANT GERM PLASMS DERIVED FROM HYBRIDS OF WHEAT WITH THINOPYRUM-PONTICUM AND THINOPYRUM-INTERMEDIUM

Twenty-five partial amphiploids (2n=8x=56), which were derived from hy brids of wheat (Triticum aestivum L.) with either Thinopyrum ponticum (Podpera) Liu & Wang, Th. intermedium (Host) Barkworth & D. Dewey, or Th. junceum (L.) A. Love, were assayed for resistance to BYDV serotype PAV by slot-blot hybridization with viral cDNA of a partial coat prot ein gene. Three immune lines were found among seven partial amphiploid s involving Th. ponticum. Seven highly resistant lines were found in t en partial amphiploids involving Th. intermedium. None of eight partia l amphiploids or 13 addition lines of Chinese Spring - Th. junceum wer e resistant to BYDV. Ge nomic in situ hybridization demonstrated that all of the resistant partial amphiploids, except TAF46, carried an ali en genome most closely related to St, whether it was derived from Th. ponticum or Th. intermedium. The two partial amphiploids carrying an i ntact E genome of Th. ponticum are very susceptible to BYDV-PAV. In TA F46, which contains three pairs of St- and four pairs of E-genome chro mosomes, the gene for BYDV resistance has been located to a modified 7 St chromosome in the addition line L1. This indicates that BYDV resist ance in perennial polyploid parents, i.e., Th. ponticum and Th. interm edium, of these partial amphiploids is probably controlled by a gene(s ) located on the St-genome chromosome(s).