MOLECULAR CHARACTERIZATION OF THE GENOME COMPOSITION OF PARTIAL AMPHIPLOIDS DERIVED FROM TRITICUM-AESTIVUM X THINOPYRUM-PONTICUM AND TRITICUM-AESTIVUM X TH-INTERMEDIUM AS SOURCES OF RESISTANCE TO WHEAT STREAK MOSAIC-VIRUS AND ITS VECTOR, ACERIA-TOSICHELLA

Wheat streak mosaic virus (WSMV), vectored by the wheat curl mite (WCM ), is one of the most important viral diseases of wheat (Triticum aest ivum) in the world. Genetic resistance to WSMV and the WCM does not ex ist in wheat. Resistance to WSMV and the WCM was evaluated in five dif ferent partial amphiploids namely Agrotana, OK7211542, ORRPX, Zhong 5 and TAF 46, which were derived from hybrids of wheat with decaploid Th inopyrum ponticum or with hexaploid Th. intermedium. Agrotana was show n to be immune to WSMV and the WCM; the other four partial amphiploids were susceptible to the WCM. Genomic in situ hybridization (GISH) usi ng genomic DNA probes from Th. elongatum (EE, 2n = 14), Th. bessarabic um (JJ, 2n = 14), Pseudoroegneria strigosa (SS, 2n = 14) and T. aestiv um (AABBDD, 2n = 42) demonstrated that three of the partial amphiploid s, Agrotana, OK7211542 and ORRPX, have almost identical alien genome c onstitutions: all have 16 alien chromosomes, with 8 chromosomes being closely related to the J(s) genome and 8 chromosomes belonging to the E or J genomes and no evidence of any S-genome chromosomes. GISH confi rmed that the alien genomes of Agrotana and OK7211542, like ORRPX, wer e all derived from Th. ponticum, and not from Th. inter-medium. Howeve r, in contrast to Agrotana, ORRPX and OK7211542 were susceptible to th e WCM and WSMV. The partial amphiploid Zhong 5 had a reconstituted ali en genome composed of 4 S-and 4 J(s)-genome chromosomes of Th. interme dium with 6 translocated chromosomes between the S and J(s) genomes. T his line was highly resistant to WSMV, but was susceptible to the WCM. TAF 46, which contained a synthetic genome consisting of 3 pairs of S -genome chromosomes and 4 pairs of E- or J-genome chromosomes in addit ion to the 21 pairs of wheat chromosomes, was susceptible to the WCM, but moderately resistant to WSMV. Agrotana offers great potential for transferring WSMV and WCM resistance into wheat.