Resistance to Wheat streak mosaic virus- a survey of resources and development of molecular markers

Wheat streak mosaic virus (WSMV) has been newly documented in Australia. The vulnerability of contemporary Australian elite wheat germplasm prompted a survey for effective resistance against an Australian isolate, WSMV-ACT. This study confirms the effectiveness of previously reported sources of resistance and shows that new sources of resistance also confer protection. The resistance derived from Thinopyrum intermedium (Wsm1) as a 4D translocation and a new 4A translocation, and two bread wheat resistances, Wsm2 and the new source c2652, were effective against WSMV-ACT in glasshouse experiments. Wsm1 was effective at lower temperatures but ineffective above 20 degrees C, a temperature sensitivity shared with many of the derivatives of Wsm2 except for one new selection which was effective at 26 degrees C. True wheats c2652 and Wsm2 selection CA745, and amphiploids Zhong1, Zhong2, Zhong4, Zhong5, TAF46, Summer1, Ot38 and OK7211542 were uniformly resistant at 20, 25 and 28 degrees C. New sources of resistance were identified in a Th.similar to scirpeum-wheat amphiploid, B84-994, and in chromosome addition lines Z2, Z6 and TAi27, derived from wheat-Th.similar to intermedium partial amphiploids. Several new, tightly linked SSR, RAPD and EST-ILP PCR markers were developed for tracking the various Th.similar to intermedium translocations associated with Wsm1, including the smaller translocations on wheat chromosome 4AS and 4DS. Three markers for the 4A-Wsm1 translocation were validated on a segregating breeding population.