New Sources and Strategies for Virus Resistance in Wheat

Each year viruses cause significant yield loses.  Wheat is no exception.  Unfortunately, genetic sources of resistance are limited in availability, thus cultural control methods must be relied upon to reduce the incidence of virus infection.  Wheat viruses are usually found in complexes including, but not limited to, Wheat streak mosaic virus (WSMV), Triticum mosaic virus (TriMV), Barley yellow dwarf virus (BYDV), and Wheat mosaic virus.  We have screened the CIMMYT synthetic wheat collection and have identified three lines that have temperature sensitive resistance to WSMV.  Two of these lines are also resistant to TriMV.  We have also used two biotechnological approaches to develop resistance.  Using RNAi, lines were developed expressing fragments of the WSMV CP and TriMV CP.  After 6 generations, and two backcrosses into adapted varieties, lines are resistant to WSMV and TriMV.  A very promising approach was taken to silence wheat eukaryotic initiation factors (eIF) 4E-2 and 4G, which are used by the viruses to complete their life cycle .  Wheat lines were developed that are resistant to WSMV, TriMV, mixed infections of both, and BYDV.