|Liu, Wenxuan -|
|Seifers, Dallas -|
|Friebe, Bernd -|
|Gill, Bikram -|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 23, 2011
Publication Date: November 1, 2011
Citation: Liu, W., Seifers, D.L., Qi, L., Friebe, B., Gill, B.S. 2011. A compensating wheat-Thinopyrum intermedium Robertsonian translocation conferring resistance to wheat streak mosaic virus and Triticum mosaic virus. Crop Science. 51:2382-2390. Interpretive Summary: Wheat streak mosaic caused by Wheat streak mosaic virus (WSMV) and transmitted by the wheat curl mite (Aceria tosichella Kiefer), is a devastating virus disease of common wheat in the Great Plains of the United States and Canada and in most spring and winter wheat-producing areas worldwide. Yield losses of wheat infected with WSMV averaged at 2.5%, but severe infection can result in complete crop loss. Deploying resistance genes is the most effective approach to protect the wheat crop from diseases and pests. Until now, only two sources of resistance to WSMV have been reported. Wsm1 is a resistance gene that was transferred from Th. intermedium, a perennial grass, to wheat. The other gene, Wsm2, is present in the wheat germplasm line CO960293-2. Both resistance genes are temperature sensitive and ineffective above 24 C. The objective of the present study was to introduce a new gene that was derived from Th. intermedium into wheat by exchanging a whole chromosome arm of Th. intermedium with a wheat chromosome arm. Both molecular marker analysis and genomic in situ hybridization analysis, which visually shows chromosome segments under a microscope, revealed that the chromosome arm of Th. intermedium, named as 7S#3L, was exchanged with the short arm of wheat chromosome 7B, resulting in the T7BS.7S#3L translocation chromosome. Homozygous T7BS.7S#3L lines were evaluated for their resistance to WSMV and Triticum mosaic virus (TriMV). The T7BS.7S#3L stock conferred resistance to WSMV at 18 C and 24 C. The T7BS.7S#3L stock also conferred resistance to TriMV at 18 C but was not effective above 24 C. Based on chromosome position and effective resistance to WSMV at 24 C where both Wsm1 and Wsm2 are ineffective, the new gene in T7BS.7S#3L was designated as Wsm3.
Technical Abstract: Wheat streak mosaic virus (WSMV), is a potentially devastating disease of common wheat in the Great Plains of North America. So far, two genes conferring resistance to WSMV have been named and used in cultivar improvement. Here we report a new source of resistance that was derived from a wheat-Th. intermedium ditelosomic addition line containing, in addition to the wheat chromosome complement, a pair of long arm telochromosomes from Th. intermedium previously believed to be of group-4 origin. New molecular marker and genomic in situ hybridization analysis revealed that this telochromosome is homoeologous to the group-7 long arms and belongs to the S genome of Th. intermedium. Accordingly, this chromosome was designated as 7S#3L. One compensating Robertsonian translocation was obtained where the 7S#3L arm was translocated to the short arm of wheat chromosome 7B, resulting in the T7BS.7S#3L translocation chromosome. Homozygous T7BS.7S#3L lines were evaluated for their resistance to WSMV and TriMV. The T7BS.7S#3L stock confers resistance to WSMV at 18 C and 24 C. The T7BS.7S#3L stock also confers resistance to TriMV at 18 C but is not effective above 24 C. Based on chromosome position and effective resistance to WSMV at 24 C where both Wsm1 and Wsm2 are ineffective, the new gene in T7BS.7S#3L is designated as Wsm3.