ARS | Publication request: Molecular cytogenetic characterization of alien introgressions with gene Fhb3 for resistance to Fusarium head blight disease of wheat

Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 16, 2008
Publication Date: August 20, 2008
Citation: Qi, L., Pumphrey, M.O., Friebe, B., Chen, P., Gill, B. 2008. Molecular cytogenetic characterization of alien introgressions with gene Fhb3 for resistance to Fusarium head blight disease of wheat. Journal of Theoretical and Applied Genetics. 117:1155-1166.

Interpretive Summary: Fusarium head blight (FHB), or scab, can cause substantial yield and grain quality losses in wheat crops of the Great Plains. Losses in the 1990’s alone exceeded $ 3 billion. Intensive resistance breeding efforts have resulted in a narrow genetic basis of FHB resistance, with most new wheat varieties sharing the same source of resistance. In order to broaden the basis of resistance, a new source of FHB resistance, named Fhb3, was identified from a wild relative of wheat, Leymus racemosus. This source is different from previously reported FHB resistance genes in wheat, providing a new source for wheat breeding programs. Fhb3 had a large effect in reducing disease severity in experimental wheat lines and may be rapidly deployed in wheat breeding programs.

Technical Abstract: Fusarium head blight (FHB) resistance was identified in the alien species Leymus racemosus, and wheat-Leymus introgression lines with FHB resistance were reported previously. Detailed molecular cytogenetic analysis of alien introgressions T01, T09, and T14 and the mapping of Fhb3, a new gene for FHB resistance, are reported here. The introgression line T09 had an unknown wheat-Leymus translocation chromosome. A total of 36 RFLP markers selected from the seven homoeologous groups of wheat were used to characterize T09 and determine the homoeologous relationship of the introgressed Leymus chromosome with wheat. Only short arm markers for group 7 detected Leymus-specific fragments in T09, whereas 7AS-specific RFLP fragments were missing. C-banding and genomic in situ hybridization results indicated that T09 has a compensating Robertsonian translocation T7AL•7Lr#1S involving the long arm of wheat chromosome 7A and the short arm of Leymus chromosome 7Lr#1 substituting for chromosome arm 7AS of wheat. Introgression lines T01 (2n = 44) and T14 (2n = 44) each had two pairs of independent translocation chromosomes. T01 had T4BS•4BL-7Lr#1S + T4BL-7Lr#1S•5Lr#1S. T14 had T6BS•6BL-7Lr#1S + T6BL•5Lr#1S. These translocations were recovered in the progeny of the irradiated line Lr#1 (T5Lr#1S•7Lr#1S). The three translocation lines, T01, T09, and T14, and the disomic addition 7Lr#1 were consistently resistant to FHB in greenhouse point-inoculation experiments, whereas the disomic addition 5Lr#1 was susceptible. The data indicated that at least one novel FHB resistance gene from Leymus, designated Fhb3, resides in the distal region of the short arm of chromosome 7Lr#1, because the resistant translocation lines share a common distal segment of 7Lr#1S. Three PCR-based markers, BE586744-STS, BE404728-STS, and BE586111-STS, specific for 7Lr#1S were developed to expedite marker-assisted selection in breeding programs.