Submitted to: Genome
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/10/2009
Publication Date: 5/1/2009
Publication URL: http://hdl.handle.net/10113/32632
Citation: Jauhar, P.P., Peterson, T.S., Xu, S.S. 2009. Cytogenetic and Molecular Characterization of Durum Alien Disomic Addition Line with Enhanced Tolerance to Fusarium Head Blight Resistance. Genome 52:467-483. Interpretive Summary: Scab or Fusarium head blight (FHB) is a devastating fungal disease of both bread wheat and durum or macaroni wheat, causing huge losses to farmers. There is very little or no scab resistance in current wheat cultivars. Earlier, we found that a wild grass, called diploid wheatgrass (Lophopyrum elongatum), is highly resistant to scab. By crossing a durum cultivar, Langdon, with the grass we transferred a pair of grass chromosomes (rod-like structures that carry the genes of interest) into durum wheat and produced scab-resistant durum line called “disomic addition line.” This line is stable and shows less than 21% scab infection (mean = 6.5%), while the parent cultivar Langdon has almost 80% infection. Using various sophisticated biochemical and molecular techniques, viz., Giemsa C-banding, fluorescent genomic in situ hybridization (fl-GISH), chromosome-specific markers, Targeted Region Amplified Polymorphism (TRAP) markers, and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), we have demonstrated that the extra chromosome involved is chromosome 1E of L. elongatum. This is the first time that FHB resistance has been discovered on chromosome 1E. We have established a chromosome-specific marker that may now be used to screen fertile hybrid derivatives for chromosome 1E that confers FHB resistance.
Technical Abstract: Fusarium head blight (FHB), or scab, caused by the fungus Fusarium graminearum Schwabe, is a serious disease of durum wheat (Triticum turgidum L., 2n = 4x = 28; AABB genomes). Current durum cultivars have very little or no FHB resistance. A wild relative, diploid wheatgrass Lophopyrum elongatum (Host) Á. Löve (2n = 2x = 14; EE genome) is an excellent source of genes for resistance to the disease. To transfer this resistance into durum wheat, we crossed the durum cultivar Langdon with L. elongatum. The F1 hybrids were sterile, and we produced, by backcrossing to the recurrent durum parent, followed by selfing, several hybrid derivatives with 80% or higher seed fertility. These hybrid derivatives were screened for scab resistance. We have isolated a disomic addition line, DGE-1 (2n = 28 + 2) with full chromosome complement of durum plus a pair of chromosomes from L. elongatum. Because this line forms 15 bivalents (14 of durum and one of L. elongatum) during meiosis it is meiotically regular and hence reproductively stable. The meiotic integrity of the alien chromosome is ensured by the Pairing homoeologous (Ph1) gene of durum wheat. The addition line is FHB-resistant with less than 21% infection on the visual scale; mean = 6.5%. Using various biochemical and molecular techniques – Giemsa C-banding, fluorescent genomic in situ hybridization (fl-GISH), chromosome-specific markers, Targeted Region Amplified Polymorphism (TRAP) markers, and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) – we have shown that the extra chromosome involved is 1E of L. elongatum. This is the first time that FHB resistance has been discovered on chromosome 1E. We have established a chromosome-specific marker for 1E that has the FHB resistance. This marker may now be used to screen fertile hybrid derivatives and durum alien addition lines for chromosome 1E that confers FHB resistance.