Molecular Markers For Brittle Rachis On The Third Homology Group In Tibetan Semi-wild Wheat

Tibetan semi-wild wheat(T.aestivum ssp. tibetanum Shao) is one of the Chinese endemic hexaploid wheat groups and important germplasm resources for wheat breeding and improvement. The primitive traits of Tibetan semi-wild wheat are brittle rachis and tough glume, which are important for research the classification, origin and evolution of Tibetan semi-wild wheat. For the further study the brittle rachis of Tibetan semi-wild wheat and explore the potential germplasm resources, in the present study,280recombinant inbred lines (RILs) F9and F10between Tibetan semi-wild wheat Q1028and ZM9023were used by Microsatellite markers and QTL to locate the brittle rachis genes. The results indicate that:1. Through the analysis and inspection of the seven agronomic traits and the separation amplification analysis of70molecular markers in population. It showed that, this group was a equilibrium group in genetics, and a good group for constructing the genetic linkage map.2.42molecular markers, on the third homology group, were used to construct the linkage map of the RILs.The the linkage map contained three linkage groups and28molecular markers. The total length of linkage group was396.4cM, the average genetic distance between markers was14.16cM, and it was distributed in three chromosomes:3A,3B and3D.3. Through statistic the brittle rachis data in F9RILs, the separation between brittle rachis and tough rachis was2:1, which was unfitted to the expected separationl:1. The result indicated there may be another one main effect gene with the Brl co-control the brittle rachis.4. As the qualitative trait, using microsatellite linkage map, the brittle rachis was mapped on the short arm of chromosome3D, and the distance with the markers Xgdm72、Xcfd70、 Xgpw5104、Xcfd4、Xgdm8and Xgpw5213was21.9cM、25.7cM、28.7cM、34.5cM.40.1cM and41.4cM respectively.5. As the quantitative trait, composite interval mapping, using two years of the phenotypic data, revealed three tight quantitative trait loci (QTL) on3DS consistently affecting the brittle rachis trait. The total proportion of the phenotypic variance explained by these three QTLs ranged from80.89%-85.24%.