Analysis Of Glu-3 Locus In Tetraploid Wheat "Langdon" By BAC Sequencing

Low-molecular-weight glutenin subunits (LMW-GS) are a major fraction of wheat glutenin and account for 60% of the glutenins. They play an important role in determining the processing properties of wheat. The LMW-GS are encoded by Glu-A3, Glu-B3 and Glu-D3 on the short arm of chromosome 1A, 1B and 1D. LMW-GS are present as a multigene family in close association with gliadin and have shown extensive polymorphism, this may lead to the difficulty in studying LMW-GS. In order to obtain an insight into Glu-3 locus at large DNA fragment level, BAC clones carrying Glu-3 were screened from tetraploid wheat BAC library, two BAC clones (BAC B9 and D5) were sequenced and analyzed. The results were as follows:1. Thirty-one BAC clones carrying Glu-3 were identified by SSR marker, gene specific PCR marker and Southern blot from the BAC library of Langdon (T. durum). After BAC clones were digested by Hind HI, FPC analysis showed that 8 BAC clones of Glu-A3 belong to one group, 4 BAC clones of Glu-B3 belong to another group, The others are singletons.2. BAC B9 from Glu-B3 group was selected to construct shotgun library. All of subclones were sequenced and assembled, the full length of BAC B9 is 139,403 bp. Sequence analysis of BAC B9 showed that it contained one Glu-B3, four intact ω-gliadin genes, four ω-gliadin fragments, two unknown proteins and two powdery mildew resistance gene fragments. The physical distance between Glu-B3 and ω-gliadin gene is 56.4kb. It is the first finding on the physical distance between Glu-B3 and glidian gene in the world.3. BAC D5 from Glu-A3 group was selected to construct shotgun library. All of...