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Abstract To characterize the ω-gliadin gene family of Shaan 253, six pieces of complete coding regions were amplified from this wheat (Tricicum aestivum) variety using primer pairs designed according to the known ω-gliadin gene sequences. The amplified DNA fragments were separated and recovered from agarose gel, subsequently ligated into pMD19-T vector, and then transformed into Escherichia coli strain DH5α. Five positive clones were sequenced. And five ω-gliadin gene sequences were obtained, designated as Gli-S253-1, Gli-S253-2, Gli-S253-3, Gli-S253-4 and Gli-S253-5, respectively and the corresponding GenBank accession numbers were GQ423428, GQ423429, GQ423430, GQ423431and GQ423432, respectively. Sequence analysis showed that: (1) There were four main types of ω-gliadin gene silence(Q→*, I→*, R→* and W→*), of which the first type was dominant(about 66.6%); (2) Two kinds of coding glutamine (Q) were the most likely to nonsense mutations (CAA→TAA and CAG→TAG); (3) Gene silence occurred mainly in the triplet code of the first base (accounting for 77.8%), mutation frequency of the second base was about 33.3%, while the third one has not been reported; there was a rare silence mutation (ATA→TAA) in GQ423428, while two loci involved in variation in a triplet code at a time; (4) The number of gene silence mutation was up to six in GQ423428 and GQ423429, including four sites (349, 373, 478 and 592) which occurred in all of the five genes. (5) From the structure of mature protein, nonsense mutations appeared mainly in the repeat region, rather than the signal peptide or the N-terminus of ω-gliadin; (6) Phylogenetic analysis indicated that ω-gliadin/secalin of tribe Triticeae was divided into three branches. The results from this study indicated that five pieces of ω-gliadin genes were successfully separated from Shaan 253, which could expand the genetic variation for wheat quality improvement, and even provide molecular assists during the conventional wheat breeding.
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Received: 04 November 2009
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