| Aegilops tauschii is the D-genome donor of common wheat. Genetic variations detected in Ae. tauschii were much higher than that of D genome in common wheat, and Ae.tauschii had been considered as useful genetic resources for the improvement of wheat quality, such as HMW-GSl.5+10 and 5+12, which are closely associated with good quality. In this study, three coding sequences of LMW-GS were isolated and characterized from Aegilops tauschii accession AS63 with HMW-GS 5+12. The results were as following:1. Primers P1 and P2 were designed based on the highly conserved distal sequences of 5 ' and 3' ends of known LMW-GS genes and utilized to amplify LMW-GS genes from Aegilops tauschii accession AS63 with HMW-GS 5+12. Two PCR bands, with predicted length about 900bp and 1000bp, were detected on 1% agarose gel. The lengths accorded to that of the coding regions of known LMW-GS genes.2. Directly sequencing of several positive clones resulted in three different sequences, designated as LMWD-1, LMWD-2, and LMWD-3, and the GenBank accession numbers are AY841013, AY841014, and AY841015, respectively. The lengths of them are 1065bp, 972bp, and 900bp, respectively. LMWD-1 and LMWD-2 could be translated, by universal genetic codes, to two mature proteins consisting of 322 and 302 amino acid residues, respectively. LMWD-3 is a putative pseudogene due to the presence of three inframe stop codons.3. The estimated molecular weight of LMWD-1 and LMWD-2 are 38 kDa and 34 kDa,respectively, indicating that they are C types of LMW-GS. Based on the predicted protein sequences of N-terminal domain, LMWD-1 and LMWD-2 belong to LMW-m type. Each gene had the similar polypeptide structure with known LMW-GS genes. Alignment of deduced amino acids sequences showed that LMWD-1, LMWD-2, andLMWD-3 (ignoring the inframe stop condons)had strong sequence similarity with known LMW-GS genes, especially with those encoded by Glu-D3 locus in common wheat. |
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