具有5+12优质亚基节节麦的低分子量谷蛋白基因序列分析

根据低分子量谷蛋白亚基(LMW-GS)基因编码区保守序列设计引物，对具优质高分子量谷蛋白亚基(HMW-GS)5 12的节节麦材料AS63进行扩增，得到长度约为900bp和1000bp的DNA片段，克隆测序后获得3个LMW-GS基因序列LMWD-1(GenBank登录号AY841013)、LMWD-2(GenBank登录号AY841014)和LMWD-3(GenBank登录号AY841015)。它们具有小麦低分子量谷蛋白基因的典型结构特征。其中，LMWD-1和LMWD-2具有完整编码区，长度分别为1065bp和972bp，可分别编码333和302个氨基酸残基的成熟蛋白，且第一个半胱氨酸残基均出现在重复区第13位。在重复区，LMW-1的两个疏水单元为PIIIL和PVIIL，而LMWD-2的两个疏水单元为PIIIL和SVIIL。LMW-1的重复区中还存在一个连续13个Q组成的短肽。LMWD-3由于编码区内存在提前终止密码子，为不表达的假基因。氨基酸序列比较发现，LMW-GS基因的N-末端区序列具有位点特异性，且LMW-1和LMWD-2与普通小麦Gtu-D3位点的LMW-GS基因有很高的一致性。

Sequence analysis of LMW-GS genes from Aegilops tauschii containing HMW glutenin subunits 5+12 with good quality

According to the conservative sequences of known low-molecular-weight glutenin subunit (LMW-GS) genes, the PCR primers were designed, and the full coding regions of LMW-GS genes were amplified from the Aegilops tauschii accession AS63, which contains HMW glutenin subunits 5+12 with good quality. Three novel genes, LMWD-1 (GenBank accession AY841013), LMWD-2 (GenBank accession AY841014) and LMWD-3 (GenBank accession AY841015), were identified from the expected 900 and 1000 bp amplification products. LMWD-1, LMWD-2 and LMWD-3 had the typical structure of LMW-GS genes. The coding regions of LMWD-1 and LMWD-2 were 1065 and 972 bp, and encoded two mature proteins with 322 and 302 amino acid residues, respectively. The first cysteine residue of LMWD-1 and LMWD-2 were observed at position 13 in the repetitive domains, respectively. In the repetitive domain, the two hydrophobic motifs of LMWD-1 were PIIIL and PVIIL, whereas the two hydrophobic motifs of LMWD-2 were PIIIL and SVIIL. A repeat motif with 13 glutamines was found in the repetitive domain of LMWD-1. LMWD-3 was a pseudogene due to three stop codons in its coding region. By sequence analysis, it was found that the LMW-GS genes on each locus had specific N-terminal region, and LMWD-1 and LMWD-2 were highly similar to the known LMW-GS genes encoded by Glu-D3 locus in common wheat.