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采用PCR方法,从滨麦(Leymus mollis)基因组中分离出8条LMW-GS基因序列。核苷酸序列分析表明,序列GQ169791在起始密码子上游包含318 bp的启动子序列,该序列包含-300元件、GCN4 motif、种子贮藏蛋白盒等基因特异表达的顺式或反式作用调控元件。推导的氨基酸序列分析表明,8条序列的编码区依次有信号肽,N-末端区,中部重复区和C-末端Ⅰ、Ⅱ、Ⅲ区等典型LMW-GS多肽一级结构特征;序列HQ416909、HQ416914和HQ416915具有单一完整的开放阅读框(ORF);序列GQ169791、HQ416910、HQ416911、HQ416912和HQ416913在中部重复区和C-末端区出现了4个或5个提前终止密码子,推断其为假基因。8条序列都含有8个或9个半胱氨酸残基(C),N-末端区起始氨基酸序列为METSRIPG-或METTRIPG-,推断其为LMW-m型LMW-GS基因。系统进化分析表明,8条序列与华山新麦草(Psathyrostachys huashanica)LMW-GS基因(HM475146,GQ223386)和野大麦(Hordeum brevisubulatum)的B-hordein基因(AY695368)具有相对较近的同源关系。该研究为挖掘利用滨麦LMW-GS的基因提供了理论依据,对小麦品质改良具有一定参考价值。
Eight LMW-GS gene sequences were isolated from Leymus mollis genome by PCR. Nucleotide sequence analysis showed that the sequence of GQ169791 contained a 318 bp promoter sequence upstream of the start codon and contained a cis- or trans-acting regulatory element that was specifically expressed in a gene such as -300, GCN4 motif, and seed storage protein . The deduced amino acid sequence analysis showed that the coding region of the eight sequences had the first order structural characteristics of typical LMW-GS polypeptides such as signal peptide, N-terminal region, middle repeat region and C-terminal region. The sequences of HQ416909, HQ416914 and HQ416915 have a single intact open reading frame (ORF); sequences GQ169791, HQ416910, HQ416911, HQ416912 and HQ416913 have 4 or 5 early stop codons in the middle repeat region and C-terminal region, which are deduced to be pseudogenes . Each of the 8 sequences contained 8 or 9 cysteine residues (C). The initial amino acid sequence of the N-terminal region was METSRIPG- or METTRIPG-, suggesting that it is the LMW-m LMW-GS gene. Phylogenetic analysis showed that the eight sequences have relatively close homology with the B-hordein gene (AY695368) of LMW-GS gene (HM475146, GQ223386) and Hordeum brevisubulatum in Psathyrostachys huashanica. This study provides a theoretical basis for mining and utilizing the LMW-GS gene of wheat and has certain reference value for wheat quality improvement.