关键词: 野生二粒小麦, 低分子量谷蛋白, 基因克隆, 序列分析, 二级结构

Abstract: In this paper,PCR for the genomic DNA from Triticum dicoccoides was conducted by using a pair of primers designed according to the conservative domain from the known low molecular weight glutenin subunit genes.The two LMW-GS genes,LMW-D81 and LMW-D42 (GenBank accession number FJ461691 and FJ461690),were obtained from the accession D81 with the low protein content at 13.17% and D42 with the high protein content at 27.20%,respectively.LMW-D42 and LMW-D81 possessed the nucleotide sequences with 1011 bp and 1053 bp,and the deduced amino acid sequences with 336 and 350 amino acid residues,respectively.LMW-D42 and LMW-D81 belonged to C type genes owing to their molecular weight about 38 kDa and 39 kDa,respectively,as well as to LMW-m type genes based on the predicted protein sequences of N-terminal domain with METSHIP-.Meanwhile,LMW-D42 and LMW-D81 being allelic Glu-B3 genes were implied by homologous and cluster analyses.The similarities between their sequences were 93.94% in nucleotide and 92.57% in deduced amino acid,respectively.A single deletion for 42 bp occurred in LMW-D42 besides the substitutes at 22 interval sites,compared with LMW-D81.The predicted secondary structures of the amino acid sequences deduced from the two genes were similar.The signal peptide and C-terminal region consisted of many α-helixs.The N-terminal region was formed by a short section of both α-helixs and coils.The repetitive region was mainly occupied by coil.A single β-sheet structure was observed only in C-terminal region.Their amino acid sequences had 8 cysteine residues with similar distribution,and the first and seventh cysteine residues located in the coils.So,these structural characters of LMW-D42 and LMW-D81 might be of importance to quality improvement of bread wheat.

Key words: Triticum dicoccoides, low molecular weight glutenin, gene cloning, sequence analysis, secondary structure