燕麦葡聚糖合酶基因AsCSLH的克隆及特征分析

摘要

Beta-glucan [(1→3,1→4)-β-D-glucan]is one of the important components in oat (Avena sativa L.) that has the function of health protection for human beings.Cloning the β-glucan synthase gene is of significance to reveal the molecular mechanism of β-glucan accumulation and guide oat breeding for β-glucan enhancement.A β-glucan synthase gene, designated AsCSLH, and its genomic DNA sequence were cloned from the oat landrace Xiayoumai using rapid amplification of cDNA ends (RACE) and GenomeWalk from the cDNA, respectively.The AsCSLH gene contains a 2 277 bp open reading frame and encodes a peptide of 758 amino acid residues.Six introns were found in AsCSLH gene with typical GT/AG characteristic after comparison of its sequences of genomic DNA and cDNA.Sequences analysis showed that AsCSLH gene shared the highest identity with rice CSLH gene (BK000084).Structure analysis of predicted encoded protein also confirmed that this cDNA sequence was the oat β-glucan synthase gene.The tissue-specific expression analysis by semiquantitative RT-PCR assays suggested that AsCSLH was expressed in different tissues of oat with the highest level in immature seeds.These results suggested that AsCSLH plays an important role in oat β-glucan synthesis.%β-葡聚糖是燕麦发挥保健作用的重要功能因子,分离其合成关键基因有助于解析燕麦β-葡聚糖积累的分子机制.以高β-葡聚糖燕麦地方品种夏莜麦为材料,通过RACE和染色体步移的方法克隆了燕麦β-葡聚糖合酶基因AsCSLH及其基因组序列并分析其序列结构特征,采用半定量RT-PCR方法研究该基因组织表达特性.分离出的燕麦CSLH基因包含6个内含子,内含子剪接方式均符合GT/AG剪接规则,编码区全长2 277 bp,在序列上与水稻CSLH基因的编码区序列相似性最高,所预测的编码蛋白含有相关多糖合成酶保守结构域.AsCSLH基因在燕麦各组织中均有表达,在灌浆期籽粒中表达水平最高.推测AsCSLH基因在燕麦籽粒的β-葡聚糖合成中起重要作用.