中文摘要：

为了明确淀粉分支酶（SBE）在木薯淀粉合成中的功能,利用RT-PCR方法克隆得到了MeSBE2.2序列,并通过实时定量PCR（Q-PCR）分析其转录特点。结果表明,MeSBE2.2全长2 053bp,编码616个氨基酸,其编码蛋白质序列与蓖麻SBEII氨基酸序列的同源性最高,为91%。研究其转录特点发现：MeSBE2.2在块根和叶片中的表达模式有品种间差异性;器官特异性表达分析结果表明,MeSBE2.2主要在木薯块根中柱中表达;于3个不同生长时期的表达分析发现,MeSBE2.2在块根中表达平稳,在叶片中其表达量随植株生长呈显著下降趋势。本研究结果为进一步研究SBE家族在木薯块根淀粉合成中的功能提供了重要依据。

英文摘要：

To investigate the function of starch branching enzyme（SBE）in starch biosynthesis in cassava,one gene encoding starch branching enzyme,named MeSBE2.2 was cloned by RT-PCR and its expression patterns were studied by real-time quantitative PCR（Q-PCR）.The results showed that the 2 053 bp full-length sequence encoded 616 amino acids and the deduced protein sequence shared the highest similarity of 91% with Ricinus communis SBEII protein sequence.Expression analysis results showed that MeSBE2.2 was differentially expressed in roots and leaves in various cultivars.Organ-specific expression analysis revealed that MeSBE2.2 was mainly expressed in stele.The expression level of MeSBE2.2 in roots at three different growth stages remained stable while it was significantly decreased in leaves as the plant aged.This study paves a way for further understanding the function of SBE gene family in starch metabolism in cassava.