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SWEET基因家族为新发现的一类糖转运蛋白家族,具有转运蔗糖及单糖的功能,在真核生物中广泛存在,其特点为具有1~2个MtN3_slv结构域及7个跨膜结构域,对植物生长发育、生理代谢及植物-病原菌互作等方面具有重要的调控作用。为了探索热带作物木薯中SWEET基因的功能,本研究采用RT-PCR技术,从木薯Ku50成熟叶片中克隆得到MeSWEET1基因的编码序列,并对其进行了生物信息学预测分析和功能初步研究。本研究结果表明:MeSWEET1蛋白含有植物SWEET家族两个保守的MtN3_Slv功能域,还具有7个跨膜结构域。系统进化树分析显示,MeSWEET1与拟南芥AtSWEET1、水稻OsSWEET1a和OsSWEET1b亲缘关系最近,属于SWEET蛋白家族进化树的Clade I分枝class II小家族。亚细胞定位结果表明,MeSWEET1蛋白定位于细胞膜上。组织特异性表达分析揭示,MeSWEET1在木薯成熟叶片中相对表达量最高,而在新叶和果实中相对表达量最低。本研究的结果将为进一步研究木薯MeSWEET1基因在糖转运及与病原互作等方面的功能奠定了初步的理论基础。
The SWEET gene family is a newly discovered family of sugar transporters with the function of transporting sucrose and monosaccharides. It exists widely in eukaryotes and is characterized by having 1 to 2 MtN3_slv domains and 7 transmembrane domains, The plant growth and development, physiological metabolism and plant-pathogen interactions and so has an important regulatory role. In order to explore the function of SWEET gene in tropical crop Cassava, the coding sequence of MeSWEET1 gene was cloned from the mature leaves of cauliflower Ku50 by RT-PCR, and the bioinformatics prediction and functional studies were carried out. The results of this study indicate that MeSWEET1 contains two conserved MtN3_Slv domains of SWEET family and seven transmembrane domains. Phylogenetic tree analysis showed that MeSWEET1 has the closest relationship with Arabidopsis AtSWEET1, rice OsSWEET1a and OsSWEET1b and belongs to Clade I clade class II clade of SWEET protein family phylogenetic tree. Subcellular localization results showed that MeSWEET1 protein was located on the cell membrane. Tissue-specific expression analysis revealed that MeSWEET1 had the highest relative expression level in mature leaves of cassava and the lowest expression level in new leaves and fruits. The results of this study will provide a preliminary theoretical basis for further study on the function of Cassava MeSWEET1 gene in sugar transport and interaction with pathogens.