木薯糖转运蛋白基因MeSWEET17b的克隆及表达分析

Cloning and expression analysis of sugar transporter gene MeSWEET17b in cassava

关键词:  木薯，糖转运蛋白，亚细胞定位，糖转运能力，非生物胁迫

Key words:  Cassava, Sugar  transporter, Subcellular  localization, Sugar  transport capacity, Abiotic  stress

摘要:

糖转运蛋白SWEETs是植物的主要转运蛋白，能够促进糖在细胞间的流动。木薯（Manihot esculenta Crantz）是热带亚热带地区重要的粮食作物。为了明确 SWEET 家族基因在木薯生长发育过程中的功能，该研究以木薯KU50作为实验材料，克隆糖转运蛋白基因MeSWEET17b并进行生物信息学分析，研究其亚细胞定位、糖转运能力以及不同器官及不同发育时期的表达情况及在非生物胁迫下的表达趋势。结果表明:MeSWEET17b基因开放阅读框为726 bp，编码242个氨基酸残基，蛋白分子质量为26.32 kDa，理论等电点为7.72，不稳定系数为40.54，属于不稳定类蛋白。MeSWEET17b蛋白含有7个跨膜结构域，属于疏水性蛋白。系统进化树分析发现MeSWEET17b属于CladeⅣ，与AtSWEET16、AtSWEET17 亲缘关系最近；MeSWEET17b定位于细胞质膜，主要转运果糖。qRT-PCR 结果表明，MeSWEET17b在叶柄中表达水平最高。对KU50水培苗进行高盐（8 g/L NaCl）、干旱（100 mmol/L甘露醇）、氧化（10% H2O2）和低温（15 ℃ 24 h，后降至4 ℃ 24 h）等非生物胁迫，结果发现，MeSWEET17b在叶片、叶柄、茎杆和根等不同器官的表达出现不同程度的变化。推测MeSWEET17b在木薯的非生物胁迫中起着重要作用。

Abstract:

SWEETs are a major transporter of plants that facilitates the flow of sugar between cells. Cassava (Manihot esculenta Crantz) is an important food crop in tropical and subtropical regions. In order to clarify the function of SWEET family genes in cassava growth and development, this study used cassava KU50 as experimental material to clone the sugar transporter gene MeSWEET17b and conduct bioinformatics analysis. To study its subcellular localization, sugar transport capacity, expression in different organs and developmental stages, and the trend of its expression under abiotic stress. The results showed that MeSWEET17b gene was an instability protein with an open reading frame of 726 bp, encoding 242 amino acid residues, molecular weight of 26.32 kDa, theoretical isoelectric point of 7.72 and instability coefficient of 40.54. MeSWEET17b is a hydrophobic protein, which contains 7 transmembrane domains. Phylogenetic tree analysis showed that MeSWEET17b belonged to CladeⅣ and was closely related to AtSWEET16 and AtSWEET17. MeSWEET17b located in the cell membrane and mainly transport fructose. The results of qRT-PCR showed that MeSWEET17b expression level was the highest in petiole. The KU50 seedlings were subjected to abiotic stress such as high salt (8g/L NaCl), drought (100 mmol/L mannitol), oxidation (10% H2O2) and low temperature (15℃ for 24 h, then dropped to 4℃ for 24 h). The expression of MeSWEET17b in different organs such as leaves, petioles, stems and roots changed to different degrees. It is speculated that MeSWEET17b plays an important role in cassava abiotic stress.