Cloning and expression analysis of sugar transporter protein gene MeSWEET17b in cassava

Cassava(Manihot esculenta)is an important food crop in tropical and subtropical regions. Sugar transporter protein SWEETs facilitate the flow of sugar between cells and play an important role in plant growth and development. In order to clarify the function of SWEET family genes in cassava, cassava‘KU50' was used as material in this study, and the gene properties of MeSWEET17b were studied by gene cloning, bioinformatics analysis, subcellular localization, in vitro yeast detection and RT-qPCR, etc. The results were as follows:(1)The open reading frame of MeSWEET17b was 726 bp, encoding 242 amino acids, and located in the plasma membrane. MeSWEET17b had the closer genetic relationship with AtSWEET16 and AtSWEET17, containing 7 transmembrane domains, and belonging to hydrophobic protein.(2)MeSWEET17b mainly transport fructose through the in vitro yeast detection.(3)The results of RT-qPCR showed that the expression trend of MeSWEET17b in stem was basically consistent with in petiole, and the expression was the highest at maturity. The relative expression of MeSWEET17b was relatively low in leaves, and the highest in the expansion stage of tuberous root, while decreased rapidly with the growth of tuberous roots.(4)The ‘KU50' seedlings were subjected to abiotic stress treatments such as high salt(8 g·L-1 NaCl), drought(100 mmol·L-1 mannitol), oxidation(10% H2O2)and cold(15 ℃ for 24 h, then dropped to 4 ℃ for 24 h). RT-qPCR showed that the relative expressions of MeSWEET17b in leaf and stem had the greatest difference under drought stress. The relative expressions of MeSWEET17b in leaf and fibrous root changed most significantly under salt stress; under oxidation and cold stress, the relative expressions of MeSWEET17b in fibrous root and petiole increased significantly with the extention of treating time. This study provides a theoreticac reference for further studying the function mechanism of sugar transporter protein SWEETs in cassava.