Cloning and functional analysis of the sweet potato sucrose transporter <italic>IbSUT3</italic>

Abstract

Sucrose, as the main transporter of photosynthate, is transported by sucrose transporters. In this study, we cloned Ib-SUT3 gene from sweet potato (Ipomoea batatas Lam. GenBank accession number MN233361), by RACE technique. The full-length sequence of the gene is 1607 bp and the complete open reading frame is 1518 bp, encoding 505 amino acids. The predicted protein has the molecular weight of 53.82 kD and isoelectric point of 9.19, containing 12 transmembrane domains. Multiple sequence alignment analysis indicated the protein, belonging to Group I, was significantly different from Group IV in evolution and shared high similarities with SUTs from other plant species. IbSUT3 had the function of transporting sucrose verified by SUSY7/ura3 system. Subcellular localization showed that IbSUT3 protein was located in the tobacco protoplasts plasma membrane. The qRT-PCR results showed that IbSUT3 highly expressed in leaves and induced by drought, high salt, low temperature and exogenous abscisic acid, suggesting that IbSUT3 is involved in response to various abiotic stresses, including abscisic acid.