Molecular Cloning and Expressional Analysis of Five Sucrose Transporter (SUT) Genes in Sugarcane

Five SUT genes, namely SoSUT1, SoSUT2, SoSUT3, SoSUT4, and SoSUT5, were cloned, and their expressions in roots, stems, leaves, inflorescence, and buds at physiological mature stage were analyzed by qRT-PCR. Major findings of the study were: (1) the molecular mass of deduced sugarcane sucrose transporter proteins was between 53.44 and 61.80 kDa, and the pIs were between 5.94 and 10.68; (2) all sugarcane sucrose transporter proteins had 12 typical transmembrane domains; (3) there were two DNA sequences encoding the SoSUT3 gene with six exons and five introns; (4) while SoSUT2, SoSUT4, and SoSUT5 belonged to Clades SUT2, SUT4, and SUT5, other SoSUT proteins belonged to Clade SUT3; (5) real-time PCR analyses results showed SoSUT1, SoSUT4, and SoSUT5 had highly abundant expression in the inflorescence, and SoSUT2 and SoSUT3 highly expressed in the buds and inflorescence at physiological maturity. These data may indicate that different SUT genes may be transcribed during the sucrose accumulation process in sugarcane stems and that the expressions of SoSUTs may play an important role in sugarcane inflorescence development.