Abstract: Two sucrose transporter (SUT) cDNAs, OsSUT2M and OsSUT5Z, were isolated from rice (Oryza sativa L.) by reverse transcription polymerase chain reaction (RT-PCR). Sequencing results indicate they are 1 531 bp and 1 635 bp in length including complete open reading frame 1 506 bp and 1 608 bp, which encode 502 amino acids and 536 amino acids, respectively. The TopPred program suggested that both sucrose transporter proteins, OsSUT2M and OsSUT5Z, consist of potentially 12 transmembrane domains. Semi-quantitative RT-PCR was carried out to investigate the gene expression patterns of OsSUT2M and OsSUT5Z. In vegetative organs, transcripts of OsSUT2M were higher in source leaf blades than in other organs at the same development stage, whereas transcripts of OsSUT5Z were less traceable in all organs investigated. In reproductive organs, both transcripts of these two genes were high in panicles from the booting stage to 7 days after flowering (DAF) and then sharply declined. The potential physiology functions of these two sucrose transporters are discussed. OsSUT2M and OsSUT5Z. In vegetative organs, transcripts of OsSUT2M were higher in source leaf blade than in other organs at the same development stage, whereas transcripts of OsSUT5Z were less traceable in all organs investigated. In reproductive organs, both transcripts of these two genes were high in panicles from booting stage to 7 day after flowering (DAF) and then sharply declined. The potential physiology functions of these two sucrose transporters are discussed.

Key words: cDNA cloning, expression pattern, OsSUT2M, OsSUT5Z, rice sucrose transporter.