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We analyzed the function of a rice sucrose transporter, OsSUT1, by using antisense rice. There was no difference between antisense and wild-type plants in carbohydrate content and photosynthetic ability of the flag leaves in the vegetative growth stage, suggesting that OsSUT1 may not play an important role in carbon metabolism, at least in these materials. [ABSTRACT FROM AUTHOR]

To investigate the role of Ser162 in phosphorylationdependent regulation of maize sucrose-phosphate synthase (SPS) activities in rice, transgenic rice plants expressing wild-type or mutagenized maize SPS were produced. Our results indicate that Ser162 was responsible for overproduction- induced inactivation of SPS protein and for light/ dark modulation of this protein in vivo. [ABSTRACT FROM AUTHOR]

Here we report the cloning of a sucrose transporter cDNA from maize (Zea mays L.) and an analysis of the expression of the gene. A cDNA clone (ZmSUT1) was identified as a sucrose transporter cDNA from its sequence homology at the amino acid level to sucrose transporters that have been cloned from other higher plant species. Based on the results of genomic Southern hybridization, ZmSUT1 appears to be a single copy gene. A Northern blot analysis of seedlings and leaf blades suggests that the sucrose transporter is involved in the export of accumulated carbohydrates from source leaf blades. From the measurements of transcript levels and carbohydrate contents in mature leaf blades, we propose that the expression of the gene for the maize sucrose transporter is positively regulated by the amounts of soluble sugars such as sucrose arid glucose in source leaves of maize. In addition, based on the tissue specificity of the expression of the gene in maize plants at the reproductive stage, it is possible that the sucrose transporter acts in sink tissues such as pedicels as well as in source tissues such as leaf blades. [ABSTRACT FROM AUTHOR]