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Geographic Mapping for sugar and nitrogen compands and their transporters

糖和氮化合物及其转运蛋白的地理制图

基本信息

批准号：
11460004
负责人：
YAMAGUCHI Junji
金额：
$ 9.86万
依托单位：
NAGOYA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

We investigated sugar uptake and transport in rice (Oryza sativa L.) embryo during grain germination. Endogenous sugar levels, accumulation of starch granules and gene expression of a rice sucrose transporter (OsSUT1) were examined using rice embryos germinated with or without exogenous sugar supply. Starch granules remarkably accumulated in the cells around vascular bundles, as a consequence of the sugar taken up by the embryos, indicating that the taken up sugars are transiently converted into starch. In silo detection for OsSUT1 mRNA indicated its localization in the phloem companion cells. Furthermore, northern blot and in situ hybridization analyses showed that OsSUT1 expression is not detectable in embryos subjected to sugar starvation conditions while its expression is enhanced by an increased endogenous sugar level. Overall results indicate that the expression of companion cell-specific sucrose transporter, OsSUT1 is regulated by the endogenous sugar status as well as light exposure.This study examines the cloning and characterization of monosaccharide transporter cDNAs in rice. The 0sMST1-3 (Oryza sativa monosaccharide transporter 1-3) has two sets of putative six transmembrane domains separated by a central long hydrophilic region. Heterologous expression of the OsMST3 protein in yeast Saccharomyces cerevisiae revealed that OsMST3 has transport activity for some monosaccharides and an energy-dependent H+ co-transport manner. Northern blot and in situ hybridization analysis showed that OsMST3 mRNA is detectable in leaf blade, leaf sheath, callus and root, especially the xylem as well as in sclerenchyma cells in root. These results suggested that OsMST3 is involved in the accumulation of monosaccharides required for cell wall synthesis at the stage of cell thickness.

我们研究了水稻 (Oryza sativa L.) 胚胎在谷物发芽过程中的糖吸收和运输。使用有或没有外源糖供应的发芽水稻胚检查内源糖水平、淀粉颗粒的积累和水稻蔗糖转运蛋白（OsSUT1）的基因表达。由于胚胎吸收了糖，淀粉颗粒在维管束周围的细胞中显着积累，表明吸收的糖瞬时转化为淀粉。 OsSUT1 mRNA 的筒仓检测表明其定位于韧皮部伴随细胞中。此外，Northern印迹和原位杂交分析表明，在糖饥饿条件下的胚胎中检测不到OsSUT1表达，而内源糖水平增加则增强了其表达。总体结果表明，伴随细胞特异性蔗糖转运蛋白 OsSUT1 的表达受到内源糖状态以及光照的调节。本研究检查了水稻中单糖转运蛋白 cDNA 的克隆和表征。 0sMST1-3（稻单糖转运蛋白 1-3）具有两组假定的六个跨膜结构域，由中央长亲水区域分隔开。 OsMST3 蛋白在酿酒酵母中的异源表达表明，OsMST3 对某些单糖具有转运活性，并且具有能量依赖的 H+ 共转运方式。 Northern印迹和原位杂交分析表明，OsMST3 mRNA在叶片、叶鞘、愈伤组织和根中，尤其是木质部以及根的厚壁细胞中均可检测到。这些结果表明OsMST3参与细胞厚度阶段细胞壁合成所需的单糖的积累。