水稻蔗糖转运蛋白OsSUT4参与蔗糖转运的功能研究

Function Analysis of Sucrose Transporter OsSUT4 in Sucrose Transport in Rice

【目的】植物蔗糖的跨膜运输主要借助蔗糖转运蛋白(sucrose transporter,SUT)进行。在已鉴定出的5个水稻SUT编码基因中,OsSUT4的作用尚不清楚。【方法】采用CRISPR/Cas9基因编辑技术构建ossut4缺失变体,出现株高降低、分蘖数增加及产量下降等表型。【结果】通过进一步分析,发现ossut4突变体水稻叶片蔗糖、淀粉积累,反馈抑制光合速率;因源端光合同化物装载受阻,导致库端籽粒蔗糖供应不足,灌浆延迟。对Os SUT4进行亚细胞和组织化学定位,发现OsSUT4在细胞质膜上,且在萌发种子的胚、胚芽鞘的维管束、小穗颖壳、花药、颖果的糊粉层中都有表达,该现象表明OsSUT4具备转运蔗糖的特征。【结论】综上所述,OsSUT4在水稻蔗糖源端装载以及籽粒库端卸载等生理过程发挥重要作用。

【Objective】The transmembrane transport of sucrose is mainly mediated by sucrose transporters,among which five SUT coding genes have been identified in rice.However,the role of OsSUT4 in the sucrose transport is unclear.【Method】CRISPR/Cas9 techniques were used to construct ossut4-deleted mutants.The ossut4 mutant was featured by lower plant height and grain yield as well as higher tiller number as compared with wild type plants.【Result】Sucrose and starch accumulation in the leaf of the ossut4 mutants lead to slower net photosynthetic rate;insufficient sugar supply results in the postpone of grain filling.Base on the subcellular and histochemical localization,OsSUT4 was located on the cytoplasmic membrane.Tissue localization showed that Os SUT4 was expressed in the embryo of germinating seed,vascular bundles of coleoptile,glume shell,anthers at flowering stage and aleurone layer of caryopsis at filling stage.【Conclusion】Os SUT4 plays an important role in sucrose transport.