PMID:21771914

Citation	Eom, JS, Cho, JI, Reinders, A, Lee, SW, Yoo, Y, Tuan, PQ, Choi, SB, Bang, G, Park, YI, Cho, MH, Bhoo, SH, An, G, Hahn, TR, Ward, JM and Jeon, JS (2011) Impaired function of the tonoplast-localized sucrose transporter in rice, OsSUT2, limits the transport of vacuolar reserve sucrose and affects plant growth. Plant Physiol. 157:109-19
Abstract	Physiological functions of sucrose (Suc) transporters (SUTs) localized to the tonoplast in higher plants are poorly understood. We here report the isolation and characterization of a mutation in the rice (Oryza sativa) OsSUT2 gene. Expression of OsSUT2-green fluorescent protein in rice revealed that OsSUT2 localizes to the tonoplast. Analysis of the OsSUT2 promoter::β-glucuronidase transgenic rice indicated that this gene is highly expressed in leaf mesophyll cells, emerging lateral roots, pedicels of fertilized spikelets, and cross cell layers of seed coats. Results of Suc transport assays in yeast were consistent with a H(+)-Suc symport mechanism, suggesting that OsSUT2 functions in Suc uptake from the vacuole. The ossut2 mutant exhibited a growth retardation phenotype with a significant reduction in tiller number, plant height, 1,000-grain weight, and root dry weight compared with the controls, the wild type, and complemented transgenic lines. Analysis of primary carbon metabolites revealed that ossut2 accumulated more Suc, glucose, and fructose in the leaves than the controls. Further sugar export analysis of detached leaves indicated that ossut2 had a significantly decreased sugar export ability compared with the controls. These results suggest that OsSUT2 is involved in Suc transport across the tonoplast from the vacuole lumen to the cytosol in rice, playing an essential role in sugar export from the source leaves to sink organs.
Links	PubMed PMC3165862 Online version:10.1104/pp.111.176982
Keywords	Biological Transport; Carrier Proteins/metabolism; Molecular Sequence Data; Mutation; Organelles/metabolism; Oryza sativa/genetics; Oryza sativa/growth & development; Oryza sativa/metabolism; Plant Proteins/metabolism; Sucrose/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ORYSJ:SUT2	part_of	GO:0009705: plant-type vacuole membrane	ECO:0000314: direct assay evidence used in manual assertion		C		Seeded From UniProt	complete
ORYSJ:SUT2		GO:0009705: plant-type vacuole membrane	ECO:0000314:		C		Figure 1 shows OsSUT2-GFP "signal was evident on the inside of the nucleus, thereby confirming that it is on the tonoplast, not the plasma membrane"	complete CACAO 5738
ORYSJ:SUT2		GO:0008506: sucrose:hydrogen symporter activity	ECO:0000314:		F		3B shows that, in yeast expressing OsSUT2, the protonophore CCCP eliminates sucrose uptake similarly to in yeast expressing a known H+/sucrose symporter from potato.	complete CACAO 5739

References

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