title: Reducing phosphorus accumulation in rice grains with an impaired transporter in the node.
abstract: Phosphorus is an important nutrient for crop productivity. More than 60% of the total phosphorus in cereal crops is finally allocated into the grains and is therefore removed at harvest. This removal accounts for 85% of the phosphorus fertilizers applied to the field each year. However, because humans and non-ruminants such as poultry, swine and fish cannot digest phytate, the major form of phosphorus in the grains, the excreted phosphorus causes eutrophication of waterways. A reduction in phosphorus accumulation in the grain would contribute to sustainable and environmentally friendly agriculture. Here we describe a rice transporter, SULTR-like phosphorus distribution transporter (SPDT), that controls the allocation of phosphorus to the grain. SPDT is expressed in the xylem region of both enlarged- and diffuse-vascular bundles of the nodes, and encodes a plasma-membrane-localized transporter for phosphorus. Knockout of this gene in rice (Oryza sativa) altered the distribution of phosphorus, with decreased phosphorus in the grains but increased levels in the leaves. Total phosphorus and phytate in the brown de-husked rice were 20-30% lower in the knockout lines, whereas yield, seed germination and seedling vigour were not affected. These results indicate that SPDT functions in the rice node as a switch to allocate phosphorus preferentially to the grains. This finding provides a potential strategy to reduce the removal of phosphorus from the field and lower the risk of eutrophication of waterways.
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Chuo 2-20-1, Kurashiki 710-0046, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Yamaji
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Chuo 2-20-1, Kurashiki 710-0046, Japan.
authors.forename: Yuma
authors.initials: Y
authors.lastname: Takemoto
authors.affiliation: Advanced Science Research Center, Okayama University, Okayama 700-8530, Japan.
authors.forename: Takaaki
authors.initials: T
authors.lastname: Miyaji
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Chuo 2-20-1, Kurashiki 710-0046, Japan.
authors.forename: Namiki
authors.initials: N
authors.lastname: Mitani-Ueno
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Kaoru T
authors.initials: KT
authors.lastname: Yoshida
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Chuo 2-20-1, Kurashiki 710-0046, Japan.
authors.forename: Jian Feng
authors.initials: JF
authors.lastname: Ma
mesh_terms: D000383:Agriculture / Q000379:methods*; D000818:Animals; D001692:Biological Transport; D002523:Edible Grain / Q000378:metabolism; D005068:Eutrophication; D005308:Fertilizers; D055786:Gene Knockout Techniques; D018525:Germination; D006801:Humans; D026901:Membrane Transport Proteins / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism*; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D009928:Organ Specificity; D012275:Oryza / Q000033:anatomy & histology* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism*; D010833:Phytic Acid / Q000378:metabolism; D059828:Plant Cells / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D036226:Seedlings / Q000254:growth & development; D052584:Xylem / Q000378:metabolism
chemical_list: D005308:Fertilizers; D026901:Membrane Transport Proteins; D050505:Mutant Proteins; D010940:Plant Proteins; D010758:Phosphorus; D010833:Phytic Acid