Mutational reconstructed ferric chelate reductase confers enhanced tolerance in rice to iron deficiency in calcareous soil.
Iron (Fe) deficiency is a worldwide agricultural problem on calcareous soils with low-Fe availability due to high soil pH. Rice plants use a well documented phytosiderophore-based system (Strategy II) to take up Fe from the soil and also possess a direct Fe2+ transport system. Rice plants are extremely susceptible to low-Fe supply, however, because of low phytosiderophore secretion and low Fe3+ reduction activity. A yeast Fe3+ chelate-reductase gene refre1/372, selected for better performance at high pH, was fused to the promoter of the Fe-regulated transporter, OsIRT1, and introduced into rice plants. The transgene was expressed in response to a low-Fe nutritional status in roots of transformants. Transgenic rice plants expressing the refre1/372 gene showed higher Fe3+ chelate-reductase activity and a higher Fe-uptake rate than vector controls under Fe-deficient conditions. Consequently, transgenic rice plants exhibited an enhanced tolerance to low-Fe availability and 7.9x the grain yield of nontransformed plants in calcareous soils. This report shows that enhancing the Fe3+ chelate-reductase activity of rice plants that normally have low endogenous levels confers resistance to Fe deficiency.
Ishimaru
Yasuhiro
Y
Department of Global Agricultural Sciences, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Tokyo 113-8657, Japan.
Kim
Suyeon
S
Tsukamoto
Takashi
T
Oki
Hiroyuki
H
Kobayashi
Takanori
T
Watanabe
Satoshi
S
Matsuhashi
Shinpei
S
Takahashi
Michiko
M
Nakanishi
Hiromi
H
Mori
Satoshi
S
Nishizawa
Naoko K
NK
D002119:Calcium Carbonate / Q000032:analysis*; D038181:FMN Reductase / Q000235:genetics* / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D005822:Genetic Vectors / Q000235:genetics; D007501:Iron / Q000378:metabolism; D000090463:Iron Deficiencies; D009154:Mutation / Q000235:genetics; D012275:Oryza / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D030821:Plants, Genetically Modified; D012987:Soil / Q000032:analysis*
D012987:Soil; D007501:Iron; D038181:FMN Reductase; C023903:ferric citrate iron reductase; D002119:Calcium Carbonate