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鈴木 基史*; 塚本 崇志*; 井上 晴彦*; 渡辺 智; 松橋 信平; 高橋 美智子*; 中西 啓仁*; 森 敏*; 西澤 直子*
Plant Molecular Biology, 66(6), p.609 - 617, 2008/04
被引用回数：138 パーセンタイル：95.23(Biochemistry & Molecular Biology)Rice secretes Deoxymugineic acid (DMA) in response to Fe deficiency to take up Fe in the form of Fe(III)-DMS complex. In contrast with barley, the roots of which secrete DMS in response to Zn deficiency, the amount of DMA secreted by rice roots was slightly decreased under conditions of low Zn supply. There was a concomitant increase in endogenous DMA in rice shoots, suggesting that DMA plays a role in the translocation of Zn within Zn-deficient rice plants. The expression of 
and 
was not increased in Zn-deficient roots but that of 
was increased in Zn-deficient roots and shoots. The expression of 
was also increased in Zn-deficient roots and dramatically increased in shoots; correspondingly, HPLC analysis was unable to detect nicotianamine in Zn-deficient shoots. The expression of 
was increased in Zn-deficient shoots. Analyses using the positron-emitting tracer imaging system (PETIS) showed that Zn-deficient rice roots absorbed less 
Zn-DMA than Zn
. Importantly, supply of Zn-DMA rather than Zn increased the translocation of Zn into the leaves of Zn-deficient plants. This was especially evident in the discrimination center (DC). These results suggest that DMA in Zn-deficient rice plants has an important role in the distribution of Zn within the plant rather than in the absorption of Zn from the soil.
石丸 泰寛*; Kim, S.*; 塚本 崇志*; 大木 宏之*; 小林 高範*; 渡辺 智; 松橋 信平; 高橋 美智子*; 中西 啓仁*; 森 敏*; et al.
Proceedings of the National Academy of Sciences of the United States of America, 104(18), p.7373 - 7378, 2007/05
被引用回数：131 パーセンタイル：93.39(Multidisciplinary Sciences)Fe deficiency is a worldwide agricultural problem on calcareous soils. Rice plants use a well documented phytosiderophore-based system to take up Fe from the soil. Rice plants are extremely susceptible to low-Fe supply, however, because of low phytosiderophore secretion and low Fe
reduction activity. A yeast Fe chelate-reductase gene 
, selected for better performance at high pH, was fused to the promoter of the Fe-regulated transporter, 
, 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 gene showed higher Fe 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.
鈴木 基史*; 高橋 美智子*; 塚本 崇志*; 渡辺 智; 松橋 信平; 矢崎 潤史*; 岸本 直己*; 菊池 尚志*; 中西 啓仁*; 森 敏*; et al.
Plant Journal, 48(1), p.85 - 97, 2006/10
被引用回数：172 パーセンタイル：95.74(Plant Sciences)Mugineic acid family phytosiderophores (MAs) are metal chelators that are produced in graminaceous plants in response to Fe deficiency, but current evidence regarding secretion of MAs during Zn deficiency is contradictory. HPLC analysis showed that Zn deficiency induces the synthesis and secretion of MAs in barley plants. Studies of the genes involved in the methionine cycle using microarray analysis showed that the transcripts of these genes were increased in both Zn-deficient and Fe-deficient barley roots. Analysis using the PETIS confirmed that more Zn(II)-MAs than Zn were absorbed by the roots of Zn-deficient barley plants. These data suggest that the increased biosynthesis and secretion of MAs arising from a shortage of Zn are not due to an induced Fe deficiency, and that secreted MAs are effective in absorbing Zn from the soil.
-phytosiderophore and as Fe石丸 泰寛*; 鈴木 基史*; 塚本 崇志*; 鈴木 一正*; 中園 幹生*; 小林 高範*; 和田 泰明*; 渡辺 智; 松橋 信平; 高橋 美智子*; et al.
Plant Journal, 45(3), p.335 - 346, 2006/02
被引用回数：549 パーセンタイル：99.64(Plant Sciences)
gean was isolated from rice, which is highly homologous to . Real-time PCR analysis revealed that and are expressed predominantly in roots, and these transporters are induced by low-Fe condition. Analysis using the positron-emitting tracer imaging system showed that rice plants are able to take up both an Fe-phytosiderophore and Fe. This result indicates that, in addition to absorbing an Fe-phytosiderophore, rice possesses a novel Fe-uptake system that directly absorbs the Fe, a strategy that is advantageous for growth in submerged conditions.
