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Deoxymugineic acid increases Zn translocation in Zn-deficient rice plants.

Suzuki M, Tsukamoto T, Inoue H, Watanabe S, Matsuhashi S, Takahashi M, Nakanishi H, Mori S, Nishizawa NK - Plant Mol. Biol. (2008)

Bottom Line: In contrast with barley, the roots of which secrete MAs in response to Zn deficiency, the amount of DMA secreted by rice roots was slightly decreased under conditions of low Zn supply.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Global Agricultural Sciences, Graduate School of Agricultural and Life Science, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.

ABSTRACT
Deoxymugineic acid (DMA) is a member of the mugineic acid family phytosiderophores (MAs), which are natural metal chelators produced by graminaceous plants. Rice secretes DMA in response to Fe deficiency to take up Fe in the form of Fe(III)-MAs complex. In contrast with barley, the roots of which secrete MAs 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 OsNAS1 and OsNAS2 was not increased in Zn-deficient roots but that of OsNAS3 was increased in Zn-deficient roots and shoots. The expression of OsNAAT1 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 OsDMAS1 was increased in Zn-deficient shoots. Analyses using the positron-emitting tracer imaging system (PETIS) showed that Zn-deficient rice roots absorbed less (62)Zn-DMA than (62)Zn(2+). Importantly, supply of (62)Zn-DMA rather than (62)Zn(2+) increased the translocation of (62)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.

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62Zn movement from cut leaf in Zn-deficient rice using PETIS (a) Plant image (left) and BAS image (right). Arrows indicate the point where 62Zn was absorbed. (b) Radioactivity in the entire plant except for the second newest leaf after 8 h of absorption. (c) Time course of the accumulation of radioactivity as determined by PETIS analysis. The data were scored every 3 min, and the images shown were taken at 120-min intervals for 8 h after supplying 62Zn through the shoots
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Fig6: 62Zn movement from cut leaf in Zn-deficient rice using PETIS (a) Plant image (left) and BAS image (right). Arrows indicate the point where 62Zn was absorbed. (b) Radioactivity in the entire plant except for the second newest leaf after 8 h of absorption. (c) Time course of the accumulation of radioactivity as determined by PETIS analysis. The data were scored every 3 min, and the images shown were taken at 120-min intervals for 8 h after supplying 62Zn through the shoots

Mentions: We conducted an additional PETIS experiment in which Zn-DMA or Zn2+ was supplied to Zn-deficient rice at the cut second newest leaf (Fig. 6; supplemental movie 2, supplemental Fig. 2). Plant images and the localization of 62Zn after 6 h of absorption are shown in Fig. 6a. Most of the 62Zn absorbed from the second newest leaf remained in that leaf, but some 62Zn was translocated to the other leaves and roots as well as to the DC and leaf sheath. The level of radioactivity in the entire plant, except for the second newest leaf, was higher in the plant supplied with 62Zn-DMA than in the plant supplied with 62Zn2+ (Fig. 6b), while that of the second newest leaf was not higher in the plant supplied with 62Zn-DMA than in the plant supplied with 62Zn2+ (supplemental Fig. 3). PETIS analysis showed that more 62Zn appeared continuously in the plant supplied with 62Zn-DMA than in the plant supplied with 62Zn2+. This suggests that 62Zn-DMA is translocated more rapidly than 62Zn2+ within the plant.Fig. 6


Deoxymugineic acid increases Zn translocation in Zn-deficient rice plants.

Suzuki M, Tsukamoto T, Inoue H, Watanabe S, Matsuhashi S, Takahashi M, Nakanishi H, Mori S, Nishizawa NK - Plant Mol. Biol. (2008)

62Zn movement from cut leaf in Zn-deficient rice using PETIS (a) Plant image (left) and BAS image (right). Arrows indicate the point where 62Zn was absorbed. (b) Radioactivity in the entire plant except for the second newest leaf after 8 h of absorption. (c) Time course of the accumulation of radioactivity as determined by PETIS analysis. The data were scored every 3 min, and the images shown were taken at 120-min intervals for 8 h after supplying 62Zn through the shoots
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2268730&req=5

Fig6: 62Zn movement from cut leaf in Zn-deficient rice using PETIS (a) Plant image (left) and BAS image (right). Arrows indicate the point where 62Zn was absorbed. (b) Radioactivity in the entire plant except for the second newest leaf after 8 h of absorption. (c) Time course of the accumulation of radioactivity as determined by PETIS analysis. The data were scored every 3 min, and the images shown were taken at 120-min intervals for 8 h after supplying 62Zn through the shoots
Mentions: We conducted an additional PETIS experiment in which Zn-DMA or Zn2+ was supplied to Zn-deficient rice at the cut second newest leaf (Fig. 6; supplemental movie 2, supplemental Fig. 2). Plant images and the localization of 62Zn after 6 h of absorption are shown in Fig. 6a. Most of the 62Zn absorbed from the second newest leaf remained in that leaf, but some 62Zn was translocated to the other leaves and roots as well as to the DC and leaf sheath. The level of radioactivity in the entire plant, except for the second newest leaf, was higher in the plant supplied with 62Zn-DMA than in the plant supplied with 62Zn2+ (Fig. 6b), while that of the second newest leaf was not higher in the plant supplied with 62Zn-DMA than in the plant supplied with 62Zn2+ (supplemental Fig. 3). PETIS analysis showed that more 62Zn appeared continuously in the plant supplied with 62Zn-DMA than in the plant supplied with 62Zn2+. This suggests that 62Zn-DMA is translocated more rapidly than 62Zn2+ within the plant.Fig. 6

Bottom Line: In contrast with barley, the roots of which secrete MAs in response to Zn deficiency, the amount of DMA secreted by rice roots was slightly decreased under conditions of low Zn supply.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Global Agricultural Sciences, Graduate School of Agricultural and Life Science, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.

ABSTRACT
Deoxymugineic acid (DMA) is a member of the mugineic acid family phytosiderophores (MAs), which are natural metal chelators produced by graminaceous plants. Rice secretes DMA in response to Fe deficiency to take up Fe in the form of Fe(III)-MAs complex. In contrast with barley, the roots of which secrete MAs 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 OsNAS1 and OsNAS2 was not increased in Zn-deficient roots but that of OsNAS3 was increased in Zn-deficient roots and shoots. The expression of OsNAAT1 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 OsDMAS1 was increased in Zn-deficient shoots. Analyses using the positron-emitting tracer imaging system (PETIS) showed that Zn-deficient rice roots absorbed less (62)Zn-DMA than (62)Zn(2+). Importantly, supply of (62)Zn-DMA rather than (62)Zn(2+) increased the translocation of (62)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.

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