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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: 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.

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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Related in: MedlinePlus

Concentration of endogenous DMA and NA in rice shoots (a) Concentration of endogenous DMA. (b) Concentration of endogenous NA. The plants were harvested after collection of root exudates (Fig. 2), then DMA or NA was measured using HPLC. -Zn, zinc deficiency; -Fe, iron deficiency; N.D., not detected. Values are mean ± SD (n = 4)
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Fig4: Concentration of endogenous DMA and NA in rice shoots (a) Concentration of endogenous DMA. (b) Concentration of endogenous NA. The plants were harvested after collection of root exudates (Fig. 2), then DMA or NA was measured using HPLC. -Zn, zinc deficiency; -Fe, iron deficiency; N.D., not detected. Values are mean ± SD (n = 4)

Mentions: Higuchi et al. (2001) reported that the concentration of endogenous DMA was increased in Fe-deficient rice shoots. We confirmed that the concentration of endogenous DMA in Fe-deficient shoots was about three times higher than that in control shoots (Fig. 4a). The concentration of endogenous DMA in Zn-deficient shoots was about two times higher than that in control shoots (Fig. 4b). Although the concentration of endogenous DMA in Zn-deficient shoots was lower than that in Fe-deficient shoots, the expression of OsNAAT1, which encodes the enzyme that converts nicotianamine to its 3′′-keto acid, in Zn-deficient shoots was much higher than that in Fe-deficient shoots (Fig. 3a). Therefore, we measured the endogenous NA, which is an intermediate of DMA. Corresponding to the expression pattern of OsNAAT1, endogenous NA in Zn-deficient shoots was under the detection limit by HPLC, while in Fe-deficient shoots NA was lower than in the control shoots (Fig. 4b).Fig. 4


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)

Concentration of endogenous DMA and NA in rice shoots (a) Concentration of endogenous DMA. (b) Concentration of endogenous NA. The plants were harvested after collection of root exudates (Fig. 2), then DMA or NA was measured using HPLC. -Zn, zinc deficiency; -Fe, iron deficiency; N.D., not detected. Values are mean ± SD (n = 4)
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Related In: Results  -  Collection

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

Fig4: Concentration of endogenous DMA and NA in rice shoots (a) Concentration of endogenous DMA. (b) Concentration of endogenous NA. The plants were harvested after collection of root exudates (Fig. 2), then DMA or NA was measured using HPLC. -Zn, zinc deficiency; -Fe, iron deficiency; N.D., not detected. Values are mean ± SD (n = 4)
Mentions: Higuchi et al. (2001) reported that the concentration of endogenous DMA was increased in Fe-deficient rice shoots. We confirmed that the concentration of endogenous DMA in Fe-deficient shoots was about three times higher than that in control shoots (Fig. 4a). The concentration of endogenous DMA in Zn-deficient shoots was about two times higher than that in control shoots (Fig. 4b). Although the concentration of endogenous DMA in Zn-deficient shoots was lower than that in Fe-deficient shoots, the expression of OsNAAT1, which encodes the enzyme that converts nicotianamine to its 3′′-keto acid, in Zn-deficient shoots was much higher than that in Fe-deficient shoots (Fig. 3a). Therefore, we measured the endogenous NA, which is an intermediate of DMA. Corresponding to the expression pattern of OsNAAT1, endogenous NA in Zn-deficient shoots was under the detection limit by HPLC, while in Fe-deficient shoots NA was lower than in the control shoots (Fig. 4b).Fig. 4

Bottom Line: 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.

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.

Show MeSH
Related in: MedlinePlus