Dataset Information

2'-Deoxymugineic acid promotes growth of rice (Oryza sativa L.) by orchestrating iron and nitrate uptake processes under high pH conditions.

ABSTRACT: Poaceae plants release 2'-deoxymugineic acid (DMA) and related phytosiderophores to chelate iron (Fe), which often exists as insoluble Fe(III) in the rhizosphere, especially under high pH conditions. Although the molecular mechanisms behind the biosynthesis and secretion of DMA have been studied extensively, little information is known about whether DMA has biological roles other than chelating Fe in vivo. Here, we demonstrate that hydroponic cultures of rice (Oryza sativa) seedlings show almost complete restoration in shoot height and soil-plant analysis development (SPAD) values after treatment with 3-30 ?m DMA at high pH (pH 8.0), compared with untreated control seedlings at normal pH (pH 5.8). These changes were accompanied by selective accumulation of Fe over other metals. While this enhanced growth was evident under high pH conditions, DMA application also enhanced seedling growth under normal pH conditions in which Fe was fairly accessible. Microarray and qRT-PCR analyses revealed that exogenous DMA application attenuated the increased expression levels of various genes related to Fe transport and accumulation. Surprisingly, despite the preferential utilization of ammonium over nitrate as a nitrogen source by rice, DMA application also increased nitrate reductase activity and the expression of genes encoding high-affinity nitrate transporters and nitrate reductases, all of which were otherwise considerably lower under high pH conditions. These data suggest that exogenous DMA not only plays an important role in facilitating the uptake of environmental Fe, but also orchestrates Fe and nitrate assimilation for optimal growth under high pH conditions.

SUBMITTER: Araki R

PROVIDER: S-EPMC4309410 | biostudies-literature | 2015 Jan

REPOSITORIES: biostudies-literature

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2'-Deoxymugineic acid promotes growth of rice (Oryza sativa L.) by orchestrating iron and nitrate uptake processes under high pH conditions.

Araki Ryoichi R Kousaka Kayoko K Namba Kosuke K Murata Yoshiko Y Murata Jun J

The Plant journal : for cell and molecular biology 20141216 2

Poaceae plants release 2'-deoxymugineic acid (DMA) and related phytosiderophores to chelate iron (Fe), which often exists as insoluble Fe(III) in the rhizosphere, especially under high pH conditions. Although the molecular mechanisms behind the biosynthesis and secretion of DMA have been studied extensively, little information is known about whether DMA has biological roles other than chelating Fe in vivo. Here, we demonstrate that hydroponic cultures of rice (Oryza sativa) seedlings show almost ...[more]

PMID: 25393516

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Project description:Iron and Zn deficiencies are worldwide nutritional disorders that can be alleviated by increasing the metal concentration of rice (Oryza sativa L.) grains via bio-fortification approaches. The overproduction of the metal chelator nicotianamine (NA) is among the most effective ones, but it is still unclear whether this is due to the enrichment in NA itself and/or the concomitant enrichment in the NA derivative 2'-deoxymugineic acid (DMA). The endosperm is the most commonly consumed portion of the rice grain and mediates the transfer of nutrients from vegetative tissues to the metal rich embryo. The impact of contrasting levels of DMA and NA on the metal distribution in the embryo and endosperm of rice seeds has been assessed using wild-type rice and six different transgenic lines overexpressing nicotianamine synthase (OsNAS1) and/or barley nicotianamine amino transferase (HvNAATb). These transgenic lines outlined three different DMA/NA scenarios: (i) in a first scenario, an enhanced NA level (via overexpression of OsNAS1) would not be fully depleted because of a limited capacity to use NA for DMA synthesis (lack of -or low- expression of HvNAATb), and results in consistent enrichments in NA, DMA, Fe and Zn in the endosperm and NA, DMA and Fe in the embryo; (ii) in a second scenario, an enhanced NA level (via overexpression of OsNAS1) would be depleted by an enhanced capacity to use NA for DMA synthesis (via expression of HvNAATb), and results in enrichments only for DMA and Fe, both in the endosperm and embryo, and (iii) in a third scenario, the lack of sufficient NA replenishment would limit DMA synthesis, in spite of the enhanced capacity to use NA for this purpose (via expression of HvNAATb), and results in decreases in NA, variable changes in DMA and moderate decreases in Fe in the embryo and endosperm. Also, quantitative LA-ICP-MS metal map images of the embryo structures show that the first and second scenarios altered local distributions of Fe, and to a lesser extent of Zn. The roles of DMA/NA levels in the transport of Fe and Zn within the embryo are thoroughly discussed.

Project description:Selenite and phosphate share similar uptake mechanisms, as a phosphate transporter is involved in the selenite uptake process. However, the mechanism by which selenium (Se) transformation in plants is mediated by phosphorus (P) remains unclear. In this hydroponic study, the absorption, translocation, and biotransformation of Se in selenite-treated rice (Oryza sativa L.) seedlings were investigated under varying P nutrient status. The results showed that P-deficient cultivation increased the Se concentration in roots with Se-only treatment by 2.1 times relative to that of the P-normal condition. However, co-treating roots with additional P caused the Se concentration to decline by 20 and 73% compared to Se treatment alone under P-normal and P-deficient cultivation, respectively. A similar pattern was also observed in Se uptake by rice roots. With an Se-transfer factor elevated by 4.4 times, the shoot Se concentration was increased by 44% with additional P supply compared to the concentration under Se-only treatment of P deficiency; however, no significant differences were observed regarding P-normal cultivation. P deficiency increased the Se percentage by 28% within the cell wall, but reduced it by 60% in the soluble fraction of Se-only treated roots relative to that of the P-normal condition. Contrarily, compared with the Se-only treatment under P deficiency, additional P supply enhanced Se storage in the root soluble fraction by 1.3 times. The opposite tendency was observed for rice shoots. Moreover, P deficiency reduced the proportion of SeMet by 22%, but increased MeSeCys by 1.3 times in Se-only treated roots compared to those under the P-normal condition. Interestingly, MeSeCys was not detected when additional P was added to the two cultivation conditions. Unlike in the roots, only SeMet was generally detected in the rice shoots. The results demonstrate that the P nutrient status strongly affects the Se biofortification efficiency in rice seedlings by altering the Se subcellular distribution and speciation.

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Dataset Information

2'-Deoxymugineic acid promotes growth of rice (Oryza sativa L.) by orchestrating iron and nitrate uptake processes under high pH conditions.

Publications

2'-Deoxymugineic acid promotes growth of rice (Oryza sativa L.) by orchestrating iron and nitrate uptake processes under high pH conditions.

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