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Query: UMLS:C0240066 (iron deficiency)
 7,156 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nicotianamine and nicotianamine synthase (NAS) play key roles in iron nutrition in all higher plants. However, the mechanism underlying the regulation of NAS expression differs among plant species. Sequences homologous to iron deficiency-responsive elements (IDEs), i.e., cis-acting elements, are found on the promoters of these genes. We aimed to verify the interspecies compatibility of the Fe-deficiency response of NAS1 genes and understand the universal mechanisms that regulate their expression patterns in higher plants. Therefore, we introduced the graminaceous (Hordeum vulgare L. and Oryza sativa L.) NAS1 promoter::GUS into dicots (Nicotiana tabacum L. and Arabidopsis thaliana L.). Fe deficiency induced HvNAS1 expression in the shoots and roots when introduced into rice. HvNAS1 promoter::GUS and OsNAS1 promoter::GUS induced strong expression of GUS under Fe-deficient conditions in transformed tobacco. In contrast, these promoters only definitely functioned in Arabidopsis transformants. These results suggest that some Fe nutrition-related trans-factors are not compatible between graminaceous plants and Arabidopsis. HvNAS1 promoter::GUS induced GUS activity only in the roots of transformed tobacco under Fe-deficient conditions. On the other hand, OsNAS1 promoter::GUS induced GUS activity in both the roots and shoots of transformed tobacco under conditions of Fe deficiency. In tobacco transformants, the induction of GUS activity was induced earlier in the shoots than roots. These results suggest that the HvNAS1 and OsNAS1 promoters are compatible with Fe-acquisition-related trans-factors in the roots of tobacco and that the OsNAS1 promoter is also compatible with some shoot-specific Fe deficiency-related trans-factors in tobacco.
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PMID:Interspecies compatibility of NAS1 gene promoters. 1752 56

Nicotianamine (NA) is a non-protein amino acid derivative synthesized from S-adenosyl L-methionine able to bind several metal ions such as iron, copper, manganese, zinc, or nickel. In plants, NA appears to be involved in iron availability and is essential for the plant to complete its biological cycle. In graminaceous plants, NA is also the precursor in the biosynthesis of phytosiderophores. Arabidopsis lines accumulating 4- and 100-fold more NA than wild-type plants were used in order to evaluate the impact of such an NA overaccumulation on iron homeostasis. The expression of iron-regulated genes including the IRT1/FRO2 iron uptake system is highly induced at the transcript level under both iron-sufficient and iron-deficient conditions. Nevertheless, NA overaccumulation does not interfere with the iron uptake mechanisms since the iron levels are similar in the NA-overaccumulating line and wild-type plants in both roots and leaves under both sufficient and deficient conditions. This observation also suggests that the translocation of iron from the root to the shoot is not affected in the NA-overaccumulating line. However, NA overaccumulation triggers an enhanced sensitivity to iron starvation, associated with a decrease in iron availability. This study draws attention to a particular phenotype where NA in excess paradoxically leads to iron deficiency, probably because of an increase of the NA apoplastic pool sequestering iron. This finding strengthens the notion that extracellular NA in the apoplast could be a major checkpoint to control plant iron homeostasis.
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PMID:Increased sensitivity to iron deficiency in Arabidopsis thaliana overaccumulating nicotianamine. 1918 76