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Deregulated overexpression of the high affinity Cu transporter COPT1 alters iron homeostasis in Arabidopsis

ABSTRACT: The present work describes the effects on iron homeostasis when copper transport was deregulated in Arabidopsis thaliana by overexpressing copper transporters (COPTOE). A genome-wide analysis conducted on COPT1OE plants, highlighted that iron homeostasis gene expression was affected, both under copper deficiency and excess. Among the inhibited genes were those encoding the iron uptake machinery and their transcriptional regulators. Subsequently, COPTOE seedlings contained less iron and were more sensitive than controls to iron deficiency. These results emphasized the importance of appropriate spatiotemporal copper uptake for iron homeostasis under copper deficiency. The deregulation of copper-I uptake difficulted the transcriptional activation of the subgroup Ib of basic helix-loop-helix (bHLH-Ib) factors. Oppositely, copper excess inhibited the expression of the master regulator FIT but activate bHLH-Ib expression in COPTOE plants, in both cases leading to the lack of an adequate iron uptake response. As copper increased in the media, iron-III was accumulated in roots, accounting for a defective iron mobilization to the aerial parts, and this effect was exacerbated in COPTOE plants. Thus, iron-III overloading in roots inhibited local iron deficiency responses, aimed to metal uptake from soil, leading to a general lower iron content in the COPTOE seedlings. The understanding of the role of copper uptake in iron metabolism could be applied for increasing crops resistance to iron deficiency

ORGANISM(S): Arabidopsis thaliana

PROVIDER: GSE143857 | GEO | 2020/02/04

REPOSITORIES: GEO

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Project description:Copper and iron are essential micronutrients for most living organisms because they participate as cofactors in biological processes including respiration, photosynthesis and oxidative stress protection. In many eukaryotic organisms, including yeast and mammals, copper and iron homeostases are highly interconnected; however such interdependence is not well established in higher plants. Here we propose that COPT2, a high-affinity copper transport protein, functions under copper and iron deficiencies in Arabidopsis thaliana. COPT2 is a plasma membrane protein that functions in copper acquisition and distribution. Characterization of the COPT2 expression pattern indicates a synergic response to copper and iron limitation in roots. We have characterized a knockout of COPT2, copt2-1, that leads to increased resistance to simultaneous copper and iron deficiencies, measured as reduced leaf chlorosis and improved maintenance of the photosynthetic apparatus. We propose that COPT2 expression could play a dual role under Fe deficiency. First, COPT2 participates in the attenuation of copper deficiency responses driven by iron limitation maybe aimed to minimize further iron consume. On the other hand, global expression analyses of copt2-1 mutants versus wild type Arabidopsis plants indicate that low phosphate responses are increased in copt2-1 plants. In this sense, COPT2 function under Fe deficiency counteracts low phosphate responses. These results open up new biotechnological approaches to fight iron deficiency in crops. Four biological replicates of Arabidopsis seedlings were generated for 2 genotypes, Col-0 and copt2-1 mutant; and 3 growth condictions; first one an iron(Fe) and copper(Cu) sufficient medium (+Fe + Cu), second one an Fe deficient and Cu sufficient medium (-Fe+Cu) and third one an Fe and Cu deficient medium (-Fe-Cu). For each growth one comparasion was made, copt2-1 mutant versus Col-0; in each comparasion four biological replicates were made, two replicas were labeled with Cy5 for the mutant sample and Cy3 for the Col-0 sample, while the other two replicas were reversed-labeled.

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Deregulated overexpression of the high affinity Cu transporter COPT1 alters iron homeostasis in Arabidopsis

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