Modulation of iron responsive gene expression and enzymatic activities in response to changes of the iron nutritional status in _Cucumis sativus_ L.

Regulation exerted by the iron status of the plant on the iron deficiency responses was investigated in cucumber roots (_Cucumis sativus_ L.) both at the biochemical and molecular level. Absence of iron induced the expression of the CsFRO1, CsIRT1, CsHA1 and the Cspepc1 transcripts that was followed by an increase in the corresponding enzymatic activities. Supply of iron repressed gene expression, in particular those of the Fe(III)-chelate reductase and for the high affinity iron transporter and reduce the enzymatic activities. Our results confirm and extend the hypothesis of a coordinate regulation of these responses. Besides these two activities strictly correlated with iron deficiency adaptation, we considered also the H+-ATPase and the phosphoenolpyruvate carboxylase, that have been shown to be involved in this response

Modulation of iron responsive gene expression and enzymatic activities in response to changes of the iron nutritional status in Cucumis sativus L.

Regulation exerted by the iron status of the plant on the iron deficiency responses was investigated in cucumber roots (_Cucumis sativus_ L.) both at the biochemical and molecular level. Absence of iron induced the expression of the CsFRO1, CsIRT1, CsHA1 and the Cspepc1 transcripts that was followed by an increase in the corresponding enzymatic activities. Supply of iron repressed gene expression, in particular those of the Fe(III)-chelate reductase and for the high affinity iron transporter and reduce the enzymatic activities. Our results confirm and extend the hypothesis of a coordinate regulation of these responses. Besides these two activities strictly correlated with iron deficiency adaptation, we considered also the H+-ATPase and the phosphoenolpyruvate carboxylase, that have been shown to be involved in this response

Cellular iron homeostasis and metabolism in plant

International audienc

Effect of iron deficiency on the localization of phosphoenolpyruvate carboxylase in common bean nodules

Phosphoenolpyruvate carboxylase (PEPC) plays an important role in nodules, when there is an increase in the demand for energy. This enzyme provides carbon skeletons to sustain amino acid synthesis and malate to support energy required to fix nitrogen. Since PEPC is important for nodules, and there is lack of information about the effect of some nutrient deficiency in the expression and localization of this enzyme in legume nodules, this work focused on the localization of PEPC in nodules under iron deficiency of two common bean cultivars: Flamingo tolerant and Coco blanc sensitive to iron (Fe) deficiency. The results of immunolocalization using polyclonal antibody showed that this enzyme was detected in all regions of nodule sections; but the signal intensity was increased in Fe-deficient nodules as compared to Fe-sufficient ones in the tolerant cultivar, whereas the intensity was less pronounced in nodules of Fe-deficient plants than in those of Fe-sufficient plants for the sensitive cultivar Coco blanc. This work showed that the symbiotic tolerance of Flamingo to iron deficiency was linked to the increase of PEPC enzymes expression. However, the activity of these enzymes supported the energy required in bacteroids to maintain the nitrogenase activity.Keywords: Common bean, immunolocalization, iron deficiency, nodules, phosphoenol pyruvate carboxylas

Changes in the proteomic and metabolic profiles of Beta vulgaris root tips in response to iron deficiency and resupply

<p>Abstract</p> <p>Background</p> <p>Plants grown under iron deficiency show different morphological, biochemical and physiological changes. These changes include, among others, the elicitation of different strategies to improve the acquisition of Fe from the rhizosphere, the adjustment of Fe homeostasis processes and a reorganization of carbohydrate metabolism. The application of modern techniques that allow the simultaneous and untargeted analysis of multiple proteins and metabolites can provide insight into multiple processes taking place in plants under Fe deficiency. The objective of this study was to characterize the changes induced in the root tip proteome and metabolome of sugar beet plants in response to Fe deficiency and resupply.</p> <p>Results</p> <p>Root tip extract proteome maps were obtained by 2-D isoelectric focusing polyacrylamide gel electrophoresis, and approximately 140 spots were detected. Iron deficiency resulted in changes in the relative amounts of 61 polypeptides, and 22 of them were identified by mass spectrometry (MS). Metabolites in root tip extracts were analyzed by gas chromatography-MS, and more than 300 metabolites were resolved. Out of 77 identified metabolites, 26 changed significantly with Fe deficiency. Iron deficiency induced increases in the relative amounts of proteins and metabolites associated to glycolysis, tri-carboxylic acid cycle and anaerobic respiration, confirming previous studies. Furthermore, a protein not present in Fe-sufficient roots, dimethyl-8-ribityllumazine (DMRL) synthase, was present in high amounts in root tips from Fe-deficient sugar beet plants and gene transcript levels were higher in Fe-deficient root tips. Also, a marked increase in the relative amounts of the raffinose family of oligosaccharides (RFOs) was observed in Fe-deficient plants, and a further increase in these compounds occurred upon short term Fe resupply.</p> <p>Conclusions</p> <p>The increases in DMRL synthase and in RFO sugars were the major changes induced by Fe deficiency and resupply in root tips of sugar beet plants. Flavin synthesis could be involved in Fe uptake, whereas RFO sugars could be involved in the alleviation of oxidative stress, C trafficking or cell signalling. Our data also confirm the increase in proteins and metabolites related to carbohydrate metabolism and TCA cycle pathways.</p

Plasticity, exudation and microbiome-association of the root system of Pellitory-of-the-wall plants grown in environments impaired in iron availability

The investigation of the adaptive strategies of wild plant species to extreme environments is a challenging issue, which favors the identification of new traits for plant resilience. We investigated different traits which characterize the root-soil interaction of Parietaria judaica, a wild plant species commonly known as "Pellitory-of-the-wall". P. judaica adopts the acidification-reduction strategy (Strategy I) for iron (Fe) acquisition from soil, and it can complete its life cycle in highly calcareous environments without any symptoms of chlorosis. In a field-to-lab approach, the microbiome associated with P. judaica roots was analyzed in spontaneous plants harvested from an urban environment consisting in an extremely calcareous habitat. Also, the phenolics and carboxylates content and root plasticity and exudation were analyzed in P. judaica plants grown under three different controlled conditions mimicking the effect of calcareous environments on Fe availability: results show that P. judaica differentially modulates root plasticity under different Fe availability-impaired conditions, and that it induces, to a high extent, the exudation of caffeoylquinic acid derivatives under calcareous conditions, positively impacting Fe solubility.13n

The fate and the role of mitochondria in Fe-deficient roots of strategy I plants

In well aerated soils, iron exists, mainly as scarcely soluble oxides and oxi-hydroxides and, therefore, not freely available to plants uptake, notwithstanding its abundance. Multifaceted strategies involving reductase activities, proton processes, specialized storage proteins, and other, act in concert to mobilize iron from the environment, to take it up and to distribute it inside the plant. Because of its fundamental role in plant productivity several questions concerning homeostasis of iron in plants are currently a matter of intense debate. We discuss some recent studies on Strategy I responses in dicotyledonous plants focusing on metabolic change induced by iron deficiency, mainly concerning the involvement of mitochondria