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Krouk G.,New York University | Krouk G.,CNRS Biochemistry and Plant Molecular Physiology Laboratory | Crawford N.M.,University of California at San Diego | Coruzzi G.M.,New York University | Tsay Y.-F.,Academia Sinica, Taiwan
Current Opinion in Plant Biology

Nitrate (NO 3 -) is a key nutrient as well as a signaling molecule that impacts both metabolism and development of plants. Understanding the complexity of the regulatory networks that control nitrate uptake, metabolism, and associated responses has the potential to provide solutions that address the major issues of nitrate pollution and toxicity that threaten agricultural and ecological sustainability and human health. Recently, major advances have been made in cataloguing the nitrate transcriptome and in identifying key components that mediate nitrate signaling. In this perspective, we describe the genes involved in nitrate regulation and how they influence nitrate transport and assimilation, and we discuss the role of systems biology approaches in elucidating the gene networks involved in NO 3 - signaling adaptation to fluctuating environments. © 2010. Source

Krouk G.,CNRS Biochemistry and Plant Molecular Physiology Laboratory
Plant Molecular Biology

During their sessile mode of life, plants need to endure variations in their environment such as a drastic variability in the nutrient concentration in soil solution. It is almost trivial to say that such fluctuations in the soil modify plant growth, development and phase transitions. However, the signaling pathways underlying the connections between nitrogen related signaling and hormonal signaling controlling growth are still poorly documented. This review is meant to present how nitrate/nitrogen controls hormonal pathways. Furthermore, it is very interesting to highlight the increasing evidence that the hormonal signaling pathways themselves seem to feed back control of the nitrate/nitrogen transport and assimilation to adapt nutrition to growth. This thus defines a feed-forward cycle that finely coordinates plant growth and nutrition. © 2016 Springer Science+Business Media Dordrecht Source

Medici A.,CNRS Biochemistry and Plant Molecular Physiology Laboratory | Krouk G.,CNRS Biochemistry and Plant Molecular Physiology Laboratory
Journal of Experimental Botany

Nitrate (NO3-) application strongly affects gene expression in plants. This regulation is thought to be crucial for their adaptation in response to a changing nutritional environment. Depending on the conditions preceding or concomitant with nitrate provision, the treatment can affect up to a 10th of genome expression in Arabidopsis thaliana. The early events occurring after NO3- provision are often called the Primary Nitrate Response (PNR). Despite this simple definition, PNR is a complex process that is difficult to properly delineate. Here we report the different concepts related to PNR, review the different molecular components known to control it, and show, using meta-analysis, that this concept/pathway is not monolithic. We especially bring our attention to the genome-wide effects of LBD37 and LBD38 overexpression, NLP7, and CHL1/NRT1.1 mutations. © The Author 2014. Source

Prado K.,CNRS Biochemistry and Plant Molecular Physiology Laboratory | Maurel C.,CNRS Biochemistry and Plant Molecular Physiology Laboratory
Frontiers in Plant Science

The water status of plant leaves is dependent on both stomatal regulation and water supply from the vasculature to inner tissues. The present review addresses the multiple physiological and mechanistic facets of the latter process. Inner leaf tissues contribute to at least a third of the whole resistance to water flow within the plant. Physiological studies indicated that leaf hydraulic conductance (Kleaf) is highly dependent on the anatomy, development and age of the leaf and can vary rapidly in response to physiological or environmental factors such as leaf hydration, light, temperature, or nutrient supply. Differences in venation pattern provide a basis for variations in Kleaf during development and between species. On a short time (hour) scale, the hydraulic resistance of the vessels can be influenced by transpiration-induced cavitations, wall collapses, and changes in xylem sap composition. The extravascular compartment includes all living tissues (xylem parenchyma, bundle sheath, and mesophyll) that transport water from xylem vessels to substomatal chambers. Pharmacological inhibition and reverse genetics studies have shown that this compartment involves water channel proteins called aquaporins (AQPs) that facilitate water transport across cell membranes. In many plant species, AQPs are present in all leaf tissues with a preferential expression in the vascular bundles. The various mechanisms that allow adjustment of Kleaf to specific environmental conditions include transcriptional regulation of AQPs and changes in their abundance, trafficking, and intrinsic activity. Finally, the hydraulics of inner leaf tissues can have a strong impact on the dynamic responses of leaf water potential and stomata, and as a consequence on plant carbon economy and leaf expansion growth. The manipulation of these functions could help optimize the entire plant performance and its adaptation to extreme conditions over short and long time scales. © 2013 Prado and Maurel. Source

Bouguyon E.,CNRS Biochemistry and Plant Molecular Physiology Laboratory | Gojon A.,CNRS Biochemistry and Plant Molecular Physiology Laboratory | Nacry P.,CNRS Biochemistry and Plant Molecular Physiology Laboratory
Seminars in Cell and Developmental Biology

Nitrate (NO 3 -) is a major nutrient for plants, taken up by their roots from the soil. Plants are able to sense NO 3 - in their environment, allowing them to quickly respond to the dramatic fluctuations of its availability. Significant advances have been made during the recent period concerning the molecular mechanisms of NO 3 - sensing and signaling in the model plant Arabidopsis thaliana. The striking action of NO 3 - as a signal regulating genome expression has been unraveled. Note worthily, NO 3 - sensing systems have been identified. These correspond to membrane transporters also ensuring the uptake of NO 3 - into root cells, thus generalizing the nutrient 'transceptor' (transporter/receptor) concept defined in yeast. Furthermore, components of the downstream transduction cascades, such as transcription factors or kinases, have also been isolated. A breakthrough arising from this improved knowledge is a better understanding of the integration of NO 3 - and hormone signaling pathways, that explains the extraordinary developmental plasticity of plants in response to NO 3 -. © 2012 Elsevier Ltd. Source

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