Browsing by Author "O’Brien, José Antonio"

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    Genome-wide analysis in response to nitrogen and carbon identifies regulators for root AtNRT2 transporters
    (2021) Ruffel, Sandrine; Chaput, Valentín; Przybyla Toscano, Jonathan; Fayos, Ian; Ibarra, Catalina; Moyano, Tomás; Fizames, Cécile; Tillard, Pascal; O’Brien, José Antonio; Gutiérrez, Rodrigo A.; Gojon, Alain; Lejay, Laurence
    In Arabidopsis (Arabidopsis thaliana), the High-Affinity Transport System (HATS) for root nitrate (⁠NO3−⁠) uptake depends mainly on four NRT2 NO3− transporters, namely NRT2.1, NRT2.2, NRT2.4, and NRT2.5. The HATS is the target of many regulations to coordinate nitrogen (N) acquisition with the N status of the plant and with carbon (C) assimilation through photosynthesis. At the molecular level, C and N signaling pathways control gene expression of the NRT2 transporters. Although several regulators of these transporters have been identified in response to either N or C signals, the response of NRT2 gene expression to the interaction of these signals has never been specifically investigated, and the underlying molecular mechanisms remain largely unknown. To address this question we used an original systems biology approach to model a regulatory gene network targeting NRT2.1, NRT2.2, NRT2.4, and NRT2.5 in response to N/C signals. Our systems analysis of the data identified three transcription factors, TGA3, MYC1, and bHLH093. Functional analysis of mutants combined with yeast one-hybrid experiments confirmed that all three transcription factors are regulators of NRT2.4 or NRT2.5 in response to N or C signals. These results reveal a role for TGA3, MYC1, and bHLH093 in controlling the expression of root NRT2 transporter genes.
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    Nitrate and hormonal signaling crosstalk for plant growth and development
    (2019) Gutiérrez Ilabaca, Rodrigo Antonio; O’Brien, José Antonio; Vega C., Andrea
    Nitrate is an essential macronutrient for plants, a primary nitrogen source in natural and human-made ecosystems. Nitrate can also act as a signaling molecule that directs genome-wide gene expression changes with an impact on plant metabolism, physiology, growth and development. Nitrate and phytohormone signaling pathways crosstalk to modulate growth and developmental programs in a multifactorial manner. Nitrate-signaling controls plant growth and development using molecular mechanisms that involve phytohormone-signaling pathways. In contrast, many phytohormones modulate or impact nitrate signaling in interconnected pathways. In this review, we explore recent progress in our understanding of well-documented connections between nitrate and phytohormones such as auxin, cytokinin and abscisic acid. We also discuss recent studies connecting nitrate to other phytohormones such as ethylene, salicylic acid, gibberellins and brassinosteroids. While many molecular details remain to be elucidated, a number of core signaling components at the intersection between nitrate and the major hormonal pathways have been described. We focus on established interactions of nitrate and different hormonal pathways to bring about cellular, growth and developmental processes in Arabidopsis thaliana.