Publications by authors named "Alaeddine Safi"

Plant roots explore the soil for water and nutrients, thereby determining plant fitness and agricultural yield, as well as determining ground substructure, water levels, and global carbon sequestration. The colonization of the soil requires investment of carbon and energy, but how sugar and energy signaling are integrated with root branching is unknown. Here, we show through combined genetic and chemical modulation of signaling pathways that the sugar small-molecule signal, trehalose-6-phosphate (T6P) regulates root branching through master kinases SNF1-related kinase-1 (SnRK1) and Target of Rapamycin (TOR) and with the involvement of the plant hormone auxin.

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Protein activities depend heavily on protein complex formation and dynamic posttranslational modifications, such as phosphorylation. The dynamic nature of protein complex formation and posttranslational modifications is notoriously difficult to monitor in planta at cellular resolution, often requiring extensive optimization. Here, we generated and exploited the SYnthetic Multivalency in PLants (SYMPL)-vector set to assay protein-protein interactions (PPIs) (separation of phases-based protein interaction reporter) and kinase activities (separation of phases-based activity reporter of kinase) in planta, based on phase separation.

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Much of what we know about the role of auxin in plant development derives from exogenous manipulations of auxin distribution and signaling, using inhibitors, auxins, and auxin analogs. In this context, synthetic auxin analogs, such as 1-naphthalene acetic acid (1-NAA), are often favored over the endogenous auxin, indole-3-acetic acid (IAA), in part due to their higher stability. While such auxin analogs have proven instrumental in revealing the various faces of auxin, they display in some cases bioactivities distinct from IAA.

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Plants need to cope with strong variations of nitrogen availability in the soil. Although many molecular players are being discovered concerning how plants perceive NO3- provision, it is less clear how plants recognize a lack of nitrogen. Following nitrogen removal, plants activate their nitrogen starvation response (NSR), which is characterized by the activation of very high-affinity nitrate transport systems (NRT2.

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Dynamic reprogramming of gene regulatory networks (GRNs) enables organisms to rapidly respond to environmental perturbation. However, the underlying transient interactions between transcription factors (TFs) and genome-wide targets typically elude biochemical detection. Here, we capture both stable and transient TF-target interactions genome-wide within minutes after controlled TF nuclear import using time-series chromatin immunoprecipitation (ChIP-seq) and/or DNA adenine methyltransferase identification (DamID-seq).

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Nitrogen (N) and phosphorus (P) are key macronutrients sustaining plant growth and crop yield and ensuring food security worldwide. Understanding how plants perceive and interpret the combinatorial nature of these signals thus has important agricultural implications within the context of (1) increased food demand, (2) limited P supply, and (3) environmental pollution due to N fertilizer usage. Here, we report the discovery of an active control of P starvation response (PSR) by a combination of local and long-distance N signaling pathways in plants.

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All living organisms require a variety of essential elements for their basic biological functions. While the homeostasis of nutrients is highly intertwined, the molecular and genetic mechanisms of these dependencies remain poorly understood. Here, we report a discovery of a molecular pathway that controls phosphate (Pi) accumulation in plants under Zn deficiency.

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Plant specific GARP transcription factor family (made of ARR-B and G2-like) contains genes with very diverse in planta functions: nutrient sensing, root and shoot development, floral transition, chloroplast development, circadian clock oscillation maintenance, hormonal transport and signaling. In this work we review: first, their structural but distant relationships with MYB transcription factors, second, their role in planta, third, the diversity of their Cis-regulatory elements, fourth, their potential protein partners. We conclude that the GARP family may hold keys to understand the interactions between nutritional signaling pathways (nitrogen and phosphate at least) and development.

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