Biology subjects

Fouche, M.

Publications and source records attributed to Fouche, M..

4 recordsLinked to original sources

bioRxiv2025

Molecular characterization of flower bud dormancy under constrained temperatures unveils a shallow dormancy stage induced by cold deprivation

Mild winters are becoming increasingly common in temperate regions due to climate change, which may have important impacts on ecosystems and agriculture. In particular, rising temperatures affect the progression of winter dormancy--a crucial developmental stage in perennial plants--making tree development and reproduction particularly vulnerable to climate change. A better understanding of how future temperature conditions will disrupt dormancy in cultivated fruit trees is crucial for anticipating the impeding consequences and identifying potential adaptation strategies. We investigated the effect of very constrained temperature conditions, i.e. several levels of cold deprivation and early cold exposure, on sweet cherry flower buds during dormancy onset and maintenance, using phenological observations and transcriptomic analyses. We show that temperature is a major driver of dormancy progression as cold deprivation and early cold exposure strongly modify the timing of phenological phases as well as gene expression patterns. We identified genes and signaling pathways specifically activated and/or repressed by cold temperatures, and therefore potentially involved in the optimal progression of dormancy. Finally, thanks to an integrative analysis of molecular data obtained under natural and prolonged warm conditions, we characterize a distinct shallow dormancy phase induced by cold deprivation, with a unique molecular signature. HighlightsOur phenological and molecular analysis of sweet cherry dormancy under constrained conditions reveals a gene expression timeline in response to temperature and uncovers a shallow dormancy stage induced by cold deprivation.

plant biology↗

bioRxiv2025

Experimental conditions to retrieve intrinsic cooperativity α directly from single binding assay data exemplified by the ternary complex formation of FKBP12, MAPRE1 and macrocyclic molecular glues

The incorporation of disease-relevant targets in a compound-dependent manner into ternary complexes with an assisting chaperone protein has become a common modality. Among the various types of ternary complex-forming compounds, molecular glues are of particular interest because they do not require significant binary (independent) target affinity. Instead, ternary complexes formed by molecular glues retrieve a significant part of their thermodynamic stability through newly induced chaperone-target or glue-target interactions that occur only in the ternary complex. These interactions lead to enhanced ligand binding - termed intrinsic cooperativity - which can be retrieved via the apparent cooperativity either by monitoring ligand binding through the chaperone or through the target protein. In this publication, the advantage of measuring the apparent cooperativity to determine the cooperativity by the weaker binding protein is discussed and illustrated using the example of ternary complexes between FKBP12, MAPRE1 and macrocyclic molecular glues derived from the rapamycin binding motif for FKBP12. Furthermore, the impact of the following three parameters on the apparent cooperativity is illustrated: 1.) the concentration of the monitoring protein, 2.) the excess of the counter protein, 3.) the affinity of the glue to the weaker binding protein in combination with the degree of intrinsic cooperativity . From this, experimental conditions to determine the intrinsic cooperativity with only one binding assay and without the need for a comprehensive mathematical model covering all simultaneous events under non-saturating conditions are highlighted. However, this framework requires a binding assay capable of measuring or at least estimating very weak binary affinities. If this is not possible for experimental reasons, but binding assays for both proteins are available within a normal bandwidth and the affinity to the stronger binding protein is not too high, it is discussed how the binding curve for the weaker binding protein in the presence of an excess of the weaker binding protein can be used to overcome the missing binary Kd for the weakly binding protein.

biochemistry↗

bioRxiv2019

From bud formation to flowering: transcriptomic state defines the cherry developmental phases of sweet cherry bud dormancy

BackgroundBud dormancy is a crucial stage in perennial trees and allows survival over winter to ensure optimal flowering and fruit production. Recent work highlighted physiological and molecular events occurring during bud dormancy in trees. However, they usually examined bud development or bud dormancy in isolation. In this work, we aimed to further explore the global transcriptional changes happening throughout bud development and dormancy onset, progression and release.\n\nResultsUsing next-generation sequencing and modelling, we conducted an in-depth transcriptomic analysis for all stages of flower buds in several sweet cherry (Prunus avium L.) cultivars that are characterized for their contrasted dates of dormancy release. We find that buds in organogenesis, paradormancy, endodormancy and ecodormancy stages are defined by the expression of genes involved in specific pathways, and these are conserved between different sweet cherry cultivars. In particular, we found that DORMANCY ASSOCIATED MADS-box (DAM), floral identity and organogenesis genes are up-regulated during the pre-dormancy stages while endodormancy is characterized by a complex array of signalling pathways, including cold response genes, ABA and oxidation-reduction processes. After dormancy release, genes associated with global cell activity, division and differentiation are activated during ecodormancy and growth resumption. We then went a step beyond the global transcriptomic analysis and we developed a model based on the transcriptional profiles of just seven genes to accurately predict the main bud dormancy stages.\n\nConclusionsOverall, this study has allowed us to better understand the transcriptional changes occurring throughout the different phases of flower bud development, from bud formation in the summer to flowering in the following spring. Our work sets the stage for the development of fast and cost effective diagnostic tools to molecularly define the dormancy stages. Such integrative approaches will therefore be extremely useful for a better comprehension of complex phenological processes in many species.

plant biology↗

bioRxiv2018

Multiple C2 domains and Transmembrane region Proteins (MCTPs) tether membranes at plasmodesmata

AO_SCPLOWBSTRACTC_SCPLOWIn eukaryotes, membrane contact sites (MCS) allow direct communication between organelles. Plants have evolved unique MCS, the plasmodesmata intercellular pores, which combine endoplasmic reticulum (ER) - plasma membrane (PM) contacts with regulation of cell-to-cell signalling. The molecular mechanism and function of membrane tethering within plasmodesmata remains unknown.\n\nHere we show that the Multiple C2 domains and Transmembrane region Protein (MCTP) family, key regulators of cell-to-cell signalling in plants, act as ER - PM tethers specifically at plasmodesmata. We report that MCTPs are core plasmodesmata proteins that insert into the ER via their transmembrane region whilst their C2 domains dock to the PM through interaction with anionic phospholipids. A mctp3/4 loss-of-function mutant induces plant developmental defects while MCTP4 expression in a yeast {Delta}tether mutant partially restores ER-PM tethering. Our data suggest that MCTPs are unique membrane tethers controlling both ER-PM contacts and cell-cell signalling.

plant biology↗