Biology subjects

Lefebvre-Legendre, L.

Publications and source records attributed to Lefebvre-Legendre, L..

3 recordsLinked to original sources

bioRxiv2025

GWAs reveals SUBER GENE1-mediated suberization via Type One Phosphatases

Suberin deposition in the root endodermis is critical for plant nutrient acquisition and environmental adaptation. Here, we used an unbiased forward genetic approach based on natural variation across 284 Arabidopsis thaliana accessions to identify novel regulators of endodermal suberization. This screen revealed striking diversity in suberin levels and patterns, uncovering broader roles for suberin beyond those observed in the reference accession Col-0. A genome-wide association study pinpointed SUBER GENE1 (SBG1), a previously uncharacterized gene encoding a 129-amino acid protein, as a key regulator of suberin deposition. SBG1 acts through physical interaction with type one protein phosphatases (TOPPs) via conserved SILK and RVxF motifs. Disrupting this interaction abolishes SBG1 function, while topp mutants exhibit enhanced endodermal suberization, mirroring SBG1 overexpression. Our findings uncover a previously unknown regulatory module linking suberin formation to TOPP activity and ABA signaling and provide a framework for improving plant stress resilience through targeted manipulation of root barrier properties.

plant biology↗

bioRxiv2024

Directional Cell-to-cell Transport in Plant Roots

Cell-to-cell communication is critical for multicellular organisms. In plants, plasmodesmata--cytoplasmic channels--enable molecular transport between adjacent cells. In roots, this transport is predicted to be essential in nutrient acquisition and delivery to the vasculature. We demonstrate that plasmodesmatal transport persists in differentiated roots, despite apoplastic barriers such as Casparian strips and suberin lamellae in the endodermis, suggesting plasmodesmata as the sole pathway for water and nutrient flow at this stage. We also reveal a developmental switch in plasmodesmata function resulting in an unidirectional transport in differentiated roots. A genetic screen identified mutations that disrupt this directionality, leading to bidirectional transport. These mutations correlate with larger plasmodesmatal apertures, linked to defects in pectin composition and cell wall organization. This discovery underscores the role of plasmodesmatal aperture regulation and pectin in controlling directional transport. Our findings provide insights into plasmodesmata function and their regulation in roots.

plant biology↗

bioRxiv2019

A key role for phosphorylation of PsbH in the biogenesis and repair of photosystem II in Chlamydomonas

Phosphorylation of the core subunits of photosystem II (PSII) is largely governed by a protein kinase and an antagonistic protein phosphatase. In plants the respective mutants show alterations in the architecture of thylakoid membranes and in the repair of PSII after photo-inhibition. However the protein kinase targets several subunits of PSII, as well as other proteins. To specifically investigate the role of phosphorylation of the different PSII subunits, we used site-directed mutagenesis and chloroplast transformation in Chlamydomonas reinhardtii. Major, evolutionarily-conserved sites of phosphorylation in three components of PSII (CP43, D2 and PsbH) were mutated to replace the corresponding serine or threonine residues with alanine. The alanine substitution mutant of D2 had no apparent phenotype, while the mutant of CP43 presented a minor delay in recovery from photo-inhibition. Alanine substitutions of the phosphorylation sites in PsbH had significant effects on the accumulation of PSII or on its recovery from photo-inhibition. When mutations in two of the target subunits were combined through a second cycle of chloroplast transformation, the strongest phenotype was observed in the mutant lacking phosphorylation of both PsbH and CP43, which showed delayed recovery from photo-inhibition. Surprisingly this phenotype was reversed in the mutant defective for phosphorylation of all three subunits. Our analysis indicates a prominent role for the N-terminus of PsbH in the stable accumulation of PSII and of PsbH phosphorylation in its repair cycle.\n\nSIGNIFICANCE STATEMENTTo specifically investigate the role of PSII phosphorylation, alanine-substitution mutants of the major phospho-sites in the subunits of PSII were generated individually or in combinations using chloroplast transformation. PSII assembly was defective in some of the PsbH mutants. PSII repair after photo-inhibition was delayed most strongly in the mutant lacking phosphorylation of both PsbC (CP43) and PsbH.

plant biology↗