Biology subjects

Burlat, V.

Publications and source records attributed to Burlat, V..

3 recordsLinked to original sources

bioRxiv2024

Receptor kinase LecRK-I.9 regulates cell wall remodelling and signalling during lateral root formation in Arabidopsis

Assembling and remodelling the cell wall is essential for plant development. Cell wall dynamic is controlled by cell wall proteins and a variety of sensor and receptor systems. LecRK-I.9, an Arabidopsis thaliana plasma membrane-localised lectin receptor kinase, was previously shown to be involved in cell wall-plasma membrane contacts and to play roles in plant-pathogen interactions, but so far, its role in development was unknown. LecRK-I.9 is transcribed at a high level in root tissues including the pericycle. Comparative transcript profiling of a loss-of-function mutant vs wild type identifies LecRK-I.9 as a regulator of cell wall metabolism. Consistently, lecrk-I.9 mutants display an increased pectin methylesterification level correlated with decreased pectin methylesterase and increased polygalacturonase activities. Also, LecRK-I.9 impacts lateral root development through the regulation of genes encoding (i) cell wall remodelling proteins during early events of lateral root initiation, and (ii) cell wall signalling peptides (CLE2, CLE4) repressing lateral root emergence and growth. Besides, low nitrate reduces LecRK-I.9 expression in pericycle and interferes with its regulatory network: however, the control of CLE2 and CLE4 expression is maintained. Altogether, the results show that LecRK-I.9 is a key player in a signalling network regulating both pre-branch site formation and lateral root emergence. HighlightThe lectin receptor kinase LecRK-I.9 regulates the molecular events leading to lateral root formation in both the initiation and emergence processes in Arabidopsis through cell wall remodelling enzymes and signalling peptides.

plant biology↗

bioRxiv2023

Genome wide association study of Arabidopsis seed mucilage layers at a regional scale

The myxospermous species Arabidopsis thaliana extrudes a polysaccharidic mucilage from the seed coat epidermis during imbibition. The whole seed mucilage can be divided into a seed-adherent layer and a fully soluble layer, both layers presenting natural genetic variations. The adherent mucilage is variable in size and composition, while the soluble mucilage is variable in composition and physical properties. Studies reporting both the genetic architecture and the putative selective agents acting on this natural genetic variation are scarce. In this study, we set up a Genome Wide Association study (GWAS) based on 424 natural accessions collected from 166 natural populations of A. thaliana located south-west of France and previously characterized for a very important number of abiotic and biotic factors. We identified an extensive genetic variation for both mucilage layers. The adherent mucilage was mainly related to precipitation and temperature whereas the non-adherent mucilage was unrelated to any environmental factors. By combining a hierarchical Bayesian model with a local score approach, we identified 55 and 28 candidate genes, corresponding to 26 and 10 QTLs for the adherent and non-adherent mucilages, respectively. Putative or characterized function and expression data available in the literature were used to filter the candidate genes. Only one gene among our set of candidate genes was already described as a seed mucilage actor, leaving a large set of new candidates putatively implicated inseed mucilage synthesis or release. The present study lay out foundation to understand the influence of regional ecological factors acting on seed mucilage in A. thaliana.

plant biology↗

bioRxiv2023

TBL38 is an atypical homogalacturonan acetylesterase with a peculiar cell wall microdomain localization in Arabidopsis seed mucilage secretory cells

Plant cell walls are made of complex polysaccharidic/proteinaceous network whose biosynthesis and dynamics implicate several cell compartments and impact plant development. The synthesis and remodeling of homogalacturonan pectins is associated with multiple developmental processes ranging from growth to response to biotic/abiotic stress. It encompasses Golgi-localized methylation and acetylation and subsequent demethylation and deacetylation in the cell wall. In the last decade, our comprehension of plant polysaccharides acetylation has increased significantly thanks to the study of the TRICHOME BIREFRINGENCE-LIKE (TBL) protein family. TBLs are mostly described as Golgi-localized acetyltransferases specifically targeting diverse hemicelluloses or pectins. Various tbl mutants showed altered wall mechanical properties and dynamics. Here, we study TBL38 that is co-expressed with PECTIN METHYLESTERASE INHIBITOR6 (PMEI6) and PEROXIDASE 36 (PRX36) during the development of Arabidopsis seed mucilage secretory cells (MSCs). We demonstrate the atypical TBL38 cell wall localization restricted to the PMEI6/PRX36 MSC cell wall microdomain. A tbl38 mutant displays an intriguing homogalacturonan immunological phenotype in this cell wall microdomain and in a MSC surface-enriched abrasion powder. This fraction was further characterized by mass spectrometry oligosaccharide profiling revealing an increased homogalacturonan acetylation phenotype. Finally, a recombinant TBL38 is shown to display pectin acetylesterase activity in vitro. These results indicate that TBL38 is an atypical cell wall-localized TBL that displays a homogalacturonan acetylesterase activity rather than a Golgi-localized acetyltransferase activity as observed in previously studied TBLs. TBL38 function during seed development is discussed.

plant biology↗