Biology subjects

Poussereau, N.

Publications and source records attributed to Poussereau, N..

5 recordsLinked to original sources

bioRxiv2026

A miniaturized Arabidopsis thaliana - Botrytis cinerea seedling pathosystem and the GreenDayz workflow for longitudinal image-based phenotyping

Plant-pathogen interactions are strongly influenced by host developmental stage, yet many Arabidopsis thaliana-Botrytis cinerea assays remain centred on mature rosette leaves and rely on inoculum loads that may exceed those involved in a primary infection. We established a miniaturized in vitro A. thaliana-B. cinerea seedling pathosystem initiated with a very low conidial dose (nominally ~25 conidia per plate) compatible with both destructive molecular sampling and repeated, non-destructive RGB imaging. The pathosystem was coupled to a low-cost smartphone photo station and to GreenDayZ Phenotyping, a guided image-analysis application with an intuitive graphical interface that standardizes longitudinal RGB image processing and extracts quantitative colour-based phenotypes. Together, the pathosystem and GreenDayZ Phenotyping provide an accessible and reproducible framework for longitudinal phenotyping of low-inoculum seedling infections, in which image-derived trajectories can be aligned with independent molecular readouts.

pathology↗

bioRxiv2024

DUAL SECRETORY VESICLES CLUSTERING AND DYNAMICS DURING POLAR CELL ELONGATION IN THE PHYTOPATHOGENIC FUNGUS BOTRYTIS CINEREA

Polarized elongation in filamentous fungi depends on secretory vesicles being supplied and fusing at the apex. In Ascomycota and Basidiomycota, these vesicles have mostly been reported to accumulate into a spheroidal structure known as the spitzenkorper. Using time-lapse microscopy, the spatial and temporal dynamics of fluorescently-labelled vesicles were investigated in 13 apices of the phytopathogenic fungus Botrytis cinerea. Over time, the fluorescent signal highlighted the spheroid spitzenkorper in half the sample and a crescent-shaped region of the apical dome in the other half. A linear relationship was found between the roundness of the fluorescent region and the hyphal elongation rate. Temporal Dynamics Clustering and Fourier transform showed periodic pulses of fluorescence intensity in the spitzenkorper that were absent in the crescent-shape region. These results reveal a dual mode of secretory vesicles accumulation at the apex of growing hyphae. Highlights- Secretory Vesicles accumulation at the apex form a spheroid spitzenkorper or a crescent - Vesicles accumulation of at the spitzenkorper is periodic - Roundness of SV accumulation regions correlates with elongation rates

microbiology↗

bioRxiv2024

Role of the clathrin adaptor AP-1 in cell wall integrity and virulence factor secretion in the plant pathogen Botrytis cinerea

In filamentous fungi, the secretory pathway plays a key role in polarized growth through the dlivery of vesicles carrying enzymes and components necessary to cell wall synthesis and fungal nutrition. In pathogenic species, it moreover supports the delivery of virulence factors. In metazoa and yeast, the formation of several secretory vesicles occurs at the Golgi apparatus and endosomes through a complex and partially characterized machinery involving clathrin and adaptor proteins such as AP-1. Data on the molecular mechanisms controlling this process are still scarce in filamentous fungi. Using a mutant under-expressing the {beta}-subunit of the heterotetrameric AP-1 clathrin adaptor complex, we investigated the importance of intracellular vesicle trafficking in the phytopathogenic fungus Botrytis cinerea. The mutant exhibits pleiotropic developmental defects, an abnormality in cell wall integrity associated with a mislocalization of the plasma-membrane chitine synthase BcCHSIIIa. Moreover, the AP-1 mutant is affected in the secretion of hydrolytic enzymes and displays a severe defect in pathogenicity. This study confirms the importance of the AP1/clathrin machinery in the secretory pathway of B. cinerea.

microbiology↗

bioRxiv2022

A multifunctional LysM effector of Botrytis cinerea contributes to plant infection

O_LILysM effectors are suppressors of chitin-triggered plant immunity in biotrophic and hemibiotrophic fungi. Their role in necrotrophic fungi is unclear as these last are known to activate plant defenses and induce cell death. C_LIO_LITo characterize the role of the BcLysM1 gene encoding a putative LysM effector in the necrotrophic fungus Botrytis cinerea, its expression was followed by transcriptional fusion and by RT-qPCR in planta. Two tagged-recombinant proteins were produced, and two independent deletion strains were constructed and characterized. C_LIO_LIBcLysM1 is induced in the early phase of infection, and more specifically in multicellular appressoria called infection cushions. The BcLysM1 protein binds the chitin in the fungus cell wall and protects hyphae against degradation by external chitinases. It is also able to sequester chitooligosaccharides and to prevent them from inducing ROS production in A. thaliana. Using mycelium as inoculum, deletion strains show a delay in infection initiation and a default in adhesion to bean leaf surfaces. C_LIO_LIThis study demonstrates for the first time a dual role for a LysM effector in mycelium adhesion on the plant and in host defenses suppression, both of them occurring during the asymptomatic phase of infection by a necrotrophic fungus. C_LI

microbiology↗

bioRxiv2020

The infection cushion: a fungal weapon of plant-biomass destruction

O_LIGrey mold disease affects fruits, vegetables and ornamental plants around the world, causing considerable losses every year. Its causing agent, the necrotrophic fungus Botrytis cinerea, produces infection cushions (IC) that are compound appressorial structures dedicated to the penetration of the plant tissues. C_LIO_LIA microarray analysis was performed to identify genes up-regulated in mature IC. The expression data were supported by RT-qPCR analysis performed in vitro and in planta, proteomic analysis of the IC secretome and mutagenesis of two candidate genes. C_LIO_LI1,231 up-regulated genes and 79 up-accumulated proteins were identified. They highlight a secretion of ROS, secondary metabolites including phytotoxins, and proteins involved in virulence: proteases, plant cell wall degrading enzymes and necrosis inducers. The role in pathogenesis was confirmed for two up-regulated fasciclin genes. DHN-melanin pathway and chitin deacetylases genes are up-regulated and the conversion of chitin into chitosan was confirmed by differential staining of the IC cell wall. In addition, up-regulation of sugar transport and sugar catabolism encoding genes was found. C_LIO_LIThese results support a role for the B. cinerea IC in plant penetration and suggest other unexpected roles for this fungal organ, in camouflage, necrotrophy or nutrition of the pathogen. C_LI

microbiology↗