Biology subjects

Hamandjian, A.

Publications and source records attributed to Hamandjian, A..

2 recordsLinked to original sources

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↗