Biology subjects

Akary, E.

Publications and source records attributed to Akary, E..

3 recordsLinked to original sources

bioRxiv2023

Inositolphosphate glycans accumulate and suppress plant defense during Arabidopsis/Botrytis interaction

This study investigates the presence and significance of previously undiscovered oligosaccharides that accumulate during the interaction between Arabidopsis thaliana and Botrytis cinerea, a pathogenic fungus. Initially focused on characterizing cell wall-derived oligosaccharides, the research uncovered inositol phosphate glycans (IPGs) originating from plant sphingolipids, specifically glycosylinositol phosphorylceramides. Advanced chromatography, mass spectrometry techniques and molecular biology were employed to identify these IPGs, determine their origins, and study their role in the A. thaliana-B. cinerea interaction. Contrary to the conventional belief that oligosaccharides trigger plant defense, this research suggests that B. cinerea releases IPGs identical to those generated by host plant to actually downregulate plant defense mechanisms. This discovery offers insight into the dynamic strategies used by B. cinerea to evade plant defenses and establish successful infections. One-Sentence SummaryA plant pathogen releases products identical to those generated by host plant that aids in evasion of the plant defense.

plant biology↗

bioRxiv2023

Sterol 3-beta-Glucosyltransferase TRANSPARENT TESTA15 Controls Seed Development and Flavanol Accumulation through its Role in Vacuole Biogenesis and Maintenance in Arabidopsis

The Arabidopsis sterol 3-beta-glucosyltransferase UGT80B1/TRANSPARENT TESTA15 (TT15) catalyzes sterol glucoside biosynthesis. Its loss of function causes reduced seed size, defective flavanol, polysaccharide and lipid polyester deposition at the seed coat and reduced seed dormancy. How TT15 controls seed development and physiology is unknown. Here we show that tt15 mutants exhibit seed lethality with incomplete penetrance and maternal determinism that is correlated with endosperm cellularization defects, together with an increased sensitivity of seed germination to exogenous abscisic acid and paclobutrazol. We also reveal that flavanol deposition in the vacuole during tt15 seed development triggers premature endothelium cell death. An autoimmune-like syndrome characterized by callose and H2O2 accumulation was detected in endothelium at the seed abaxial pole. Similar phenotypes were observed with tt9/gfs9, a mutant defective in endomembrane trafficking and homotypic vacuole fusion. Double mutant analysis showed that tt9 partially rescued tt15 endothelium phenotypes. Consistent with seed mutant phenotypes, TT15 promoter activity was detected in endothelium and endosperm and TT15 protein was located mainly at the vacuolar membrane (tonoplast). Using fluorescence recovery after photobleaching, we demonstrated that tonoplast fluidity was increased in tt15 roots. Altogether our data suggest that TT15 regulates seed development and flavanol accumulation by modulating vacuole biogenesis and maintenance.

plant biology↗

bioRxiv2023

A pectin-binding peptide with a structural and signaling role in the assembly of the plant cell wall

Pressurized cells with strong walls make up the hydrostatic skeleton of plants. Assembly and expansion of such stressed walls depend on a family of secreted RAPID ALKALINIZATION FACTOR (RALF) peptides which, curiously, bind both a membrane receptor complex and wall-localized LEUCINE-RICH REPEAT EXTENSINs (LRXs) in a mutually exclusive way. Here we show that, in root hairs, the RALF22 peptide has a dual structural and signaling role in cell expansion. Together with LRX1, it directs the compaction of charged pectin polymers at the root hair tip into periodic circumferential rings. Free RALF22 induces the formation of a complex with LORELEI-LIKE-GPI-ANCHORED PROTEIN 1 (LLG1) and FERONIA (FER), triggering adaptive cellular responses. These findings show how a peptide simultaneously functions as a structural component organizing cell wall architecture and as a signaling molecule that regulates this process. This mechanism may also underlie wall assembly and expansion in other plant cell types.

plant biology↗