Biology subjects

Seydel, C.

Publications and source records attributed to Seydel, C..

4 recordsLinked to original sources

bioRxiv2026

Pathogen cell wall degrading enzymes facilitate extracellular vesicles to deliver RNA into plants

Extracellular vesicles (EVs) can deliver RNA and proteins into host cells to manipulate immunity; but how EVs transverse the cell wall is unknown. Using the fungal pathogen Botrytis cinerea that induces cross-kingdom RNA interference in plants, we uncovered that EV-mediated RNA delivery was dependent on cell wall degrading enzymes. Through fluorescence and transmission electron microscopy, and molecular genetic techniques, we demonstrate that EV-associated proteins compromise the plant cell wall, thereby facilitating RNA delivery. Notably, cell wall degrading enzymes are commonly associated with EVs across plant-colonizing bacterial, fungal and oomycete species, indicating a conserved role in EV transport across cell walls. These findings uncover a formerly unknown mechanism by which cell wall degrading enzymes facilitate EVs to transverse the cell wall for cargo delivery in cross-kingdom communication.

plant biology↗

bioRxiv2024

Subcellular plant carbohydrate metabolism under elevated temperature

In many plant species, exposure to a changing environmental temperature regime induces an acclimation response which ultimately increases a plants thermotolerance. Under elevated temperature, membrane systems need remodelling to counteract de-stabilising thermodynamic effects. This also affects photosynthesis and carbohydrate metabolism due to heat affected protein functions, enzyme activities and transport processes across membrane systems. In the present study, a combination of electrolyte leakage assays and chlorophyll fluorescence measurements was applied to quantify heat tolerance before and after heat acclimation of Arabidopsis thaliana at different temperature regimes. Subcellular carbohydrate concentrations were determined in a combined approach of non-aqueous fractionation and 3D reconstruction of mesophyll cells and subcellular compartments using serial block-face scanning electron microscopy. Across temperature regimes between 32 {degrees}C and 38 {degrees}C, 7 days heat acclimation at 34 {degrees}C was found to most efficiently increase tissue heat tolerance. Under such conditions, cytosolic sucrose concentrations were stabilised by a shift of sucrose cleavage rates into the vacuolar compartment while invertase-driven cytosolic sucrose cleavage was found to be efficiently quenched by fructose and glucose acting as competitive and non-competitive inhibitors, respectively. Finally, this study provides strong evidence for a sucrose concentration gradient from the cytosol into the vacuole which might directly affect the physiological role and direction of proton gradient-driven sugar transport across the tonoplast.

plant biology↗

bioRxiv2023

Temperature acclimation of photosynthesis and carbohydrate metabolism are related to the geographical origin of Arabidopsis thaliana

Acclimation is a multigenic trait by which plants adjust photosynthesis and metabolism to cope with a changing environment. Here, natural variation of photosynthetic and metabolic acclimation was analyzed in response to low and elevated temperature. For this, 18 natural accessions of Arabidopsis thaliana, originating from Africa and Europe, were grown at 22{degrees}C before being exposed to 4{degrees}C and 34{degrees}C for cold and heat acclimation, respectively. Amounts of carbohydrates were quantified together with their subcellular distribution across plastids, cytosol and vacuole. Linear electron transport rates (ETRs) were determined together with maximum quantum efficiency of photosystem II (Fv/Fm) for all growth conditions and under temperature fluctuation. Under elevated temperature, residuals of ETR under increasing photosynthetic photon flux densities were found to significantly correlate with the longitudinal gradient of the geographic origin of accessions indicating a naturally occurring east-west gradient of photosynthetic acclimation capacities. Further, in heat acclimated plants, vacuolar fructose amount was found to positively correlate with longitude while plastidial and cytosolic amounts were found to be negatively correlated. Plastidial sucrose concentrations were found to positively correlate with maximal ETRs under fluctuating temperature indicating a stabilizing role within the chloroplast. In summary, our findings revealed specific subcellular carbohydrate distributions which contribute differentially to photosynthetic efficiencies of natural Arabidopsis thaliana accessions across a longitudinal gradient. This sheds light on the relevance of subcellular metabolic regulation for photosynthetic performance in a fluctuating environment and supports the physiological interpretation of naturally occurring genetic variation of temperature tolerance and acclimation.

plant biology↗

bioRxiv2021

Integration of plant carbohydrate dynamics by Fourier polynomials

Quantification of system dynamics is a central aim of mathematical modelling in biology. Defining experimentally supported functional relationships between molecular entities by mathematical terms enables the application of computational routines to simulate and analyse the underlying molecular system. In many fields of natural sciences and engineering, trigonometric functions are applied to describe oscillatory processes. As biochemical oscillations occur in many aspects of biochemistry and biophysics, Fourier analysis of metabolic functions promises to quantify, describe and analyse metabolism and its reaction towards environmental fluctuations. Here, Fourier polynomials were developed from experimental time-series data and combined with block diagram simulation of plant metabolism to study heat shock response of photosynthetic CO2 assimilation and carbohydrate metabolism. Findings suggest that increased capacities of starch biosynthesis stabilize photosynthetic CO2 assimilation under transient heat exposure. Among soluble sugars, fructose concentrations were observed to fluctuate least under heat exposure which might be the consequence of high respiration rates under elevated temperature. Finally, Col-0 and two mutants of Arabidopsis thaliana with deficiencies in starch and sucrose metabolism were discriminated by fundamental frequencies of Fourier polynomials across different experiments. This suggests balance modelling based on Fourier polynomials as a suitable approach for mathematical analysis of dynamic plant-environment interactions. HighlightA balance equation model is developed to quantify effects of transient heat exposure on plant carbon assimilation. The model is based on Fourier polynomials for quantitative assessment of system dynamics.

plant biology↗