Biology subjects

Fuertauer, L.

Publications and source records attributed to Fuertauer, L..

5 recordsLinked to original sources

bioRxiv2026

Chilling Nights Do Not Cause Starch Over-Accumulation and Trigger a Shift in Carbon Partitioning via SPS Toward Sucrose in Arabidopsis - Differing from Acclimation to Permanent Cold

Plants acclimate to low temperatures by remodeling carbohydrate metabolism. Permanent cold at 4/5{whitebullet} C induces well-characterized cold acclimation in plants, including accumulation of starch and soluble sugars. In natural environments, however, annual plants in their vegetative phase more frequently experience chilling nights (0-6{whitebullet} C nights followed by days at least 12{whitebullet} C warmer), whose metabolic consequences remain poorly understood. We investigated Col-0 Arabidopsis thaliana exposed to one or seven chilling nights and quantified central carbohydrate metabolites, starch, photosynthetic parameters, and maximal activities of enzymes linking sucrose synthesis and cleavage. We integrated these time-series data into a biologically constrained augmented neural ordinary differential equation (ANODE) model to infer diurnal reaction-rate dynamics. Chilling nights induced strong accumulation of sucrose, glucose, and fructose, particularly after seven nights. Both measured sucrose phosphate synthase (SPS) capacity and ANODE-predicted SPS rates increased. In contrast to permanent cold acclimation, daytime starch over-accumulation was absent. Thus, lacking starch over-accumulation together with increased SPS rates, chilling nights invoke distinct carbohydrate-partitioning patterns towards sucrose, indicating a fundamentally different acclimation strategy compared to well described permanent cold.

plant biology↗

bioRxiv2025

Unraveling synergistic and antagonistic effects of simultaneous versus single hypoxia-salt conditions in an evolutionary adapted plant species

Plants frequently encounter simultaneous stressors, requiring complex adaptive responses across regulatory levels. Although morphological and metabolic effects of combined hypoxia-salt stress are known in halophytes, transcriptional impacts remain largely unexplored. This study uses RNA sequencing to analyze Salicornia europaea which is an intertidal salt-marsh plant naturally adapted to these conditions. Combined hypoxia-salt stress induced a distinct gene expression profile in which 16% of genes were exclusively changed. Synergistic, antagonistic, and additive effects were observed across all evaluated functional pathway categories. A data-driven analysis of carbohydrate metabolism, cellular respiration/fermentation, and amino acid pathways revealed that antagonistic effects were more prevalent than synergistic ones in both roots and shoots. Notably higher gene expression levels during hypoxia-salt of sucrose biosynthesis (consistent with salt), sucrose synthase (SUS) and trehalose-6-phosphate phosphatase (TPP, consistent with hypoxia) indicate enhanced sucrose and trehalose metabolism. The parallel down-regulation of invertase genes (consistent with hypoxia) suggests strategic carbon flux redistribution for optimized energy supply. Under hypoxic conditions, lactate dehydrogenase (LDH) expression was up-regulated, indicating active lactate fermentation rather than ethanol production via alcohol dehydrogenase (ADH). Enhanced proline synthesis under combined stress suggests improved osmoprotection. These insights into transcriptional reprogramming under single and combined hypoxia-salt conditions emphasize the intricate regulatory strategies plants utilize to manage concurrent stressors, showcasing their ability to adapt and develop stress resilience.

plant biology↗

bioRxiv2024

TEtrimmer: a novel tool to automate the manual curation of transposable elements

Transposable elements (TEs) are repetitive DNA sequences capable of moving within genomes. Accurate annotation and classification of TEs is crucial but challenging due to their sequence diversity and often fragmented occurrence. We present TEtrimmer, a novel tool to automate manual TE curation. TEtrimmer integrates multiple sequence alignment (MSA) clustering, MSA sequence extension, MSA cleaning, TE boundary definition, and TE classification, and provides report plots and a graphical user interface (GUI) application to inspect and improve results. Benchmarked on the genomes of six organisms from various kingdoms of life, TEtrimmer consistently improved the identification of intact TEs compared to established tools.

bioinformatics↗

bioRxiv2020

Impaired chloroplast positioning affects photosynthetic capacity and regulation of the central carbohydrate metabolism during cold acclimation

Photosynthesis and carbohydrate metabolism of higher plants need to be tightly regulated to prevent tissue damage during environmental changes. The intracellular position of chloroplasts changes due to a changing light regime. Chloroplast avoidance and accumulation response under high and low light, respectively, are well known phenomena, and deficiency of chloroplast movement has been shown to result in photodamage and reduced biomass accumulation. Yet, effects of chloroplast positioning on underlying metabolic regulation are less well understood. Here, we analysed photosynthesis together with metabolites and enzyme activities of the central carbohydrate metabolism during cold acclimation of the chloroplast unusual positioning 1 (chup1) mutant of Arabidopsis thaliana. We compared cold acclimation under ambient and low light and found that maximum quantum yield of PSII was significantly lower in chup1 than in Col-0 under both conditions. Our findings indicated that net CO2 assimilation in chup1 is rather limited by biochemistry than by photochemistry. Further, cold-induced dynamics of sucrose phosphate synthase differed significantly between both genotypes. Together with a reduced rate of sucrose cycling derived from kinetic model simulations our study provides evidence for a central role of chloroplast positioning for photosynthetic and metabolic acclimation to low temperature.

plant biology↗

bioRxiv2017

Vacuolar invertase activity shapes photosynthetic stress response of Arabidopsis thaliana and stabilizes central energy supply

Stabilization of the central carbohydrate and energy metabolism plays a key role in plant stress response. As the primary photosynthetic products, carbohydrates are substrate for numerous metabolic and stress-protective reactions. Further, they have been shown to be involved in diverse signalling processes finally affecting and regulating plant stress response on a whole plant level. Sucrose metabolism is known to be central to many stress-related processes and enzymes catalysing its biosynthesis, transport and degradation have been shown to significantly impact stress resistance and acclimation output. However, due to the cyclic structure of sucrose metabolism involving sucrose cleavage in multiple compartments as well as energy-demanding re-synthesis via hexose phosphorylation, it is challenging to derive an unambiguous picture of its contribution to stress reactions. In the present study, a combined stress experiment comprising cold and high-light identified metabolism of sucrose and fumaric acid to significantly separate the stress response of a cold susceptible and a tolerant natural accession of Arabidopsis thaliana. Kinetic modelling and simulation of subcellular rates of invertase-driven sucrose cleavage revealed a contrasting picture between the susceptible and the tolerant accession pointing to an important role of vacuolar invertase during initial stress response. Using a T-DNA insertion mutant with a dramatically reduced invertase activity provided evidence for a central role of the enzyme in stabilizing photosynthesis and the central energy metabolism during freezing and high-light stress. Reducing vacuolar invertase activity to about 3% of the wild type resulted in a strong increase of ADP and ATP levels indicating a severe effect on cytosolic and plastidial energy balance. Together with a significant decrease of maximum quantum yield of photosystem II (Fv/Fm) these results suggest that vacuolar invertase activity stabilizes cytosolic energy metabolism by supplying hexose equivalents being phosphorylated in the cytosol. Finally, the accompanying ATP consumption is essential for cytosolic phosphate balance which directly affects photosynthetic performance by the supply of ADP being crucial for photosynthetic ATP production.

plant biology↗