Biology subjects

Ruzicka, K.

Publications and source records attributed to Ruzicka, K..

3 recordsLinked to original sources

bioRxiv2024

ER-located PIN5 transporter generates potent auxin sinks driven by the IAA decarboxylation pathway

Auxin is an essential and well-investigated regulator of plant development. Still, many aspects determining its (sub-)cellular distribution, as well as its metabolic turnover, are obscure. PIN5 is a transporter that resides on the endoplasmic reticulum and is presumed to influence internal auxin homeostasis by direct sequestration and subsequent degradation. Due to its distinct expression pattern and incomplete metabolomics analyses, the exact role of PIN5 protein and the identity of downstream auxin degradation products show significant gaps. To this end, we utilized morphologically homogeneous tobacco BY-2 cell cultures. We show that the expression of Arabidopsis thaliana AtPIN5 in the BY-2 system phenocopies so-called auxin starvation defects. Moreover, we reveal that the activity of AtPIN5 leads, in extreme cases, to the broad range of processes accompanying programmed cell death (PCD). Notably, based on the recently updated knowledge on auxin metabolism, we also show that a significant part of auxin metabolites downstream of the AtPIN5 activity are part of the re-emerged auxin decarboxylation pathway. Taking together, we report the direct induction of PCD by auxin stimulus and propose the physiological framework of the auxin decarboxylation route.

plant biology↗

bioRxiv2022

RaPiD-chamber: Easy to self-assemble live-imaging chamber with adjustable LEDs allows to track small differences in dynamic plant movement adaptation on tissue level

Plants rely on fine-tuning organ movement to ensure their survival and productivity. Even subtle loss of directional growth orchestration can result in a huge impact when the plant is impaired to adapt to an ever-changing environment, where it is exposed to manifold exogenous stimuli simultaneously. We present a newly designed chamber to obtain live images to track organ growth and movement differences, called RaspberyPi Dark Chambers (RaPiD-chamber). The RaPiD-chamber is easy to self-assemble and cost-efficient and allows to monitor the continuous growth of etiolated seedlings, as well as their response to light of different wavelengths and from chosen positions. We tested the advice by comparing hypocotyl elongation rate and response to unilateral white and blue light exposure of Arabidopsis thaliana Col0. Additionally, we compared the elongation rate of etiolated hypocotyls between Col0 and kin10, a mutant lacking the catalytic subunit of the cellular signaling hub SUCROSE NON-FERMENTING RELATED KINASE 1 (SnRK1). kin10 is known for its diminished ability to control hypocotyl elongation. As a case study, we compared the growth dynamics of etiolated Col0 versus kin10. Without further energy source supplementation to the growth medium, the mutant cannot keep up with hypocotyl elongation. Additionally, continuous observation of the dark-grown seedlings allowed us to determine a shift in the dynamics of apical hook angle formation for the mutant.

plant biology↗

bioRxiv2020

Mutually opposing activity of PIN7 splicing isoforms is required for auxin-mediated tropic responses in Arabidopsis thaliana

Advanced transcriptome sequencing has uncovered that the majority of eukaryotic genes undergo alternative splicing (AS). Nonetheless, little effort has been dedicated to investigating the functional relevance of particular splicing events, even those in the key developmental and hormonal regulators. Here we reveal, in the plant model Arabidopsis thaliana, that the PIN7 gene, which encodes a polarly localized transporter for the phytohormone auxin, produces two evolutionary-conserved transcripts. These isoforms PIN7a and PIN7b, differing in a 4 amino acid motif, are present at nearly equal levels in most cells. Although both variants do not differ in the subcellular localization and transport auxin with similar capacity, they closely associate and mutually influence their stability within the plasma membrane. Phenotypic complementation tests reveal that the functional contribution of PIN7b per se is minor but it markedly attenuates the prominent PIN7a activity, which is required for correct seedling apical hook formation and auxin-mediated tropic responses. These results establish alternative splicing of the PIN family as a conserved, functionally-relevant mechanism, unveiling an additional regulatory level of auxin-mediated plant development.

plant biology↗