Biology subjects

Marsik, P.

Publications and source records attributed to Marsik, P..

5 recordsLinked to original sources

bioRxiv2026

Decarboxylation of indoleacetic acid illuminates its evolution into a plant hormone

The evolution of indoleacetic acid (IAA) into the plant hormone auxin remains unclear. Here, we compared IAA response and metabolism in land plants and their closest living relatives, the streptophyte algae, using chemical treatments, phytohormone profiling, and targeted and untargeted metabolomics. Streptophyte algae showed neither plant-like auxin responses nor canonical IAA metabolism. Here, we demonstrate IAA side-chain decarboxylation as a novel pathway of cellular IAA metabolism, operating in streptophyte algae and land plants alike. Decarboxylation also underpinned IAA's innate photolability and yielded cytotoxic intermediates, which also accumulated endogenously under simulated sunlight. Together, these findings establish IAA decarboxylation as a major, conserved metabolic pathway, and suggest that the metabolic constraints arising from IAA's instability and indirect cytotoxicity contributed to its adoption as a plant hormone.

plant biology↗

bioRxiv2025

Pattern-triggered immunity in blue and white seed cultivars of Papaver somniferum

Papaver somniferum (poppy) is a traditional component of Central and Eastern European cuisine and an important oilseed crop in the region. The crucial thread for poppy stable yield is pathogen infection. Thus, we need to understand poppy defence mechanisms in detail. The first robust layer of plant immunity, which plays a crucial role in combat against pathogens, is pattern-triggered immunity (PTI). Here, we provide the first insights into PTI in poppy. We selected four poppy varieties used in the food industry. We investigated poppy response to various peptide elicitors acting as microbe-associated molecular patterns (MAMPs) and damage-associated molecular patterns (DAMPs). Flg22 induced the most robust reactive oxygen species (ROS) burst among all tested peptides. Flg22 also triggered putative mitogen-activated protein kinase (MAPK) phosphorylation and seedling growth inhibition in all tested cultivars. We identified PsWRKY22 and PsPR2 as candidate marker genes suitable for monitoring poppy PTI responses. The tested poppy cultivars have low levels of salicylic acid. Callose accumulation was triggered by wounding but not by flg22. For studying PTI in poppy, wounding is a challenge that needs to be considered as it can obscure potential PTI responses. Our findings highlight conserved aspects of poppy immunity and challenges in studying poppy PTI. The established pipeline facilitates improving our understanding of poppy immunity and has the potential for widespread application in poppy breeding and improving selection for broad-spectrum disease resistance provided by enhanced PTI. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=147 SRC="FIGDIR/small/639761v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@1680d52org.highwire.dtl.DTLVardef@42895eorg.highwire.dtl.DTLVardef@488ffeorg.highwire.dtl.DTLVardef@1e5a95d_HPS_FORMAT_FIGEXP M_FIG Graphical abstract The establishment of the methods for studying pattern-triggered immunity (PTI) in Papaver somniferum L. (poppy) was inspired by the knowledge of the model plant Arabidopsis thaliana. The study showed a similarity between Arabidopsis and poppy in response to flg22 but also pointed out the obstacles for PTI analysis in poppy and the differences compared to the model plant. Created with BioRender.com. C_FIG

plant biology↗

bioRxiv2023

Study of auxin metabolism using stable isotope labeling and LCMS; evidence for in planta auxin decarboxylation pathway.

The natural plant hormone auxin indole-3-acetic acid (IAA) influences many physiological processes in plants. Here, the metabolism of IAA was studied in detail using tobacco BY-2 cells as a model and compared with the in planta metabolism in several plant species. A combination of labeled/unlabeled substrate feeding, global untargeted mass spectrometric (MS) scanning, and selective MS filtering allowed the detection of 17 auxin metabolites, 15 of which were identified. Subsequent study of intermediate metabolism and dynamics revealed eight major pathways: three amino acid conjugation pathways with aspartate, glutamate, and glutamine, followed by their 2-oxidation with the help of the DAO enzyme; side-chain glucosyl ester formation; direct 2-oxidation; two decarboxylation pathways; and a pathway producing an unidentified metabolite. Interestingly, the first intermediates of the two decarboxylation pathways, indole-3-carbinol and oxoindole-3-carbinol, were formed outside the cells. We found that the majority of the detected auxin metabolites occur naturally in several plant species and that IAA is their precursor, indicating that the auxin metabolic pathways observed in BY-2 cells also occur in planta. Our finding that the IAA decarboxylation pathway occurs in planta, and the previous reports of auxin activity of some metabolites of this pathway, suggest that at least some of the biological effects of IAA may be explained by its conversion to decarboxylative metabolites.

plant biology↗

bioRxiv2019

Body coloration and mechanisms of colour production in Archelosauria: The case of deirocheline turtles

Animal body coloration is a complex trait resulting from the interplay of multiple colour-producing mechanisms. Increasing knowledge of the functional role of animal coloration stresses the need to study the proximate causes of colour production. Here we present a description of colour and colour producing mechanisms in two non-avian archelosaurs, the freshwater turtles Trachemys scripta and Pseudemys concinna. We compare reflectance spectra; cellular, ultra-, and nano-structure of colour-producing elements; and carotenoid/pteridine derivatives contents in the two species. In addition to xanthophores and melanocytes, we found abundant iridophores which may play a role in integumental colour production. We also found abundant dermal collagen fibres that may serve as thermoprotection but possibly also play role in colour production. The colour of yellow-red skin patches results from an interplay between carotenoids and pteridine derivatives. The two species differ in the distribution of pigment cell types along the dorsoventral head axis, as well as in the diversity of pigments involved in colour production, which may be related to visual signalling. Our results indicate that archelosaurs share some colour production mechanisms with amphibians and lepidosaurs, but also employ novel mechanisms based on the nano-organization of the extracellular protein matrix that they share with mammals.

zoology↗

bioRxiv2018

Regulatory changes in pterin and carotenoid genes underlie balanced color polymorphisms in the wall lizard

Reptiles use pterin and carotenoid pigments to produce yellow, orange, and red colors. These conspicuous colors serve a diversity of signaling functions, but their molecular basis remains unresolved. Here, we show that the genomes of sympatric color morphs of the European common wall lizard, which differ in orange and yellow pigmentation and in their ecology and behavior, are virtually undifferentiated. Genetic differences are restricted to two small regulatory regions, near genes associated with pterin (SPR) and carotenoid metabolism (BCO2), demonstrating that a core gene in the housekeeping pathway of pterin biosynthesis has been co-opted for bright coloration in reptiles and indicating that these loci exert pleiotropic effects on other aspects of physiology. Pigmentation differences are explained by extremely divergent alleles and haplotype analysis revealed abundant trans-specific allele sharing with other lacertids exhibiting color polymorphisms. The evolution of these conspicuous color ornaments is the result of ancient genetic variation and cross-species hybridization.

evolutionary biology↗