Biology subjects

Pecenkova, T.

Publications and source records attributed to Pecenkova, T..

5 recordsLinked to original sources

bioRxiv2026

A plasmodesmata-specific exocyst complex regulates symplastic connectivity by affecting callose turnover

Plasmodesmata are intercellular channels that mediate symplastic communication between plant cells. Molecular transport through these channels is critically regulated by dynamic callose deposition and degradation, yet the secretory mechanisms that deliver regulatory components to plasmodesmata remain poorly understood. Here, we identify and characterize a non-canonical plasmodesmata-associated module of the exocyst, an evolutionarily conserved protein complex involved in secretory vesicle tethering and exocytosis. Exocyst subunits EXO70G1, SEC15A, EXO84C, and SEC10A specifically accumulate at plasmodesmata, whereas the canonical exocyst subunits EXO70A1 and SEC8 do not. Genetic and interaction analyses show that EXO70G1 acts as a landmark for recruiting SEC15A and EXO84C to plasmodesmata, revealing a distinct mode of exocyst targeting at these membrane domains. EXO70G1-dependent exocyst targeting to plasmodesmata depends on phosphoinositides and sphingolipids, consistent with the specialized lipid environment of plasmodesmal membranes. Loss of EXO70G1 results in increased callose accumulation and reduced symplastic transport, and strongly enhances developmental defects of a callose-overproducing mutant. In addition, exo70G1 mutants display enhanced resistance to bacterial pathogen Pseudomonas syringae, linking reduced plasmodesmal permeability to anti-bacterial defense. Cross-species analysis further indicates that plasmodesmata association is a derived feature of the EXO70G clade, present in angiosperms but absent from non-angiosperm EXO70 homologs. Together, our findings show that exocyst diversification in plants has generated a specialized trafficking module - plasmodesmata-associated exocyst - that links vesicle delivery to callose homeostasis at plasmodesmata, thereby regulating intercellular communication, development, and immunity. TeaserA specialized secretion module of the exocyst complex regulates plant cell-to-cell connectivity by controlling callose turnover at plasmodesmata

plant biology↗

bioRxiv2026

Loss of PR1 function enhances Arabidopsis resistance to Botrytis cinerea

PATHOGENESIS-RELATED 1 (PR1) is one of the most widely used markers of salicylic acid (SA)-dependent plant immunity, yet its direct functional contribution to pathogen defence remains poorly understood. Here, we investigated the role of PR1 in Arabidopsis thaliana by analyzing a pr1 loss-of-function mutant challenged with bacterial and fungal pathogens and fumonisin B1 (FB1)-induced cell death. Notably, loss of PR1 led to markedly different responses to distinct pathogens; while it moderately increased susceptibility to the pathogenic bacterium Pseudomonas syringae, it substantially enhanced resistance to the necrotrophic fungus Botrytis cinerea, and the responses to the necrotroph Sclerotinia sclerotiorum remained unaltered. The pr1 mutant also displayed reduced spread of FB1-induced cell death, linking PR1 function to the promotion of stress-associated cell death. In line with the susceptibility changes, we observed the strongest PR1 accumulation and cell wall enrichment during B. cinerea infection using mCherry-tagged PR1 expressed under its endogenous promoter. Complementation with full-length PR1 and with a C-terminally truncated PR1 variant lacking the CAPE peptide restored wild-type susceptibility, whereas a non-cleavable PR1 variant did not. These results indicate that proteolytic processing at the CAPE cleavage motif, rather than the CAPE peptide itself, is required for PR1 function. Our data thus strongly suggest that PR1 may act as a susceptibility factor for necrotrophic pathogens by promoting host cell death.

Plant Biology↗

bioRxiv2025

Salicylic acid accumulation correlates with low anthocyanin production in Arabidopsis

Anthocyanins, flavonoid pigments, are essential photoprotective agents and play a pivotal role in enhancing plant resilience to environmental stressors. It has been shown that anthocyanin production is inhibited when pattern-triggered immunity (PTI) is activated in Arabidopsis thaliana. An important component of PTI is the phytohormone salicylic acid (SA). Interestingly, exogenous treatment with SA has been shown to induce anthocyanin content in grape, apple, maize roots, rose callus, or Arabidopsis seedlings. In this study, we used several A. thaliana mutants with modulated SA content to decipher the role of endogenous SA in anthocyanin production in A. thaliana. We treated WT and mutants with anthocyanin-inducible conditions and measured anthocyanin content using spectroscopy. We showed that high endogenous SA accumulation correlates with low anthocyanin production. This was confirmed by the treatment of the A. thaliana seedlings with exogenous SA. Additionally, using microscopy in the 5gt mutant, which exhibits enhanced production of anthocyanin vesicular inclusions (AVIs) due to the inhibition of ligandin-dependent vacuolar import, we showed that high endogenous SA also correlates with lower AVI abundance. Comparative analysis of Arabidopsis WT and mutants used in this study indicates a possible inhibitory effect of SA accumulation on anthocyanin content under anthocyanin-inducible conditions (AICs). We suggest that under AICs, SA downstream signaling independent of NPR1 is responsible for lower anthocyanin accumulation. HighlightsO_LIHigh endogenous SA correlates with low anthocyanin content under AIC in Arabidopsis C_LIO_LISA signaling, not biosynthesis, is responsible for the inhibition of anthocyanins C_LIO_LIHigh SA concentration decreases the abundance of AVI bodies C_LI GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=146 HEIGHT=200 SRC="FIGDIR/small/658514v1_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@183500corg.highwire.dtl.DTLVardef@1fc5e3forg.highwire.dtl.DTLVardef@18fb48forg.highwire.dtl.DTLVardef@1975181_HPS_FORMAT_FIGEXP M_FIG C_FIG Graphical abstract. Anthocyanin-inducible conditions (AICs), such as changes in day length, high sucrose in the medium, or treatment with kinetin, trigger the biosynthesis of anthocyanins. Previously, it was shown that activated pattern-triggered immunity (PTI), caused by the recognition of microbe-associated molecular patterns (MAMPs) by pattern recognition receptors (PRRs), inhibits anthocyanin production. A typical PTI response is an increased production of salicylic acid (SA). In this study, we show that a high concentration of SA and its downstream signaling, rather than SA biosynthesis itself, reduces anthocyanin accumulation.

plant biology↗

bioRxiv2023

Chitosan stimulates root hair callose deposition and inhibits root hair growth

Although angiosperm plants have a general capacity to react after the immunity elicitor chitin or chitosan treatment by the cell wall callose deposition, this response in particular cell types and its evolutionary conservation is not understood. Here we show that also the growing root hairs (RHs) of Arabidopsis can respond to a mild (0.001%) chitosan treatment by the callose deposition and by a deceleration of the RH growth. We demonstrate that the glucan synthase-like 5 (GSL5)/PMR4 is vital for chitosan-induced callose deposition but not for RH growth inhibition. Upon the higher chitosan concentration (0.01%) treatment, RHs do not deposit callose, while growth inhibition is prominent. To understand the specificities of the low and high concentration chitosan treatments, we analysed the corresponding PTI signalling components, gene expression, and RH cellular endomembrane and cytoskeleton modifications. Importantly, chitosan-induced callose deposition is also present in the functionally analogous and evolutionarily only distantly related RH-like structures rhizophores (lycophytes) and rhizoids (bryophytes). Our results point to the RH callose deposition as a conserved strategy of soil-anchoring plant cells (rhizoids/rhizophores/RHs) to deal with mild biotic stress. At the same time, high chitosan concentration prominently disturbs intracellular dynamics, tip-localised endomembrane compartments and RH growth, precluding callose deposition.

plant biology↗

bioRxiv2021

The EXO70B2 exocyst subunit contributes to papillae and encasement formation in anti-fungal defence in Arabidopsis

In the reaction to non-adapted Blumeria graminis f. sp. hordei (Bg), Arabidopsis thaliana leaf epidermal cells deposit cell wall reinforcements called papillae or seal fungal haustoria in encasements, both of which involve intensive exocytosis. A plant syntaxin SYP121/PEN1 has been found to be of key importance for the timely formation of papillae, and the vesicle tethering complex exocyst subunit EXO70B2 has been found to contribute to their morphology. Here, we identify a specific role for the EXO70B2-containing exocyst complex in the papillae membrane domains important for the callose deposition and GFP-SYP121 delivery to the focal attack sites, as well as its contribution to encasement formation. The mRuby2-EXO70B2 co-localises with the exocyst core subunit SEC6 and GFP-SYP121 in the membrane domain of papillae, and both proteins have the capacity to directly interact. The exo70B2/syp121 double mutant has a reduced number of papillae and haustorial encasements in response to Bg, indicating an additive role of the exocyst in SYP121 coordinated non-host resistance. In summary, we report cooperation between the plant exocyst and a SNARE protein in penetration resistance against non-adapted fungal pathogens. HighlightThe exocyst complex containing EXO70B2 subunit has specific role in papilla and encasement formation, implemented in coordination with the pathway regulated by the SYP121 SNARE complex in defence.

cell biology↗