Biology subjects

Santrucek, J.

Publications and source records attributed to Santrucek, J..

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↗

bioRxiv2024

PRC2 facilitates the transition from heterotrophy to photoautotrophy during seedling emergence

Seed-to-seedling transition represents a key developmental and metabolic switch in plants. Catabolism of seed storage reserves fuels germination and early seedling emergence until photosynthesis is established. The developmental transition is controlled by Polycomb repressive complex 2 (PRC2). However, the coordination of PRC2 activity and its contribution to transcriptional reprogramming during seedling establishment is unknown. By analysing the re-distribution of H3K27me3 and changes in gene transcription in shoot and root tissues of heterotrophic and photoautotrophic seedlings, we reveal two phases of PRC2-mediated gene repression. The first phase is independent of light and photosynthesis and results in irreversible repression of the embryo maturation programme, marked by heterotrophy and biosynthesis of reserve storage molecules. The second phase is associated with the repression of metabolic pathways related to germination and early seedling emergence, and H3K27me3 deposition in this phase is sensitive to photosynthesis inhibition. We show that preventing transcription of the PRC2-repressed glyoxylate cycle gene ISOCITRATE LYASE is sufficient to drive the vegetative phase transition in PRC2-depleted plants. This underscores a key role of PRC2 repression in the coordinated metabolic and developmental switches during seedling emergence and emphasizes the close connection between metabolic and developmental identities.

plant biology↗

bioRxiv2024

Mechanisms of Anammox Adaptation to High Temperatures: Increased Cyclization of Ladderane Lipids and Proteomic Insights

O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=170 SRC="FIGDIR/small/604647v1_ufig1.gif" ALT="Figure 1"> View larger version (42K): org.highwire.dtl.DTLVardef@14c383borg.highwire.dtl.DTLVardef@ffdb64org.highwire.dtl.DTLVardef@19cacceorg.highwire.dtl.DTLVardef@115168b_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical abstractC_FLOATNO C_FIG Although anammox-based processes have been widely applied in mesophilic conditions of reject water and recently in mainstream conditions, the potential of their implementation in high-temperature wastewaters remains largely unexplored. Therefore, this study investigated the operation parameters for the successful adaptation of anammox bacteria and the mechanisms involved on the proteomic and cellular level including unique ladderane lipids. For this purpose, the enrichment of Candidatus Brocadia was cultivated in two fed-batch reactors (FBRs) at a lab scale. The temperature of one FBR was gradually increased from 30 to 40 {degrees}C while the other FBR was maintained at 30 {degrees}C with four consecutive replicates of this experiment. For this adaptation to be successful, the original loading rate had to be at least halved, or ideally maintained below half the value of the specific anammox activity at the time. The most notable adaptation mechanisms included: (1) upregulation of chaperones and (2) doubled ladderane cyclization via the replacement of non-ladderane fatty acid by a ladderane fatty acid in ladderane lipids (p-value 0.005). To our best knowledge, this is the first study to describe the novel mechanism of ladderane cyclization which together with other adaptation strategies presents crucial indicators in anammox adaptation to high-temperature wastewaters.

microbiology↗

bioRxiv2022

Cuticular wax, but not the cutin matrix, is renewed during the lifespan of Clusia rosea leaves13CO2 labelling and gas exchange study

O_LIThe plant cuticle, which aided the water-to-land transition of plants, provides various services to the plant surface, and its synthesis and maintenance represent substantial metabolic costs. Nevertheless, only limited information regarding cuticle dynamics is available. C_LIO_LIWe determined the composition and dynamics of Clusia rosea cuticular waxes and matrix using 13CO2 labelling, compound-specific and bulk isotope ratio mass spectrometry. Collodion was used for wax collection; gas exchange techniques were employed to test for any collodion effects on living leaves. C_LIO_LICutin matrix (MX) area density did not vary between young and mature leaves and between leaf sides. Only young leaves incorporated new carbon into their MX. Collodion-based sampling discriminated between epicuticular (EW) and intracuticular wax (IW) effectively. EW differed in composition from IW. The newly synthetized wax was deposited in IW first and later in EW. Both young and mature leaves synthetized IW and EW; the faster dynamics in young leaves was not due to a faster synthesis rate but was the result of lower wax coverage. Longer-chain alkanes were deposited preferentially on the abaxial, stomatous leaf side, producing differences between leaf sides in wax composition. C_LIO_LIWe introduce a new, sensitive isotope labelling method and demonstrate that cuticular wax is renewed during leaf ontogeny of Clusia rosea. We discuss the ecophysiological significance of the new insights. C_LI

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↗