Biology subjects

Barymow-Filoniuk, I.

Publications and source records attributed to Barymow-Filoniuk, I..

4 recordsLinked to original sources

bioRxiv2026

Annexin 5 is a key player in orchestrating the pollen sequestrome

Like dry seeds, mature pollen grains store a large reservoir of RNA species that enables rapid activation and germination under favorable conditions. The molecular mechanisms governing the accumulation of these RNA reservoirs remain poorly understood. Here, we show that the Arabidopsis pollen-specific protein annexin 5 (ANN5) localizes to the nucleolus and exerts dose-dependent control over ribosome biogenesis, as evidenced by altered steady-state rRNA levels in mature pollen. Ectopic expression of ANN5 also induced the accumulation of translationally repressed RNA in plant somatic tissues. Mechanistically, ANN5 interacts with histone deacetylase 2B (HD2B) and nucleolin (NUC1), which are known epigenetic modulators of ribosome biogenesis. In metabolically active cells, ANN5 associates with ribosomal and ribosome-associated proteins, suggesting it modulates the regulatory landscape of translation. We propose that the primary physiological role of ANN5 is to coordinate the formation and subsequent availability of RNA reserves during pollen maturation and activation.

cell biology↗

bioRxiv2025

Dynamic Rysto receptor remodeling controls its ability to confer extreme resistance

Plant nucleotide-binding leucine-rich repeat receptors (NLRs) mediate effector-triggered immunity (ETI), often accompanied by a hypersensitive response (HR). Conversely, extreme resistance (ER) provides exceptionally rapid and effective antiviral protection without visible cell death, yet the molecular and physiological mechanisms underlying ER remain poorly defined. The TIR-NLR receptor Rysto recognizes the coat protein (CP) of potato virus Y (PVY) and can trigger either ER or HR depending on the context. Here, we demonstrate that the efficacy of Rysto-mediated ER relies on the orchestration of various defense mechanisms. These involve transcriptional priming, and spatial redistribution of the receptor and a subset of chaperones. Rysto-expressing lines exhibit a preactivated immune state, including increased expression of genes encoding glycine-rich proteins associated with the cell wall interface and thickness. Upon PVY infection, Rysto plants undergo rapid transcriptome reprogramming, including redox- and defense-related pathways. At the protein level, Rysto initially forms a pre-active complex with Hsp70 and CP-interacting cochaperonins (CPIPs) which is remodeled upon PVY CP binding. PVY CP competes for Hsp70, enabling Rysto to oligomerize into an active resistosome. This process is further accompanied by relocalization of a subpool of the receptor toward an interface of plasma membrane, cell wall. Our research reveals a chaperone-mediated activation mechanism and spatial immune repositioning that differentiate ER responses from traditional HR, offering a detailed system for achieving durable antiviral resistance in plants.

plant biology↗

bioRxiv2025

Structural basis for heat tolerance in plant NLR immune receptors.

Nucleotide-binding leucine-rich repeat (NLR) immune receptors sense pathogen molecules and oligomerize, initiating defense signaling. Some NLRs function poorly at elevated temperatures for unknown reasons. We show that temperature-sensitive NLRs retain ligand binding at elevated temperatures but are impaired in oligomerization. We identify key residues involved in temperature resilience. Structural modeling reveals stabilizing intramolecular interactions of the NB-ARC domain with surface residues of the adjacent leucine-rich repeat (LRR) that preserve receptor integrity and functionality under heat stress. These insights enable in silico classification of NLRs as temperature-sensitive or -tolerant and underpin design of temperature tolerant variants of temperature sensitive NLRs. These findings provide a mechanistic basis for temperature sensitivity in plant immune receptors and enable engineering of temperature-tolerant disease resistance in crops.

plant biology↗

bioRxiv2018

Nucleus- and plastid-targeted annexin 5 promotes reproductive development in Arabidopsis and is essential for pollen and embryo formation

BackgroundPollen development is a strictly controlled post-meiotic process during which microspores differentiate into microgametophytes and profound structural and functional changes occur in organelles. Annexin 5 is a calcium- and lipid-binding protein that is highly expressed in pollen grains and regulates pollen development and physiology. To gain further insights into the role of ANN5 in Arabidopsis development, we performed detailed phenotypic characterization of Arabidopsis plants with modified ANN5 levels. In addition, interaction partners and subcellular localization of ANN5 were analyzed to investigate potential functions of ANN5 at cellular level.\n\nResultsHere, we report that RNAi-mediated suppression of ANN5 results in formation of smaller pollen grains, enhanced pollen lethality, and delayed pollen tube growth. ANN5 RNAi knockdown plants also displayed aberrant development during the transition from the vegetative to generative phase and during embryogenesis, reflected by delayed bolting time and reduced embryo size, respectively. At the subcellular level, ANN5 was delivered to the nucleus, nucleolus, and cytoplasm, and was frequently localized in plastid nucleoids, suggesting a likely role in interorganellar communication. Furthermore, ANN5-YFP co-immunoprecipitated with RABE1b, a putative GTPase, and interaction in planta was confirmed in plastidial nucleoids using FLIM-FRET analysis.\n\nConclusionsOur findings let us to propose that ANN5 influences basal cell homeostasis via modulation of plastid activity during pollen maturation. We hypothesize that the role of ANN5 is to orchestrate the plastidial and nuclear genome activities via protein-protein interactions however not only in maturing pollen but also during the transition from the vegetative to the generative growth and embryo development.

plant biology↗