Biology subjects

Krzymowska, M.

Publications and source records attributed to Krzymowska, M..

6 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↗

bioRxiv2026

Epigenetic priming with valeric acid unlocks multi-stress resistance in plants by targeted histone deacetylase inhibition

Progressive climate change is driving increasingly devastating crop losses through droughts, heatwaves and other adverse weather. Combined with shrinking arable land and spreading plant diseases, this makes it crucial to enable crops to grow efficiently in unfavorable, dynamic environments. Because stressors demand prompt, highly coordinated responses, plant stress adaptations rely heavily on epigenetic regulation. Histone deacetylases (HDAs), particularly class I, were recently shown to repress these responses. As constitutive defense is energetically costly, tools enabling temporal modulation of such mechanisms are highly sought after in crop biotechnology. This study evaluated whether valeric acid (VA), a five-carbon carboxylic acid, can inhibit HDA and activate plant defense responses. Here we show that VA is a potent HDA inhibitor that confers resistance to multiple abiotic and biotic stresses in Arabidopsis, and further validate the abiotic component in maize and tomato. Despite its simple chemical structure, structural and transcriptomic evidence shows that VA acts by selectively inhibiting two major stress-repressing deacetylases, HDA19 and HDA6. By targeting these epigenetic switches, VA activates natural defense and acclimation responses. Time-course transcriptomic analyses further revealed that priming with VA induces transcriptional memory, which, together with VA-induced metabolic rewiring, enables rapid and efficient responses to future stressors. Most importantly, despite activating energetically demanding defenses, VA promotes vegetative growth and increases yield under normal conditions, thereby breaking the growth-defense trade-off. These findings establish VA as the first epigenetic biostimulant of its kind, capable of improving plant performance under both abiotic and biotic stress while simultaneously increasing crop yield. As the epigenetic mechanisms underlying its action are evolutionarily conserved, VA priming emerges as a promising universal strategy to mitigate the climate-driven global crisis of crop losses.

plant 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

The NLR immune receptor Roq1 recognizes the Pseudomonas syringae HopAG1 effector via its Nudix domain

O_LIPlant nucleotide-binding leucine-rich repeat receptors (NLRs) sense directly or indirectly effectors - proteins employed by pathogens during infection. While indirect recognition can be initiated by unrelated effectors targeting the same cellular component, direct recognition is restricted by conformational constraints of the pathogen protein and corresponding receptor. C_LIO_LIRecognition of XopQ (Roq1) receptor confers resistance to bacteria expressing members of the highly conserved effector family comprising XopQ/HopQ1/RipB. The structure of the activated Roq1 was solved previously, revealing that LRR and C-JID domains of Roq1 are involved in XopQ binding. C_LIO_LIIn this study, we found that Roq1 detects HopAG1, a member of a structurally different effector family. Presence of HopAG1 in Pseudomonas syringae reduced bacterial growth and symptoms development in wild-type but not in roq1 Nicotiana benthamiana plants. Moreover, HopAG1 co-immunoprecipitated with Roq1 indicating that both proteins associate. Based on deletion and structural analyses, we postulate that this interaction occurs via the Nudix domain of HopAG1 that binds to a similar receptor interface like XopQ. C_LIO_LINudix fold is predicted in multiple pathogen effectors suggesting that Roq1 may recognize effector families other than XopQ and HopAG1. Accordingly, it is also conceivable that other TNLs may detect a broader range of effector families than supposed. C_LI

plant biology↗

bioRxiv2021

Arabidopsis annexin 5 controls plasma membrane properties in mature pollen grains

In Arabidopsis, a dry stigma surface enables a gradual hydration of pollen grains by a controlled release of water. Occasionally the grains may be exposed to extreme precipitations that cause rapid water influx, swelling and eventually lead to pollen membrane (PM) rupture. In metazoans, calcium- and phospholipids-binding proteins, referred to as annexins participate in repair of the plasma membrane damages. It remains unclear, however, how this process is conducted in plants. Here, we examined whether the plant annexin 5 (ANN5), the most abundant member of the annexin family in pollen, is involved in the restoration of PM integrity. We analyzed a cellular dynamics of ANN5 in the pollen grains undergoing in vitro and in vivo hydration. We observed a transient ANN5 association to PM during the in vitro hydration that did not occur in the pollen grains being hydrated on the stigma. To simulate a rainfall, we performed spraying of the pollinated stigma with deionized water that induced ANN5 accumulation at PM. Similarly, calcium or magnesium application affected PM properties and induced ANN5 recruitment to PM. Our data suggest a model, in which ANN5 is involved in the maintenance of membrane integrity in pollen grains exposed to osmotic or ionic imbalances.

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↗