Biology subjects

Pecinkova, J.

Publications and source records attributed to Pecinkova, J..

7 recordsLinked to original sources

bioRxiv2026

MO25 binds CBL-interacting protein kinases associated with ribonucleoprotein condensates and regulates meiotic exit

Meiotic (M)-bodies are multiphasic ribonucleoprotein (RNP) condensates composed of a P-body core surrounded by a stress granule-like shell that promote meiotic exit through transient translational repression. This process depends on the phosphoserine-binding protein SMG7, which recruits the meiotic regulator TDM1 to M-bodies during meiosis II. Here, we identify the evolutionarily conserved scaffold protein MO25 as a regulator of SMG7 and TDM1 partitioning into M-bodies in Arabidopsis thaliana. Disruption of MO25A1 enhances the accumulation of SMG7 and TDM1 in M-bodies and increases the reduced fertility in the hypomorphic smg7-6 mutant, which exhibits impaired M-body association. In fungi and animals, MO25 proteins act as allosteric activators of STE20-family kinases. Interaction screening revealed that, whereas Arabidopsis MO25B proteins interact with STE20-family MAP4K kinases, MO25A paralogues have evolved specificity toward a subset of CBL-interacting protein kinases (CIPKs). Notably, the MO25A-interacting CIPKs localize to diverse nuclear and cytoplasmic RNP condensates. Among them, CIPK6 is required for fertility and pollen development, and disruption of its MO25-binding domain enhances SMG7 condensation. Together, our findings identify a previously unrecognized MO25A-CIPK interaction module that regulates M-body organization and may more broadly contribute to the regulation of RNP condensates.

plant biology↗

bioRxiv2026

Identification and characterization of a TRF2-like telomere-binding protein in Arabidopsis

Telomere protection and maintenance are mediated by proteins that bind telomeric DNA and recruit additional components of telomeric chromatin. While these factors are well characterized in yeast and mammals, their counterparts in plants remain poorly defined. Here, we used a proteomic approach in Arabidopsis thaliana to identify nuclear proteins that preferentially associate with telomeric DNA. We identified TRFL7, a previously uncharacterized member of the TRF-like (TRFL) protein family, as a prominent candidate. We show that TRFL7, together with its close homologues TRFL5 and TRFL11, associates with telomeric chromatin and forms distinct nuclear foci that preferentially localize near the nucleolus, resembling the nucleolus-associated telomere clustering characteristic of Arabidopsis. Genetic inactivation of TRFL7 in combination with either TRFL5 or TRFL11 results in telomere elongation, indicating a role for these proteins in telomere length homeostasis. Notably, TRFL7 contains an iDDR sequence motif that is also present in human TRF2, where it limits the activity of the Mre11-Rad50-Nbs1 complex. Together, our findings identify TRFL7 as a functional component of plant telomeric chromatin and suggest that it represents a plant orthologue of human TRF2.

molecular biology↗

bioRxiv2025

Post-transcriptional regulation of meiotic transcripts by the RNA binding protein CDM1 is associated with cytoplasmic condensate assemblies

The transition from diploid to haploid life phases requires extensive reprogramming of gene expression that drive meiotic cell division and the differentiation of haploid forms. A hallmark of meiosis is widespread post-transcriptional regulation, including delayed translation that ensures timely protein production at specific stages. Here, we identify a mechanism controlling the translation of meiotic transcripts in Arabidopsis pollen mother cells, mediated by CALLOSE DEFECTIVE MICROSPORES1 (CDM1). We show that CDM1 affects several meiotic processes, including chromosome pairing, condensation, and cytokinesis. CDM1 forms dynamic, meiosis specific cytoplasmic foci that associate with components of processing bodies and stress granules, giving rise to three-phase condensate assemblies. Biochemical and cellular analyses reveal that CDM1 is an RNA-binding protein with an intrinsic ability to form ribonucleoprotein condensates. Furthermore, we demonstrate that CDM1 binds mRNAs expressed in prophase I and represses their translation until later meiotic stages, coinciding with the disassembly of CDM1 condensates. These findings establish CDM1 as a key post-transcriptional regulator that fine-tunes the expression of meiotic genes to ensure proper progression of microsporogenesis.

plant biology↗

bioRxiv2024

Cytokinin acts as a systemic signal coordinating reproductive effort in Arabidopsis

The duration of the flowering phase is a key adaptive trait related to reproductive effort and plant longevity. In plants with indeterminate inflorescences, the number of flowers produced is determined by the activity of the inflorescence meristem. However, the integration of inflorescence meristem activity with the physiological and developmental status of a plant is not well understood. We combined quantitative imaging of the inflorescence meristem with the manipulation of cytokinin levels and distribution to investigate how meristem activity is regulated. Our data support the hypothesis that emerging fruits drain the acropetal flow of cytokinin away from the meristem inducing its proliferative arrest. We further show that the duration of flowering and cytokinin signaling in the inflorescence meristem is influenced by nitrate availability. Taken together, these data suggest that cytokinin functions as a systemic signal that integrates information about ongoing reproductive effort and plant nutrient status to control flower production.

plant biology↗

bioRxiv2023

Heat stress impairs centromere structure and segregation of meiotic chromosomes in Arabidopsis

Heat stress is a major threat to global crop production, and understanding its impact on plant fertility is crucial for developing climate-resilient crops. Despite the known negative effects of heat stress on plant reproduction, the underlying molecular mechanisms remain poorly understood. Here, we investigated the impact of elevated temperature on centromere structure and chromosome segregation during meiosis in Arabidopsis thaliana. Consistent with previous studies, heat stress leads to a decline in fertility and micronuclei formation in pollen mother cells. Our results reveal that elevated temperature causes a decrease in the amount of centromeric histone and the kinetochore protein BMF1 at meiotic centromeres with increasing temperature. Furthermore, we show that heat stress increases the duration of meiotic divisions and prolongs the activity of the spindle assembly checkpoint during meiosis I, indicating an impaired efficiency of the kinetochore attachments to spindle microtubules. Our analysis of mutants with reduced levels of centromeric histone suggests that weakened centromeres sensitize plants to elevated temperature, resulting in meiotic defects and reduced fertility even at moderate temperatures. These results indicate that the structure and functionality of meiotic centromeres in Arabidopsis are highly sensitive to heat stress, and suggest that centromeres and kinetochores may represent a critical bottleneck in plant adaptation to increasing temperatures.

plant biology↗

bioRxiv2022

High temperature increases centromere-mediated genome elimination frequency in Arabidopsis deficient in cenH3 or its assembly factor KNL2

Double haploid production is the most effective way of creating true-breeding lines in a single generation. In Arabidopsis, haploid induction via mutation of the centromere-specific histone H3 (cenH3) has been shown when outcrossed to wild-type. Here we report that a mutant of the cenH3 assembly factor KNL2 can be used as a haploid inducer. We elucidated that short temperature stress of the knl2 mutant increased the efficiency of haploid induction from 1 to 10%. Moreover, we have demonstrated that a point mutation in the CENPC-k motif of KNL2 is sufficient to generate haploid inducing lines, suggesting that haploid inducing lines in crops can be identified in a naturally occurring or chemically induced mutant population, avoiding the GMO approach at any stage. In addition, we have shown that the cenh3-4 mutant, which does not induce haploids under standard growth conditions, functions as a haploid inducer after exposure to short temperature stress.

plant biology↗

bioRxiv2019

Imaging plant germline differentiation within Arabidopsis flower by light sheet microscopy

In higher plants, germline differentiation occurs during a relatively short period within developing flowers. Understanding of the mechanisms that govern germline differentiation lags behind other plant developmental processes. This is largely because the germline is restricted to relatively few cells buried deep within floral tissues, which makes them difficult to study. To overcome this limitation, we have developed a methodology for live imaging of the germ cell lineage within floral organs of Arabidopsis using light sheet fluorescence microscopy. We have established reporter lines, cultivation conditions, and imaging protocols for high-resolution microscopy of developing flowers continuously for up to several days. We used multiview imagining to reconstruct a three-dimensional model of a flower at subcellular resolution. We demonstrate the power of this approach by capturing male and female meiosis, asymmetric pollen division, movement of meiotic chromosomes, and unusual restitution mitosis in tapetum cells. This method will enable new avenues of research into plant sexual reproduction.

plant biology↗