Biology subjects

Antoniadi, I.

Publications and source records attributed to Antoniadi, I..

4 recordsLinked to original sources

bioRxiv2025

The Q-Warg Pipeline: A Robust and Versatile Workflow for Quantitative Analysis of Protoplast Culture Conditions

Single cells offer a simplified model for investigating complex mechanisms such as cell-cell adhesion. Protoplasts, plant cells without cell walls (CWs), have been instrumental in plant research, industrial applications, and breeding. However, due to the absence of a CW, protoplasts are not considered "true" plant cells and making them less relevant for biophysical studies. Current protocols for CW recovery in protoplasts vary widely among laboratories and starting materials, requiring lab-specific optimizations that often depend on expert knowledge and qualitative assessments. To address this, we have developed a user-friendly streamlined workflow, the Q-Warg pipeline, which enables quantitative comparison of various conditions for CW recovery post-protoplasting. This pipeline employs fluorescence imaging and tailored processing to measure parameters such as morphometry, cell viability, and CW staining intensity. Using this approach, we optimized culture conditions to obtain single plant cells (SPCs) with recovered CWs. Additionally, we demonstrated the robustness and versatility of the workflow by quantifying different fluorescent signals in protoplast suspensions. Overall, the Q-Warg pipeline provides a widely available and user-friendly solution for robust and unbiased characterization of protoplasts culture. The quantitative data generated by the pipeline may be useful in the future to decipher the mechanisms regulating protoplast viability and regeneration. Significance statementSeveral fields of plant biology, ranging from biotechnology to biomechanics, have recently regained a strong interest in using and studying protoplasts and single cells. Here, we developed a widely accessible quantitative workflow to characterize cell culture recovery after protoplasting along with the demonstration of its usefulness and versatility in various cases. We hope this tool can help other research groups to streamline the procedure needed to establish single plant cell approaches in their lab.

plant biology↗

bioRxiv2022

IPT9, a cis-zeatin cytokinin biosynthesis gene, promotes root growth

Cytokinin and auxin are plant hormones that coordinate many aspects of plant development. Their interactions in plant underground growth are well established, occurring at the levels of metabolism, signaling, and transport. Unlike many plant hormone classes, cytokinins are represented by more than one active molecule. Multiple mutant lines, blocking specific parts of cytokinin biosynthetic pathways, have enabled research in plants with deficiencies in specific cytokinin-types. While most of these mutants have confirmed the impeding effect of cytokinin on root growth, the ipt29 double mutant instead surprisingly exhibits reduced primary root length compared to wild type. This mutant is impaired in cis-zeatin (cZ) production, a cytokinin-type that had been considered inactive in the past. Here we have further investigated the intriguing ipt29 root phenotype, opposite to known cytokinin functions, and the (bio)activity of cZ. Our data suggest that despite the ipt29 short-root phenotype, cZ application has a negative impact on primary root growth and can activate a cytokinin response in the stele. Grafting experiments revealed that the root phenotype of ipt29 depends on local signaling which does not relate to directly to cytokinin levels. Notably, ipt29 displayed increased auxin levels in the root tissue. Moreover, analyses of the differential contributions of ipt2 and ipt9 to the ipt29 short-root phenotype demonstrated that, despite its deficiency on cZ levels, ipt2 does not show any root phenotype or auxin homeostasis variation while ipt9 mutants were indistinguishable from ipt29. We conclude that IPT9 functions may go beyond cZ biosynthesis, directly or indirectly, implicating effects on auxin homeostasis and therefore influencing plant growth.

plant biology↗

bioRxiv2020

DNA damage inhibits root growth by enhancing cytokinin biosynthesis in Arabidopsis thaliana.

Plant root growth is influenced by external factors to adapt to changing environmental conditions. However, the mechanisms by which environmental stresses affect root growth remain elusive. Here we found that DNA double-strand breaks (DSBs) induce the expression of genes for the synthesis of cytokinin hormones and enhance the accumulation of cytokinins in the Arabidopsis root tip. This is a programmed response to DSBs through the DNA damage signaling pathway. Our data showed that activation of cytokinin signalling suppresses the expression of PIN-FORMED genes that encode efflux carriers of another plant hormone, auxin, thereby disturbing downward auxin flow and causing cell cycle retardation in the G2 phase. Elevated cytokinin signalling also promotes an early transition from cell division to endoreplication, resulting in a reduction of the root meristem size. We propose that in response to DNA stress, plants inhibit root growth by orchestrating hormone biosynthesis and signalling.

plant biology↗

bioRxiv2019

Cell-surface receptors enable perception of extracellular cytokinins

Cytokinins are mobile multifunctional plant hormones with roles in development and stress resilience 1,2. Although cytokinin receptors are substantially localised to the endoplasmic reticulum 3-5, the cellular sites of cytokinin perception continue to be debated 1,6,7. Several cytokinin types display bioactivity 8,9 and recently a cell-specific cytokinin gradient was reported in roots 10. Yet, the importance of spatially heterogeneous cytokinin distribution and the specific cytokinin(s) that account for the different responses remain unclear. Here we show that cytokinin perception by plasma membrane receptors is an effective path for cytokinin response in root cells. Readout from a Two Component Signalling cytokinin-specific reporter (TCSn::GFP;11) is closely matched to intracellular cytokinin content, yet a proportion of bioactive cytokinins are detected in the extracellular fluid. Using cytokinins covalently linked to beads that could not pass the plasma membrane, we demonstrate that strong TCSn activation still occurs and that this response is greatly diminished in cytokinin receptor mutants. Although intracellular receptors play significant roles, we argue for a revision of concepts of cytokinin perception to include the spatial dimensions. In particular, selective ligand-receptor affinities, cellular localisation and tissue distribution of bioactive cytokinins, their receptors, transporters and inactivation enzymes appear all to be components of the signalling regulatory mechanisms.

plant biology↗