Biology subjects

Gallei, M.

Publications and source records attributed to Gallei, M..

6 recordsLinked to original sources

bioRxiv2025

TMK interacting network of receptor like kinases for auxin canalization and beyond

Receptor-like kinases (RLKs), particularly the Transmembrane Kinase (TMK) family, play essential roles in signaling and development, with TMKs being key components of auxin perception and downstream phosphorylation events. While TMKs involvement in auxin canalization, a process essential for vasculature formation and regeneration, has been established, nonetheless, the additional signaling and regulatory partners remain poorly understood. In this study, we identify and characterize seven leucine-rich repeat RLKs (TINT1-TINT7) as novel interactors of TMK1, revealing their diverse evolutionary, structural, and functional characteristics. Our results show that TINTs interact with TMK1 and highlight their roles in regulating various developmental processes. Majority of TINTs contributes, together with TMK1, to auxin canalization, with TINT5 linking TMK1 to other canalization component CAMEL. Beyond canalization, we also establish the role of TINT-TMK1 interactions in processes such as stomatal movement and the hypocotyls gravitropic response. These findings suggest that TINTs, through their interaction with TMK1, are integral components of various signaling networks, contributing to both auxin canalization and broader plant development.

plant biology↗

bioRxiv2024

Super-resolution expansion microscopy in plant roots

Super-resolution methods enable spatial resolution far better than the optical diffraction limit of about half the wavelength of light ([~]200-300 nm) but have yet to attain widespread use in plants, owing in large part to plants challenging optical properties. Expansion microscopy improves effective resolution by isotropically increasing physical distances between sample structures while preserving relative spatial arrangements, and clears the sample. However, its application to plants has been hindered by the rigid, mechanically cohesive structure of plant tissues. Here, we report on whole-mount expansion microscopy of Arabidopsis thaliana root tissues (PlantEx), achieving 4-fold resolution increase over conventional microscopy, highlighting microtubule cytoskeleton organization and interaction between molecularly defined cellular constituents. By combining PlantEx with STED microscopy, we increase nanoscale resolution further and visualize the complex organization of subcellular organelles from intact tissues by example of the densely packed COPI-coated vesicles associated with the Golgi apparatus and put these into cellular structural context.

plant biology↗

bioRxiv2022

Self-regulation of PIN1-driven auxin transport by cell surface-based auxin signaling in Arabidopsis

PIN-FORMED (PIN)-driven auxin transport contributes to establishing and maintaining a dynamic auxin concentration gradient alongside plant tissues, which drives the majority of developmental processes in plants. To maintain developmental plasticity in ever-changing environments, plants have evolved self-organizing feedback machinery between auxin signaling and its transport, which has been shown to play essential roles in many fundamental plant processes. However, the molecular mechanism behind this mutual regulation has not yet been clarified. Here, we identified a cell surface-triggered auxin signaling that regulates the PIN1-mediated auxin efflux and further developmental patterning in Arabidopsis. Auxin was able to stimulate PIN1 phosphorylation in plants through transmembrane kinases (TMKs), key components in auxin signaling, at the plasma membrane. TMK1 and TMK4 directly interacted with and phosphorylated PIN1 and functioned redundantly in the regulation of PIN1 polarity in plant cells. The phosphorylation sites in PIN1 proteins, targeted by both auxin and TMKs, were required for PIN1 trafficking and polarity, which further controlled auxin responses and downstream developmental patterning in Arabidopsis. Therefore, our findings provide a direct mechanism for the self-regulation between auxin signaling and transport that drives the auxin flows and proper development in plants.

plant biology↗

bioRxiv2022

Decoy Receptor Fine-tunes Cytokinin Signaling

Hormone perception and signaling pathways play a fundamental regulatory function in cell growth, developmental, and physiological processes in both plant and animal systems. Those pathways are activated by hormone binding to the receptor to trigger cellular responses. Equally important are mechanisms that suppress activated transduction cascades to reset the system. Different mechanisms at the level of hormone biosynthesis and deactivation through degradation, conjugation, and production of repressors that attenuate transduction cascades downstream of receptors are known. In animal systems, decoy receptors have been identified as another important mechanism for fine-tuning the activity of the signaling pathways in processes like inflammatory responses, apoptosis, and blood vessel formation. Decoy receptors recognize and bind specific signaling molecules, but they cannot activate downstream signaling pathways thus providing competitive inhibition. Here we describe the first decoy receptor in plants. We show that the splicing variant of CRE1/AHK4 receptor of cytokinin, a hormone with a key role in the regulation of cell division and meristem maintenance in plants, acts as a decoy receptor to attenuate cytokinin signaling. We propose that this novel mechanism of signaling control applies in processes when modulation of CK signaling is needed.

plant biology↗

bioRxiv2021

TOPLESS promotes plant immunity by repressing auxin signaling and is targeted by the fungal effector Naked1

In plants, the antagonism between growth and defense is hardwired by hormonal signaling. Perception of Pathogen Associated Molecular Patterns (PAMPs) from invading microorganisms inhibits auxin signaling and growth. Conversely, pathogens manipulate auxin signaling to promote disease, but how this hormone inhibits immunity is not fully understood. Ustilago maydis is a maize pathogen that induces auxin signaling in its host. We characterized an U. maydis effector protein, Naked1 (Nkd1), that is translocated into the host nucleus. Through its native EAR motif, Nkd1 binds to the transcriptional co-repressors TOPLESS/TOPLESS related (TPL/TPRs) and prevents the recruitment of transcriptional repressors involved in hormonal signaling, leading to de-repression of auxin and jasmonate signaling. Moderate up-regulation of auxin signaling inhibits an early defense response, PAMP-triggered ROS burst. Thus, our findings establish a clear mechanism for auxin-induced pathogen susceptibility. Manipulation of TPL by Nkd1 is evolutionary well balanced as engineered Nkd1 variants with increased expression or increased EAR-mediated TPL/TPR binding trigger typical salicylic acid mediated defense reactions, leading to pathogen resistance.

plant biology↗

bioRxiv2019

The Pleiades cluster of fungal effector genes inhibit 1 host defenses

SummaryBiotrophic plant pathogens secrete effector proteins to manipulate the host physiology. Effectors suppress defenses and induce an environment favorable to disease development. Sequence-based prediction of effector function is difficulted by their rapid evolution rate. In the maize pathogen Ustilago maydis, effector-coding genes frequently organize in clusters. Here we describe the functional characterization of the pleiades, a cluster of ten symplastic effectors. Deletion of the pleiades leads to strongly impaired virulence and accumulation of reactive oxygen species (ROS) in infected tissue. Eight of the Pleiades suppress the production of ROS upon perception of pathogen associated molecular patterns (PAMPs). Although genetically redundant, the Pleiades target different host components. The paralogs Taygeta1 and Merope1 suppress ROS production in either the cytoplasm or nucleus, respectively. Merope1 targets and promotes the autoubiquitination activity of RFI2, a conserved family of E3 ligases that regulates the production of PAMP-triggered ROS burst and influences flowering time in plants.

microbiology↗