Biology subjects

Glanc, M.

Publications and source records attributed to Glanc, M..

3 recordsLinked to original sources

bioRxiv2024

Transport properties of canonical PIN-FORMED proteins and the role of the loop domain in auxin transport

Indole-3-acetic acid (IAA), the most abundant endogenous auxin is transported in plants in a polar fashion by PIN-FORMED (PIN) transporters and controls virtually all plant growth and developmental processes. Canonical PINs possess a long and largely disordered cytosolic loop domain which is shorter in non-canonical PINs. Auxin transport by canonical PINs is activated loop phosphorylation by kinases. While the structure of the transmembrane domains of these transporters was recently solved, their transport properties remained poorly characterized and particularly the relative roles of the transmembrane and loop domain therein. In this study we used flux studies to obtain quantitative kinetic parameters of IAA transport mediated by canonical PINs as well as of chimeras between transmembrane and loop domains of different PINs upon their activation by D6 PROTEIN KINASE or PINOID. We found that the transporters possess distinct transport properties that are due to both the transmembrane and loop domain. To demonstrate the physiological relevance of these distinct transport properties, we modelled root tip IAA distribution patterns and investigated the potential of different PINs to complement the agravitropic root growth phenotype of the pin2 mutant when expressed in the PIN2 domain. We found a strong correlation between transport parameters and physiological output indicating that in addition to PIN polarity a low transport rate in the PIN2 expression domain is required for gravitropic growth. Overall, the data show that the loop domain is not only required for activation of PIN-mediated auxin transport but has an additional role in the transport cycle by a currently unknown mechanism.

plant biology↗

bioRxiv2023

A precise balance of TETRASPANIN1/TORNADO2 activity is required for vascular proliferation and ground tissue patterning in Arabidopsis

The molecular mechanisms guiding oriented cell divisions in the root vascular tissues of Arabidopsis thaliana are still poorly characterized. By overlapping bulk and single-cell transcriptomic datasets, we unveiled TETRASPANIN1 (TET1) as a putative regulator in this process. TET1 is expressed in root vascular cells and loss-of-function mutants contain fewer vascular cells files. We further generated and characterized a CRISPR deletion mutant and show, unlike previously described mutants, that the full knock out is additionally missing endodermal cells in a stochastic way. Finally, we show that HA-tagged versions of TET1 are functional in contrast to fluorescent TET1 translational fusions. Immunostaining using HA-TET1 lines complementing the mutant phenotype revealed a dual plasma membrane and intracellular localization in the root vasculature and a polar membrane localization in young cortex, endodermal and initial cells. Taken together, we show that TET1 is involved in both vascular proliferation and ground tissue patterning. Our initial results pave the way for future work into deciphering its precise mode of action. Summary statementThis study reveals a novel role of tetraspanin TET1/TRN2 in root vascular development and ground tissue patterning in the model plant Arabidopsis thaliana.

plant biology↗

bioRxiv2022

MYB12 spatiotemporally represses TMO5/LHW-mediated transcription in the Arabidopsis root meristem

Transcriptional networks are crucial to integrate various internal and external signals into optimal responses during plant growth and development. Primary root vasculature patterning and proliferation are controlled by a network centred around the basic Helix-Loop-Helix transcription factor complex formed by TARGET OF MONOPTEROS 5 (TMO5) and LONESOME HIGHWAY (LHW), which control cell proliferation and orientation by modulating cytokinin response and other downstream factors. Despite recent progress, many aspects of the TMO5/LHW pathway are not fully understood. In particular, the upstream regulators of TMO5/LHW activity remain unknown. Here, using a forward genetic approach to identify new factors of the TMO5/LHW pathway, we discovered a novel function of the MYB-type transcription factor MYB12. MYB12 physically interacts with TMO5 and dampens the TMO5/LHW-mediated induction of direct target gene expression as well as the periclinal/radial cell divisions. The expression of MYB12 is activated by the cytokinin response, downstream of TMO5/LHW, resulting in a novel MYB12-mediated negative feedback loop that restricts TMO5/LHW activity to ensure optimal cell proliferation rates during root vascular development.

plant biology↗