Biology subjects

Slane, D.

Publications and source records attributed to Slane, D..

4 recordsLinked to original sources

bioRxiv2026

Before auxin distribution matters: Prepatterning of the Arabidopsis embryo axis by MPK6-dependent AUX/IAA8 phosphorylation

In growth and development of plants, the signaling molecule auxin plays an instrumental role. Many patterning processes are controlled by auxin signaling in a self-organizing matter. After fertilization, such a patterning process needs to be started for the first time during plant life. Contrary to previous models, we show that the first differential auxin response that separates embryonic from extra-embryonic development in the two zygotic daughter cells happens independently of a detectable auxin gradient. Instead, differential phosphorylation of the transcriptional inhibitor Aux/IAA8 by MAP kinase signaling leads to differences in auxin sensitivity between the two daughter cells, initiating embryonic development in the apical cell. IAA8 phosphorylation in the basal cell prevents proteasomal degradation, suppressing canonical auxin responses, which initiates extra-embryonic development. MAP kinase signaling therefore precedes auxin gradients and prepatterns the apical-basal axis independently of an auxin gradient.

plant biology↗

bioRxiv2026

Osmotic-stress-inducible nuclear condensates restrict gene inducibility

Plants, as sessile organisms, have developed various mechanisms to respond to environmental stress conditions. The plant hormone abscisic acid (ABA) is necessary for the plant to adapt to osmotic stress conditions. However, the molecular mechanisms preceding ABA accumulation remain largely unknown. To isolate transcriptional complexes on the promoter region of NINE-CIS-EPOXYCAROTENOID DIOXYGENASE 3 (NCED3) encoding a rate-limiting enzyme in the ABA biosynthetic pathway in planta, we developed the insertional chromatin immunoprecipitation (iChIP) screen method. The identified ALBA proteins formed condensates through liquid-liquid phase separation (LLPS) in response to osmotic stress conditions. ALBA4 directly binds to stress-inducible genes, including NCED3, and suppresses their stress inducibility. Our results demonstrate how plants respond to osmotic stress at early timepoints before ABA biosynthesis through condensate formation as osmo-sensors.

plant biology↗

bioRxiv2024

Phosphorylation-Dependent Activation of the bHLH Transcription Factor ICE1/SCRM Promotes Polarization of the Arabidopsis Zygote

Asymmetric cell divisions are a key mechanism for breaking symmetry and orchestrating different cell identities in multicellular organisms. In Arabidopsis thaliana, as in most flowering plants, the first zygotic cell division is asymmetric, giving rise to the embryo proper and an extraembryonic suspensor. Zygotic polarization and differential cell identities in the daughter cells are controlled by the ERECTA-YODA pathway, a prototype receptor kinase-MAP kinase signaling pathway. This pathway also controls asymmetric cell divisions in the epidermis during stomatal development. In this context, the bHLH transcription factor ICE1/SCRM is a direct target of MPK3/6, and phosphorylation negatively controls SCRM activity by targeting the protein for proteasomal degradation. This raises the question if this regulatory module is also involved in the asymmetric division of the zygote. Our results show that SCRM has a critical function in zygote polarization and acts in parallel with the known MPK3/6 target WRKY2 in activating the homeobox transcription factor gene WOX8. Our work further demonstrates that SCRM activity in the early embryo is positively controlled by MPK3/6-mediated phosphorylation. Therefore, the mode of MAP kinase regulation of the same target protein fundamentally differs between the embryo and the epidermis, shedding light on cell type-specific, differential gene regulation by common signaling pathways.

plant biology↗

bioRxiv2019

Initiation and regulation of vascular tissue identity in the Arabidopsis embryo

Development of plant vascular tissues involves tissue specification, growth, pattern formation and cell type differentiation. While later steps are understood in some detail, it is still largely unknown how the tissue is initially specified. We have used the early Arabidopsis embryo as a simple model to study this process. Using a large collection of marker genes, we find that vascular identity is established in the 16-cell embryo. After a transient precursor state however, there is no persistent uniform tissue identity. Auxin is intimately connected to vascular tissue development. We find that while AUXIN RESPONSE FACTOR5/MONOPTEROS/ (ARF5/MP)-dependent auxin response is required, it is not sufficient for tissue establishment. We therefore used a large-scale enhanced Yeast One Hybrid assay to identify potential regulators of vascular identity. Network and functional analysis of suggest that vascular identity is under robust, complex control. We found that one candidate regulator, the G-class bZIP transcription factor GBF2, modulates vascular gene expression, along with its homolog GBF1. Furthermore, GBFs bind to MP and modulate its activity. Our work uncovers components of a gene regulatory network that controls the initiation of vascular tissue identity, one of which involves the interaction of MP and GBF2 proteins.

plant biology↗