Novel hormone receptor complexes control organ formation

Lead Research Organisation: University of East Anglia
Department Name: Graduate Office

Abstract

Plant development is shaped by the hormone auxin. Embryonic development requires auxin gradients already after the first zygotic division, and local extrema of auxin concentration guide initiation of organogenesis and tissue differentiation in post-embryonic development. Recent studies have established molecular principles governing i) auxin gradient formation, ii) intracellular auxin perception and activation of auxin response genes and iii) extracellular auxin perception and cytoskeleton remodelling. In the canonical auxin-signalling pathway, auxin binding to intracellular ubiquitin ligases of the auxin-signalling F-box (AFB) family mediates degradation of Aux/IAA transcriptional repressors. This liberates the auxin response factor (ARF) family of transcription factors to regulate target genes. Nonetheless, it remains an outstanding question how specific responses, ultimately different organs, are generated at auxin maxima in different tissues. Since eukaryotic differentiation is guided by waves of transcription factors, the answer to that question is expected to involve interplay between auxin, ARFs and tissue-specific transcription factors.

The aim of this proposal is to provide a precise molecular and developmental understanding of a novel mechanism for auxin signalling. This pathway involves direct interaction between auxin and transcription factors to regulate gene expression and ultimately tissue polarity.

The student will work in a dynamic environment alongside postdoctoral researchers and will receive a very broad range of training from this project. Particular areas of science include plant developmental genetics, molecular biology, biological chemistry and bio-informatics. The student should therefore be excellently prepared for a career in biology.

Studentship Projects

Project Reference Relationship Related To Start End Student Name
BB/M011216/1 01/10/2015 30/09/2023
1654170 Studentship BB/M011216/1 01/10/2015 30/09/2019 Andre Kuhn
 
Description Hormonal signalling in animals often involves direct transcription factor-hormone interactions that modulate gene expression. In contrast, plant hormone signalling is most commonly based on de-repression via the degradation of transcriptional repressors. Recently, we uncovered a non-canonical signalling mechanism for the plant hormone auxin in organ development with strong similarity to animal hormonal pathways. In this mechanism, auxin directly affects the activity of the auxin response factor ETTIN (ETT) towards regulation of target genes without the requirement for protein degradation. We discovered that auxin binds ETT to modulate gene expression. At the molecular level, this ETT-auxin interaction leads to dissociation of ETT from co-repressor proteins of the TOPLESS/TOPLESS-RELATED family followed by histone acetylation and the induction of target gene expression. Whilst the activity of canonical ARFs is affected indirectly by auxin via degradation of Aux/IAA repressors, direct ETT-auxin interactions allow switching chromatin locally between repressive and de-repressive states in an instantly-reversible auxin-dependent manner.
Exploitation Route Probably, but this will be decided by my supervisor Prof Lars Ostergaard
Sectors Agriculture, Food and Drink,Chemicals,Other

URL https://www.biorxiv.org/content/10.1101/863134v2