PhD defence by Ashleigh Edwards

DNA double helix

The role of microProteins in responses to changing environments

A central question underlying developmental biology is how the same genetic material can give rise to many different cellular fates. Plants are an interesting case study as they remain phenotypically pliable post-embryonically and throughout all life stages. Investigating the mechanisms that underly their phenotypic plasticity might provide not only valuable insights into fundamental biological processes but also the tools to engineer more hardy and economically valuable crops.

In this thesis, I present three original research articles that aim to address gaps in our knowledge regarding plant development and adaptation. In the first, we characterise FIONA1, an m6A methyltransferase and its role in flowering time. Using a combination of RNA sequencing, phenotypic analysis, and PCR-based methods, we provide evidence that FIONA1 targets the 3’UTR of the floral repressor FLC to influence its stability and to repress flowering.

Secondly, I report the findings of a forward genetics screen in which we employed whole genome re-sequencing and identified seven novel alleles of the floral repressor SVP. A component of the ambient temperature sensing pathway, SVP represses flowering under cool temperatures. Our data suggests it is the main actor in this pathway and that its DNA binding domain is essential for it to repress flowering.

Finally, we investigate the role of a novel microProtein in the shade avoidance response; ATHB2miP is a cis-microProtein containing a leucine zipper domain and encoded by a sequence overlapping the 3’ end of ATHB2, a known regulator of hypocotyl elongation during shade adaptation. Through differential gene expression analysis and protein interaction assays, our results suggest that ATHB2miP behaves as a bona fide microProtein, sequestering and interfering with ATHB2 at the post-translational level by preventing it binding to its gene targets. MicroProteins and other small open reading frames have long been computationally and experimentally difficult to annotate and study, but with advances in sequencing technologies and a greater understanding of the molecular pathways that drive plant development, as we aimed to achieve in these three studies, they could prove to be valuable tools in bioengineering healthier crops.


Associate Professor Fernando Geu-Flores, PLEN

Professor Stephan Wenkel, Umeå University

Assessment committee

Prof. Sascha Laubinger, Carl Von Ossietzky Universität Oldenburg

Staff Scientist and Principle Investigator Martin Balczerowicz, University of Dundee

Professor Meike Burow, PLEN (Chair) 

Time and Venue 

Thursday 30 May 2024 at 09:00

A1-01-02 (Bülowsvej, next to the Festauditorium)