MSc Defence: Karsten Wiberg Andersen
Title: New insights into the relation between the glucosinolate transcription factors and the ROS related SRO family in Arabidopsis thaliana
Supervisors: Prof Meike Burow & PhD Henrik Munk Frisenvang
Censor: Simona Radutoiu, Associate Professor, University of Aarhus
Abstract
This thesis investigates the relation between glucosinolates (GLS) and Reactive Oxygen Species (ROS) at the protein and transcriptional level. GLS are important plant defence compounds in plants of the order of Brassicales. The enzymes in the GLS pathway are under strict regulation by Transcription Factors (TF), since different ratios and amounts of GLS are necessary to fight different types of pathogens and herbivores. ROS have evolved to become central cellular signals for the cell to interpret the current status of the cell and the environment. It is, therefore, likely that GLS TFs are connected to ROS signaling in the plant.
The investigation of the ROS-GLS-TF relation was conducted in Arabidopsis thaliana. Microarray data from the knockout (KO) of two GLS TFs, myb28 and myb29, were analysed by Gene Ontology (GO) term analysis and by comparison to ROS signature genes. Members of the Similar to Radical induced cell Death One (SRO) family, which is described as ROS modulating enzymes that interact with TFs, were tested in Yeast two Hybrid (Y2H) for Protein-Protein interactions (PPIs) with 6 GLS TFs. Truncation of the two SROs and MYB29 was further conducted in Y2H to generate more information about the function of the
interaction.
The PPIs between the GLS TFs and the SROs revealed an interaction network with 22 interactions of which 20 are undescribed in the literature. In myb28 and myb29 KOs many ROS signature genes had changes in their expression under non-stressed conditions. GO term analysis on the genes with expression changes in the myb28 and myb29 KOs displayed relation to several categories related to ROS. These findings contribute to a growing body of evidence that the GLS TFs are involved in ROS signaling. The connection between the SRO family and the GLS TFs demonstrate that this relation is established on a PPI level. Interaction in two SROs were shown to take place in a domain, which to our knowledge, is undescribed for PPIs in literature.
This study provides new insight into how interpretation of environmental changes in the plant are linked to the regulation of secondary metabolism on a PPI level. Future research should focus on establishing the in planta interactions between SROs and GLS TF, the biological relevance of the interaction and understanding the molecular function of the SROs.