The doctoral dissertation in the field of Biology will be examined at the Faculty of Science, Forestry and Technology, Joensuu Campus and online.
What is the topic of your doctoral research? Why is it important to study the topic?
Metabolomics investigates molecules within biological systems, in cellular, tissue and organism levels. Metabolites are small-molecular-weight molecules, which have numerous functions in all living organisms. In plants, primary metabolites are directly involved in growth and reproduction, while secondary metabolites have specialized functions, especially during stress. In addition to proteomics and transcriptomics, metabolomics provides a possibility to study gene functions and signalling, as metabolites are the end products and intermediates of the metabolism. They are also the most rapid to respond in changing (cellular) conditions when compared to response times in protein and transcript levels. Mass spectrometry (MS)-based plant metabolomics approaches are finding an increasing number of applications to investigate gene functions and the molecular and biochemical mechanisms underlying plant responses to changing environment and stress.
What are the key findings or observations of your doctoral research?
We used metabolomics as a tool to investigate gene function and stress responses, and to determine possible oxidative stress markers in plants. In addition, a large-scale transcriptomics was used to study responses in the gene expression level, as well as how the gene expression is regulated differently by RCD1, the integrative node between development and stress responses. The results show that significantly changed metabolite levels are regulated transcriptionally not only by inducing/repressing genes connected to biosynthetical routes, but by via various transcription factors and highly complex networks of interacting proteins. RCD1 being one of the key players.
How can the results of your doctoral research be utilised in practice?
To understand plants adaptability to stress conditions, we need to understand how plants regulate and reconfigure central metabolic pathways (i.e., carbon, nitrogen, and energy metabolism) as well as the specialized metabolism (i.e. antioxidants, pigments) during stress. It is also important to understand are the responses to various stress's (e.g. stressors) similar or do they vary, and if so, how and why. When we understand the cellular processes, we can apply them in e.g. in the fields of agriculture and forestry, and improve the crop yields and ensure the reproductions and welfare of the plants/crops.
What are the key research methods and materials used in your doctoral research?
We used two approaches, metabolomics and transcriptomics, to study stress responses in plants, and how the cellular metabolism is rerouted during oxidative stress. We used wild type Col-0 and rcd1 mutant of model plant Arabidopsis thaliana in our studies. The wild type Col-0 is ozone-resistant, paraquat-sensitive, while rcd1 is ozone-sensitive and paraquat-resistant. RCD1 was discovered by Prof. Jaakko Kangasjärvi and this research was a collaboration between Universities of Eastern Finland/Joensuu (Dr. M. Keinänen) and Helsinki (Prof. J. Kangasjärvi). Both untargeted metabolomics and transcriptomic approaches gave us information how RCD1 functions as an integrative node in development and stress responses, as well as how the genes and metabolites respond against abiotic stress.
The doctoral dissertation of Nina Sipari, MSc, entitled Metabolomics as a tool to investigate abiotic stress responses in plants will be examined at the Faculty of Science, Forestry and Technology, Joensuu Campus. The opponent will be Assistant Professor Carla Pinheiro, Universidade NOVA de Lisboa, Portugal, and the custos will be Research Manager Markku Keinänen, University of Eastern Finland. Language of the public defence is English.