Katarzyna Krawczyk

Peroxisomes of photosynthetic organs - modulate resource allocation during abiotic stress

Peroxisomes are eukaryotic organelles, which in plants play critical role in photorespiration, fatty acid degradation and detoxification of reactive oxygen species (ROS). Many abiotic stress factors like heat or excessive illumination can lead to an accumulation of ROS. As a consequence, these toxic products have to be efficiently eliminated by various antioxidative systems, which are essential for the plant to minimize the damaging effect of ROS. Even though the detoxification pathways in peroxisomes are already described, there is still little knowledge how the resource allocation in peroxisomes is taking place, especially during abiotic stress. The research on exchange of metabolites between peroxisomes and other cell compartments through the peroxisomal membrane showed that specific peroxisomal membrane proteins (PMPs) are responsible for respective solute flux: ATP binding cassette transporters facilitate the transport of substrates for β-oxidation, peroxisomal adenine nucleotide carriers mediate an ATP/AMP exchange, and peroxisomal NAD carrier. Recently, another peroxisomal membrane transporter, called PERTL6, was discovered, however its function is still unknown. Moreover, previous studies indicate that PERTL6 is highly upregulated during heat and under high light stress. To elucidate the mechanism of shuttling antioxidant compounds in and out of plant peroxisomes, further studies on PERTL6 are crucial.

Thus, the proposed project addresses the whole-plant phenotyping in order to unravel resource allocation patterns during abiotic stress and describing the effects of an individual gene on them. To achieve this, transgenic Arabidopsis plants will be generated in which the pertl6 gene is mutated via the CRISPR/Cas9 genome editing system. Once the pertl6 loss-of-function mutant has been confirmed, a comprehensive analysis of these Arabidopsis knockout plants in varied conditions of light intensity and temperature will be performed. To assess the effects of the gene mutation under abiotic stress, pertl6 mutants will be analyzed using phenotyping setups. To investigate how abiotic stress affects peroxisome biogenesis, morphology and function will be studied. In addition to the physiological analyses, metabolomics and transcriptomics will lead to understand the role of PERTL6 in the cellular stress network. It will also help us to narrow down putative transport substrates for PERTL6, which can be tested by the liposome uptake system using recombinant protein.

This described research proposal will allow to fully portray the function of PERTL6 in resource allocation during abiotic stress, resulting in a model of how different genes affect optimal resource allocation in plants during abiotic stress.

Starting date: 01.06.2021 / Doctoral Researcher - DAAD GSSP Scholarshipholder

Thesis committee members: Nicole Linka, Andreas Weber, Shizue Matsubara