Rebecca Schulzke (Philipps-Universität Marburg)
Rebecca Schulzke's Master thesis was awarded with the Prize for the Best Plant Science Master Thesis, which was carried out at Marburg University in the year 2023 with the title:
The importance of ABA signalling for the interaction of Arabidopsis thaliana and Colletotrichum higginsianum
The present work on the interaction of the model plant Arabidopsis thaliana and the hemibiotrophic fungus Colletotrichum higginsianum provides some indication for a potential novel mechanism for the suppression of early defense signals by the phytohormone abscisic acid (ABA).
The phytohormone abscisic acid (ABA) is produced in response to abiotic stress factors such as cold, drought or osmotic stress. The role of ABA in plant resistance to pathogens has not been fully understood, since both negative and positive effects have been described depending on the plant-pathogen system investigated. To better understand the role of ABA in plant resistance, mutants of the model plant Arabidopsis thaliana that were either defective in ABA production or perception were employed and their defense response to infection with the hemibiotrophic fungal pathogen Colletotrichum higginsianum was characterized.
During the necrotrophic phase of the interaction, ABA-deficient A. thaliana mutants showed increased resistance towards C. higginsianum compared to the wild type. Since C. higginsianum is sensitive to the salicylic acid (SA) regulated defense response during the preceding biotrophic phase, the levels of SA and its downstream metabolites were determined by HPLC. The increased resistance of the ABA-deficient mutants at 3.5 days post infection (dpi) was preceded by increased levels of SA and its metabolite 2,3-dihydroxybenzoic acid (DHBA) during the early biotrophic phase at 2 dpi. Further analysis on the role of ABA for the regulation of SA metabolism suggested an antagonistic interaction between ABA and SA in the pathosystem studied, in which ABA may specifically suppress the SA response during the early biotrophic phase by attenuating 2,3-DHBA production and glycosylation. Whether increased DHBA levels play a functional role in the immune response or are consequences of increased SA production is not yet sufficiently clear and requires further research.
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Rebecca Schulzke conducted this work at the Philipps University of Marburg, Chair of Molecular Plant Physiology in the working group of Professor Dr. Lars Voll.
