Kristina Munzert (Philipps-Universität Marburg)
Exemplary display of the screening of hypersusceptibility suppressor mutants in starch-free A. thaliana background. Plants were infected with C. higginsianum after 12 days to select for resistant mutants compared to the starch-free A. thaliana mutant pgm (red markers). Photo: Kristina Munzert
Kristina S. Munzert's Master thesis was awarded with the Prize for the Best Plant Science Master Thesis, which was carried out at Kristina Munzert Philipps University Marburg in the year 2021
Title: Characterisation of mutants suppressing the hypersusceptibility of starch-free Arabidopsis thaliana to Colletotrichum higginsianum
Munzert mapped Arabidopsis suppressor mutants of carbohydrate-dependent pathogen hypersusceptibility and characterised alterations in their defence responses.
Starch-free Arabidopsis plants show a strongly increased susceptibility to the hemibiotrophic pathogen C. higginsianum, as the lack of carbohydrate availability limits the defence response of the plant. This affects, for example, the composition of the plant cell wall as a penetration barrier, as well as the production of secondary metabolites for pathogen defence. Using a forward genetic approach, EMS-mutagenized starch-free plants were identified that showed suppression of hypersusceptibility. The selected mutants were examined via biochemical analysis and infection assays. It was shown that the increased resistance was partially established in the early biotrophic interaction with C. higginsianum and that there were changes in cell wall composition, as well as in the production of secondary metabolites. The specific changes in pectin and hemicellulose polymers of the cell wall could directly affect the penetration success of C. higginsianum or influence the induced defence response of the plant. Elevated levels of the phytohormone salicylic acid and the phytoalexin camalexin were detected partially independent of pathogen infection and could indicate priming of the mutants with defence compounds prior to infection and could account for early established resistance. In addition to physiological characterization, causative mutations in the genome of the selected mutants were mapped by next-generation sequencing.
Anthracnose caused by Colletotrichum spp. is a severely yield-reducing plant disease, the effects of which could be mitigated by a better understanding of plant defences following Colletotrichum spp. infestation.
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Kristina S. Munzert conducted this work at the Department of Biology of Philipps University of Marburg under supervision of Dr. Timo Engelsdorf in the group of Prof. Dr. Lars Voll.