Seminar of the Department of Microbiology

MSc Student Session 2

Adina Schmid - AG Illmer - University of Innsbruck

Chiara Ellensohn - AG Zeilinger-Migsich - University of Innsbruck

03.02.2022, 11:00 - Join online



Schmid: Above-ground applied microplastic and agro-additives affect plant properties and rhizosphere microorganisms of an agriculturally relevant soil-plant system

Microplastics and their impact on the environment have been intensively studied in aquatic systems, while terrestrial ecosystems have hardly been investigated. The aim of the present thesis is to investigate the cascading effect of airborne microplastics on the "shoot - root - exudate" axis and the resulting impact on the microbial community in the rhizosphere. The experimental set-up includes different treatments of strawberry plants with the following additives: microplastic, lignin, zinc, iron and copper and a control water approach. After the treatment of the plants and the ripening phase of the strawberry fruits, plant and fruit material was collected and rhizosphere soil was gathered. Various chemical, physical and plant-associated measurements were carried out to determine the growth performance of the plants in relation to the treatments. Rhizosphere soil was studied for microbial activities and droplet digital PCR (ddPCR) was used to quantify the abundance of bacteria, fungi, archaea and Paenibacillus polymyxa (a soil quality indicator organism). Miniaturized biochemical enzyme tests were used to assess the microbial activities within the rhizosphere soils as influenced by the above-mentioned plant treatments. The presentation gives insight into the first results of my master thesis performed in the working group of Paul Illmer under the supervision of Nadine Präg in collaboration with the University of Bolzano.

Ellensohn: pyr4 as an auxotrophic marker gene in Trichoderma atroviride for CRISPR/Cas9 mediated gene editing

T. atroviride is a filamentous soil fungus that is known as biocontrol agent since it acts as a mycoparasite. Therefore, research on these fungi is important for agriculture. To facilitate genetic manipulation in this species, like multiple gene deletions and retransformations, the expanding of the genetic toolbox is important. The aim of this thesis project was the establishment of a T. atroviride uridine/uracil auxotrophic strain via pyr4 loss of function and its application in fungal transformation for selection, as an alternative for conventional selectable markers. Two important questions were dealt with: Does retransformation of a functional heterologous Neursopora crassa pyr4 restores the prototrophy of this auxotrophic strain and can it be used for gene knock out approaches by gene replacement? The pex5 gene coding for the peroxisomal targeting signal type-1 receptor was selected as specific target. Furthermore, the CRISPR/Cas9 gene editing system was implemented as well for increasing target specific transformation rate. The presentation will give an insight into the results of my master thesis.

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