Dependence of endophytic fungus - grass symbioses on land-use intensity (DEFENSE)
Endophytic fungi in cool-season grass species (Poaceae) produce herbivore-toxic alkaloids which can affect species communities and ecosystem functioning. These alkaloids can be toxic for vertebrate (e.g. cattle, sheep, horses) and invertebrate herbivores, depending on the concentration and composition of produced alkaloids. If infection rates of grass species and alkaloid production depend on land-use intensity is not well known. Knowledge gaps also exist about the effects of abiotic and biotic factors on pathway alkaloids and the effect of Epichloë endophytes on other microorganisms.
In this project we like to quantify the infection rates (occurrence and abundance) and alkaloid concentrations of Poaceae species in the 150 grassland EPs of the Biodiversity Exploratories.
In the first phase of the project (DEFENSE I) we sampled different grass species and detected infections with immunoblot assays and staining methods. We also used UPLC-MS/MS to detect alkaloid concentrations. First results show that on a grassland level the toxicity thresholds for herbivores were not reached. In addition we study the effects of land-use intensity and Epichloë infection of Lolium perenne on the diversity of endophytes in leaves using NGS barcoding in cooperation with the University of Bochum.
In the second phase (DEFENSE II) we collected in 2017 around 4000 samples from 8 different grass species. In this project we will also determine the infection rates together with alkaloid concentrations and will compare these findings with our data achieved in 2015. Additionally we will observe alkaloid concentration in 2018 throughout the vegetation period in several grasslands were high alkaloid concentration occurred in 2015 to detect peak concentration periods. Furthermore we want to investigate with molecular methods in cooperation with the Noble Foundation in the USA the alkaloid biosynthesis of the fungi, to detect potential regional chemotypes.
With our data we like to address the following key research questions focusing on the diversity of endophytic fungus - host grass symbiosis and ecosystem functioning of infected host grass:
1. Which endophytic fungus - grass symbioses are present in grasslands and are they affected by land-use intensity?
2. Are alkaloid profiles and concentrations produced by endophyte-grass symbioses in the Biodiversity Exploratories toxic for herbivores?
3. Which pathway alkaloids are produced by the different endophyte-grass symbiosis and are these dependent on land use intensity.
4. Do Epichloë infected grass species modify microorganism communities of the host grass?
Previous project contribution of PD Dr. Jochen Krauss: BATMAN