• CUBE - Computational Systems Biology

  • DOME - Microbial Ecology

  • TER - Terrestrial Ecosystem Research

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Latest publications

Phytosiderophore-induced mobilization and uptake of Cd, Cu, Fe, Ni, Pb and Zn by wheat plants grown on metal-enriched soils

We investigated to which extent phytosiderophores (PS), released by grasses for the acquisition of iron, solubilize other metals in contaminated soils, and how this affects metal mobilization and uptake in wheat plants. A plant-based bioassay (‘RHIZOtest’) and batch extraction scheme were carried out for assessing metal mobilisation in soil, PS exudation and metal accumulation in wheat. Increased PS exudation was observed in Fe-deficient wheat, leading to enhanced Zn, Cu, Mn and Ni concentrations in wheat shoots on some soils. In contrast, plant Cd and Pb concentrations were not affected. Likewise, in the batch experiment, strongly increased extractable Cu, Ni and Zn concentrations were observed, in particular when 100 or 1000 μM PS were added. Our results suggest that Fe deficiency can enhance the accumulation of some metals in shoots of grass species. Although our results indicate that the risk of enhanced accumulation of Cd and Pb in Fe deficient wheat shoots is rather small, further experiments conducted on soil for the complete vegetation period would be needed to confirm this observation.

Puschenreiter M, Gruber B, Wenzel WW, Schindlegger Y, Hann S, Spangl B, Schenkeveld WDC, Kraemer SM, Oburger E
2017 - Environmental and Experimental Botany, 138: 67-76

Time-course expression QTL atlas of the global transcriptional response of wheat to Fusarium graminearum.

Fusarium head blight is a devastating disease of small grain cereals such as bread wheat (Triticum aestivum). The pathogen switches from a biotrophic to a nectrotrophic lifestyle in course of disease development forcing its host to adapt its defence strategies. Using a genetical genomics approach we illustrate genome-wide reconfigurations of genetic control over transcript abundances between two decisive time points after inoculation with the causative pathogen Fusarium graminearum. Whole transcriptome measurements have been recorded for 163 lines of a wheat doubled haploid population segregating for several resistance genes yielding 15 552 at 30 hours and 15 888 eQTL at 50 hours after inoculation. The genetic map saturated with transcript abundance-derived markers identified of a novel QTL on chromosome 6A, besides the previously reported QTL Fhb1 and Qfhs.ifa-5A. We find a highly different distribution of eQTL between time points with about 40% of eQTL being unique for the respective assessed time points. But also for more than 20% of genes governed by eQTL at either time point genetic control changes in time. These changes are reflected in the dynamic compositions of three major regulatory hotspots on chromosomes 2B, 4A and 5A. In particular control of defence-related biological mechanisms concentrated in the hotspot at 4A shift to hotspot 2B as the disease progresses. Hotspots do not colocalize with phenotypic QTL and within their intervals no higher than expected number of eQTL was detected. Thus, resistance conferred by either QTL is mediated by few or single genes. This article is protected by copyright. All rights reserved.

Samad-Zamini M, Schweiger W, Nussbaumer T, Mayer KF, Buerstmayr H
2017 - Plant Biotechnol. J., in press

Crenothrix are major methane consumers in stratified lakes

Methane-oxidizing bacteria represent a major biological sink for methane (Oremland and Culbertson 1992) and are thus Earth’s natural protection against this potent greenhouse gas. Here we show that in two stratified freshwater lakes a substantial part of upward-diffusing methane was oxidized by filamentous gamma-proteobacteria related to Crenothrix polyspora. These filamentous bacteria have been known as contaminants of drinking water supplies since 1870 (Cohn 1870) but their role in the environmental methane removal has remained unclear. While oxidizing methane, these organisms were assigned an ‘unusual’ methane monooxygenase (MMO) which was only distantly related to ‘classical’ MMO of gamma-proteobacterial methanotrophs (Stoecker et al., 2006). We now correct this assignment and show that C. polyspora as well as its lacustrine relative encode a typical gamma-proteobacterial pmoA. Stable-isotope labeling in combination with single-cell imaging mass spectrometry revealed methane-dependent growth of the lacustrine Crenothrix with oxygen as well as under oxygen-deficient conditions. Concurrently, Crenothrix genomes encoded pathways for the respiration of oxygen as well as for the reduction of nitrate to N2O. Due to their large biomass and rapid planktonic growth Crenothrix might constitute a major biological sink for methane and should be considered in the context of environmental removal of methane. 

Oswald K, Graf JS, Liftmann S, Tierken D, Brand A, Wehrli B, Albertsen M, Daims H, Wagner M, Kuypers MMM, Schubert CJ, Milucka J
2017 - ISME J, in press