Wheat and barley are one of the most important crops for global food security and a significant economic sector for the world's leading wheat producers, such as the European Union. Some of the biggest threats to crop production in the future will be a changing climate and increasing levels of contaminants, such as heavy metals, in agricultural soils. While there are reports on the individual effects of these two factors on the quantity and quality of crop yields, it is still largely unknown if and how their combination will affect production in the future. The main research objective of this project is to determine threats to crop production from climate change and metal pollution, and investigate which agricultural practices are most beneficial to minimize potential losses. For this purpose, we make use of UFZ’s own long-term experiments (Global Change Experimental Facility and Static Fertilization Experiment) at Bad Lauchstädt Research Station at which crops are cultivated under various climatic conditions, soil contamination regimes and farming practices and compare crop yield quantity and quality with regard to metal and nutrient accumulation. To reveal the processes responsible for final crop yield, we collect rhizosphere samples during growth and analyzed geochemically (soil properties, metal bioavailability, metal binding sites in soil) and microbiologically (abundance, diversity, taxonomy, functionality) to indicate the processes which drive metal distribution from soil to crop.

People involved:
Aleksandra Pienkowska, Alexandra Glöckle
 

This project is part of the Young Investigator Grant RhizoThreats: Rhizospheres under Attack from Coupled Climate and Soil Contaminant Stress, which is funded by the Helmholtz Association and the Centre for Environmental Research.

Phytoremediation is an environmental sanitation tool that uses the ability of plants to accumulate contaminants, such as heavy metals, ultimately reducing the burden of harmful compounds in soils. We investigate how environmental parameters affect phytoremediation efficacy by studying the metal-hyperaccumulating model plant Arabidopsis halleri. For this purpose, we carry out greenhouse studies with different soils, metal contamination levels, climatic conditions, and plant ecotypes. We assess how this model plant's root system interacts with soil microbial communities and soil geochemistry. The combination of physiological plant responses (root architecture, metal accumulation, enzymes, chlorophyll content), a high-end soil microbial community assessment (omics, enzymatics), and key soil geochemical processes involved in metal availability and nutrient cycling (extractions, isotope pool dilution assays, synchrotron-based X-ray absorption spectroscopy) will provide novel insights into the functioning of phytoremediator rhizospheres exposed to today’s and future climatic conditions. Understanding the underlying mechanisms of phytoremediation is an important step towards a successful application of this technique, potentially even in agricultural settings.

People involved
Dr. Carolina Vergara Cid
Natalia Sánchez
Mara Breit

This project is part of the Young Investigator Grant RhizoThreats: Rhizospheres under Attack from Coupled Climate and Soil Contaminant Stress, which is funded by the Helmholtz Association and the Centre for Environmental Research.
 

Northern permafrost regions experience stronger warming than other regions in the world, thus are very sensitive to environmental change. A direct consequence is the thawing of permafrost in soils which is known to unlock huge amounts of C and N to biogeochemical cycling. Thawing results in a simultaneous ecosystem and plant-community shift from elevated, dry and nutrient-poor patches (palsa) inhabited by shrubs and mosses to inundated, wet and nutrient-rich areas (fen) dominated by mosses and sedges.

Plant type and cover are important controls to greenhouse gas balances in soils and may be decisive on whether soils are a sink or a source of gases to the atmosphere. So far, the role of root-mediated greenhouse gas producing versus consuming, transporting, releasing versus retaining processes is largely unknown. Root contributions to greenhouse gas emissions may range from root architecture to root microbiome and rhizosphere biogeochemistry impacts. This project evaluates a full thawing succession at the Abisco Scientific Research Station in Northern Sweden. Field installations, complex freeze-thaw incubation experiments followed by comprehensive analyses of rhizosphere biogeochemistry as well as microbiome signatures in combination with greenhouse gas flux measurements will be used to obtain a better understanding of root-soil interactions and the implications to greenhouse gas emissions from permafrost-affected soils. Specifically, we want to unravel the following research questions:

1. What role do root architectural variations play for both the transport versus entrapment of greenhouse gases and the presence, activity, and localization of greenhouse gas – producing versus consuming microbial communities?
2. What role do different root exudates and plant detritus play in microbially mediated greenhouse gas emissions?

This project is funded by the German Research Foundation (DFG) and is located at the University of Tübingen.
 

As rice sustains more than half of the global population, its production needs to increase to meet future demands of a growing population. Of most concern to rice production are a changing climate and increasing levels of toxic arsenic in paddy soils. In a recent study we showed that the combined threat of climate change and soil arsenic will increase arsenic bioavailability in the soil, and subsequently decrease rice productivity and increase grain arsenic levels more than currently anticipated. Soil microbial communities are responsible drivers for shifts in arsenic bioavailability in the rhizosphere and, thus, are directly influenced by soil arsenic levels, climate and the plant itself.

In collaboration with the Fendorf Lab at Stanford University, we will investigate how differences in soil arsenic, climate and plant performance cause shifts in plant communication with the rhizosphere microbiome. Using molecular tools, differences in the trancription of genes within rice's roots will be linked to soil microbial community dynamics, identifying microbial key players.

We are looking for a motivated MSc student to investigate how rice roots transcriptionally respond to the coupled threats of climate and soil arsenic and how the rhizobiome adapts to root activity. Optimal expertise in Molecular Biology and/or Microbial Ecology.


This project was funded by the German Research Foundation and the Marie Sklodowska Curie Action of the European Union in form of individual Postdoc scholarships. 

Courses are offered through the Geoscience Department of the University of Tuebingen.

• 20-31.03.2023: Block course (lecture, seminar and lab course) at Master degree level Rhizosphere Processes in a Changing World (M, 6 ECTS)
• Summer Semester 2023: Geosphere-Biosphere interactions (co-teaching with Prof. Dr. Michaela Dippold)
  

Bachelor Theses:

• Jenin Fleischmann: Soil microbiome adaptation to metal stress under different farming practices. 2022
  
• Julia Kost: DNA/RNA Stability in Environmental Samples. 2021
• Alexandra Glöckle: Effect of cadmium on (a)biotic greenhouse gas emissions in agricultural soil. 2020
• Katja Lenge: Long term effect of cadmium contamination and climatic stress on soil microorganisms and greenhouse gas emissions. 2020
• Sebastian Müller: Cadmium stress combined with elevated temperature will increase greenhouse gas emissions more than elevated carbon dioxide combined with or without cadmium. 2020
  

Master Theses:

• Mara Breit: What determines intraspecific variability in heavy metal hyper-accumulation efficacy of Arabidopsis halleri? – Plant traits or soil biogeochemistry? 2022
  
• Esmira Bibaj: Cadmium (Cd) and climate-impacted greenhouse gas emissions from agricultural soils. 2022
  
• Viktoria Skudlik: Combined impact of elevated atmospheric CO₂ and soil Cd on the nitrogen cycle in agricultural soils. 2022