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Serpentine as a Model System for Edaphic Adaptation: Addressing the Role AMF Play in Plant Adaptation to Toxic Soils

EPA Grant Number: F6F11217
Title: Serpentine as a Model System for Edaphic Adaptation: Addressing the Role AMF Play in Plant Adaptation to Toxic Soils
Investigators: Peters, Shannon M.
Institution: University of California - Berkeley
EPA Project Officer: Manty, Dale
Project Period: September 1, 2006 through September 7, 2008
Project Amount: $107,224
RFA: STAR Graduate Fellowships (2006)
Research Category: Academic Fellowships , Fellowship - Terrestrial Systems Ecology , Ecological Indicators/Assessment/Restoration

Description:

Objective:

A distinct class of ultramafic soils called “serpentine” is found worldwide. The chemical and physical, or edaphic, features of serpentine soil create unique, locally adapted vegetation. Serpentine inhabitants must contend with multiple stresses including toxic levels of magnesium, extremely low levels of calcium, high concentrations of heavy metals, low essential nutrients, and drought. Thus, adaptive mechanisms of serpentine flora may include several traits, including those that affect symbiotic relationships. Arbuscular mycorrhizal fungi (AMF) are common root symbionts that can increase the plant hosts’ establishment and growth in stressful environments by enhancing nutrient and water uptake and/or through protection against toxic conditions. Therefore, plant and fungal traits that affect the symbiotic functioning in serpentine may greatly contribute to plant growth and fitness in harsh edaphic conditions.

Using serpentine ecosystems as a model for toxic sites, I will examine the effects of persistent exposure to severe edaphic conditions on AMF populations and how these fungi affect plant adaptation to toxic soils.

  1. To determine if serpentine edaphic features shape AMF communities.
  2. To establish if adapted plant ecotypes require specific AMF taxa.
  3. To determine what impact AMF have on plant growth and fitness in serpentine soil.

Approach:

  1. I will sample natural communities of AM fungi within the fine scale mosaic of serpentine and non-serpentine soils present at McLaughlin Reserve in Northern California. I will chose 6 plots of each soil type, collect 6 soil cores from each plot, extract AMF spores and measure species richness, relative abundance, composition and sequence diversity.
  2. I will use molecular methods to identify root associated AM fungi present in serpentine and non-serpentine adapted ecotypes of field collected California native plant Collinsia sparsiflora. I will also employ a common garden greenhouse experiment exposing both ecotypes to a common pool of serpentine and non-serpentine AMF isolates.
  3. I will conduct greenhouse experiments utilizing serpentine and non-serpentine collected AM fungi and ecotypes of C. sparsiflora. Both ecotypes will be grown in sterilized serpentine soil with either serpentine or non-serpentine isolates or a non-AMF control. Plant fitness, growth and tissue concentrations of essential nutrients and heavy metals will be measured.

Expected Results:

I expect that AMF community composition will differ between serpentine and non-serpentine soil and that I will find some AMF taxa that will be unique to serpentine substrates.  Additionally, I expect that the field AMF communities associating with the serpentine ecotype of C. sparsiflora will be distinct from those of the non-serpentine ecotype. Finally I anticipate that serpentine isolated AMF are essential for the growth and fitness of the C. sparsiflora ecotype and that these isolates will also improve growth of the non-serpentine ecotype over those isolated from non-serpentine soil.

Supplemental Keywords:

arbuscular mycorrhizal fungi, AMF community ecology, symbiosis, serpentine soil, Collinsia sparsiflora, heavy metals, toxic soil, ultramafic soil, ecotypes, edaphic adaptation, , Ecosystem Protection/Environmental Exposure & Risk, POLLUTANTS/TOXICS, Scientific Discipline, RFA, Chemicals, Monitoring/Modeling, Ecology and Ecosystems, Environmental Monitoring, heavy metals, plant fungus, edaphic adaptation, serpentiine soils, soil, ecological models, plant microbe interactions

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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