Mutualism and environmental stress: heavy metal tolerance in a mycorrhizal system

Virtually all plants are involved in mutualistic associations where partners benefit from each other. Mutualists strongly influence plant growth and survival and can be particularly important for plant establishment under sub-optimal environments, however details on how mutualistic partners impact plant stress tolerance are still lacking. The project seeks to fill this gap by studying how mycorrhizal fungi (widespread obligate root-associated mutualistic fungi that provide water and nutrients to their partner plants) enable tree survival in heavy metal contaminated soils.

Specifically, they will use a combination of field and experimental approaches to detect naturally occurring mycorrhizal fungal heavy metal tolerance, investigate the fungal physiological mechanisms underlying the ability to withstand high metal levels, and ultimately test the role of metal tolerant fungi in plant survival under soil contamination. Results from this research will contribute for better understanding plant biotic interactions and their role in stressful environments.

The research will also allow the development of technology and tools to enhance plant establishment and productivity, as well as assist in mitigating the overall negative impacts of soil contamination. In addition, an important component of the project is to create opportunities for the participation of women and minority students in science, including mentorship for Native American and underserved students.

The project will thoroughly investigate the mechanisms by which natural variation in the widespread mycorrhizal fungal genus Suillus enables its pine hosts to persist in soils recently contaminated with Zn. The research will build on previous research on the genus and use controlled reciprocal transplant experiments, along with gene editing, and physiological and transcriptomics approaches.

The goal is to investigate how the fungus ameliorates plant metal toxicity and allows pines to grow in toxic Zn environments. This project will make unique contributions for 1) understanding how mycorrhizal fungi persist in contaminated soils, 2) elucidating how mycorrhizal fungi protect their plant mutualists from environmental stress, 4) better predicting the effects of pollution on mutualisms, and 4) developing a framework and protocols useful for mitigating the effects of soil contamination and improving reforestation of contaminated sites.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.