NSF-BSF: Synthetic mycorrhizal community and parasitism management in rhizosphere ecosystems guided by systems biology of mycoparasitism

Fungi are organisms that are present in almost every conceivable ecological niche and play significant roles in natural carbon and nitrogen turnover. In most natural environments, fungi reside, function and interact with other organisms. They can be beneficial symbionts or exhibit pathogenic behavior in plant and animal hosts.

One area of high plant-fungal interactions is the rhizosphere, the root ecosystem in which root secretions affect the composition and activity of a plant-associated microbial community. This microbial community can include a variety of fungi, ranging from those that have a mutually-beneficial symbiotic relationship with the plant (mycorrhizae) to fungal species that can be detrimental to the plant (pathogens) and fungi that can interact among themselves.

One such group of fungi can attack other fungi and are referred to as mycoparasites. Some mycoparasites belonging to the genus Trichoderma have been used to control fungal plant pathogens. However, the organismal regulatory networks that govern these genetic and environmental interactions are not well understood.

This project addresses fundamental questions to better understand mycoparasitism and interactions among members of the rhizosphere fungal community. The researchers will study the nature and dynamic changes of networks that regulate mycoparasitism, which are crucial to understanding how ecological diversity and associated interactions evolved in fungi.

The broader impacts of this project include professional training for college students and postdocs. This research will also provide training to local high school students and teachers about the importance of fungi in agriculture and forestry.

The research will primarily focus on the interactions between mycorrhizae revealed by laboratory co-cultivation of mycorrhizal fungi Pisolithus and Laccaria with mycoparasitic Trichoderma fungi, along with a non-rhizosphere fungus (Neurospora) as a control, with the intention of deciphering the genetic networks that regulate mycoparasitic interactions. Once key components of the regulatory network are identified, the researchers will inactivate genes that are involved in mycoparasitism to determine the nature of their involvement in the process (e.g., at what stage the process is affected, and to what extent these effects have consequences on other morphological or nutritional traits of the fungus).

Lastly, the researchers will engineer the mycorrhizal components of the interaction to silence relevant genes in the mycoparasite, with the intention of conferring a higher degree of tolerance to the beneficial fungal component of the rhizosphere when mycorrhizae and mycoparasites are in close physical proximity. This silencing will be performed by constructing strains that secrete RNA molecules that can, through molecular processes, inactivate the relevant corresponding traits of the mycoparasite.

The project will improve understanding of genetic basis of interspecies recognition and parasitism and will empower applied research on utilization of fungi in forestry, industry, and agriculture toward the maintenance of a healthy and sustainable environment and for plant disease control.

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.