Collaborative Research: EDGE FGT: Functional Genomic Tools for Parasitic Nematodes and their Bacterial Symbionts

All animals, including humans live in association with microbes and parasites that can promote health and cause disease. The mechanisms by which animals communicate with microbes and parasites to block, initiate, maintain, and dissolve such associations are just beginning to be uncovered. Because these mechanisms are often conserved across biology, they can be investigated using model animals such as roundworms, or nematodes, which associate with microbes and are themselves parasites.

This project will develop new experimental tools in roundworms that have developed partnerships, or symbioses, with specific bacteria. Together these roundworms and their bacterial partners infect and kill insects, using them as a food source. Developing new tools to study this elegant animal-bacterium system will help expand our understanding how animals and bacteria form partnerships, and how they work together to parasitize other animals.

The tools and knowledge gained in this project will be rapidly shared with the community of researchers involved in drug discovery, agricultural control of crop pests, and in the study of parasitism, infectious disease, beneficial microbiome function, and fundamental cell, molecular, developmental, and evolutionary biology. As part of this project, undergraduates will be involved in a discovery-based microbiology lab where they will practice isolating and identifying new insect-killing roundworms from the environment.

Young people (K-12) and educators will be engaged through collaboration with the Science Journal for Kids, where a basic curriculum and summary of key research findings will be developed for classroom use.

Entomopathogenic nematodes in the genera Heterorhabditis and Steinernema are mutualistically associated with bacteria in the genera Photorhabdus and Xenorhabdus, respectively. The nematode-bacterium symbiotic pair obligately parasitizes insects as a nutrient source for reproduction and has utility as a biological control agent for agricultural insect pests and as a source of novel compounds.

The entomopathogenic pair and their insect hosts are models to understand fundamental biological principles, including the evolution and molecular and cellular basis of mutualistic and antagonistic organismal interactions. Numerous features make this system an excellent experimental model including ease and cost of husbandry, fast generation time, and optical transparency.

Although genetic techniques have been developed for representative bacterial symbiotic partners and insect hosts, to date there have been no broadly adopted, reliable genetic modification tools in either Steinernema or Heterorhabditis nematodes. This inability to interrogate nematode gene function has hobbled full use of this system to yield much-needed insights into parasitism, animal microbiome interactions, and other areas.

Here we propose to capitalize on a recently isolated Steinernema nematode that has promising characteristics for development of genetic tools, including hermaphroditic reproduction, amenability to long-term freezing, healthy development on agar bacterial lawns, resilience to microinjection, and significant pathogenicity to lab insects and agricultural pests. By fully sequencing the genomes and developing genetic techniques and tools for both nematode and symbiont, including CRISPR-Cas9 genome editing in the nematode, and creating an arrayed mutant library for the bacterium, our team will help realize the full potential of this elegant animal-microbe model system.

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.