CAREER: IGNITE Integrating the next Generation into Novel Investigations of Toxin Ecology and evolution

The IGNITE CAREER project will shed light on a fundamental question in biology: How does microbial warfare lead to ecological success of pathogens? Importantly, this project develops foundational knowledge in economically important plant pathogens. These plant pathogens cause devastating epidemics of wilt disease on crops that are major components of the American diet, including potato, tomato, banana, and peanut.

These wilt pathogens are more than just threats to food security; they are complex organisms with extensive warfare strategies. To pioneer understanding their intricate warfare mechanisms, this project leverages innovative computational analyses and synthetic biology methodologies to study their ‘weapons’—toxins—at every level, from the smallest molecule to their impact on entire ecosystems.

The IGNITE project has significant societal benefits—it establishes a cutting-edge STEM educational program, the IGNITE CURE, that provides hands-on research experience to undergraduate students, with an emphasis on community college transfer students and additional groups that are historically underrepresented in STEM professions. This initiative will prepare the next generation of scientists, equipping them with the technical and essential soft skills that will empower them to tackle emerging plant health and public health challenges.

Students will gain critical thinking skills and gain confidence in analyzing big-data (population genomic data relevant to plant epidemics). Moreover, the data from the CURE will be openly and rapidly shared on the national genomic database, NCBI, benefitting national and international surveillance programs to predict and mitigate emerging plant pathogens.

Overall, the IGNITE CAREER project promotes two major domestic interests: food security and the education of emerging scientists.

The central hypothesis of this project is that the molecular mechanisms and evolution of type 6 secretion system (T6SS) toxins and immunity proteins drives the ability of phytopathogenic Ralstonia to antagonistically compete against other plant-colonizing bacteria. To understand T6SS toxins across biological scales, the project has three aims: (1) explore the evolution of Ralstonia T6SS genes, (2) characterize the molecular and cellular impacts of Ralstonia toxins and immunity proteins, and (3) test the ecological role of the Ralstonia T6SS in inter-bacterial competition.

The project will generate and leverage new public sequence data to shed light into the evolutionary processes that shape phytopathogen diversity at the population and molecular scales. Through cytological profiling and forward genetic screens (random-barcoded transposon mutant sequencing, RB-TnSeq), the researchers will connect the evolutionary diversity of toxin/immunity pairs to their phenotypic impacts on bacterial cells.

With a cutting-edge barcoded bacterial mutagenesis approaches, they will quantify the in planta antagonism between bacteria with diverse repertoires of toxin/immunity pairs. By combining experimental and discovery-driven data from single cells to landscapes, they have developed a set of aims that will not only allow them to understand how pathogen genotypes lead to success in an environment but also how competition and successional dynamics modulate core evolutionary concepts like “survival of the fittest.”

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.