PurSUiT: Revealing undiscovered diversity and distribution of phytoplasmas through screening of potential host insects in a museum biorepository

Phytoplasmas, a group of plant-parasitic bacteria transmitted from plant to plant by sap sucking insects (Hemiptera, including leafhoppers, planthoppers and jumping plant lice), were previously known mainly because they cause severe diseases of cultivated crops. Recent screening of DNA samples from preserved museum specimens of hemipteran insects indicated that phytoplasmas are widespread in nature and that natural areas worldwide harbor many previously undocumented phytoplasma strains. This project aims to uncover the true diversity of phytoplasmas worldwide, reconstruct their evolutionary relationships, and document their associations with insects and plants by screening a large collection of insects preserved in a museum biorepository and modern DNA sequencing techniques. The new data will help identify hotspots of phytoplasma diversity worldwide, clarify the extent to which phytoplasmas have affected the evolution of their host plants and insect vectors, and contribute to training of a new generation of experts on phytoplasma ecology, epidemiology and evolution. Emergence of new plant diseases may be driven by environmental change (including climate change) that triggers the colonization of managed habitats (e.g., croplands) by previously unknown disease agents from adjacent natural areas. Improved knowledge on the overall phytoplasma diversity in natural areas will greatly facilitate efforts to predict and manage new disease outbreaks. Specific goals of the project include: 1) screen insect specimens for presence of phytoplasmas using next-generation DNA-sequencing technology; 2) obtain partial phytoplasma genomes and host plant data for newly detected insect-associated phytoplasmas; 3) reconstruct phylogenetic relationships among all known phytoplasmas, classify newly discovered strains and estimate the times of origin of individual lineages; 4) update an existing online database to include all previously known and newly discovered phytoplasma-host associations; 5) cultivate new expertise by training and mentoring students in leading-edge methods for studying a diverse and poorly known lineage of agriculturally important microbes. 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.