Intellectual merit: There is extraordinary genomic diversity across all domains of life, yet little is understood about the evolutionary processes that shape genome structure and function. The mitochondrial genomes of plants are remarkable among eukaryotes: they are extremely large and highly recombinogenic, their nucleotide sequences evolve very slowly, their genes are intron-rich and occasionally undergo horizontal gene transfer (HGT), and their transcripts experience numerous modifications due to RNA editing. In contrast to most plants, the mitochondrial genomes from species in genus Plantago (Plantaginaceae; Lamiales) exhibit drastic deviations in structure and content including highly elevated substitution rates, unprecedented reductions in intron and RNA editing content, and increased susceptibility to HGT. These events have occurred within the last few million years, providing a rare opportunity to trace their evolution and to evaluate their effects on genome structure and function over a short evolutionary timescale. A comparative genomics study will be performed within the Plantaginaceae, and in comparison to other plants, to reveal the full diversity in substitution rates, intron content, edit site content, and HGT across the family. This project will provide greater understanding of the causes and consequences of the unusual evolutionary trends in Plantago mitochondria, and these results should provide significant insight into the evolution of genome structure and content in all living organisms.
Broader impacts: The PI is committed to training scientists of all backgrounds and skill levels including women, minorities, and rural students from the high school to the postgraduate level. This project will involve high school students, who will participate through a summer research experience. In addition, research training will be provided for undergraduates, a graduate student, and a postdoctoral researcher. A foreign student exchange program will provide opportunities for US students to do international field work and for international students to visit the PI's lab to learn molecular techniques. Results of the project will be widely disseminated through journal publications, in presentations at national and international conferences, and as part of a series of public presentations at the University of Nebraska State Museum.