Intellectual Merit: Both plants and animals have evolved ways to prevent interbreeding between species. In other words, each species is reproductively isolated from other species because of reproductive barriers that prevent hybridization. The focus of this research is to understand the nature of reproductive barriers between species within the genus Solanum, which includes two important crop species, potato and tomato. In the previous funding period, the timing of reproductive barrier formation and site of barrier action in inter-species crosses was determined, and male and female genes involved in forming reproductive barriers were identified. In the current project, this information will be used to pursue the detailed molecular mechanisms that constitute inter-species recognition and rejection during mating attempts. Prior research has identified a population of S. habrochaites (a wild tomato species) with incipient reproductive barriers that isolate it from other populations. This system will now be developed as a powerful model for answering fundamental questions about how new species evolve. In the previous funding period, studies were conducted using tomato because it is an excellent model system for genetic and genomic studies. In the current project, research on reproductive barriers will be expanded into potato, an increasingly important crop worldwide.
Broader Impacts: Undergraduates, graduate students, and postdoctoral fellows in the research laboratories will participate in the teaching of undergraduate 'Many Minds' laboratories in an Introductory Biology course; this will ensure that integration of research and teaching becomes second nature as their careers advance. Public outreach will also be a key component of the project. During this project three 90-second radio spots will be produced to air on the public radio Earth & Sky series, which reaches about 15 million listeners. In addition, three podcasts will be produced for the EarthSky (www.earthsky.org) and the project (www.irbtomato.org) web sites. One topic of these media efforts will be the importance of preserving wild germplasm, using tomato as an example, which should truly resonate with lay audiences. The project will also impact society by advancing crop improvement. The wild relatives of tomato and potato possess genes for resistance to pathogens, drought, cold and salinity--traits that are particularly important in a time of global climate change. Unfortunately, accessing these important agronomic traits is often prevented or impeded by reproductive barriers. This project will lead to understanding that will facilitate inter-species crosses between domesticated and wild species by altering reproductive barriers; this advance will greatly expand the genetic base for crop improvement to include resistance to disease and environmental stresses.