Comparative organellar genomics in heterotrophic plants

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Some plants steal nutrients and/or water from regular green plants and consequently have reduced or completely lost their ability to photosynthesize. We study plastid genomes in a variety of these so-called heterotrophic plants (commonly known as parasitic plants). Comparative analyses of the plastomes along the full trophic spectrum, from autotrophy to mixotrophy to full heterotrophy, will allow us to assess the degree to which genomic changes take place prior to complete loss of photosynthesis, and to dissect the evolutionary pressures on plastomes exerted by other plastid metabolic functions. Many groups of heterotrophic plants arose separately from their respective photosynthetic relatives. The basic idea we take advantage of in this proposal is that each of those lineages of heterotrophs represents an independent natural genetic experiment whose plastids and genes have evolved under relaxed functional constraints; therefore, each represents a unique opportunity to study genome function and evolution. Given the difficulties or even the impossibility of reverse genetic approach in this system, study of multiple natural plastid 'mutants' will contribute to our deeper understanding of photosynthesis, its molecular components, and their interaction.