Investigating recurrent cooption of mitochondrial cytochrome c maturation systems in Archaeplastida

University Of Nebraska-Lincoln, Lincoln NE

Investigators

Abstract

Convergent evolution is the independent origin of the same feature in different species. Often, the adaptive benefit of a convergent feature is apparent, such as the convergent evolution of powered flight in birds, bats and insects. However, not all cases of convergent evolution have an obvious advantage. For example, the post-translational modification of c-type cytochromes is essential for their proper function as part of the mitochondrial electron transport chain, which produces and regulates energy flow in cells. Two distinct biochemical pathways are used to achieve this modification, and many species have convergently switched between these two distinct pathways. Yet, both pathways achieve the same goal, so the evolutionary advantage of this pathway switch is unknown. This project will investigate the numerous convergent pathway switches in plants and green algae. The project will use a combination of molecular biology, genetic engineering, plant growth and development assays, and computational biology to assess the mechanisms and evolutionary importance of this pathway switch. Project participants will receive advanced training in genomics research. Research results will be disseminated through journal articles and conference presentations. Outreach experiences will include public presentations, demonstrations, and hands-on activities that educate the public on plant science research and applications. The project will use transgenic approaches and functional assays to assess mitochondrial localization, evaluate knock out/down lines, and restore function via transformation rescue of a key enzyme. The expectation, based on comparative genomics, is that the gain of this enzyme has enabled the convergent pathway switch in diverse plants and algae. The project will also use transgenics to create an artificial system switch in a model plant. These transgenic plants will be assessed using metabolomics, functional assays, and high-throughput phenotyping to evaluate the potential adaptive or detrimental effects of this switch. Phylogenetics and comparative genomics will be used to evaluate the macroevolutionary patterns of cytochrome c maturation across plants and eukaryotes by exploring the number of pathway switches during eukaryotic evolution, evaluating whether other alternate pathways exist to facilitate the switch, and assessing the role of horizontal transfer in spreading alternative pathways among eukaryotes. The results will broaden understanding of the processes and influences that promote convergent evolution under a scenario where there is no obvious adaptive benefit, which contrasts with other well-known examples of parallel evolution for which the adaptive benefit is obvious. This proposal was co-reviewed and will be co-funded by the Genetic Mechanisms Cluster in the Division of Molecular and Cellular Biosciences and by the Evolutionary Processes Cluster of the Division of Environmental Biology. Funding was also provided by the Established Program to Stimulate Competitive Research. 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.