RoL: FELS: EAGER: Genetic Constraints on the Increase of Organismal Complexity Over Time

University Of Nebraska-Lincoln, Lincoln NE

Investigators

Abstract

In both plants and animals, the emergence of new specialized body parts is rare. Specialized organs appear to originate as specialized versions of existing organs, yet their specialization requires a divergence in regulation between different copies of the same organ. This project will test a proposed rule of life, that states that the largest and most complex changes in the evolution of multicellular organisms are easier to achieve when the entire set of chromosomes of an organism is duplicated in the course of evolution. Links between whole genome duplication and an increase in the number of body parts has been suggested to explain the evolution of early tetrapods or the emergence of flowering plants, but these are harder to study experimentally as they have occurred tens or hundreds of millions of years ago. A more recent event is the emergence in corn with two types of inflorescences (group or cluster of flowers arranged on a stem) for male and female reproduction - tassel and ear; contrasting to the situation in close relatives of maize that produce only a single type of inflorescence. This research will use comparative genetics techniques in maize and one such relative, sorghum, to identify which genetic systems, when turned on or off, change the inflorescence types. The project will provide valuable training to undergraduate students, supported by institutional UCARE and REU programs. This EAGER project tests the hypothesis that the development and evolution of specialized reproductive organs of maize are controlled by the specialized ensembles of duplicate copies of one set of ancestral genes that was required for development of non-specialized sexual organ, before it underwent a duplication in the course of the whole-genome polyploidization. Generation and phenotypic characterization of knockouts of syntenic orthologous genes in polyploidized maize and nonpolyploidized sorghum will provides a systematic test of the Ortholog Conjecture, a rule of life that tells that genes evolved by speciation tend to preserve function, whereas genes produced by duplication tend to evolve related but not identical functions. 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.