Abstract Detail

Functional Genetics/Genomics

Field, Richard [1], Heyduk, Karolina [2], Leebens-Mack, Jim [3].

Gene family expansion and expression divergence in two closely-related Yucca species.

Gene family diversification is the process by which genes in related species (orthologs) evolve new functions after a speciation event. This process is an important source of adaptive potential in evolving species. In plants, orthologs often arise after a whole-genome duplication event (WGD), wherein a plant species’ genetic content is doubled, providing new copies of genes that may either undergo evolution of a new function (i.e., neofunctionalization), or degeneration. All major plant lineages exhibit evidence for at least one WGD in their evolutionary history. However, recently diverged species can also change their gene content through smaller scale, gene-specific duplications events such as tandem duplication, wherein a gene is copied locally to a region on the same chromosome. We use a comparative phylogenomics approach to detect gene duplication events and expression pattern divergence in two closely related Yucca species that differ in photosynthetic mode. Since divergence from the last common ancestor (LCA) of the genus Yucca (approximately 5 million years ago) Y. aloifolia evolved the canonical crassulacean acid-metabolism (CAM) pathway, which is a time-of-day based adaptation to water challenged environments. Meanwhile, Y. filamentosa has retained C3 photosynthesis, the presumed ancestral photosynthetic mode. Our results indicate that after divergence from the LCA, key genes involved in the CAM pathway (which were present in the LCA) were duplicated and subsequently evolved time-structured expression patterns that are central to CAM function. These results suggest gene regulatory evolution is an important contributor to adaptive phenotypes, even in the absence of protein-coding sequence evolution. Future work will include analyzing cis-regulatory sequences of CAM genes to uncover the regulatory mechanisms driving CAM in Y. aloifolia.

1 - University Of Georgia, 280 Weatherly Woods Dr, 120 Carlton St, 2203, Athens, GA, 30602, United States
2 - University Of Hawai'i, School Of Life Sciences, 1800 East-West Road, Honolulu, HI, 96822, United States
3 - University of Georgia, Genetics, 120 Carlton St. , Athens, GA, 30602, USA

Keywords:
genetics
phylogenomics
genomics
gene expression
Evolution.

Presentation Type: Poster
Number: PCG002
Abstract ID:460
Candidate for Awards:None