Abstract Detail

Evolutionary Developmental Biology (Evo-Devo)

Di Stilio, Veronica S [1], Hewett Hazelton, Kristen [2], Wong, Melissa J [2].

Reconstructing the ancestral role of a key transcription factor involved in flowering.

Flowers are the key innovation that propelled angiosperms into one of theâ€Â¨ most notable adaptive radiations of all times. â€Â¨While much is known about the developmental process for transforming leaves into floral organs in angiosperms, it is unclear how this mechanism evolved. LEAFY (LFY) encodes a transcriptional regulator that induces flower formation in the mature angiosperms sporophyte; it is also present in mosses, where it governs early cell divisions of the zygote (the unicellular sporophyte stage). Here, we examine LFY function in ferns, the sister lineage to seed plants and a class of vascular plants that lies midway in the evolutionary tree between mosses and flowering plants. The overarching biological questions we address are: What was the ancestral role of this key flowering gene prior to the â€Â¨evolution of seed plants? Were flowering functions co-opted â€Â¨from more general reproductive roles, or did they evolve de novo? Recent advances in stable transgenic techniques in the emerging model fern Ceratopteris richardii present a golden opportunity to address these questions. We first looked at gene expression ontogenetically in wildtype and found no expression in spores, low levels in reproductive gametophytes before fertilization and a peak in young sporophyte tissue, followed by a decline to a steady state as the sporophyte aged. A loss-of-function approach using RNA interference lines allowed us to identify mutant lines with highly altered phenotypes and down-regulation of the target genes. Our preliminary results suggest an early role of CrLFY in initial sporophyte development. Therefore, it appears that this transcription factor may have maintained its broader function in early sporophyte development throughout at least 50 million years of land plant evolution, before being recruited into flower meristem identity with the rise of the angiosperms.

1 - University Of Washington, Department Of Biology, PO BOX 351800, SEATTLE, WA, 98115-1800, USA
2 - University of Washington, Biology, PO Box 351800, Seattle, Wa, 98115-1800, USA

Keywords:
Ceratopteris richardii
LEAFY
fern
flowering
evo-devo
transgenics.

Presentation Type: Poster
Session: P, Evolutionary Developmental Biology (Evo-Devo) Special Topic:Posters
Location: Exhibit Hall/Savannah International Trade and Convention Center
Date: Monday, August 1st, 2016
Time: 5:30 PM This poster will be presented at 6:15 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PEV008
Abstract ID:832
Candidate for Awards:None