Abstract Detail

Systematics

Giraldo, Giovanny [1], Cameron, Kenneth [2].

Genome size and phylogenetics of Vanilloideae (Orchidaceae) inferred from NextGen anchored phylogenomics.

Phylogenetic relationships among genera of tribe Vanilleae continue to remain elusive. One of the possible reasons is that five of the nine genera of the tribe are mycoheterotrophs. These orchids are poorly represented in earlier molecular studies that relied heavily on plastid loci. Interestingly, even the relationships among some photosynthetic genera remain unresolved (e.g., the relationship between South American Epistephium and the clade of New Caledonian endemic genera Clematepistephium+Eriaxis). We have inferred the phylogeny of tribe Vanilleae through the use of Anchored Phylogenomics that targets ca. 500 low copy nuclear genes via Next Generation DNA Sequencing. Furthermore, we are able to recover the plastome sequence from most of our sample, and compare the trees. Our results are different from any previous study in that they show Epistephium forming a clade with Clematepistephium + Eriaxis, as well as Lecanorchis. Challenges were met in sequencing members of tribe Pogonieae for outgroup anlysis because of the enormous genome size exhibited by these orchids (the largest in the family). As such, we embarked on a study also to estimate genome size for most genera of Vanilloideae. Not only does the subfamily have the largest known orchid genome, but it also contains the largest diploid chromosome number reported for Orchidaceae: Epistephium lucidum (2n= ca. 170). Our data shows that there is at least an 18-fold range of genome size in Vanilloideae, from 2.99 pg for Eriaxis rigida to 55.40 pg in Pogonia ophioglossoides.

1 - University of Wisconsin-Madison, Botany, Madison, WI, 53706, USA
2 - University of Wisconsin, Department of Botany, 154 Birge Hall, 450 Lincoln Drive, Madison, WI, 53706, USA

Keywords:
Orchid
Orchidaceae
Next Generation
Evolution.

Presentation Type: Oral Paper
Session: 3, Systematics I--Tracheophytes, Pteridophytes to Monocots 1
Location: 110/Mayo Civic Center
Date: Monday, July 23rd, 2018
Time: 9:00 AM
Number: 3005
Abstract ID:373
Candidate for Awards:None