Abstract Detail

Systematics Section/ASPT

Windham, Michael D [1], BECK, JAMES [2], ALEXANDER, PATRICK [3], Li, Fay-Wei [4], Rushworth, Catherine [5], Bailey, C. Donovan [6], Allphin, Loreen [7], Al-Shehbaz, Ihsan [8].

Newly documented hybrids in the tribe Boechereae (Brassicaceae) challenge current generic circumscriptions in the group.

As circumscribed by Al-Shehbaz in 2012, the largely North American mustard tribe Boechereae included 126 accepted species divided among eight genera: Anelsonia (1), Boechera (110), Borodinia (1), Cusickiella (2), Nevada (1), Phoenicaulis (1), Polyctenium (1), and Sandbergia (1). A subsequent publication by Alexander et al. in 2013 transferred seven species from Boechera to Borodinia and added the monospecific genus Yosemitea, also segregated from Boechera, based on a combination of molecular and morphological evidence. Boechera, by far the most diverse genus in the tribe, is notorious for harboring a network of interspecific hybrids constrained only by geographic isolation or deep phylogenetic divergence. Now, microsatellite-based studies of Boechera and related genera reveal the existence of three previously undocumented hybrids that challenge the efficacy of even phylogenetic distance in preventing hybridization within Boechereae. One of the new hybrids is an apomictic triploid combining genomes from two core Boechera species (B. arcuata and B. perennans) with a genome from B. davidsonii, a distinctive species robustly resolved as sister to all other Boechera s.s.. The species currently called B. tiehmii is shown to have arisen through hybridization between B. lemmonii and the monospecific genus Nevada. Finally, all eastern North American populations previously assigned to B. stricta prove to be allotetraploid hybrids between that species and Borodinia laevigata. Whereas the Boechera/Nevada hybrids do not appear to backcross with either parental lineage and could be assigned to a new nothogenus, this is not true for tetraploid Boechera stricta × Borodinia laevigata. This taxon hybridizes with several species of Boechera s.s., in addition to forming rare triploid backcrosses with B. laevigata.

1 - Duke University, Department of Biology, Box 90338, Durham, NC, 27708, USA
2 - Wichita State University, Biology, 1845 Fairmount, Box 26, Wichita, KS, 67260-0026, USA
3 - New Mexico State University, Biology Department, 248 Foster Hall, MSC 3AF, Las Cruces, NM, 88003, USA
4 - Duke University, Biology Department, Box 90338, Durham, NC, 27708, USA
5 - Duke University, PO Box 90338, Durham, NC, 27708, USA
6 - New Mexico State University, PO Box 30001 MSC 3AF, Las Cruces, NM, 88003, USA
7 - Brigham Young University, DEPT INTEGRATIVE BIOLOGY, 275 WIDB, Provo, UT, 84602, USA
8 - Missouri Botanical Garden, P.O. Box 299, St. Louis, MO, 63166-0299, USA

Keywords:
apomixis
hybridization 
polyploidy
Phylogeny
Boechereae
Boechera
Borodinia
Nevada.

Presentation Type: Oral Paper:Papers for Sections
Session: 44
Location: Firs North/Boise Centre
Date: Wednesday, July 30th, 2014
Time: 3:45 PM
Number: 44008
Abstract ID:312
Candidate for Awards:None