ORIGINAL ARTICLE Closing the gaps: phylogenetic relationships in the Brassicaceae based on DNA sequence data of nuclear ribosomal ITS region Suzanne I. Warwick • Klaus Mummenhoff • Connie A. Sauder • Marcus A. Koch • Ihsan A. Al-Shehbaz Received: 25 August 2009 / Accepted: 24 January 2010 / Published online: 13 April 2010 Ó Springer-Verlag 2010 Abstract Sequence data from the nuclear encoded ribo- somal internal transcribed spacer (ITS) region were used to determine monophyly of tribes, tribal limits, and tribal relationships of 96 so far unassigned or tentatively assigned genera (represented by 101 taxa/accessions) within the Brassicaceae. Maximum-parsimony and maximum- likelihood analyses of 185 ITS Brassicaceae sequences, which also included representatives of each of the 34 cur- rently recognized tribes, supported the separate phylogenetic distinctness of these tribes and permitted the tribal assign- ment of all but 12 of the unassigned genera into tribal clades. The data support the recognition of eight new, well-resolved, uni- or oligogeneric tribes recognized herein as the Alyss- opsideae [96% bootstrap support (BS); including the central and southwestern Asian Alyssopsis and Calymmatium], Asteae (100% BS; including the Mexican Asta), Eudemeae (97% BS; South American Brayopsis, Eudema, and Xerodraba), Kernereae (96% BS; European Kernera and Rhizobotrya), Notothlaspideae (100% BS; New Zealandic Notothlaspi), Oreophytoneae (100% BS; eastern African Oreophyton and southern European Murbeckiella), and Yinshanieae (100% BS; Chinese Yinshania), as well as the moderately supported Microlepidieae (75% BS; Australian Microlepidium and Carinavalva). Furthermore, the results fully support the recent findings that the tribes Schizopeta- leae and Thelypodieae ought to be recognized as two distinct tribes instead of a single tribe, as well as provide some support for the re-establishment of the tribe Cremolobeae, bringing the total number to 44 tribes in the family. Nearly 92% (308) of the 336 genera in the family have been assigned to a tribe. The earlier-published Anastaticeae is taken here to replace the Malcolmieae. Keywords Brassicaceae Á ITS region Á Phylogeny Á Systematics Á Tribal assignments Introduction The Brassicaceae is a large family of ca. 338 genera and over 3,700 species distributed throughout the world, primarily in temperate and alpine regions (Al-Shehbaz 1984; Al-Shehbaz et al. 2006; Warwick et al. 2006b). It is a natural family, easily distinguished by floral and fruit morphology, i.e., cruciform corolla, tetradynamous stamens, and characteris- tic siliques. Tribal classification of the family, however, has long been problematic and not well understood phyloge- netically. The characters traditionally used in the delimita- tion of tribes are few and include orientation of the radicle in relation to the cotyledons in the embryo, fruit length- to-width ratio, fruit compression and dehiscence, number of Electronic supplementary material The online version of this article (doi:10.1007/s00606-010-0271-8) contains supplementary material, which is available to authorized users. S. I. Warwick (&) Á C. A. Sauder Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, K.W. Neatby Bldg., Central Experimental Farm, Ottawa, ON K1A 0C6, Canada e-mail: Suzanne.Warwick@AGR.GC.CA K. Mummenhoff FB Biologie/Chemie, Botanik, Universita ¨t Osnabru ¨ck, 49069 Barbarastrasse II, Germany M. A. Koch Heidelberg Institute of Plant Sciences, Biodiversity and Plant Systematics, University of Heidelberg, Im Neuenheimer Feld 345, 69120 Heidelberg, Germany I. A. Al-Shehbaz Missouri Botanical Garden, P.O. Box 299, St. Louis, MO 63166-0299, USA 123 Plant Syst Evol (2010) 285:209–232 DOI 10.1007/s00606-010-0271-8