Brassicaceae phylogeny and trichome evolution

Abstract

To estimate the evolutionary history of the mustard family (Brassicaceae or Cruciferae), we sampled 113 species, representing 101 of the roughly 350 genera and 17 of the 19 tribes of the family, for the chloroplast gene ndhF. The included accessions increase the number of genera sampled over previous phylogenetic studies by four-fold. Using parsimony, likelihood, and Bayesian methods, we reconstructed the phylogeny of the gene and used the Shimodaira-Hasegawa test (S-H test) to compare the phylogenetic results with the most recent tribal classification for the family. The resultant phylogeny allowed a critical assessment of variations in fruit morphology and seed anatomy, upon which the current classification is based. We also used the S-H test to examine the utility of trichome branching patterns for describing monophyletic groups in the ndhF phylogeny. Our phylogenetic results indicate that 97 of 114 ingroup accessions fall into one of 21 strongly supported clades. Some of these clades can themselves be grouped into strongly to moderately supported monophyletic groups. One of these lineages is a novel grouping overlooked in previous phylogenetic studies. Results comparing 30 different scenarios of evolution by the S-H test indicate that five of 12 tribes represented by two or more genera in the study are clearly polyphyletic, although a few tribes are not sampled well enough to establish para- or polyphyly. In addition, branched trichomes likely evolved independently several times in the Brassicaceae, although malpighiaceous and stellate trichomes may each have a single origin.

Molecular phylogeny and systematics of the tribe Chorisporeae (Brassicaceae)

“…Recent family-wide studies (e.g., Beilstein et al 2006Beilstein et al , 2008Beilstein et al , 2010Warwick et al 2007Warwick et al , 2010; Koch et al 2007;Koch and Al-Shehbaz 2009;Franzke et al 2009;German et al 2009;Couvreur et al 2010;Zhao et al 2010) were congruent and showed that the vast majority of tribes can be assigned to three phylogenetic lineages (designated I, II, and III in Beilstein et al 2006). These studies are further congruent in the placement in lineage III of Chorisporeae C.A.…”

“…Dorof. The chloroplast (cp) ndhF phylogeny of Beilstein et al (2006) confirmed the distinctness of the clade including Chorispora R. Br. ex DC.…”

“…Family-wide phylogenetic studies of the Brassicaceae (e.g., Bailey et al 2006;Beilstein et al 2006Beilstein et al , 2008Koch et al 2007;Franzke et al 2009;Koch and Al-Shehbaz 2009;Couvreur et al 2010;Warwick et al 2010) show a lack of resolution in the basal polytomy regardless of the molecular marker used. Similar results were observed within lineages (e.g., Warwick et al 2007) and speciose genera (e.g., Carlsen et al 2009).…”

“…It is often difficult to unravel phylogeny at various levels and to create a natural classification because of substantial homoplasy in almost all morphological characters (e.g., Koch et al 2003;Al-Shehbaz et al 2006;Warwick et al 2010). However, considerable progress has recently been made both in phylogeny and systematics at the generic and tribal levels Bailey et al 2006;Beilstein et al 2006Beilstein et al , 2008Al-Shehbaz and Warwick 2007;Koch et al 2007;Warwick et al 2007;German and Al-Shehbaz 2008a;Mandáková and Lysak 2008;Koch and Al-Shehbaz 2009;Franzke et al 2009;German et al 2009; Electronic supplementary material The online version of this article (doi:10.1007/s00606-011-0452-0) contains supplementary material, which is available to authorized users. Khosravi et al 2009;Mandáková et al 2010;Couvreur et al 2010).…”

Diversity of non-glandular trichomes in subtribe Lychnophorinae (Asteraceae: Vernonieae) and taxonomic implications

“…Also, trichome morphology has already been used to clarify tribal or sectional classifications (Webster et al 1996;Al-Shehbaz et al 2006) and, more recently, has been used as data in phylogenetic studies (e.g. Belstein et al 2006Belstein et al , 2008Caruzo et al 2011;van Ee and Berry 2011).…”