[show abstract][hide abstract] ABSTRACT: The Brassicaceae family (mustards or crucifers) includes Arabidopsis thaliana as one of the most important model species in plant biology and a number of important crop plants such as the various Brassica species (e.g. cabbage, canola, mustard). Moreover, the family comprises an increasing number of species that serve as study systems in many fields of plant science and evolutionary research. However, systematics and taxonomy of the family are very complex and access to scientifically valuable and reliable information linked to species and genus names and its interpretation are often difficult. BrassiBase is a continuously developing and growing knowledge database (http://brassibase.cos.uni-heidelberg.de) that aims at providing direct access to many different types of information ranging from taxonomy and systematics to phylo- and cytogenetics. Providing critically revised key information, the database intends to optimize comparative evolutionary research in this family and supports the introduction of the Brassicaceae as the model family for evolutionary biology and plant sciences. The new version 1.1.9. has now implemented some features that should help to accomplish these goals within a comprehensive taxonomic framework. A "phylogenetic placement tool" should help to identify critical accessions and germplasm and provide a first visualization of phylogenetic relationships. The "cytogenetics tool" provides in-depth information on genome sizes, chromosome numbers and polyploidy and sets this information into a Brassicaceae-wide context.
Plant and Cell Physiology 11/2013; · 4.13 Impact Factor
[show abstract][hide abstract] ABSTRACT: Draba includes over 390 species distributed globally, mostly in extreme ecosystems at high elevations and latitudes making it the most successful and species-rich genus of the Brassicaceae, particularly in mountain and alpine regions. In this analysis, species richness data were collected from floras and checklists, and species distribution patterns were compared on a global scale for 367 of the species. A compilation of the geographical distribution of the entire genus using a presence/absence matrix was generated and displayed upon geographical maps. The three areas of highest species richness are the northern Andes (48 spp.), central Rocky Mountains (49 spp.), and Tibetan Plateau/C-SW Chinese (Hengduan) mountains (52 spp.). Previous phylogenetic analyses are in congruence with the area cladogram shown herein. It is shown that Draba has a diverse range of distribution patterns from widely spread to narrowly endemic. Species with wider distributions are frequently found in the Arctic, while those with a more narrow distribution are restricted to high elevations. However, ploidy-level information as well as recently presented genetic data convincingly indicates that the European and West Asian biota have served as a primary source and center of origin of the large diversity in the genus. A complete list of accepted Draba species is provided.
[show abstract][hide abstract] ABSTRACT: Boechera (Brassicaceae) is a diverse genus of ± 70 sexual diploid species and numerous apomictic hybrids concentrated in western North America. It is the largest genus in tribe Boechereae, which also includes seven other small genera. Boechera is closely related to Arabidopsis and is becoming a model genus for diverse studies, focusing particularly on apomixis and hybrid speciation. As part of an ongoing effort to clarify the taxonomy of the group, we present phylogenetic analyses of Boechereae, including all genera of the tribe and most of the sexual diploid species of Boechera. Ten loci are used, including two plastid loci, nrDNA ITS, and seven low-copy nuclear loci. These analyses indicate that Boechera, as currently circumscribed, is polyphyletic, comprising three main clades. Eastern North American species previously assigned to Boechera form a distinct clade with the Asian taxon Borodinia macrophylla and are herein transferred to the genus Borodinia, resulting in seven new combinations (Borodinia burkii, Borodinia canadensis, Borodinia dentata, Borodinia laevigata, Borodinia missouriensis, Borodinia perstellata, and Borodinia serotina). Boechera repanda, a morphologically aberrant species endemic to the Sierra Nevada, is recognized in the new genus Yosemitea (as Yosemitea repanda). A primarily western North American clade comprising all remaining species is strongly supported and retains the name Boechera. Although resolution within Boechera sensu stricto is limited, a number of well-supported clades are identified.
[show abstract][hide abstract] ABSTRACT: Six new species of Brassicaceae (Brayopsis chacasensis Al-Shehbaz & A. Cano, Descurainia canoensis Al-Shehbaz, Draba canoensis Al-Shehbaz, Trinidad, Ed. Navarro & D. Rodr.-Paredes, D. punoensis Al-Shehbaz, Ed. Navarro, Trinidad & A. Cano, Neuontobotrys camanaensis Al-Shehbaz & A. Cano, and Weberbauera ayacuchoensis Al-Shehbaz, A. Cano & Trindad) are described and illustrated, and their distinguishing characters from nearest relatives are discussed. Brief notes on the diversity of these five genera in South America, especially Peru, are discussed.
[show abstract][hide abstract] ABSTRACT: We are developing an online-accessible knowledge and database system of cross-referenced information and resources on Brassicaceae (Cruciferae) taxonomy, systematics and evolution, including chromosome numbers, traits and characters, germplasm resources, and accurate enumeration of all species, genera and tribes. Biological, molecular and evolutionary knowledge is exponentially increasing in the mustard family. However, because of the complex and overwhelming biological diversity of the family, it is difficult to assess research results within a larger evolutionary framework. Many species have proven to be remarkable study objects but are rarely available. Biological material and resources, either collected directly in the wild or held in germplasm collections, have often been taxonomically misidentified; and only very rarely has the material been further characterized and documented. There is also no comprehensive survey of character and trait distribution among Brassicaceae lineages, though family-wide phylogenies are meanwhile available. In order to close these gaps, we will make accessible to the scientific community the research data focusing on adaptive characters and their evolution in the Brassicaceae. In this context, we will also provide a comprehensive documentation of the taxonomy and systematics of the entire family. This will include a database with all relevant taxonomic, systematic and phylogenetic literature, a comprehensive data collection of characters and traits, a DNA-based identification tool for genera and species, electronic interactive keys for the identification of genera and species, and a setup of a carefully selected and documented germplasm collection representing main lineages of the family. This knowledge database, hereafter BrassiBase, has been launched within the framework of the DFG priority programme SSP 1529 “Adaptomics – Evolutionary plant solutions to ecological challenges/Molecular mechanisms underlying adaptive traits in the Brassicaceae s.l.”
[show abstract][hide abstract] ABSTRACT: Gametophytic apomixis is a common form of asexual reproduction in plants. Virtually all gametophytic apomicts are polyploids, and some view polyploidy as a prerequisite for the transition to apomixis. However, any causal link between apomixis and polyploidy is complicated by the fact that most apomictic polyploids are allopolyploids, leading some to speculate that hybridization, rather than polyploidy, enables apomixis. Diploid apomixis presents a rare opportunity to isolate the role of hybridization, and a number of diploid apomicts have been documented in the genus Boechera (Brassicaceae). Here, we present the results of a microsatellite study of 1393 morphologically and geographically diverse diploid individuals, evaluating the hypothesis that diploid Boechera apomicts are hybrids. This genus-wide dataset was made possible by the applicability of a core set of microsatellite loci in 69 of the 70 diploid Boechera species and by our ability to successfully genotype herbarium specimens of widely varying ages. With few exceptions, diploid apomicts exhibited markedly high levels of heterozygosity resulting from the combination of disparate genomes. This strongly suggests that most apomictic diploid Boechera lineages are of hybrid origin, and that the genomic consequences of hybridization allow for the transition to gametophytic apomixis in this genus.
[show abstract][hide abstract] ABSTRACT: The new species Englerocharis dentata and Eudema peruviana are described, illustrated, and their relationships to nearest relatives are discussed. The former is readily distinguished from its other congeners by it broadly spatulate, 7–9-dentate leaves (vs. narrower, entire leaves). Eudema peruviana is the smallest plant in the genus and is hardly 1 cm tall and with linear, glabrous leaves, unbranched caudex without leaf remains, persistent sepals, and broadly globose, angustiseptate fruits. Keys to species of Englerocharis and to the Peruvian species of Eudema are given.
[show abstract][hide abstract] ABSTRACT: A synopsis of the South American genus Aschersoniodoxa Gilg & Muschl. is presented, and the new species A. peruviana Al-Shehbaz, Eduardo Navarro & A. Cano is described and illustrated. An updated generic description of Aschersoniodoxa, a discussion of its tribal placement, and a key to its four species are given.
[show abstract][hide abstract] ABSTRACT: A synopsis of the largely Peruvian genus Englerocharis Muschl. is presented, and the new species E. ancashensis Al-Shehbaz, A. Cano & Trinidad is described and illustrated. An updated generic description of Englerocharis and a key to its four species are given. The generic differences between Englerocharis and Brayopsis Gilg & Muschl. are discussed.
[show abstract][hide abstract] ABSTRACT: The genus Stubendorffia (Brassicaceae) is distinguished from Lepidium solely by the dehiscent vs. indehiscent angustiseptate fruits. By contrast, Winklera is separated from Lepidium by a combination of perennial habit, pinnatisect leaves, yellow flowers, and wingless fruits, characters all of which occur individually and in various combinations within Lepidium. Extensive molecular studies strongly show that Winklera and polyphyletic Stubendorffia are nested within the earlier-published Lepidium and, therefore, the three genera are herein formally united. The new name Lepidium pavlovii and 10 new combinations, L. afghanicum, L. apterum, L. botschantzevii, L. curvinervium, L. lipskyi, L. olgae, L. orientalis, L. patrinoides, L. pterocarpum, and L. silaifolium, are proposed. Lepidium apterum is lectotypified. A complete generic synonymy of Lepidium and an expanded generic description are presented.
Edinburgh Journal of Botany 06/2011; 68(02):165 - 171.
[show abstract][hide abstract] ABSTRACT: Sequence data from the nuclear ribosomal internal transcribed spacer (ITS) region of 45 taxa were used to determine the phylogenetic relationship of Arabis arenicola to Arabis, Arabidopsis, Braya, and Eutrema, and that of Eutrema to the purportedly related genera Aphragmus, Lignariella, Neomartinella, Platycraspedum, Taphrospermum, and Thellungiella. Arabis arenicola was originally described as Eutrema in 1830, transferred to Arabis in 1898, and has remained in Arabis to the present, even though it is morphologically more similar to Arabidopsis, Braya, and Eutrema. Sequence data were obtained from representative taxa of Arabis, Arabidopsis, and related Boechera and Catolobus, Braya and Neotorularia, and Eutrema, Aphragmus, Lignariella, Neomartinella, Platycraspedum, Taphrospermum, and Thellungiella. The five Arabis arenicola accessions examined had ITS sequences that were identical to each other and to four Arabidopsis lyrata accessions. In both maximum parsimony and maximum likelihood analyses, Arabis arenicola fell within the Arabidopsis clade and was closely aligned with Arabidopsis lyrata. Two of six purportedly related genera were not closely related to Eutrema. Both analyses placed Lignariella within a separate well-supported clade with Aphragmus, while the other four genera, Neomartinella, Platycraspedum, Taphrospermum, and Thellungiella, fell within a well-supported clade with Eutrema. Morphology and molecular data strongly suggest transferring Arabis arenicola to Arabidopsis, expanding Aphragmus to include Lignariella, and expanding Eutrema to include Neomartinella, Platycraspedum, Taphrospermum, and Thellungiella. New combinations in Arabidopsis and Aphragmus are proposed.
Canadian Journal of Botany 03/2011; 84(2):269-281. · 1.40 Impact Factor
[show abstract][hide abstract] ABSTRACT: Based on extensive molecular studies and critical evaluation of morphological characters, the tribe Stevenieae and the genus Pseudodraba are described as new to science. The Stevenieae include the genera Macropodium, Pseudoturritis, and Stevenia with a total of 11 species; a key separating these three genera is presented. Draba hystrix is placed in the monotypic Pseudodraba due to its morphological distinctness supported by molecular data. Arabis tenuisiliqua and A. tibetica are transferred to the genus Crucihimalaya. Three new combinations, i.e. Pseudodraba hystrix, Crucihimalaya tenuisiliqua, and C. tibetica are formed.
Plant Diversity and Evolution. 03/2011; 129(1):71-76.
[show abstract][hide abstract] ABSTRACT: A second species of the Chilean endemic Ivania, I. juncalensis, is described and illustrated. It is readily distinguished from the generic type I. cremnophila, which is also known only from the type collection, by its pinnatifid and oblong to lanceolate (vs. entire or dentate and cordate to subreniform) basal leaves, smaller flowers (ovate sepals 2.5–3 mm long and spatulate petals 6–7.5 × 2.5–3 mm vs. oblong sepals 5–6 mm long and broadly obovate petals 11–13 × 5–6 mm), and strongly 2-lobed (vs. entire) stigma.
[show abstract][hide abstract] ABSTRACT: The genus Sisymbrium as currently circumscribed includes about 94 species disjunctly distributed in the Old (41 spp.) and the New World (53 spp.). Sisymbrium has been variously delimited, with several segregate genera proposed (subtribe Sisymbriinae) primarily for the new World taxa, including Schoenocrambe, Coelophragmus, and Mostacillastrum. Using sequence data from the internal transcribed spacers of nuclear ribosomal DNA and the 5.8S rRNA gene (collectively, ITS region), we examined the evolutionary relationships of Old and New World Sisymbrium species with its segregate genera and the validity of O.E. Schulz's classical sectional treatment of Sisymbrium. Sequence data were obtained from 33 Sisymbrium species, representing all 14 sections and two Sisymbrium species formerly assigned to segregate genera Coelophragmus and Mostacillastrum (subtribe Sisymbriinae), and two putative Sisymbrium species currently assigned to Neotorularia. Sequence data were also obtained from 26 taxa from segregate or related genera includingSchoenocrambe, Werdermannia (subtribe Sisymbriinae), eight genera in the Thelypodieae, Sibara (tribe Arabideae) and Pringlea (tribe Pringleeae), four members of the tribe Brassiceae, and three other Neotorularia species. Results from maximum parsimony analysis showed a polyphyletic origin for Sisymbrium and did not correspond well to Schulz's sectional classification. Sisymbrium species were split into three major clades: Old World Sisymbrium (including Neotorularia aculeolata, Neotorularia afghanica, and the type species of Schoenocrambe, Schoenocrambe linifolia, the sole New World member of this Old World clade); New World Sisymbrium (along with the remaining New World taxa) and designated as the New World Thelypodieae alliance; and the tribe Brassiceae ( including Sisymbrium supinum and Sisymbrium thellungii).Key words: Sisymbrium, Schoenocrambe, ITS, Thelypodieae, taxonomy, Brassicaceae.
Canadian Journal of Botany 02/2011; 80(9):1002-1017. · 1.40 Impact Factor
[show abstract][hide abstract] ABSTRACT: Life without the mustard family (Brassicaceae) would be a world without many crop species and the model organism Arabidopsis (Arabidopsis thaliana) that has revolutionized our knowledge in almost every field of modern plant biology. Despite this importance, research breakthroughs in understanding family-wide evolutionary patterns and processes within this flowering plant family were not achieved until the past few years. In this review, we examine recent outcomes from diverse botanical disciplines (taxonomy, systematics, genomics, paleobotany and other fields) to synthesize for the first time a holistic view on the evolutionary history of the mustard family.
Trends in Plant Science 02/2011; 16(2):108-16. · 11.81 Impact Factor
[show abstract][hide abstract] ABSTRACT: Limits of the monospecific genus Planodes are expanded to include an additional species previously placed in Arabis, Cardamine, or Sibara. The new combination P. mexicanum is proposed. The distinguishing characters separating Planodes from related genera are given, as well as a detailed generic description and a key to the two species of this genus.
[show abstract][hide abstract] ABSTRACT: Sibara includes 12 species exhibiting amphitropical disjunction. Six of these grow in California and Baja California, and six in northern Chile and Argentinean Mendoza and Patagonia. The new species S. davidsonii and S. dilloniorum are described from Baja California and Chile, respectively. The genera Pterygiosperma and Werdermannia are reduced to synonymy of Sibara, and the new combinations S. anethifolia, S. macrostachya, S. mendocina, S.pinnata, and S. tehuelches are proposed. Four species described by Philippi in Nastrutium and Sisymbrium are lectotypified.
[show abstract][hide abstract] ABSTRACT: The relationships and taxonomy of the genus Thysanocarpus (Brassicaceae) are reassessed based on molecular phylogenetic analyses of nuclear ribosomal (ITS) and chloroplast (trnL-F) sequences and a critical re-examination of morphology and nomenclatural types. Based on these results, Thysanocarpus is well-supported as a member of tribe Thelypodieae, but no illuminating phylogenetic structure is found within the tribe. The independent origin of similar fruit morphology in Thysanocarpus and Athysanus is confirmed. Within Thysanocarpus, seven species are recognized: T. conchuliferus, T. curvipes, T. desertorum, T. erectus, T. laciniatus, T. radians, and T. rigidus comb. nov. Thysanocarpus laciniatus is found to have originated through hybridization. However, T. desertorum and T. rigidus, which have previously been included within T. laciniatus (as T. laciniatus var. hitchcockii and T. laciniatus var. rigidus, respectively), do not share that species' hybrid origin and are distinct both phylogenetically and morphologically. Within T. curvipes, five subspecies are recognized: T. curvipes subsp. amplectens comb. nov., T. curvipes subsp. curvipes, T. curvipes subsp. elegans comb. nov., T. curvipes subsp. longistylus comb. nov., and T. curvipes subsp. eradiatus comb. nov. Thysanocarpus curvipes subsp. elegans and T. curvipes subsp. longistylus form clades in ITS and/or trnL-F cladograms as well as showing morphological distinction. The remaining three subspecies are recognized based on a combination of morphology and geography.
[show abstract][hide abstract] ABSTRACT: The circumscription of the genus Arabis underwent many and drastic changes within the past. Using DNA sequence information from the nuclear ribosomal RNA and parts of the plastid genome (trnL-trnLF), as well as a critical evaluation of herbarium material from East Asia and North America, we circumscribe the various Arabis taxa of North America. The American and East Asian Arabis species are closely related and, contrary to what was previously believed, they are not closely related to the Eurasian A. hirsuta. Using cpDNA, we found five North American lineages of Arabis with distinct distribution patterns, of which only the purple/red-flowered lineage consists of proven diploids that evolved directly from East Asian progenitors. All other four lineages evolved via ancient hybridization either on the Asian continent prior to migration to North America or showed significant evidence for hybridization and reticulation while diversifying on the American continent. We also provide the first evidence for the systematic circumscription of East Asian Arabis taxa, which together with the North American taxa, form one clade distantly related to European A. ciliata and Eurasian A. hirsuta. The findings also represent the first record of A. pycnocarpa for the floras of China, Japan, and Russian Far East.
American Journal of Botany 06/2010; 97(6):1040-57. · 2.59 Impact Factor
[show abstract][hide abstract] ABSTRACT: Phylogenetic analyses of sequence data from the internal transcribed spacer regions of the nuclear ribosomal DNA (ITS) and the plastid trnL-F region were conducted to reconstruct the phylogenetic history of Draba and related genera. Out of the approximately 370 Draba species, 169 geographically and morphologically representative species are sampled here, including such "controversial" segregates as Abdra, Arabis, Athysanus, Drabopsis, Erophila, Graellsia, Heterodraba, Schivereckia and Tomostima. Phylogenetic analyses of the combined ITS and trnL-F markers indicate that Draba represents a monophyletic evolutionary lineage within the tribe Arabideae, but previously proposed infrageneric classification systems are mostly artificial (i.e. do not reflect true evolutionary history). Draba muralis formed an independent genus, possibly between Draba and Arabis, whereas D. hystrix fell outside Draba and was closely associated with Arabis. The New World annual, lowland Draba, D. platycarpa, D. reptans, D. cuneifolia, D. australis, D. arabidoides, (section Abdra) and D. brachycarpa and D. aspera (section Tomostima), appear to be independent genera that fall outside Draba and are monophyletic with the endemic North American Heterodraba unilateralis and Athysanus pusillus. Graellsia hederifolia and Erophila verna appear to be earlier diverging Draba species, with weak evidence of ancient hybridization in G. hederifolia. Core Draba species were organized into three major groups that encompass the segregate genera Drabopsis and Schivereckia. The three groups have geographic significance: Group I-Europe to Iran; Group II-North and South American Cordillera; Group III-Asian, Arctic, and Beringian. These three groups also have significant petal color and base chromosome level similarities. We also found that Arabis rimarum is a synonym for Draba aucheri, and is well within Group I of Core Draba. Therefore, we propose that many of the lowland and coastal temperate species often associated with Draba should be excluded from that genus. The compilation of these data indicate that true Draba are highly migrating arctic and higher alpine species that are most often perennial with white petals and n=8 as plesiomorphic characters.
Molecular Phylogenetics and Evolution 02/2010; 55(2):524-40. · 4.07 Impact Factor