A phylogenetic study ofSaxifraga sect.Saxifraga (Saxifragaceae) based on nrDNA ITS sequences

Parsimony analyses of 54 nrDNA ITS (Internal Transcribed Spacer) sequences ofSaxifraga sect.Saxifraga were performed. In addition to some unresolved clades, there is strong disagreement between the ITS phylogeny and previous classifications based primarily on morphology. The extensive cytological instability of sect.Saxifraga prevents previous cytotaxonomical results from resolving the incongruence between molecular and morphological data. Dissimilar topologies between chloroplast (matK) and nuclear (ITS) trees for eight species of sect.Saxifraga suggest that gene trees and the true species tree are not coincident. Recent and mid-term reticulation is proposed as an explanation for the incongruence between morphological, cytological, organellar, and nuclear data. Homogenization in multigene families, such as the ITS region, via concerted evolution may be the key to the interpretation of results based on ITS sequences within sect.Saxifraga. The use of organellar genes in a larger sample should help to determine whether extensive reticulation occurs in sect.Saxifraga, as has been documented in various genera of Saxifragaceae.     

Phylogenetic relationships among Lactuca (Asteraceae) species and related genera based on ITS-1 DNA sequences

Internal transcribed spacer (ITS-1) sequences from 97 accessions representing 23 species of Lactuca and related genera were determined and used to evaluate species relationships of Lactuca sensu lato (s.l.). The ITS-1 phylogenies, calculated using PAUP and PHYLIP, correspond better to the classification of Feráková than to other classifications evaluated, although the inclusion of sect. Lactuca subsect. Cyanicae is not supported. Therefore, exclusion of subsect. Cyanicae from Lactuca sensu Feráková is proposed. The amended genus contains the entire gene pool (sensu Harlan and De Wet) of cultivated lettuce (Lactuca sativa). The position of the species in the amended classification corresponds to their position in the lettuce gene pool. In the ITS-1 phylogenies, a clade with L. sativa, L. serriola, L. dregeana, L. altaica, and L. aculeata represents the primary gene pool. L. virosa and L. saligna, branching off closest to this clade, encompass the secondary gene pool. L. virosa is possibly of hybrid origin. The primary and secondary gene pool species are classified in sect. Lactuca subsect. Lactuca. The species L. quercina, L. viminea, L. sibirica, and L. tatarica, branching off next, represent the tertiary gene pool. They are classified in Lactuca sect. Lactucopsis, sect. Phaenixopus, and sect. Mulgedium, respectively. L. perennis and L. tenerrima, classified in sect. Lactuca subsect. Cyanicae, form clades with species from related genera and are not part of the lettuce gene pool.     

Frequent gain and loss of pyrrolizidine alkaloids in the evolution of Senecio section Jacobaea (Asteraceae)

Pyrrolizidine alkaloids (PAs) of the macrocyclic senecionine type are secondary metabolites characteristic for most species of the genus Senecio (Asteraceae). These PAs are deterrent and toxic to most vertebrates and insects and provide plants with a chemical defense against herbivores. We studied the PA composition of 24 out of 26 species of Senecio section Jacobaea using GC-MS. The PA profiles of eight of these species have not been studied before and additional PAs were identified for most other species that were included in previous studies. With one exception (senecivernine) all 26 PAs identified in sect. Jacobaea can be regarded as derivatives of the biosynthetic backbone structure senecionine. Based on the PA profiles of the species of sect. Jacobaea and the results of previous tracer studies, we constructed two hypothetical biosynthetic scenarios of senecionine diversification. Both scenarios contain two major reactions: the conversion of the necine base moiety retronecine into the otonecine moiety and site-specific epoxidations within the necic acid moiety. Further reactions are site-specific hydroxylations, sometimes followed by O-acetylations, site-specific dehydrogenations, E, Z-isomerizations, and epoxide hydrolysis and chlorolysis. The GC-MS data and both biosynthetic scenarios were subsequently used to study the evolution of PA formation in sect. Jacobaea by reconstructing the evolutionary history of qualitative PA variation in this section. This was achieved by optimizing additive presence/absence data of PAs and types of enzymatic conversions on a maximum parsimony cladogram of section Jacobaea inferred from DNA sequence and morphological data. Besides showing large intra- and interspecific variation, PA distribution appears to be largely incidental within the whole clade. These results together with the finding that all but one of the PAs identified in sect. Jacobaea are also present in species of other sections of Senecio indicate that differences in PA profiles in Senecio can not be explained by the gain and loss of PA specific genes, but rather by a transient switch-off and switch-on of the expression of genes encoding PA pathway-specific enzymes.     

Three new species of Senecio (Asteraceae) from Mexico

Senecio moranii, Senecio martirensis, andSenecio semperamatae, all from Mexico, are described as new.     

Phylogenetic position of Mediterranean Astereae and character evolution of daisies (Bellis,Asteraceae) inferred from nrDNA ITS sequences

Phylogenetic analyses of nrITS sequences of Asteraceae revealed that the Bellis group is a natural assemblage comprising all the species of Bellis and Bellium, but not Rhynchospermum. In contrast, we propose to include the genera Bellis, Bellium, and Bellidastrum in the subtribe Bellidinae in the interest of circumscribing natural groups. Our results also suggest an early diversification in the western Mediterranean Basin of two monophyletic lineages, Bellis and Bellium. Three major groups can be distinguished within BELLIS: (1) the B. perennis group, containing five annual and perennial species with three ploidy levels (diploid, octoploid, and decaploid), which are distributed throughout the Mediterranean Basin despite lack of pappus; (2) the Bellis sylvestris group, with five annual and perennial species primarily from the western Mediterranean, in which there are five ploidy levels (diploid, tetraploid, hexaploid, octoploid, and decaploid); and (3) a basal grade consisting of three diploid, perennial species which displays remarkable diversification of morphologies. Striking characteristics, such as an annual life form, polyploidy, and loss of pappus, seem to have occurred in parallel several times and in different geographical areas during the early diversification of Bellis species in the western Mediterranean. Character evolution reconstructions allow us to describe a putative ancestor of the genus Bellis (proto-Bellis).     

虎耳草属山羊臭组的界定和系统发育: 核糖体DNA ITS序列证据

虎耳草属Saxifraga山羊臭组sect. Ciliatae是该属中最大的一个组, 共有175种, 主要分布在喜马拉雅地区, 我国分布有166种, 占总种数的95%; 其中, 112种为中国特有。约80%的种类分布在我国青藏高原和西南地区, 是中国喜马拉雅植物成分的代表类群。山羊臭组内物种分化十分显著, 分类处理也很困难, 该组是否为单系类群, 组下的系统发育关系也不清楚, 均需进一步验证。本文测定了虎耳草属山羊臭组及其他组33种植物样品的核糖体DNA内转录间隔区ITS序列, 并从GenBank调取虎耳草组sect. Saxifraga等组和近缘属唢呐草属Mitella共22种植物的该序列。ITS分析结果表明: (1)所研究的山羊臭组类群聚为单独一支, 而且与垫状组sect. Porphyrion、虎耳草组、球茎组sect. Mesogyne和仅在欧洲分布的sect. Cymbalaria和sect. Cotylea等8个组聚成的另一分支构成姊妹群; (2)根据形态特征建立的山羊臭组的3个亚组即唐古拉亚组subsect. Hirculoideae、莲座状亚组subsect. Rosulares和具芽亚组subsect. Gemmiparae各自聚为一支, 但是莲座状亚组这一支的支持率较低。同时, 山羊臭组的鞭匐枝亚组subsect. Flagellares和subsect. Hemisphaericae的代表类群单独聚为一支, 位于具芽亚组类群分支内部而不能成立; (3)唐古拉亚组和莲座状亚组又聚为一亚分支与具芽亚组构成姊妹群, 而且具芽亚组最早从山羊臭组这一支中分化出来。我们的研究还发现山羊臭组内种间形态分化较大, 而ITS碱基变异较小, 这可能是山羊臭组类群在青藏高原及毗邻地区的高山环境下物种快速分化的结果。     

Circumscription and phylogeny of Saxifraga sect. Ciliatae: Evidence from nrDNA ITS sequences

The largest section of the genus Saxifraga (Saxifragaceae), sect. Ciliatae, consists of 175 morphologically diverse species. This section is mainly distributed in the Qinghai-Tibetan Plateau and adjacent regions of southwest China and more than 80% of the total number of species are endemic to this region. It remains unknown whether this section is monophyletic and up to now no study has been conducted on the infra-sectional phylogeny. In this study, ITS sequences of the nuclear ribosomal DNA were firstly determined for 33 species mainly from this section and related sections. We further downloaded the corresponding sequences of the same DNA region for the other 22 species of Saxifraga and Mitella from GenBank. All sequences were together used to construct the phy-logenetic trees. The main implications of the phylogenetic analyses include: (1) sect. Ciliatae, as traditionally defined, constitutes as a monophyletic clade and its sister group is a well supported clade that includes species from 8 sections such as sect. Porphyrion, sect. Saxifraga and sect. Mesogyne; (2) three morphological subsections, i.e., subsect. Gemmiparae, subsect. Hirculoideae and subsect. Rosulares were tentatively recovered despite the relatively low statistic bootstrap support for the last one; however, subsect. Flagellares and subsect. Hemi-sphaericae were not recognized as separate entities, and nested within subsect. Gemmiparae; (3) subsect. Hircu-loideae and subsect. Rosulares clustered together as sister subclades while subsect. Gemmiparae diverged early. In addition, our results suggest that the paired variation of ITS sequences in sect. Ciliatae is relatively low between the sampled species in spite of their diverse morphology. It is suggested that such a scenario may mirror rapid speciation in this section that probably trigged by the uplifts of the Qinghai-Tibetan Plateau and the extensive selection pressure under the alpine environments.     

A new diploid species of Hieracium sect. Pannosa (Asteraceae) from Bulgaria

Hieracium petrovae Vladimirov & Szeląg sp. nov. , a new diploid (2 n  = 18) species in H. sect. Pannosa Zahn, is described and illustrated from the Rhodope Mountains, South Bulgaria, and compared with related taxa. It grows in relict habitats in crevices of limestone rock together with many Balkan endemics. H. petrovae is morphologically similar to taxa from the H. pannosum , H. pilosissimum and H. heldreichii groups (collective species sensu Zahn) to some of which it is a presumed ancestral species.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 150 , 261–265.     

A new species of Anthemis sect. Hiorthia (Asteraceae) from SE Sicily

A new species of Anthemis sect. Hiorthia (Asteraceae) is described from Sicily. This taxon, named A. piagnattiorum, is confined to a restricted area of the Hyblaean territory (SE Sicily), in the Natural Reserve of Cava Grande (Cassibile, Siracuse), where it takes shelter on carbonate rocky habitat and participates, with other Sicilian endemic taxa, to the composition of a termophilous chasmophytic community (Putorio calabricae–Micromerietum microphyllae).     

A phylogenetic study ofPolygonum sect.Tovara (Polygonaceae) based on ITS sequences of nuclear ribosomal DNA

Polygonum sect.Tovara comprises three morphologically very similar species;P. virginianum,P. filiforme, andP. neofiliforme. Sequences of internal transcribed spacers (ITSs) of nuclear ribosomal DNA of these were determined to examine phylogenetic relationships and the levels of differentiation among them. The size of ITS 1 was 241 bp inP. filiforme andP. neofiliforme, and 242 bp inP. virginianum. The size of ITS 2 was 243 bp, and that of the 5.8S rRNA coding region was 163 bp. The ITS sequences clearly separate North AmericanP. virginianum from the eastern Asian species. Nucleotide divergence between them ranges from 3.3% to 3.8% for ITS 1 and from 9.3% to 10.7% for ITS 2. The molecular data also revealed that two eastern Asian species are closely related but should be treated as distinct species.     

A phylogenetic analysis of Antrodia s.l. based on nrDNA ITS sequences, with emphasis on rhizomorphic European species

The rhizomorphic European species of Antrodia, belonging to the traditionally called Antrodia radiculosa group, are investigated. On the basis of morphological and molecular analysis, the genus Fibroporia is supported. Specimens from Central Europe previously ascribed to Antrodia radiculosa constitute a species of their own, and are herein described as Fibroporia bohemica. Moreover, a new combination, Fibroporia citrina, is proposed.     

Eight new species of Hieracium sect. Tridentata (Asteraceae) from southern and northern Sweden

Eight new species of Hieracium sect. Tridentata, namely H. antrorsum, H. quercifolium, H. stenianum, H. vestrogothicum, and H. vetlandaënse are described from the Götaland region (southern Sweden), H. grothii from Norrbotten in the Norrland region (northeast Sweden), and H. sparsifolium var. suppansum Johanss. and H. adampliatum var. pilosius Ohlsén are raised to specific rank as H. suppansum and H. gothiciferum respectively.     

Numerical morphological analysis of Lettuce cultivars and species (Lactuca sect.Lactuca,Asteraceae)

L. sativa L. cultivars were compared morphologically with accessions ofL. saligna L.,L. serriola L., andL. virosa L. in order to define the infra- and interspecific variation. Multivariate analysis (principal component analysis) distinguished four groups corresponding with the four species. Infraspecific variation (e.g., colour, leaf shape) withinL. sativa is the largest, because breeding has caused a large variation in vegetative features; infraspecific variation withinL. serriola is also large. Three plants of one accession were placed betweenL. sativa andL. serriola because they showed morphological characteristics of both species. They are still classified asL. sativa. The morphological differences betweenL. sativa andL. serriola are too large to consider these two as one species. The descent of the cultivar groups and the four species is described.     

Chromosome numbers and meiotic studies in species of Senecio (Asteraceae) from Argentina

Meiotic chromosome counts, chromosomal behaviour and meiotic configurations of ten taxa of Senecio from Argentina were examined. Most counts are original: S. crepidifolius DC., S. francisci Phil. and S. octolepis Griseb. var. saltensis (Hicken) Cabrera & Zardini have 2 n  = 40, and S. chrysolepis Phil., 2 n  = 80 + 8B. We confirmed previous reports for S. deferens Griseb. (2 n  = 40 + 4B), S. filaginoides DC. var. filaginoides (2 n  = 40), S. hieronymi Griseb. (2 n  = 40 + 7B), S. pampeanus Cabrera (2 n  = 40) and S. rudbeckiifolius Meyen & Walp. (2 n  = 40 + 7B). In S. bracteolatus Hook. & Arn. var. bracteolatus , we found a new number (2 n  = 40) that differs from the one cited previously. In four species, numerical polymorphisms for B-chromosomes were observed. Several of the analysed species presented secondary bivalent association. This phenomenon, together with other evidence, supports x  = 5 as the basic chromosome number. The number of chiasmata and their positions were also surveyed, with the finding that open bivalents were the most frequent meiotic figures and terminal chiasmata the preferential position. These features are related to recombination rate, and the success and persistence of these polyploids. We discuss some systematic and evolutionary aspects in the light of cytogenetic data and conclude that polyploidy is the major force modelling the chromosome evolution within this genus.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 148 , 465–474.     

Two new species of Senecio section Palmatinervii (Asteraceae) from eastern Mexico

Two closely related new species,Senecio grimesii andS. marquezii, belonging to the sectionPalmatinervii are described, illustrated, and compared to their nearest relative,S. heterogamus. An erratum to this article is available at .     

Two new species of Senecio section Palmatinervii (Asteraceae) from northeastern Mexico

Two new species ofSenecio,S. sundbergii andS. neogibsonii, belonging to the sectionPalmatinervii are described, illustrated, and compared to their nearest relatives,S. aschenbornianus andS. lanicaulis.