Caryological analysis of South American species of Vernonia (Vernonieae,Asteraceae)

Abstract

In the present study 16 populations belonging to 13 species of the genus Vernonia Schreb. were examined cytologically. In total, six different chromosome numbers, which represent three basic numbers: x = 10, x = 16 and x = 17, were found. These results include the first chromosome number reports for the following four species: V. lanifera Cristóbal & Dematt. (2n = 2x = 32), V. membranacea Gardner (2n = 2x = 34), V. salzmannii DC. (2n = 2x = 20) and V. scabrifoliata Hieron. (2n = 2x = 128). Besides, a new chromosome number was found in V. saltensis Hieron. (2n = 2x = 32), for which only tetraploid populations have been previously recorded. The data obtained in this work, along with the information available from the literature, show that the genus Vernonia in South America is heterogeneous with basic chromosome numbers that range between x = 9 and x = 19. These numbers suggest that a combination of polyploidy and aneuploidy has played an important role in the evolution of the genus.     

Karyotype analysis and DNA content in some species of Chrysolaena (Vernonieae,Asteraceae)

Cytogenetic characterization by karyotyping and determination of DNA content by flow cytometry of five species of Chrysolaena (Vernonieae, Asteraceae) was performed. This is the first study of nuclear DNA content realized in the genus. The 2C-values were compared with the ploidy level and the total karyotype length (TKL) of each species. Mitotic analysis revealed a base chromosome number x = 10 for all entities and different ploidy levels, from diploid (2n = 2x = 20) to octoploid (2n = 8x = 80). All species showed bimodal karyotypes composed of metacentric and submetacentric chromosomes. The average chromosome size (ML) varied from 1.86 μm to 2.70 μm, while the TKL ranged from 18.65 μm to 80.55 μm. The intrachromosomal asymmetry index (A₁) varied from 0.27 to 0.38, while the interchromosomal asymmetry index (A₂) ranged from 0.19 to 0.25. A new cytotype is reported for the first time for C. propinqua. Accessory chromosomes found in C. verbascifolia, C. cognata, C. flexuosa, and C. propinqua are also reported as new.     

Cytotaxonomic analysis of South American species of Vernonia (Vernonieae: Asteraceae)

Chromosome numbers in 48 populations belonging to 31 species of Vernonia from South America have been determined. First chromosome counts are reported for V. propinqua var. canescens (2 n = 20), V. sceptrum (2 n = 80), V. rufogrisea (2 n = 32), V. heringeri (2 n = 32), V. hovaefolia (2 n = 64), V. hystricosa (2 n = 128), V. obtusata (2 n = 64), V. pseudoincana (2 n = 32), V. rubricaulis var.◊ australis (2 n = 64) and V. rugulosa (2 n = 30). The basic chromosome numbers x = 10, 14, 15, 16 and 17 were confirmed for New World species of Vernonia . Together with previous records, these numbers suggest that the evolution of Vernonieae has occurred through a combination of polyploidy and aneuploidy. Taxonomic implications of certain counts are also discussed.  © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 139 , 401–408.     

Pollen morphology of Diosma and Coleonema (Rutaceae: Diosminae) and its taxonomic implications

The pollen morphology of Diosma and Coleonema of the taxonomically problematic subtribe Diosminae (Rutaceae) was investigated to determine its taxonomic relevance. Pollen of 26 of the 28 species of Diosma and of each of the eight species of Coleonema was investigated by LM, SEM and TEM. In pollen of Diosma the exine sculpturing is uniform, and only one pollen type, reticulate, could be distinguished. In contrast, exine sculpturing shows interspecific variation in Coleonema and three distinct types, striate, reticulate and perforate, could be discerned. Species groupings indicated by the pollen types suggest possible relationships between species within Coleonema and with other genera that were not previously apparent. Pollen data support macromorphological evidence that suggests the generic re-classification of the Diosminae.     

Two new species of Vernonia (Asteraceae: Vernonieae) from Panama

Two new species,Vernonia cocleana andV. chiriquiensis, are described from Panama. These endemic species are distinct from those in Central America and most closely resemble taxa in the West Indies and Argentina, respectively. These taxa are described and illustrated; a key is provided to the Panamanian species ofVernonia.     

Two new species of Vernonia (Asteraceae: Vernonieae) from Peru

Two new species,Vernonia sagasteguii andV. paucartambensis, from Peru are described, illustrated, and their relationships discussed.     

Leaf epidermal morphology of Zanthoxylum s.l. (Rutaceae) from China

Leaf epidermis characters in 40 of ca. 250 species of Zanthoxylum (Rutaceae) were investigated using light microscopy (LM) and scanning electron microscopy (SEM). The stomata are anomocytic and exist only on the abaxial epidermis except in Z. nitidum, which also has stomata on the adaxial surface. The epidermal cells are usually polygonal or irregular in shape, with anticlinal walls straight, arched, repand, or sinuous. Under the SEM, the inner margin of the outer stomatal rim is nearly smooth, sinuolate or erose, and the cuticular membrane of the leaf epidermis is smooth, striate, or sometimes striate to wrinkled. These data of leaf epidermis of Zanthoxylum demonstrated that there exist many common characters between subgen. Fagara and subgen. Zanthoxylum, sug-gesting a close relationship between the two subgenera. The utility of some characters in identifying some species of Zanthoxylum was also discussed.     

Pollen morphology of some related genera of Vernonieae (Asteraceae) and its taxonomic significance

Pollen morphology is an important source of information to increase systematic resolution in Asteraceae, especially in Vernonieae. Aiming to investigate if palynological traits give support to Caatinganthus, Strophopappus and Xiphochaeta as separate genera from Stilpnopappus, we used cluster analysis followed by a test of group sharpness. Further, ordination analysis was applied to detect informative pollen traits associated with the revealed groups. The analyses evidenced five groups: (G1) Caatinganthus rubropappus as a single-species group; (G2) species of Stilpnopappus; (G3) Xiphochaeta aquatica as a single-species group; (G4) Strophopappus bicolor, S. glomeratus, S. villosus, S. ferrugineus, S. pohlii and S. speciosus; (G5) Strophopappus bullatus and S. regnelli. The interruption in the middle of the muri in apertural lacunae explains the single-species group Caatinganthus rubropappus. The thickness of sexine, the type of apertures (porate or colporate), and spine dimensions (length, thickness and distance from each other) are the traits explaining differences between species of Stilpnopappus and Strophopappus. Equatorial lacunae give support to Xiphochaeta aquatica as a single-species group, despite the smaller size of pollen grains of this species as compared to the others species analyzed. The differences among pollen morphology give support to Caatinganthus, Stilpnopappus, Strophopappus and Xiphochaeta as genera according to the taxonomic classification currently accepted. The used approach was efficient to reveal individual pollen traits informative to explain the sharp groups, and was an effective alternative to the use of “pollen types”.     

广义紫菀属(菊科紫菀族)系统学研究的现状

广义的紫菀属(Asters.l.)曾是个大包大揽的类群,产于北美和欧亚大陆.Nesom主要根据瘦果的形态和细胞学性状对Asters.l.进行了评价,将北美紫菀类植物从Aster中独立出去,使Aster成为欧亚特有类群.但是,在欧亚各国对Aster有定为一属和分为十多个属等不同的分类学处理,分歧较大.狭义紫菀属(Asters.s.)与从Asters.l.中分出的各属之间的系统学关系,以及后者中某些属与北美紫菀类和紫菀族其他亚族间的系统学关系,都存在很大疑问.过去一直认为北美是Aster的发源地,现在欧亚Asters.l.的起源与演化需要重新研究,而青藏高原是探讨Asters.l.物种多样性形成的关键地区.DNA尤其是DNA序列资料在研究Asters.l.的系统发育和分类上将发挥关键作用.     

Phylogeny and classification of the Sematophyllaceae s.l. (Hypnales,Bryophyta)

The Sematophyllaceae s.l. (Sematophyllaceae s.str. + Pylaisiadelphaceae) is one of the most diversified families of pleurocarpous mosses, distributed worldwide. The familial definition and subfamilial delimitation of the family have been controversial since their inception. Phylogenetic analyses were carried out using Bayesian inference, maximum likelihood, and maximum parsimony analyses. Our molecular phylogenetic analysis using five molecular markers (nad5, rbcL, rps4, trnL-F, and 26S) from mitochondrial, chloroplast, and nuclear genomes revealed the paraphyly of the Pylaisiadelphaceae and the monophyly of Sematophyllaceae s.l. Based on the molecular and morphological evidence, the Sematophyllaceae s.l. were further divided into six subfamilies, Taxithelioideae, Isopterygoideae, Pylaisiadelphoideae, Aptychelloideae, Platygyrioideae, and Sematophylloideae. The Taxithelioideae is established to accommodate Taxithelium, Taxitheliella, and Vernieri, the Isopterygoideae is established to accommodate Isopterygium and Yakushimabryum, the Pylaisiadelphoideae is newly circumscribed to accommodate Brotherella, Pylaisiadelpha, and Orientobryum, the Aptychelloideae is established to accommodate Aptychella, the Platygyrioideae is temporarily established to accommodate Clastobryella, Clastobryum, Gammiella, Platygyrium, and Trachyphyllum, the Sematophylloideae is resurrected to accommodate the Sematophyllaceae s.str., and Isocladiella, Isocladiellopsis, Mastopoma, Heterophyllium, Pseudotrismegistia, Trismegistia, and Wijkia are transferred to the subfamily. A new classification for the Sematophyllaceae s.l. is then proposed.     

广义飞蛾藤属(旋花科)花粉形态

对广义飞蛾藤属Porana s.l.18个分类群的花粉进行了光学显微镜和扫描电镜观察。除前人报道过的7种1变种外,其余均为首次报道。根据花粉粒的大小、形状、外壁纹饰、沟膜特征,该属花粉可细分为4个类型。研究结果不支持Staples(1993)把该属分为4个独立属的观点,而认为在属内划分为4个亚属较为合理。除毛果飞蛾藤外,花粉形态支持Staples对其它种、变种的归并。从花粉萌发孔类型上看,广义飞蛾藤属在旋花科内应处于较为原始的位置。     

Cytotaxonomy of species of Vernonia, section Lepidaploa, group Axilliflorae (Asteraceae, Vernonieae)

Mitotic chromosomes of eight populations of six species of Vernonia sensu Baker (Asteraceae, Vernonieae, section Lepidaploa , group Axilliflorae ) were studied to assess the validity of maintaining the genus as proposed currently ( sensu Baker) or of splitting it into several smaller genera ( sensu Robinson). The species were collected in areas of 'cerrado' and 'campo rupestre' in southern and central-western Brazil. The chromosome numbers were 2 n  = 20–40 and karyotypic analysis showed a predominance of metacentric chromosomes, with some submetacentrics. B chromosomes were seen in one population of V. geminata . The chromosomes varied in length from 0.9 to 4.6 µm, with a total chromatin length of 29.7–45.0 µm and a symmetry index of 41.2–46.9%. The intrachromosomal asymmetry index varied from 0.13 to 0.29, and the interchromosomal asymmetry index varied from 0.15 to 0.21. The dispersion diagram showed that population 1 of V. geminata had the most asymmetrical karyotype. These results do not provide sufficient evidence for a conclusive cytotaxonomic discussion of Vernonia , mainly because of the impossibility of associating any infrageneric group with specific karyotypic characters, and also because of the small number of species analysed so far.  © 2007 The Linnean Society of London. Botanical Journal of the Linnean Society , 2007, 154 , 99–108.     

Vernoguinosterol and vernoguinoside, trypanocidal stigmastane derivatives from Vernonia guineensis (Asteraceae)

Two bitter stigmastane derivatives, vernoguinosterol (1) and vernoguinoside (2), have been isolated from the stem bark of Vernonia guineensis and their structures eludicated using spectroscopic methods. The new compounds exhibit trypanocidal activity.     

Stigmastane derivatives and isovaleryl sucrose esters from Vernonia guineensis (Asteraceae)

Vernoguinoside, 16beta,22R;21,23S-diepoxy-3beta-O-beta-D-glucopyranosyloxy-21S,24-dihydroxy-5alpha-stigmasta-8,14-dien-28-one (1), a new stigmastane derivative, 16beta,22R;21,23S-diepoxy-21S,24-dihydroxy-5alpha-stigmasta-8,14-diene-3,28-dione (2) and two new sucrose esters, 1',3,3',4',6'-pentakis-O-(3-methylbutanoyl)-beta-D-fructofuranosyl alpha-D-glucopyranoside (3) and 1',2,3',6,6'-pentakis-O-(3-methylbutanoyl)-beta-D-fructofuranosyl alpha-D-glucopyranoside (4), have been isolated from the stem bark of Vernonia guineensis. The structures of the new compounds were determined on the basis of spectroscopic evidence.     

Antibacterial Flavonoids and Other Compounds from the Aerial Parts of Vernonia guineensis Benth. (Asteraceae)

An extensive phytochemical study of the aerial parts of Vernonia guineensis Benth. (Asteraceae) led to the isolation of a new flavone, vernoguinoflavone and a naturally isolated glycerol ester, eicosanoic acid 2‐hydroxy‐1,3‐propanediyl ester, together with eighteen known secondary metabolites including quercetin, luteolin, vernopicrin, vernomelitensin, β‐amyrin, oleanolic acid, ursolic acid, lupeol, betulinic acid, β‐carotene, a mixture of stigmasterol and β‐sitosterol, β‐sitosterol‐3‐O‐β‐D‐glucoside, 2,3‐dihydroxypropyl heptacosanoate, pentacosanoic acid, docosan‐1‐ol, tritriacontan‐1‐ol, and heptatriacontan‐1‐ol. Eleven compounds are reported herein for the first time from this species. The structures of these compounds were elucidated on the basis of extensive spectroscopic analyses, particularly 1D and 2D NMR, and HR‐ESI‐MS and by comparison of their data with those reported in the literature. The crude extract, fractions and some isolated compounds were evaluated for their antibacterial activity against Gram‐negative bacteria: Escherichia coli (ATCC 25922), Shigella flexineri (NR 518), Salmonella muenchen, Salmonella typhimurium and Salmonella typhi (ATCC 19430). All the tested compounds demonstrated inhibitory activities against the tested enteric bacteria with MIC values ranging from 3.12 to 100 μg/ml. Three flavonoids isolated from the most active fraction demonstrated the best bioactivities against Escherichia coli, Salmonella muenchen and Salmonella typhimurium with MIC values ranging from 3.12 to 25 μg/mL.     

土圞儿属和旋花豆属(豆科)的孢粉学研究

在扫描电子显微镜下,对豆科土儿属(Ap ios)和旋花豆属(Coch lianthus)7个种植物的花粉进行了观察.结果表明,2个属的花粉均为三孔沟,形状为三角球形或球形.土儿属的花粉可划分为2种类型:肉色土儿(A.carnea)的花粉外壁为典型的网状纹饰,其它种的花粉外壁较光滑,具颗粒状或短条纹状纹饰,研究结果不支持土儿属下亚属的划分;肉色土儿花粉外壁的网状纹饰式样可能反映了其在土儿属中处在较进化的位置.土儿属东亚分布种的花粉类型较为多样,原始和进化2种类型并存,表明东亚可能是土儿属的起源地和演化中心.旋花豆属的花粉特征和肉色土儿相似,说明两者之间的亲缘关系可能较近.     

Pollen morphology of Zehneria s.l. (Cucurbitaceae)

A growing body of experimental data obtained from sporoderm ontogenetic studies led to the appearance of the ‘micellar’ hypothesis. The hypothesis is that the sequence of sporoderm developmental events represents the sequence of self-assembling micellar mesophases, initiated by genomically given physico-chemical parameters, which are then picked up by physico-chemical self-assembly. However, besides morphological evidence, the best proof of this hypothesis would be an experimental modelling of sporoderm-like patterns. The main idea of this study is to remove the influence of the genome, selecting substances and their concentrations for simulations to replace it, and then to trace what ‘pure’ self-assembly is capable of constructing. Our aim in this study was to simulate mainly young structures in sporoderm development, i.e. the glycocalyx and the primexine. Several polysaccharide gels (as a callose substitute) and surfactants (as glycocalyx and sporopollenin monomer substitutes) were mixed at different concentrations and combinations, thermally set and left to condense. A number of patterns were obtained in colloidal solutions in the course of condensation, simulating structures at different stages of exine development. Their structures were observed and analysed with transmission electron microscopy (TEM). Our first experiments on the modelling of biological patterns in vitro have shown encouraging results.     

广义飞蛾藤属(旋花科)的分支系统学分析

基于33个广义的形态学性状,对广义飞蛾藤属Porana s．l．进行了分支系统学分析。经过简约性分析,得到了10个同等简约的分支树。10个同等简约树的严格一致化树表明,广义飞蛾藤属是一较为自然的分类群。与广义飞蛾藤属的孢粉学、种皮微形态学研究结果一致,分支分析的结果不支持将广义飞蛾藤属拆分为4个或5个独立的属,应在属内划分分类等级。在整个形态分支树中广义飞蛾藤属4个亚属呈并列2个分支,其中飞蛾藤亚属(subg．Porana)和白花叶亚属(subg．Poranopsis)形成姐妹群构成一分支,三翅藤亚属(subg．Tridynamia)和棒状亚属(subg．Dinetus)以姐妹群的关系构成另一支。鉴于分支分析的Bootstrap支持率不高,广义飞蛾藤属范畴的最后界定和属内等级的划分仍有待于进一步研究。     

Cytotaxonomy of some species of the South American genus Lessingianthus (Asteraceae, Vernonieae)

Mitotic chromosome numbers of 32 populations belonging to 23 species of the genus Lessingianthus H.Rob. (Vernonieae, Asteraceae) were determined. The chromosome number of all examined plants was found to be based on x = 16. The numbers observed varied from 2n = 32 to 2n = 176. The results include the first report of the chromosome number for 11 species: L. lanatus (2n = 32), L. varroniifolius (2n = 32), L. cataractarum (2n = 64), L. intermedius (2n = 64), L. argenteus (2n = 96), L. centauropsideus (2n = 96), L. profusus (2n = 96), Lessingianthus sp. nov. 1 (2n = 96), Lessingianthus sp. nov. 2 (2n = 128), L. robustus (2n = 160), and L. macrocephalus (2n = 176). New chromosome numbers were found in the four other species: L. rubricaulis, L. laniferus, and L. sellowii were tetraploid with 2n = 64, while L. oxyodontus was hexaploid with 2n = 96. B chromosomes were observed in L. coriaceus and L. varroniifolius. Lessingianthus macrocephalus (2n = 11x = 176) is reported as the first case of an odd polyploid and the higher chromosome number of Lessingianthus. The significance of the results is discussed in relation to chromosomal data available for the genus.