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A phylogenetic assessment of Lycaste and Anguloa (Orchidaceae)
Abstract
Parsimony analysis has been used to examine the phylogenetic relationships of two genera of Neotropical orchids, Lycaste and Anguloa. Within these genera, difficulties occur when assigning names to plants using traditional morphological techniques. Many herbarium specimens are in bad condition and some descriptions are incomplete. To date, infrageneric classifications have been based on very few diagnostic characters. Here, three approaches have been evaluated: A systematic analysis of the morphology, an examination of two regions of DNA sequence and an analysis of the chemical composition of the floral fragrances. Morphological analysis showed that Lycaste is not monophyletic. There was a clear division between species currently ascribed to sect. Fimbriatae and the other species of the genus. Selection of characters introduced an element of subjectivity into the analysis and it was shown that exclusion of a single character could significantly affect the topology of relationships. Parsimony analysis of the sequences of both ITS and matK placed Lycaste sect. Fimbriatae closer to Anguloa than to the other species of Lycaste. Neomoorea was identified as nearest neighbour to Lycaste and Anguloa. A combined analysis of ITS and morphological data gave congruent results. Morphological and sequence analyses also indicated that the single pendent species, L. dyeriana, should remain within sect. Fimbriatae and that the taxonomic status of the subspecies of L. macrophylla should be revised. None of the analyses provided sufficient resolution to address the sectional treatment of the remaining Lycaste species. To answer this question, comparison of sequence data from a faster evolving region of DNA will be required. The floral fragrance composition of 28 species and subspecies of Lycaste and Anguloa was determined. In its current form, the data was found to be unsuitable for addressing phylogenetic relationships at species level and above but may prove useful for population studies.
... The plant is not difficult to grow indoors, so it can be used in phytodesign, and their wonderful inflorescences are added to bouquet compositions. It is also used for the production of perfumes (Ryan, 2001;Everett, 1980). The flowers are often fragrant, with a variety of colors, their morphology is generally similar to that of Cattleya (Morales, 2002). ...
Trichopilia suavis is one of the important representatives of the genus Trichopilia, which can be used as a potted plant for the
interior design. also, its beautiful inflorescences are added unusual element to bouquet compositions and actively used in the production of perfumes. This study was carried out in order to develop and improve micropropagation method for mass clonal production of T. suavis through protocorm culture. Half-strength Murashige and Skoog culture medium (½) has been modified by adding different organic components and growth regulators. The protocorms obtained from seeds germinated by asymbiotic method were used as explants. The results showed that the optimal treatment for formation of new protocorms (7.50 ± 0.7 units per protocorm) was obtained by culture on ½ MS medium with 0.5 mg L-1 of 6-Benzylaminopurine (6-BAP) and 100 mL L-1 of coconut water. At the stage of rooting, the highest number and length of roots (7.0 ± 0.45 units per plantlet, 2.64 ± 0.18 cm) were obtained through subsequent cultivation of plantlets on ½ MS medium with 0.5 mg L-1 indolyl-3-butyric acid (IBA), 1.0 g L-1 charcoal with the addition of 50 g L-1 of banana puree. The obtained seedlings were successfully adapted in a substrate consisting of bark, perlite and peat in a ratio of 1:1:1.
ABSTRACT: Sequences of the nrDNA ITS region have been obtained from 88 named taxa of family Orchidaceae to investigate the phylogenetics of subtribe Orchidinae. The first paper in this sequence (Pridgeon et al., 1997) emphasized intergeneric relationships, but the focus here is within genera. Overall, the monophyly of most genera is well supported, whereas support within genera is more variable. Beginning with the derived, globose-tubered genera, Ophrys, Serapias, and Himantoglossum–Barlia are well supported as genera but have short internal branches, reflecting their controversial morphologically based classifications. Orchis as currently widely delimited is triphyletic, prompting extensive taxonomic revisions below. A heterogeneous group characterized by 2n = (32–)36 is placed in an expanded Anacamptis; it contains four monophyletic groups based on “Orchis” laxiflora, “O.” coriophora, “O.” papilionacea–A. pyramidalis, and “O.” morio. Species of 2n = 42 form two clades. The smaller and more derived clade, based on “O.” ustulata and “O.” tridentata, is placed in an expanded Neotinea. The larger clade contains Orchis s.s. (including the now synonymized, molecularly and morphologically similar Aceras) and, more tentatively, Traunsteinera. Orchis s.s. can be divided into an anthropomorphic grade (e.g. “Aceras”, O. militaris) and two monophyletic groups based respectively on O. mascula and O. anatolica (perhaps including the O. patens aggregate). Passing down into the digitate-tubered grade, the Platanthera s.l. clade also encompasses Galearis and, more tentatively, Pseudorchis. Platanthera s.s. is well supported, and species relationships suggest specific migration patterns. Dactylorhiza is also well supported, but surprisingly also encompasses the now synonymized Coeloglossum viride. Interspecific branches are fairly short, and internal conflicts understandably characterize data from the reticulate allotetraploid complex. The supposedly primitive diploid D. iberica is shown to be a derived member of the spotted-orchid group. “Nigritella” is nested within (and thus synonymized into) Gymnadenia, revealing far more morphological than molecular divergence between the two previously recognized genera; their relationship to Dactylorhiza remains ambiguous.
Overall, relationships among species within the revised genera show ITS disparities of 0–95 steps, and those among genera 36–165 steps. In most cases there appears to be a strong positive correlation between molecular and morphological disparities, though this has yet to be quantified. Relationships within species cannot be assessed using ITS, requiring instead a combination of morphometric and population genetic techniques plus range-wide pollinator surveys. Historical review reveals that the pre-Victorian concept of Orchis was gradually dismantled into a series of monophyletic genera delimited by morphological synapomorphies, leaving Orchis as a plesiomorphic (and thus phenotypically cryptic), triphyletic residuum. It is not surprising that past attempts at hierarchical classifications within this still species-rich genus show little congruence with the ITS phylogeny, especially as they were highly typological. Their relative accuracy depended on levels of homoplasy in the chosen morphological character suite (low homoplasy for tubers, moderate for gynostemium, high for spur dimensions and perianth hooding). Attempts to study the taxonomy and biology of the artificial construct Orchis s.l. have been further hampered by misinformation (e.g. erroneous reports of hybrids and chromosome counts) and misconceptions (e.g. that contrasts among species in the relative amounts of floral pigments could be arranged in a primitive > derived polarity). Patterns shown by these character sets are far more explicit and informative in the phylogenetic context provided by the ITS data, as are several notable morphological parallelisms and convergences.
The floral fragrance glands (osmophores) of 18 species of Stanhopea and Sievekingia were examined through a series of developmental studies at light and electron microscope levels including late bud stages through postanthesis. Various characters were identified to be of potential systematic value and were recorded for each species. These characters included: texture of the osmophore surface, number of distinct cell layers comprising the osmophore, nature of lipid inclusions in osmophore cells, and presence or absence of plastoglobuli in osmophore amyloplasts. These characters were combined with traditional features of floral lip morphology for cladistic analysis. Sievekingia was the postulated outgroup. Stanhopea ecornuta showed the largest number of plesiomorphic characters. Stanhopea pulla, S. annulata, and S. Candida were only slightly more derived. Stanhopea anfracta, S. gibbosa, S. martiana, S. oculata, S. radiosa, S. ruckeri, S. saccata, S. shuttleworthii, S. tigrina, S. vasquezii, and S. wardii form a monophyletic group that can be recognized by a labellum with an articulated epichile and a bicornuate mesochile (or hypochile). Stanhopea tricornis may be a hybrid between a species of Sievekingia and Stanhopea.
Roots of Sobralia macrantha, a largely terrestrial orchid, bear a typical multilayered velamen underlaid by a cortical exodermis. The latter consists of densely cytoplasmic passage cells regularly interspersed among much larger, elongate, vacuolate cells. A structure which may be peculiar to Sobralia, or at least unusually well developed there—the fibrous body—consists of numerous intermeshed and divided wall outgrowths arising from two or three velamen cells positioned directly over the passage cell. This body is well designed to retard root transpiration. Should the fibrillar components be appropriately hygroscopic, it may act as a valve, promoting movements of water into the cortex while the velamen is engorged. The general mode of moisture and mineral procurement proposed for the Sobralia macrantha root probably applies to many other soil- and canopy-dwelling orchids with a velamen-exodermis complex.
The floral scent glands (osmophores) of Stanhopea produce a fragrance composed of terpenoids and aromatics which attract pollinators. The terpenoid component is composed of isoprene units synthesized via the mevalonic acid pathway. Localization of hydroxymethylglutaryl CoA synthase in the mevalonic acid pathway was achieved using a technique which elicits the formation of an electron-dense precipitate of uranyl ferrocyanide at the point in the mevalonic acid pathway where an acetyl group from acetyl CoA is transferred to acetoacetyl CoA, releasing free CoA-SH. Applying this technique to cells of the osmophore of 5. anfracta resulted in a precipitate between the inner and outer mitochondrial membranes, in the smooth endoplasmic reticulum, and, to a lesser extent, on the outer surface of the tonoplast membranes and between the inner and outer membranes and granal membranes of amyloplasts indicating multiple, subcellular locations for at least some enzymes in the mevalonic acid pathway. Localization of carnitine acetyltransferase by a similar technique resulted in a precipitate between the inner and outer mitochondrial membranes and in the smooth endoplasmic reticulum indicating multiple, subcellular locations for this enzyme also.
Tilosomes, also called “fibrous bodies” or “rod bodies” in older literature, are lignified excrescences from the walls of cells of the innermost velamen cell layer adjacent to thin-walled passage cells of the exodermis in roots of many epiphytic orchids. Seven broad morphological types are recognized: spongy, lamellate, discoid, webbed, meshed, baculate, and plaited. Some types characterize specific genera or subtribes of Orchidaceae. Of the 350 species in 175 genera included in a survey of the family, tilosomes occur in 95 species and 39 genera and are concentrated in tribe Polystachyeae and subtribes Sobraliinae, Coelogyninae, Laeliinae, Pleurothallidinae, Bulbophyllinae, Lycastinae, and Maxillariinae. With the exception of the pantropical genera Bulbophyllum and Polystachya and the Paleotropical subtribe Coelogyninae, tilosomes are almost exclusively Neotropical phenomena.
The recently-developed statistical method known as the "bootstrap" can be used to place confidence intervals on phylogenies. It involves resampling points from one's own data, with replacement, to create a series of bootstrap samples of the same size as the original data. Each of these is analyzed, and the variation among the resulting estimates taken to indicate the size of the error involved in making estimates from the original data. In the case of phylogenies, it is argued that the proper method of resampling is to keep all of the original species while sampling characters with replacement, under the assumption that the characters have been independently drawn by the systematist and have evolved independently. Majority-rule consensus trees can be used to construct a phylogeny showing all of the inferred monophyletic groups that occurred in a majority of the bootstrap samples. If a group shows up 95% of the time or more, the evidence for it is taken to be statistically significant. Existing computer programs can be used to analyze different bootstrap samples by using weights on the characters, the weight of a character being how many times it was drawn in bootstrap sampling. When all characters are perfectly compatible, as envisioned by Hennig, bootstrap sampling becomes unnecessary; the bootstrap method would show significant evidence for a group if it is defined by three or more characters.
The traditional classification of plants into respective classes, orders, families, genera, and species has until recently been based on shared morphologic, cytologic, biochemical, and ecologic traits. The development of techniques in molecular biology including those for molecular hybridization, cloning, restriction endo-nuclease digestions, and protein and nucleic acid sequencing have provided many new tools for the investigation of phylogenetic relationships. At the molecular level, the most fundamental comparison possible is of the primary nucleotide sequences of homologous genes in different populations or species.
Examines the form and frequency of 3 types of change in mtDNA: base substitution, length variation and sequence rearrangement. Knowledge of molecular processes allows informed use of mtDNA variation in evolutionary studies.-P.J.Jarvis
Fragrances (volatiles) from whole flowers, petals, sepals plus gynoecium, anthers, and pollen were collected from Rosa rugosa Thunb. by headspace adsorption methods and analyzed by gas chromatography/mass spectrometry. Each flower part showed a distinctive volatile profile. Petal volatiles, dominated by terpenoid and benzenoid alcohols, contributed most to the whole-flower fragrance. Sepal odors contained mainly sesquiterpenes, together with several compounds found in the petals. The major volatiles in the androecium were more diverse and overall different from the perianth. Empty anthers shared a high proportion of their volatile profile with pollen. Pollen odor appeared to be self-contained, showing only minor adsorption of volatiles from sepals and petals. Compounds typical of the androecium were present as significant, albeit quantitatively small, components of the whole-flower fragrance, where they may well function as signals to pollen-seeking insects.
A water-jacketed syringe is described for use in studies of alfalfa (Medicago sativa L.) flower volatiles. A plexig’ass cylinder was constructed with rubber “0“ rings to fit around a 100 cc glass syringe in which freshly cut alfalfa flowers were equilibrated for 30 minutes. A 70 cc sample of the volatiles was injected into a GC equipped with a digital integrator. Reproducible results were obtained for both quantities of individual components and the percent composition due to various components.
In the last decade, mitochondrial DNA (mtDNA) analysis has had a major impact on the study of phylogeny and population genetics in animals (Avise et al., 1987; Moritz et al., 1987; Harrison, 1989). In plants, however, chloroplast DNA (cpDNA) has been the molecule of choice for molecular phylogenetic studies (Palmer et al., 1988; see also many other chapters in this volume). Studies of nuclear DNA, principally of the nuclear ribosomal RNA genes, have also been important in these efforts (Hamby and Zimmer, chapter 4, and Appels and Baum, Chapter 5, this volume). It is the purpose of this chapter to review the factors that have contributed to the relative neglect of mtDNA for phylogenetic reconstruction in plants and to assess the applications of mtDNA analysis for future systematic studies. I first review information on the structure and evolution of plant mtDNA, with emphasis on the genus Brassica, and then discuss the application of mtDNA data to phylogenetic studies.
This preliminary study is an attempt to bring together the knowledge of Taxonomy, Morphology, Phylogeny and Pollination of the species preparatory to a formal revision of the genus. New information, gathered by population study in the natural habitats, appears to be highly significant to the understanding of this complex group. The distribution of the species is mapped. The phylogenetic relationships of the genus are considered and it is believed that Stanhopea is derived from plants similar to members of the genus Sievekingia. The development of the advanced and complex species from the simpler species is discussed and the origin of certain unique species such as S. tricornis is considered. Observations of pollination of S. tricornis by Eulaema meriana and of S. bucephalus by Eulaema bomboides are discussed and pollination relationships are indicated as the major means of genetic isolation of the two species. Two highly variable populations were studied in Ecuador. The advanced and variable complexes in Stanhopea are very successful both in area of range and density of population. It is felt that this population structure suppresses speciation as a process, though variability is maintained. Various nomenclatural problems are mentioned and a key to the species is included. A list of the recognized species is given with their synonyms, and a list is appended of poorly known species which cannot as yet be properly placed.
Oaks exemplify problems with the reproductive species concept which motivate a reconsideration of the use and nature of species. Ecology is important in the reconsideration. The species level is usually overemphasized in evolutionary thought; selection acts on phenotypes and any mutualistic units. Standard definitions tend to inhibit free conceptual progress. Multispecies, sets of broadly sympatric species that exchange genes, may occur among animals as well as plants and may conceivably bridge kingdoms. This phenomenon can be adaptively important. There may be taxa without species. The degree of modality of adaptive zones can be investigated empirically.
In Turkey there are two species of Pelargonium belonging to section Jenkinsonia (Sweet) Harv., P. endlicherianum Fenzl and P. quercetorum Agnew. All other members of this section occur in South Africa along with most of the species in this genus. Both species were found to have the same chromosome number, 2n = 34, which is a new count for P. endlicherianum, (previous counts being 2n = 36) and the first record of a chromosome number for P. quercetorum. The distribution of these two Pelargonium species in Turkey is shown.
Orchid flowers representing a diversity of specieswithin that family were stained in vivo with neutral red for presumptive evidence of the presence of fragrance glands (osmophores). Additional floral material was embedded in epoxy resin, sectioned, and stained with sudan black B or methylene blue-azure II-basic fuchsin for microscopic examination of tissue with presumed involvement in fragrance production. Sudan black B stained the vacuoles in most of the presumptive osmophoric floral tissue. Neutral red was seen as a precipitate in the vacuoles of epoxy-embedded, sectioned tissue. Neutral red and sudan black B both may have an affinity for flavonoids and terpenoids present in the vacuoles of some orchid flowers. Neither staining reaction is considered an absolute indicator of osmophore tissue, but both stains are useful to establish presumptive evidence for the presence of orchid osmophores. Methylene blue-azure II-basic fuchsin is an effective general stain for this epoxy-embedded tissue, but it is not considered an indicator of orchid osmophores.
The eight species of Magnolia native to the United States are pollinated by a variety of beetles. Flower color as well as floral odors, produced primarily by the androphore, attract the insects. Analysis of the floral odors using gas chromatography and mass spectrometry, indicates that aliphatic hydrocarbons, methyl esters and terpenes comprise the fragrances. A quantitative correlation of the species of Magnolia was developed utilizing the composition of the floral odors.
Floral morphology has been the mainstay of orchid systematics, often to the exclusion of all other information. Vegetative features and chromosome number only rarely have been used in tribal, subtribal, and generic classification. Such has been the case in the oncidioid orchids, in which lip size, shape, and angle of attachment to the column often have been the sole determinants of generic affinities. A realignment of the oncidioid genera is presented and based on a series of previously under-utilized floral characteristics (e.g., the general form of lip calli, nectaries, and pollinaria), vegetative morphology, life history traits, and chromosome number. Two anomalous genera, Lockhartia Hook. and Trichocentrum Poeppig & Endl., are also discussed in relation to the two main lineages, as exemplified by Rodriguezia Ruiz Lopez & Pavon and the 56-chromosome species of Oncidium Sw.
Male euglossine bees may be attracted to pure chemicals which have been identified from orchid floral fragrances. The attraction of these bees may be reduced by the addition of other compounds which also have been identified from orchid floral fragrances. An additional compound may completely destroy the attraction of a species or group of species when present in a mixture with a potent attractant. Chemicals which are not known from orchid floral fragrances but which are structurally similar to orchid fragrance components attract a few bees, but these structurally similar compounds are not good attractants. Orchid floral fragrances may increase the area of recognition of flowers pollinated by male euglossine bees. It was suggested that male euglossine bees might be important agents for long-distance pollination of orchids and other plants which attract the bees to the floral odors, as well as plants which the male bees visit for food.
Chase, M. W. & Hills, H. H.: Silica gel: An ideal material for field preservation of leaf samples for DNA studies. ‐ Taxon 40: 215–220. 1991. ‐ ISSN 0040‐0262.
Silica gels an inexpensive and reliable substance to preserve field‐collected leaves for molecular studies of variation in DNA. A method for its utilization is explained, and results are presented, comparing total cellular DNA samples extracted from a set of fresh and silica‐gel dried samples of the same species, as well as examining the efficiency of endonuclease restriction and intactness of DNA from of a set of field‐collected leaves preserved with silica gel.
This monograph is an ecological study and complete revision of the genus Leochilus (Orchidaceae: Oncidiinae). Examination of living, liquid preserved, and pressed specimens was supplemented with fairly extensive study in the species' native habitats in Mexico, Central America, northern South America, and the Caribbean (more or less throughout the complete range of the genus). Various forms of laboratory investigations were conducted on many vegetative and floral features (most of which are illustrated). Chromosome counts are reported for L. carinatus (2n = 42), L. crocodiliceps (2n = 48), and L. oncidioides (n = 21). Twig epiphytism and the modifications of the Leochilus species for this habitat are discussed, including the psygmoid (fanshaped) juvenile habit, seed morphology, and epiphytic weediness. Pollination of Leochilus by lower hymenopteran vectors is described and discussed with special emphasis on one case of microsympatry. Five of the nine species in Leochilus are known to occur in mixed populations, yet no natural hybrids have been identified. Genetic identity appears to be maintained by adaptation for pollination by different sizes and types of insects. Contrary to historical placement, Leochilus is considered at most only a distant relative of Oncidium, with which it shares only the general vegetative, floral, and ecological features of the subtribe Oncidiinae. Leochilus is more closely related to a group of other twig epiphytes, including Capanemia, Comparettia, Ionopsis, Notylia, Papperitizia, and Rodriguezia, and is most closely related to Hybochilus leochilinus. A Groundplan-divergence Method cladogram is presented for Leochilus; four clades are identified, each with a number of parallel character states. The section on taxonomy includes a generic history and description as well as a key and descriptions, discussions, illustrations, and distribution maps for each species.