ROLE OF THE NITROGEN-FIXING BACTERIAL MICROFLORA IN THE EPIPHYTISM OF TILLANDSIA (BROMELIACEAE)

Nitrogen-fixing activity in the phyllosphere of 12 species of Tillandsia from different Mexican habitats was evaluated by the acetylene reduction assay, and nitrogen-fixing microorganisms were isolated and characterized. The leaves from eight of the 12 Tillandsia species examined exhibited nitrogenase activity in enrichment cultures. Among the microorganisms implicated—Agrobacterium, Bacillus, Erwinia, Pseudomonas, Rahnella, Vibrio, and Xanthomonas—only Bacillus megatherium reduced acetylene in pure culture. Our findings suggest that nitrogen fixation in the phyllosphere of the sampled epiphytes occurs under suitable conditions and that most of the bacteria involved are primarily soil and water inhabitants. The results also suggest a relationship between the composition of the nitrogen-fixing microbial communities grown on the leaf and the different development of the leaf area in Tillandsia due to the aerial components (wings) of the trichomes.     

Morphoanatomy and stigma receptivity in Tillandsia L. (Bromeliaceae) occurring in Bahia,Brazil

Species of Tillandsia L. are widely distributed in Brazilian ecosystems, and in the state of Bahia they can be found in the Atlantic Forest, Caatinga and Cerrado biomes. Studying the reproductive aspects of these species can support their management and conservation. In particular, stigma morphology is a conserved trait of Bromeliaceae and stigma receptivity can influence the success of pollination. The objective of this study was to characterize the morphoanatomy and classify the stigma types of Tillandsia species by means of light and scanning electron microscopy, as well as to evaluate the stigma receptivity by different methods and at three floral development stages. A total of 21 Tillandsia species found in Bahia were evaluated. The stigma receptivity was assessed with hydrogen peroxide (3%) and a solution of α-naphthyl acetate. Four stigma types were observed: conduplicate-spiral for the species of the Tillandsia subgen. Tillandsia, simple-erect for species of T. subgen. Diaphoranthema, and simple-truncate for the species of T. subgen. Phytarrhiza. The species of the T. subgen. Anoplophytum had three morphological types, conduplicate-spiral, conduplicate-patent and simple-erect. All the species had trifid stigmas, monostratified epidermis, numerous idioblasts containing raphides in the fundamental parenchyma and an individual vascular bundle for each carpel. In all the species studied by the two methods of stigma receptivity the highest enzyme activity was observed during anthesis. The morphoanatomy of the stigma and style provides important information for the taxonomy of Tillandsia and the data on stigma receptivity can support studies of the reproduction and conservation of these species.     

Ecological patterns in theBromeliaceae of the lomas formations of Coastal Chile and Peru

Studies of geographic distribution and physiological adaptations in theBromeliaceae of coastal Chile and Peru provide insights into the ecological patterns of habit selection and speciation. The hyperarid coastal Atacama and Peruvian Deserts along the Pacific coast of South America contain a surprisingly rich flora of bromeliad species. These include representatives of all threeBromeliaceae subfamilies: two terrestrialBromelioideae and two terrestialPitcairnioideae, all with rooted growth morphologies, and 14 species ofTillandsioideae (allTillandsia) with epiphytic and unrooted, terrestraial representatives. TheBromelioideae are represented by two species ofPuya Molina, one each in Peru and Chile. ThePitcairnioideae are represented by two genera,Deuterocohnia andPitcairnia, with one species each. The 14Tillandsia species are distributed in five subgenera which have successfully invaded the coastal deserts, and include both widespread and local endemics with xeromorphic adaptations. All theTillandsia species are epiphytic in the broad sense, but in addition to growing on plants, they are found growing on rocks (i.e. saxicolous or epilithic). Six species (T. purpurea, T. latifolia, T. capillaris, T. marconae, T. werdermanii, andT. landbeckii) have evolved a highly specialized substrate ecology where they grow essentially unrooted on sand (i.e. epiarenic). Nowhere in the world are bromeliads more dominant or have more biomass than in these coastal species growing on sand. Many of these species grow at the absolute limits of vascular plant tolerance, with the entire community consisting of a singleTillandsia species. Rooted, terrestrial bromeliads in the coastal lomas formations (allPitcairnioideae) include CAM, C₃, and C₃-CAM flexible taxa in their metabolic systems, the CAM species growing in the most arid sites along the coast and C₃ species growing in the most mesic habitats within the center of the coastal fog belt where fog moisture input is highest. All of the epiphyticTillandsia species of the coastal desert region utilize CAM metabolism entirely or in part. At least two species,T. latifolia andT. tragophoba, utilize a flexible C₃-CAM mode of carbon fixation. Whereas most of the desert-inhabitingTillandsia species have relatively narrow leaves covered by water absorbing trichomes on their surface,T. multiflora in northern Peru andT. tragophoba in northern Chile are tank-forming species where the bases of the leaves form a water-containing reservoir. The occurrence of the latter as a local endemic in hyperarid northern Chile is remarkable since it occurs thousands of kilometers south of its closest potential relatives in the central Andes.     

ULTRASTRUCTURAL INVESTIGATIONS ON THE TWO-NUCLEATE POLLEN GRAIN OF TILLANDSIA CAPUT-MEDUSAE MORR. (BROMELIACEAE)

The fine structure of the pollen grain of Tillandsia caput-medusae Morr. (Bromeliaceae) prior to germination has been studied. The development, after the first mitosis, is here schematized in three stages which are in accordance with the main steps described in angiosperms. The ultrastructural modifications occurring in the generative and vegetative cells are discussed in view of their different destiny. The results obtained are compared with the data known about tropical orchids and epiphyteic plants like Tillandsia. The following differences have been observed: a large vacuole in the vegetative cell; rapid thinning of the wall between the generative and vegetative cells; great quantity of ribosomes and rough endoplasmic reticulum surrounding the vacuoles in the generative cell. The above-listed ultrastructural features may have a meaning, considering the peculiar environmental conditions in which the epiphytism of Tillandsia is achieved.     

The relationship between bark peeling rate and the distribution and mortality of two epiphyte species

Tree bark characteristics influence epiphyte establishment and survival and consequently the way in which epiphytes are distributed on trees. Tree species with peeling bark have been reported as poor epiphyte hosts. We analyzed the distribution and seedling mortality of two Tillandsia species (Bromeliaceae) in relation to rate of bark peeling of Bursera fagaroides (Burseraceae). The highest peeling rate (0.12% per day) took place on the trunk and the lowest rate on twigs (0.04% per day; branches ≤2 cm in diameter). The highest proportion of Tillandsia plants appeared on twigs. The distributions of juvenile and adult plants on twigs were higher than those expected based on the distribution of first-year seedlings, suggesting that on twigs, survival could be greater than on trunks and branches, canopy areas where peeling is faster. On the trunk and branches, in contrast, the proportion of juveniles and adults were similar to or less than that expected for first-year seedlings. The main cause of mortality was peeling and the area of minor overall mortality was the trunk, suggesting that this area should be favored as the main distribution area for the Tillandsia species but is not. Our results show that the peeling rate of B. fagaroides depends on branch size and suggest that the Tillandsia distribution depends not only on peeling rate but also on seed dispersion. We suggest that to colonize B. fagaroides epiphytes would either have adaptations to counteract the peeling rate or should occur in the areas of lowest peeling rate located in the exterior crown of trees.     

MORPHOGENESIS AND DEVELOPMENT OF MICROBODIES OF HEPATOCYTES OF RATS DURING PRE- AND POSTNATAL GROWTH

In hepatocytes of fetal rats, cytoplasmic organelles identifiable as microbodies appeared, although only a few of them showed nucleoids and most of them generally had an electronlucent appearance due to the low density of their matrices. Some of these microbodies, especially those lacking the nucleoid, showed a substantial connection with granular endoplasmic reticulum (ER), suggesting that microbodies might be formed from granular ER. Agranular tubular profiles projecting from the surface of microbodies were found with a high frequency in fetal and neonatal rats; however, this phenomenon may not provide crucial evidence suggestive of the derivation of microbodies from agranular ER. Growth and maturation of microbodies are considered to be brought about by an enlargement of these organelles, an increase in their matrices, an appearance and enlargement of the nucleoids, and an increase in the enzyme involved. The specific activity of urate oxidase in the isolated nucleoid fraction was significantly lower in the earlier stages of postnatal growth than later. Increases in the enzyme activity per nucleoid (maturation of the nucleoid), in the number of microbodies containing nucleoids (formation of the nucleoid), and in the size of nucleoids (growth of the nucleoid), may contribute to increases in the enzyme activity of the tissues.     

The narrow-leaf syndrome: a functional and evolutionary approach to the form of fog-harvesting rosette plants

Plants that use fog as an important water-source frequently have a rosette growth habit. The performance of this morphology in relation to fog interception has not been studied. Some first-principles from physics predict that narrow leaves, together with other ancillary traits (large number and high flexibility of leaves, caudices, and/or epiphytism) which constitute the “narrow-leaf syndrome” should increase fog-interception efficiency. This was tested using aluminum models of rosettes that differed in leaf length, width and number and were exposed to artificial fog. The results were validated using seven species of Tillandsia and four species of xerophytic rosettes. The total amount of fog intercepted in rosette plants increased with total leaf area, while narrow leaves maximized interception efficiency (measured as interception per unit area). The number of leaves in the rosettes is physically constrained because wide-leafed plants can only have a few blades. At the limits of this constraint, net fog interception was independent of leaf form, but interception efficiency was maximized by large numbers of narrow leaves. Atmospheric Tillandsia species show the narrow-leaf syndrome. Their fog interception efficiencies were correlated to the ones predicted from aluminum-model data. In the larger xerophytic rosette species, the interception efficiency was greatest in plants showing the narrow-leaf syndrome. The adaptation to fog-harvesting in several narrow-leaved rosettes was tested for evolutionary convergence in 30 xerophytic rosette species using a comparative method. There was a significant evolutionary tendency towards the development of the narrow-leaf syndrome the closer the species grew to areas where fog is frequently available. This study establishes convergence in a very wide group of plants encompassing genera as contrasting as Tillandsia and Agave as a result of their dependence on fog. Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users.     

Contrasting breeding systems in six species of Tillandsia L. (Bromeliaceae) from woody areas of Santa Fe Province: Argentina

The reproductive biology of six native Tillandsia species that co-occurred in woody areas of Santa Fe Province (Argentina) was studied for floral biology, breeding systems and reproductive success. Flower longevity, floral phases, hand self- and cross-pollinations or natural pollinations and fluorescence microscopy observations of post-pollination events were analysed. Also pollen/ovule (P/O) ratio and pre-emergent reproductive success (PERS) were compared between species. In T. aëranthos, T. ixioides and T. meridionalis, self-pollinated flowers mostly failed to form fruits, and fluorescence microscopy studies showed that in selfed pistils pollen tube growth was arrested in the style. It is likely that these species have homomorphic, gametophytic self-incompatibility. In contrast, T. capillaris, T. tricholepis and T. recurvata regularly formed fruits following autonomous self-pollination. Floral traits, the P/O ratios and PERS indices correlate with the breeding systems found in these two groups of species: the three selfing species have inconspicuous closed flowers, and they have low P/O ratios and high PERS values. In contrast, the three self-incompatible (SI) species have conspicuous flowers with relatively high P/O and low PERS values. We described here three new cases of SI in Tillandsia species subgenera Anoplophytum and confirm the autogamous and cleistogamous status in three species of Tillandsia subgenera Diaphoranthema.     

Floral biology and potential hybridization of three sympatric epiphytic bromeliads in Veracruz,Mexico

In the Bromeliaceae, hybrids have been engineered for horticultural purposes; in addition, hybrids have been observed in natural habitats. We investigated the hybridization potential of three sympatric species of Tillandsia inhabiting secondary forests and shaded coffee plantations in the central mountains of Veracruz, Mexico. The studied species (T. juncea, T. polystachia and T. variabilis) show overlap in flowering phenology and are believed to share pollinators. We compared the floral morphology of the species, performed controlled intra- and interspecific pollinations, and recorded pollen tube growth, fruit and seed set, as well as seed germination. Flower size differed among the species, but stamen and stigma heights were similar between pairs of species, which would facilitate interspecific pollen exchange. Pollen tubes reached the ovary in interspecific crosses. The three species showed interspecific cross-compatibility, as all crosses resulted in development of mature fruit and viable seeds. Tillandsia juncea achieved the highest fruit set, whereas T. variabilis showed the highest seed set. Seed set as a result of agamospermy, autogamy, geitonogamy and interspecific cross-pollination did not differ among the species. The findings suggest that pre- and post-pollination barriers are weak among the three species of Tillandsia, which thus could potentially hybridize in natural sympatric populations.     

Eine neueTillandsia-Art aus Südmexico:T. kolbii (Bromeliaceae)

A new species ofTillandsia is described and discussed in regard to related species.

     

THE OCCURRENCE AND STRUCTURE OF MICROBODIES : A Comparative Study

Livers from chickens, rats, mongrel dogs, Dalmatian dogs, and man have been examined in the electron microscope in order to compare the microbodies with the known content of uricase. It is concluded that microbodies with inclusion are present in rats, mongrel dogs, and, although the inclusion generally is smaller, in Dalmatian dogs. The inclusion has a characteristic structural appearance. These species (rat, dog) have uricase. Chickens and man lack both the enzyme uricase and the microbody inclusion. This evidence and that from previously published electron micrographs in the literature on microbodies support the notion of a positive correlation between uricase and microbodies with an inclusion. It is recommended that the term "uricosome" be used for such microbodies that have an inclusion of the appearance here described.     

PLICATE STAMINAL FILAMENTS IN TILLANDSIA SUBGENUS ANOPLOPHYTUM (BROMELIACEAE)

Plication of staminal filaments is an important diagnostic character for Tillandsia subgenus Anoplophytum (ca. 45 species). The monophyletic integrity of subgenus Anoplophytum has recently been questioned, and we conducted an anatomical investigation of plicate staminal filaments to better characterize this putative synapomorphy. Developmental studies show that the filament plications, or folds, become visible during or soon after anthesis. Serial sections of preplication filaments and filaments in sequential stages of plication were prepared and observed with light microscopy. A uniform sequence of parenchyma cell collapse begins three to four cell layers out from the vascular bundle and proceeds centrifugally to the epidermis. Eventually the epidermal cells collapse, leaving only the vascular bundle and a few surrounding parenchyma cells intact. Above and below the zone of plication, all parenchyma and epidermal cells in the filament remain intact. Species traditionally placed in subgenera Tillandsia and Allardtia have been found with plicate staminal filaments that are anatomically and develop-mentally identical to those studied from subgenus Anoplophytum. Alone, staminal filament plication does not appear to be a good diagnostic character for subgenus Anoplophytum, and doubts concerning the monophylesis of this subgenus are reinforced. The functional significance of stamen filament plication remains unknown.     

Adattamenti fisiologici alla vita « aerea » nel genere Tillandsia

Abstract

Physiological adaptations to « aerial » life in the genus Tillandsia.—Ten « atmospheric » Tillandsia species, with different degree of adaptation to drought, were investigated to verify the occurrence of CAM and to determine their daily transpiration pattern.

Most of the species were collected during the Botanical Expeditions of the Accademia dei Lincei in Latin America in 1969 and 1971. All species had been maintained in the greenhouse of the Naples Botanical Garden during the winter months and in the open air during the warmer months, previous to experiments. The diurnal cycle of transpiration, the malic acid content and cell sap pH of the leaves were studied under outdoor conditions. Curves of malic acid and pH variations typical of CAM have been obtained for all the examined species. Moreover, the transpiration data indicate that stomata are open at night. The rates of transpiration appear to be extremely low. The highest transpiration rates refer to the species of the relatively moister habitats, the lowest to the more xeric species. Results indicate that CAM and low rates of transpiration are ecological adaptations to extremely dry habitats.     

Cylindrocladium angustatum sp. nov., a new leaf spot pathogen ofTillandsia capitata from Florida, U.S.A.

Cylindrocladium angustatum is described as a new species fromTillandsia introduced with plant material into the U.S.A. from Central America. Koch's postulates are established to prove its pathogenicity to this host. The species is compared with and distinguished fromC. heptaseptatum andC. rumohrae based on morphology, cultural characteristics and phylogenetic analysis of sequence data of the beta-tubulin gene.     

Soft scale insects (Homoptera: Coccidae) on Tillandsia in Central America*

A new genus of soft scale insect (Homoptera: Coccoidea: Coccidae), Tillancoccus, and two new species T. mexicanus and T. tillandsiae are described and illustrated from the adult females. The new species are recorded from Tillandsia plants in Guatemala, Honduras and Mexico.     

Systematics of Tillandsia subgenus Pseudalcantarea (Bromeliaceae)

Tillandsia subg.Pseudalcantarea (Bromeliaceae) includes four species as currently delimited. The phylogenetic relationships of the species in this group are investigated by a cladistic analysis using 16 morphological characters, withVriesea subg.Alcantarea employed as the outgroup.Tillandsia subg.Pseudalcantarea is found to be paraphyletic.Tillandsia grandis andT. paniculata are transferred toTillandsia subg.Tillandsia because they are hypothesized to share a more recent common ancestor withT. utriculata, the type of the genus, than they do with the other two species placed in subg.Pseudalcantarea, i.e.,T. baliophylla andT. viridiflora. These latter two species possibly constitute a basal clade withinTillandsia and are provisionally retained within subg.Pseudalcantarea.     

Survival and Growth of Juvenile Bromeliads in Coffee Plantations and Forests in Central Veracruz,Mexico

Shade coffee plantations can be important refuges for epiphytes, but are not suitable for all species. To test if the performance of early life stages, often the most sensitive phase, is responsible for the species’ ability to colonize coffee plantations, we compared growth and mortality rates of three epiphytic bromeliad species that differ in their ability to colonize secondary arboreal vegetation by transplanting juveniles to trees in forests, and shade trees in old and young coffee plantations in Central Veracruz, Mexico. Growth rates of Tillandsia viridiflora, generally restricted to forests, and Tillandsia juncea, an early colonizer, were related to the pattern of the species occurrence among habitats with growth rates of T. viridiflora being generally higher in forests and growth of T. juncea higher in coffee plantations. Performance of the third species, Tillandsia heterophylla, which is intermediate in habitat preference, was not clearly related to habitat. No difference in growth rates was found between plants transplanted in wet or dry season. In general, mortality in transplanted bromeliads was relatively low (mostly < 5% per month). In coffee plantations herbivory had a severe effect during part of the wet season, when mortality in young coffee plantations reached between 15 and 24 percent per month. Given the substantial contribution of herbivory to the mortality of juvenile plants and the significant differences between habitats, herbivory may be co‐limiting the colonization of young coffee plantations by some epiphytic bromeliads.     

CYANOPHYTE AND CYANELLE DNA: A SEARCH FOR THE ORIGINS OF PLASTIDS1

Cyanophyte-like prokaryotes are widely presumed to be the progenitors of eukaryote plastids. A few rare protistan species bearing cyanophyte-like cyanelles may represent intermediate stages in the evolution of true organelles. Cyanophyte DNA disposition in the cell, so far as is known from electron microscopy, seems uniform within the group and distinctly different from the several known arrangements of DNA in plastids. Therefore a survey of representative cyanophytes and protistan cyanelles was undertaken to determine whether forms reminiscent of plastids could be found. DNA-specific fluorochromes were utilized, along with epifluorescent microscopy, to study the DNA arrangement in situ in whole cells. Only the endospore (baeocyte)-forming Cyanophyta contained more than one, centrally located DNA skein per cell, and then only for the period just preceding visible baeocyte formation. Such forms might, with modification, presage the “scattered nucleoid” DNA disposition found in plastids of several groups, including Rhodophytes, Cryptophytes, Chlorophytes and higher plants. The DNA arrangement in cyanelles of two protists, Cyanophora and Glaucocystis, appear different from each other and possibly related to, respectively, the cyanophytes Gloeobacter and Synechococcus. Cyanelles of the third protist, Glaucosphaera, like the cells of the unique prokaryote Prochloron, appear to have multiple sites of DNA, somewhat similar to those of the “scattered nucleoid” line of plastid evolution. No obvious precursor of the “ring nucleoid” or other types of plastid DNA conformation was found.     

Charakterisierung der Microbodies aus Spadix-Appendices von Arum maculatum L. und Sauromatum guttatum Schott

Summary When the sections of the spadix appendix of Arum are incubated in a medium containing diaminobenzidine and H₂O₂, only the membrane of microbodies is stained. On the other hand, microbodies of Sauromatum show a stained matrix as usual. Catalase-containing cell organelles isolated from spadix appendices of Arum show the same typical membrane staining as the microbodies in situ do. Thus the identity of these organelles with microbodies seems to be proved. After anthesis the microbodies in situ usually do not give a positive reaction for catalase with diaminobenzidine and H₂O₂. However, cytochemical and biochemical tests for catalase on microbodies isolated during this stage of development clearly demonstrate the presence of this enzyme. Uricase is localized in the microbodies of Arum as well as catalase. No malate dehydrogenase, peroxidase, and allantoinase could be found in the microbodies. Before anthesis the microbodies of spadix appendices of Arum have an equilibrium density in aqueous sucrose of 1.22 gcm^-3. After anthesis the density changes into 1.23 to 1.24 gcm^-3.     

MORPHOLOGY OF DNA CONTAINING STRUCTURES (NUCLEOIDS) AS A PROSPECTIVE CHARACTER IN CYANOPHYTE TAXONOMY1

DNA containing structures (nucleoids) were visualized by 4′, 6-diamidino-2-phenylindole (DAPI) fluorescent staining in two groups of cyanophytes (59 filamentous oscillatorialean species and 12 coccal Synechococcus-like organisms) to test the possibility of using nucleoid morphology in cyanophyte taxonomy. The morphology of nucleoids (size, shape, and structure) in oscillatorialean species is specific for individual families. The morphology of the nucleoid in Synechococcus-like species agrees from the proposed separation of the genus Cyanothece from Synechococcus. A much different nucleoid morphology in three species of Cyanothece suggests that these species should be separated into a new genus. On the basis of other characters, the species could be returned to the genus Cyanobacterium. My results indicate that the morphology of nucleoids is a valuable character in the classification of the cyanophytes examined; thus, it is a prospective feature that could be used in the taxonomy of other groups of cyanophytes. Additionally, DAPI staining is not a complicated procedure. The new character is easy to see in samples taken from nature, both living and preserved.