Scielo RSS <![CDATA[Acta Botanica Brasilica]]> vol. 33 num. 1 lang. en <![CDATA[SciELO Logo]]> <![CDATA[Reestablishment, new records, and a key for the species of <em>Aspidosperma</em> (Apocynaceae) from the Brazilian Amazon]]> ABSTRACT As a result of systematic study of the Neotropical genus Aspidosperma (Apocynaceae), we reestablish the species A. centrale and A. duckei, and report A. steinbachii and A. tambopatense as new records for Brazil. We provide taxonomic descriptions of these species along with plates, distribution maps, and information on their conservation status, habitat and phenology. We also provide an identification key for all the species of Aspidosperma from the Brazilian Amazon. <![CDATA[Abiotic effects on the cover and richness of corticolous lichens on <em>Araucaria angustifolia</em> trunks]]> ABSTRACT Lichens play a key role in natural ecosystems, as they can function as primary producers, recycle minerals and fix nitrogen. Despite their environmental importance, little is known about lichen ecology in Brazil, and especially about how abiotic factors may influence their spatial distribution. In this study, we aimed to verify how the cover and richness of corticolous lichens on Araucaria angustifolia trunks vary between two different habitats (Forest and Grassland). The photoquadrat sampling method was applied to A. angustifolia trunks. The Coral Point Count software with Excel extensions (CPCe) was used to analyze photographs for lichen cover and richness. Additionally, a redundancy analysis was conducted to estimate how five abiotic and two biotic variables affected the spatial distribution of lichens. Twenty-five morphospecies were identified, none of them occurring exclusively in the Grassland habitat. Canopy openness, air humidity and tree trunk rugosity were important parameters influencing lichen distribution; therefore, spatial segregation of growth forms can be explained by environmental selectivity. Foliose lichens require more air humidity, which explains their predominance in the Forest habitat. Canopy openness in Grassland habitat favors fruticose lichens, which depend on factors such as wind for reproduction. <![CDATA[Palynological evidence of vegetation change during the last 10,000 years in the mid-valley of the Rio Doce, Brazil]]> ABSTRACT In order to reconstruct the vegetation history of the last 10.000 years, palynological analyses were carried out using 17 sedimentary samples of a core drilled in Parque Estadual do Rio Doce (PERD-MG). Twenty-one species of fern spores, 52 species of pollen grains and six species of fungi were identified. Phase 1 (10.375 - 9.350 cal. years BP) is characterized by a low concentration and diversity of pollen grains and is thus interpreted as a fluvial system with the presence of coarse-grained sediments. Phase 2 (9.062 - 8.195 cal. Years BP) is interpreted as a transition from a fluvial to lacustrine environment. Phase 3 (7.905 - 4.785 cal years BP) is characterized by increased trend of palynomorph concentration, highlighted by a high abundance and diversity of fern spores, which are indicative of a more a humid condition. The uppermost phase, Phase 4 (4.785 - 50 cal. Years AP), possessed a lower abundance of herbaceous flora, which is replaced by other vegetation groups (e.g. marsh, cerrado, Atlantic Forest). The uppermost sample represents the contemporary environment (~50 years), which is characterized as seasonally-flooded. <![CDATA[Fungal endophyte diversity in the leaves of the medicinal plant <em>Myracrodruon urundeuva</em> in a Brazilian dry tropical forest and their capacity to produce L-asparaginase]]> ABSTRACT We studied the fungal endophyte community of the leaves of Myracrodruon urundeuva in Brazil along with their potential to produce L-asparaginase. In total, 187 endophytes were isolated. The colonization rate of leaf fragments from caatinga (10.41 %) was lower than those from brejo de altitude (39.58 %). Sequences of ITS rDNA from all endophytes revealed relationships with Ascomycota (Botryosphaeriales, Chaetothyriales, Diaporthales, Eurotiales, Glomerellales, Hypocreales, and Pleosporales) and Basidiomycota (Polyporales). The most frequent endophytes were members of the genus Diaporthe. Talaromyces was an indicator genus for caatinga while Phyllosticta, Diaporthe, and Colletotrichum were for brejo de altitude. The composition of endophytic fungi in caatinga and brejo de altitude differed significantly, its richness and diversity (H' = 3.41) being significantly higher in brejo de altitude. Diaporthe sp. URM 7793 was the best producer of L-asparaginase (2.41 U/g), followed by Diaporthe sp. URM 7779 (2.00 U/g), Talaromyces sp. URM 7785 (1.91 U/g), and Diaporthe sp. URM 7792 (1.47 U/g). The composition of endophytic fungi assemblages is strongly influenced by the type of ecosystem. In its natural habitat, M. urundeuva harbors an important diversity of endophytes, which could be used to produce L-asparaginase. <![CDATA[Arbuscular mycorrhizal fungal communities in soils under three phytophysiognomies of the Brazilian Atlantic Forest]]> ABSTRACT Arbuscular mycorrhizal fungi (AMF) play an important role in plant community productivity and structure, and so studying the factors that affect the diversity and structure of this fungal community is important for understanding their ecology in tropical forests. We investigated AMF spore communities and root colonization under three forest phytophysiognomies (Restinga Forest, REF; Lowland Ombrophilous Dense Forest, LLF; and Montane Ombrophilous Dense Forest, MTF). Spore abundance was lowest in LLF and highest in REF, with no statistical differences relative to MTF. Spore diversity indices and root colonization rates were not statistically different among the phytophysiognomies. However, principal components analysis revealed that AMF community structure differed according to forest phytophysiognomy. Hierarchical partitioning analysis indicated that most of the AMF community variables were better explained by phytophysiognomy than by chemical and physical attributes of the soil. In addition to the plant community, clay content, pH, Boron, P, S and CEC best explained some of the AMF community variables. Thus, we conclude that while several factors determine AMF community structure in the Atlantic Forest, phytophysiognomy is the most significant. <![CDATA[Fire records in tree rings of <em>Moquiniastrum polymorphum</em>: potential for reconstructing fire history in the Brazilian Atlantic Forest]]> ABSTRACT Fire disturbance affects the composition, structure and dynamics of vegetation. Historical records of fire events exist in some places, but they are generally limited in temporal and spatial extent. Tree-ring research is a useful tool for fire history reconstruction and can contribute important long-term ecological data. We tested the hypotheses that Moquiniastrum polymorphum (Less.) G. Sancho, a widespread species in Brazil that occurs in burnt areas of Atlantic Forest, produces annual growth rings and that its wood can record fire incidence by datable fire scaring. Our results corroborate these hypotheses and indicate that the species has potential for fire history reconstruction. <![CDATA[Reproductive morphology and phenological aspects of one morphological variant of <em>Hypnea pseudomusciformis</em> (Gigartinales, Rhodophyta)]]> ABSTRACT Hypnea pseudomusciformis was recently described from South America, and has three morphological variants: “musciformis”, “nigrescens”, and “valentiae”. Information on the biology of these variants may help to explain this species’ wide morphological variation despite the absence of genetic divergence among variants. More morphological and ecological data has accumulated on the “musciformis” variant occurring on the Brazilian coast than for the others. In this study, we described the reproductive morphology of a tropical “nigrescens” population and investigated its phenology to provide crucial biological information about this taxon, and perhaps also assist in answering questions about the systematics of H. pseudomusciformis variants. The population analyzed showed no significant fluctuations in its total biomass throughout the year. All reproductive stages were frequently recorded during this study, which contributes greatly to our knowledge of the reproductive morphology of the “nigrescens” variant. Phenological variations were correlated with environment variables, such as air and sea-surface temperatures, insolation, precipitation, and humidity. Male gametophytes were frequently present, which has never been reported for the “musciformis” variant. We showed that, despite being members of the same genetic species, the “nigrescens” and “musciformis” morphological variants exhibit remarkable differences in their ecology and biology. <![CDATA[New initiatives for Brazilian aquatic plant data management]]> ABSTRACT Initiatives directed at managing information on aquatic plants can support different areas of scientific research, educational practices and political decisions for sustainable management and protection of wetlands and natural resources, as well as reveal knowledge gaps regarding aquatic plants and wetlands. Furthermore, such initiatives can contribute directly to consolidating wetland classification systems in Brazil. The objectives of this work are to present and explore the use of a data repository and online platform created specifically for the management of data on aquatic plants in Brazil. The data repository for aquatic plants was developed to store information on species occurrence records in a standardized form considering: systematics, taxonomy, habit, life form, geographic distribution, hydrographic basin, wetland, bibliographic references and herbarium material. A total of 3,903 records referring to the Southeast Region of Brazil were generated for the data repository. This total encompassed 1,036 species distributed among 132 families and 466 genera. Our results illustrate the diversity of information available regarding aquatic plants, circumscribe this group of species and serve as a source of data about them. Similar databases and electronic infrastructures can be developed for other flora in the future. <![CDATA[Local environmental controls of Atlantic Forest tree community assembly on a coastal continental island in southeastern Brazil]]> ABSTRACT Tropical forests with high species diversity are commonly found in rugged montane areas. We investigated causes of local tropical forest tree community assembly on a continental island with heterogeneous terrain. We recorded tree community (absolute species abundance), topography, soil, litter and location in 40 sampling units on two opposite sides of the island with similar heterogeneous terrain. We used transformation based Redundancy Analyses and variation partitioning to determine the contribution of environment (topography, soil and litter), spatial structure (geographic location and Moran Eigenvector Maps) and the shared effects of these to explain community assembly. The environment made a significant contribution to explain tree community patterns (species composition and abundance) across all models. Conversely, spatial structure showed minor impact. Contribution of strictly environmental effects and spatially structured environmental effects varied when evaluating each site independently as well as when evaluating the combined data. Evidence suggests that local tropical tree community assembly on heterogeneous terrain may be located much closer to the niche end of the hypothetic niche-neutral continuum. Findings indicate additionally that heterogeneity of environmental factors present in dissected mountainous terrain can affect the way tropical community assembly processes are perceived. <![CDATA[Patterns of richness and distribution of Cactaceae in the Serra da Mantiqueira, Southeast Brazil, and implications for its conservation]]> Abstract This study aimed to analyze patterns of richness and distribution of Cactaceae in the Serra da Mantiqueira (SM), a mountain range located in Southeast Brazil, and assess its conservation status. We compiled distribution data from the literature and 16 herbaria and plotted it on a map divided into grid squares of 0.5°. Richness, collection effort and similarity among grid squares were analyzed for the 33 taxa recorded in SM (five of which are endemic). Maciço do Itatiaia (in southern SM), Serra do Brigadeiro and Serra do Caparaó (in northern SM) are the richest areas. Collection effort and richness were correlated (R²=0.75). Similarity analysis revealed five clusters, one of which is composed of high elevation areas with a vegetation mosaic; the remaining clusters lack biogeographic significance, and are mainly composed of widely distributed species. Ten species had no records in any state or national conservation unit of integral protection, at least two of which are threatened with extinction. Species of Cactaceae deserve attention because several taxa are threatened and/or endemic, and because the majority of SM is environmentally degraded. These findings highlight the need for urgent conservation actions for the local biodiversity of SM. <![CDATA[What are tilosomes? An update and new perspectives]]> ABSTRACT Characterization of tilosomes and study of their development revealed that they are similar to the cell wall ingrowths of transfer cells. Roots from Anathallis sclerophylla were used to examine the development, histochemistry and ultrastructure of tilosomes using light, confocal and electron microscopy (both SEM and TEM). Tilosomes initiate as cellulosic papillae in the root elongation zone, increasing the apo/symplast surface throughout the wall-membrane apparatus. Both the development and structure of tilosomes and velamen strips appear similar to the reticulated and flange cell wall ingrowths of Vicia faba transfer cells. We suggest two functional phases for tilosomes: a) in young tissues they increase the symplast connection and thus improve outside-inside transport; and b) in mature tissues they direct solutes to passage cells. Both the physiology and the genetic mechanisms controlling the ontogeny of tilosomes remain obscure. <![CDATA[<em>Hypnea musciformis</em> (Wulfen) J. V. Lamour. (Gigartinales, Rhodophyta) responses to gasoline short-term exposure: biochemical and cellular alterations]]> ABSTRACT Presence of toxic compounds in marine coastal waters has increased exponentially since Industrial Revolution. In this way, we aimed to evaluate biochemical and physiological changes occurring within Hypnea musciformis after short-term exposure to gasoline. Hypnea musciformis was cultivated without gasoline and then exposed to various concentrations of it (0.001 % - 1.0 %, v/v) for periods of 30 min, 1 h, 12 h and 24 h. A Pricncipal Compound Analysis of UV-vis spectral window (200-700 nm) was able to discriminate gasoline-exposed samples according to both exposure time and gasoline concentration. Changes in carotenoid profile composition were observed. Decreased carotenoid content was associated to gasoline exposure time, being lutein and trans-β-carotene the major compounds found. Higher gasoline concentrations negatively interfered with phenolic compounds accumulation. In addition, increased gasoline concentrations corresponded to decreased intracellular starch grains content as well as increased its deposition on cell wall external surface. Data obtained allow us to conclude that gasoline can damage Hypnea musciformis physiology and cell morphology. This is important, considering Hypnea musciformis carotenoids and phenolics are potential biomarkers of environmental stress investigated, as well as its increased cell wall thickness to avoid gasoline diffusion. <![CDATA[<strong>Pollen morphology of Brazilian species of <em>Verbesina</em> L. (Heliantheae - Asteraceae)</strong>]]> Abstract There are nine species of the plant genus Verbesina in Brazil, which are distributed in the Northeast, Center-West, Southeast and South regions of the country. The objective of the present study was to describe the pollinic morphology of eight of these species to better characterize them and evaluate potential species-level taxonomic characters. Acetolysed pollen material was measured within seven days under light microscopy, while non-acetolyzsed pollen grains were used for scanning electronic microscopy. The pollen grains were found to be oblate-spheroidal, medium-sized, isopolar, monads that are 3-colporate with a subtriangular amb, a small polar area, a long colpus, a lalongate endoaperture, a caveate exine and an echinate sexine. Although the shape of the pollen grains of these Brazilian species of Verbesina is homogeneous, some attributes were observed to be useful for characterizing the species, such as exine thickness, distance between spines and side of the apocolpus. <![CDATA[Palynology of <em>Amphidium</em> Schimp. (Amphidiaceae M. Stech): can spore morphology circumscribe the genus?]]> ABSTRACT Amphidium Schimp. is characterized by cushion-forming erect primary stems, linear-lanceolate leaves, and gymnostome capsules. The phylogenetic position of Amphidium is uncertain, with the genus having been variously included in Zygodontaceae Schimp., Rhabdoweisiaceae Limpr., Orthotrichaceae Arn. and Amphidiaceae M. Stech. A palynological investigation was performed of the three species of the genus that occur in the Americas: Amphidium lapponicum (Hedw.) Schimp., Amphidium mougeotii (Bruch &amp; Schimp.) Schimp., and Amphidium tortuosum (Hornsch.) Cufod. Spores were observed and measured for greatest diameter under light microscopy both before and after acetolysis. Non-acetolyzed spores were observed under scanning electron microscopy to assess surface ornamentation of the sporoderm. All spores observed were smaller than 20 µm and heteropolar, with surface ornamentation reflecting a combination of different elements, such as gemmae, rugulae and perforations. The palynological characteristics observed here suggest that the genus Amphidium, and thus its contained species, be placed in their own family. <![CDATA[Complex sporoderm structure in bryophyte spores: a palynological study of Erpodiaceae Broth.]]> ABSTRACT Palynological studies of bryophytes are critical for evaluating the taxonomic relevance of their spores. They also provide important support to paleoecological investigations that, usually, treat bryophytes as a whole, which does not permit the evaluation of specific functional traits of a special taxonomic unit. The present study investigated the morphology and ultrastructure of spores of five species of Erpodiaceae (Bryophyta), and assessed the implications for taxonomy and the recognition of spores of past records. Erpodiaceae includes corticolous and saxicolous plants that are widely distributed throughout tropical and temperate regions. The spores were found to be isomorphic and apolar with a subcircular amb, granulate, inaperturate. The sporoderm possesses a perine, an exine and a stratified intine. The perine is largely responsible for spore surface ornamentation. The occurrence of exine projections, in isolation or sustaining the elements of the perine, characterizes sporoderm structure with features similar to that of a semitectum, a distinctive characteristic that has not been reported previously for bryophyte spores. <![CDATA[Taxonomic notes on species of <em>Passiflora</em> subgenus <em>Astrophea</em> (Passifloraceae <em>s.s.</em>)]]> ABSTRACT The subgenus Astrophea is one of the most critical and neglected subgenera of the genus Passiflora. Seven Brazilian species of P. subg. Astrophea were found to be in need of typification. Lectotypes are designated for the following names: Passiflora cauliflora, P. leptopoda, P. ceratocarpa, P. faroana, P. rhamnifolia, P. sclerophylla and P. tessmannii. An epitype was also designated for the name P. tessmannii. In addition, Passiflora alliacea was synonymized with Passiflora pentagona. <![CDATA[Species diversity, community structure and ecological traits of trees in an upper montane forest, southern Brazil]]> ABSTRACT Upper montane ecosystems in Brazil are little known, and their structural and functional aspects poorly understood. Our goals were to describe tree species diversity and community structure, and to characterize tree species in relation to their ecological traits, phytogeographic history and conservation status in an upper montane araucaria forest remnant. A total of 26 species belonging to 18 families were found in a 1-hectare permanent plot. The tree community mainly comprised trees with diameters of less than 20 cm and heights of between 6.5 and 9.5 m. Drimys angustifolia and Myrceugenia regnelliana had the highest importance values. Most species were shade tolerant while most individuals were pioneers. Most species and individuals presented zoophily and zoochory. Most sampled species and individuals were related to araucaria forests. Seven species are threatened to some degree while one species, Crinodendron brasiliensis, besides threatened, is also endemic to the region. The presence of endemic and endangered species demonstrates that the studied area serves important conservation purposes. Furthermore, the present study demonstrates the important role that upper montane regions have for conservation and describes the structural patterns of still poorly studied habitats, reinforcing the importance such systems have in maintaining species diversity at high elevations. <![CDATA[Mycological Diversity Description II]]> ABSTRACT Here, Diaporthe myracrodruonis is introduced as new species from Brazil, isolated as endophyte from Myracrodruon urundeuva. Asterina mandaquiensis is epitypified and ilustrated for the first time. Serpula similis is reported as new to the Neotropics, while Perenniporia centrali-africana is reported for the first time as endophyte and Preussia africana as endophyte from Spondias tuberosa in Caatinga in Brazil. <![CDATA[Abscisic acid and the antioxidant system are involved in germination of <em>Butia capitata</em> seeds]]> ABSTRACT Seed germination is an important step for plants without vegetative propagation and is a physiological process that begins with specific environmental cues resulting in biochemical responses. Breaking-dormancy is necessary to study germination in dormant seeds with asynchronous germination. We investigated the processes of breaking dormancy and germination of Butia capitata (Arecaceae) seeds, in which germination is slow and asynchronous, by operculum removal. This treatment increased germination of B. capitata to 90 %. Embryos of dry, imbibed, 24-hours post-operculum removal and early-germinated seeds were collected for biochemical analysis of the following: quantification of abscisic acid (ABA) and hydrogen peroxide (H2O2), activities of antioxidant enzymes (catalase - CAT, superoxide dismutase - SOD, glutathione reductase - GR) and histolocalization of superoxide anion (O2 -). Decreases in H2O2 and ABA were recorded 24 hours post-operculum removal. Increased GR and SOD activities during imbibition, and CAT upon germination, indicate a role in controlling reactive oxygen species. Interestingly, the accumulation of O2 - on the haustorium upon imbibition seems to be involved in germination, instead of H2O2. For B. capitata seeds, signaling from the removal of the operculum probably resulted in ABA catabolism mediated by O2 -, which thus promoted seed germination. <![CDATA[Fungi associated with <em>Copaifera oblongifolia</em> (Fabaceae) seeds: occurrence and possible effects on seed germination]]> ABSTRACT Copaifera oblongifolia is a recurrent plant species in degraded areas yet there is little information about its seed biology and interactions with fungi. The aims of this study were to identify the fungal community (endophytic and non-endophytic) associated with C. oblongifolia seeds and to test the effects of these different fungal species on germination. In general, germination of C. oblongifolia seeds was high (about 85 %), initiating four days after sowing and continuing for a total of 20 days. External asepsis with sodium hypochlorite did not influence germinability of C. oblongifolia. Seed infestation with Aspergillus niger, A. flavus, Mucor sp. and Rhizopus stolonifer did not affect the time required for germination, however, infection with A. flavus negatively affected germination percentage. Endophytic fungi were not isolated from C. oblongifolia seeds, suggesting that this species does not transmit endophytic fungi vertically. Therefore, C. oblongifolia can be classified in Class 3 with regard to the transmission and presence of endophytes.