Specialized Seed Dispersal in Epiphytic Cacti and Convergence with Mistletoes

Mistletoes represent the best example of specialization in seed dispersal, with a reduced assemblage of dispersal agents. Specific dispersal requirements mediated by the specificity of seed deposition site have apparently led to the evolution of such close relationships between mistletoes and certain frugivores. Here, we provide evidences for another case of specialization involving epiphytic cacti in the genus Rhipsalis, and small Neotropical passerines Euphonia spp., which also act as the main seed dispersers of mistletoes in the family Viscaceae. With field observations, literature search, and observations on captive birds, we demonstrated that Rhipsalis have specific establishment requirements, and euphonias are the most effective dispersers of Rhipsalis seeds in both quantitative and qualitative aspects, potentially depositing seeds onto branches of host plants. We interpret the similar dispersal systems of Rhipsalis and Viscaceae mistletoes, which involve the same dispersal agents, similar fruit morphologies, and fruit chemistry as convergent adaptive strategies that enable seeds of both groups to reach adequate microsites for establishment in host branches. © 2013 by The Association for Tropical Biology and Conservation.

The systematic significance of floral morphology, nectaries, and nectar concentration in epiphytic cacti of tribes Hylocereeae and Rhipsalideae (Cactaceae)

A long-standing interest in cactus taxonomy has existed since the Linnaean generation, but an appreciation of the reproductive biology of cacti started early in the 1900s. Numerous studies indicate that plant reproductive traits provide valuable systematic information. Despite the extensive reproductive versatility and specializations in breeding systems coupled with the striking floral shapes, the reproductive biology of the Cactaceae has been investigated in approximately 10% of its species. Hence, the systematic value of architectural design and organization of internal floral parts has remained virtually unexplored in the family. This study represents the most extensive survey of flower and nectary morphology in the Cactaceae focusing on tribes Hylocereeae and Rhipsalideae (subfamily Cactoideae). Our objectives were (1) to conduct comparative morphological analyses of flowers and floral nectaries and (2) to compare nectar solute concentration in these two tribes consisting of holo- and semi-epiphytic species. Flower morphology, nectary types, and sugar concentration of nectar have strong taxonomic implications at the tribal, generic and specific levels. Foremost, three types of nectaries were found, namely chamber nectary (with the open and diffuse subtypes), furrow nectary (including the holder nectary subtype), and annular nectary. All Hylocereeae species possess chamber nectaries, in which the nectarial tissue has both trichomes and stomata. The Rhipsalideae are distinguished by two kinds of floral nectaries: furrow and annular, both nectary types with stomata only. The annular nectary type characterizes the genus Rhipsalis. Nectar concentration is another significant taxonomic indicator separating the Hylocereeae and Rhipsalideae and establishing trends linked to nectar sugar concentration and amount of nectar production in relation to flower size. There is an inverse relationship between flower size and amount of nectar production in the smaller Rhipsalideae flowers, in which nectar concentration is more than two-fold higher despite the smaller volume of nectar produced when compared to the large Hylocereeae flowers. Variability of nectary morphology and nectar concentration was also evaluated as potential synapomorphic characters in recent phylogenies of these tribes. In conclusion, our data provide strong evidence of the systematic value of floral nectaries and nectar sugar concentration in the Cactaceae, particularly at different taxonomic levels in the Hylocereeae and Rhipsalideae. © 2013 Perspectives in Plant Ecology, Evolution and Systematics.

Molecular phylogeny of tribe Rhipsalideae (Cactaceae) and taxonomic implications for Schlumbergera and Hatiora

Tribe Rhipsalideae is composed of unusual epiphytic or lithophytic cacti that inhabit humid tropical and subtropical forests. Members of this tribe present a reduced vegetative body, a specialized adventitious root system, usually spineless areoles and flowers and fruits reduced in size. Despite the debate surrounding the classification of Rhipsalideae, no studies have ever attempted to reconstruct phylogenetic relationships among its members or to test the monophyly of its genera using DNA sequence data; all classifications formerly proposed for this tribe have only employed morphological data. In this study, we reconstruct the phylogeny of Rhipsalideae using plastid (trnQ-rps16, rpl32-trnL, psbA-trnH) and nuclear (ITS) markers to evaluate the classifications previously proposed for the group. We also examine morphological features traditionally used to delimit genera within Rhipsalideae in light of the resulting phylogenetic trees. In total new sequences for 35 species of Rhipsalideae were produced (out of 55: 63%). The molecular phylogeny obtained comprises four main clades supporting the recognition of genera Lepismium, Rhipsalis, Hatiora and Schlumbergera. The evidence gathered indicate that a broader genus Schlumbergera, including Hatiora subg. Rhipsalidopsis, should be recognized. Consistent morphological characters rather than homoplastic features are used in order to establish a more coherent and practical classification for the group. Nomenclatural changes and a key for the identification of the genera currently included in Rhipsalideae are provided. (C) 2011 Elsevier Inc. All rights reserved.

Órgãos reprodutivos em Hylocereeae e Rhipsalideae (Cactaceae): morfologia floral e desenvolvimento estrutural do fruto e da semente

Pós-graduação em Ciências Biológicas (Biologia Vegetal) - IBRC

A New Subgeneric Classification of Rhipsalis (Cactoideae, Cactaceae)

Most Cactaceae have succulent stems and inhabit dry or arid areas, but some are epiphytes of humid regions. Rhipsalis is the largest genus of epiphytic cacti. Species of Rhipsalis are notoriously difficult to identify, and the subgeneric classification of the genus has remained controversial. Between 1837 and 1995, eight different subgeneric classifications have been proposed for Rhipsalis. The most comprehensive taxonomic treatment of the genus recognized five subgenera, Phyllarthrorhipsalis, Rhipsalis, Epallagogonium, Calamorhipsalis, and Erythrorhipsalis, characterized mainly by stem morphology. Here, molecular phylogenetic information combined with morphological data is used to re-evaluate the former subgeneric classifications proposed for the genus. Three monophyletic subgenera are recognized, Rhipsalis, Calamorhipsalis and Erythrorhipsalis, which are mainly characterized by floral traits. The changes proposed include expanding the circumscription of Rhipsalis by the inclusion of species previously included in Phyllarthrorhipsalis and Epallagogoniwn and recognizing a broader Calamorhipsalis, also including species from subgenus Epallagogonium. The circumscription of Erythrorhipsalis remains unchanged. For each subgenus a list of synonyms, a brief description and a list of species included are presented. A key for the identification of subgenera is also provided.

Seedling morphology and development in the epiphytic cactus Epiphyllum phyllanthus (L.) Haw. (Cactaceae: Hylocereeae)

Seedling morphology is relevant in classification, taxonomy, and vegetation studies to understand plant life cycles, germination succession and requirements, and developmental progression. However, most morphological studies of seedlings lack analysis of organ anatomy, impeding the comprehension of series of development and establishment in a particular environment. Here, we have taken a traditional anatomical approach to examine the stages of seedling development in Epiphyllum phyllanthus, a holo-epiphytic cactus of tribe Hylocereeae. The goals were 1) to offer a comprehensive description of growth series in E. phyllanthus seedlings based on morphological and anatomical analysis and 2) to examine the initial growth phases in the life cycle of this species to identify organ development and understand their adaptive significance in relation to seedling establishment. Our results include descriptions of seed morphology, embryonic features, and seedling vascularization pattern in the root, hypocotyl, cotyledons, and epicotyl. The morphological and developmental patterns in E. phyllanthus seedlings have potential phylogenetic and ontogenetic implications in the Cactaceae. Characters such as the presence of mucilage on the seed coat, the lack of seed operculum, and large cotyledons in E. phyllanthus are comparable to basal cacti, but the root anatomy is more similar to columnar relatives. At the familial level, there is an apparent trend in decreasing number of phloem and xylem poles in the stele of primary root, correlated with degree of specialization and advanced phylogenetic position: tetrarch to septarch-octarch in basal lineages, tetrarch Cereus-type in columnar species, to the diarch vascular system in Rhipsalideae and some species with cylindric/globose stem. © Torrey Botanical Club.

Seasonal variation of epiphytic hydroids (Cnidaria: Hydrozoa) associated to a subtropical Sargassum cymosum (Phaeophyta: Fucales) bed

Hydroids are broadly reported in epiphytic associations from different localities showing marked seasonal cycles. Studies have shown that the factors behind these seasonal differences in hydroid richness and abundance may vary significantly according to the area of study. Seasonal differences in epiphytic hydroid cover and richness were evaluated in a Sargassum cymosum C. Agardh bed from Lázaro beach, at Ubatuba, Brazil. Significant seasonal differences were found in total hydroid cover, but not in species richness. Hydroid cover increased from March (early fall) to February (summer). Most of this pattern was caused by two of the most abundant species: Aglaophenia latecarinata Allman, 1877 and Orthopyxis sargassicola (Nutting, 1915). Hydroid richness seems to be related to S. cymosum size but not directly to its biomass. The seasonal differences in hydroid richness and algal cover are shown to be similar to other works in the study region and in the Mediterranean. Seasonal recruitment of hydroid species larvae may be responsible for their seasonal differences in algal cover, although other factors such as grazing activity of gammarid amphipods on S. cymosum must be taken into account.

A NOVEL EPIPHYTIC CYANOBACTERIAL SPECIES FROM THE GENUS BRASILONEMA CAUSING DAMAGE TO EUCALYPTUS LEAVES

A cyanobacterial mat colonizing the leaves of Eucalyptus grandis was determined to be responsible for serious damage affecting the growth and development of whole plants under the clonal hybrid nursery conditions. The dominant cyanobacterial species was isolated in BG-11 medium lacking a source of combined nitrogen and identified by cell morphology characters and molecular phylogenetic analysis (16S rRNA gene and cpcBA-IGS sequences). The isolated strain represents a novel species of the genus Brasilonema and is designated Brasilonema octagenarum strain UFV-E1. Thin sections of E. grandis leaves analyzed by light and electron microscopy showed that the B. octagenarum UFV-E1 filaments penetrate into the leaf mesophyll. The depth of infection and the mechanism by which the cyanobacterium invades leaf tissue were not determined. A major consequence of colonization by this cyanobacterium is a reduction in photosynthesis in the host since the cyanobacterial mats decrease the amount of light incident on leaf surfaces. Moreover, the cyanobacteria also interfere with stomatal gas exchange, decreasing CO2 assimilation. To our knowledge, this is the first report of an epiphytic cyanobacterial species causing damage to E. grandis leaves.

Atmospheric pollutants monitoring by analysis of epiphytic lichens

The Canoparmelia texana epiphytic lichenized fungi was used to monitor atmospheric pollution in the Sao Paulo metropolitan region, SP, Brazil. The cluster analysis applied to the element concentration values confirmed the site groups of different levels of pollution due to industrial and vehicular emissions. In the distribution maps of element concentrations, higher concentrations of Ba and Mn were observed in the vicinity of industries and of a petrochemical complex. The highest concentration of Co found in lichens from the Sao Miguel Paulista site is due to the emissions from a metallurgical processing plant that produces this element. For Br and Zn, the highest concentrations could be associated both to vehicular and industrial emissions. Exploratory analyses revealed that the accumulation of toxic elements in C. texana may be of use in evaluating the human risk of cardiopulmonary mortality due to prolonged exposure to ambient levels of air pollution. (c) 2007 Elsevier Ltd. All rights reserved.

Bryophytes distribution along an altitudinal gradient of native forest in Pico island (Azores): preliminary results of epiphytic genera

MOVECLIM, Mid Course Meeting, 2-6 September 2013, Réunion (Mascarenes).

Farysizyma gen. nov., an anamorphic genus in the Ustilaginales to accommodate three novel epiphytic basidiomycetous yeast species from America, Europe and Asia

FEMS Yeast Research, Vol. 8, Nº 3

Epiphytic lichens as surrogates for biodiversity and ecosystem resilience in native oakwoods of the Baixo Tamega region (Northern Portugal)

In the last 50 years, concern about the loss of lichen diversity associated with forest management and forest fragmentation has led to many studies designed to assess patterns and monitor trends of lichen biodiversity in forests worldwide. However there are surprisingly few studies focusing on the effect of natural disturbance for epiphytic lichens in forest ecosystems and, especially, on how these changes affect the relationships between epiphytic lichens and other organisms. The major goal of this thesis was to characterize and valuate the epiphytic lichens in the Baixo Tamega region (northern Portugal) and to assess its vulnerability to several drivers of change, particularly fire. The study area is located in Aboboreira and Castelo, a mountain area with 105 km2 and a top altitude of approximately 1000 m.a.s.l. In this region, fire is one of the worst natural catastrophes not only because of its high frequency and wide extension but also because of their enormous destructive effects. This thesis has included three case studies that proved the need to develop management and conservation actions for the area. In the first study we assessed the epiphytic lichen diversity in the oak woods of the Aboboreira and Castelo mountains. Results have revealed high diversity value and presence of a lichen community that has suffered general decline throughout Europe. The second study has addressed the impact of fire over epiphytic lichens and community recovering patterns. Results observed along the fire gradient showed that the most common and abundant lichen species establish themselves early in post-fire gradient while “old-growth” associated lichens tend to recover slowly along the same gradient. The third study intended to evaluate the potential use of selected lichen species or groups as biodiversity surrogates, in a scenario of fire-controlled ecological changes. Results showed that the use of epiphytic lichens as surrogates of bryophyte and vascular plant diversity should consider not only species richeness and composition, but also occurrence of disturbing factors, such fire. among the studied groups, lichen genera is the only group that can be used as surrogate of total epiphytic lichen diversity, independently of fire induced changes

Bacterial spot and early blight biocontrol by epiphytic bacteria in tomato plants

The objective of this work was to evaluate in vitro and in vivo biocontrol of bacterial spot (Xanthomonas vesicatoria) and early blight (Alternaria solani) by the epiphytic bacteria Paenibacillus macerans and Bacillus pumilus. Tomato plants were previously sprayed with epiphytic bacteria, benzalkonium chloride and PBS buffer and, after four days, they were inoculated with A. solani and X. vesicatoria. To determine the phytopathogenic bacteria population, leaflet samples were collected from each treatment every 24 hours, for seven days, and plated on semi-selective medium. The effect of epiphytic bacteria over phytopathogens was performed by the antibiosis test and antagonistic activity measured by inhibition zone diameter. The epiphytic and benzalkonium chloride drastically reduced the severity of early blight and bacterial spot in comparison to the control (PBS). In detached leaflets, the epiphytic bacteria reduced in 70% the number of phytopathogenic bacteria cells in the phylloplane. The antibiosis test showed that the epiphytic bacteria efficiently inhibit the phytopathogens growth. In all the bioassays, the epiphytic bacteria protect tomato plants against the phytopathogens

Vine-cacti pitayas: the new crops of the world

Until 1994, only scarce research existed on these plants; however the worldwide interest in this novel fruit crop is evident, as numbers of pitaya-related publications have grown rapidly, especially during the past decade .There is a big confusion about both botanical and commercial names and there is a need to clear this point. Herein, we attempt to review existing knowledge on the taxonomy, breeding and other horticultural characteristics of this unique crop. This paper comments abou taxonomy,breeding,physiology and horticultura e chatera ristics,postsharvest and uses.