RESUMO

The specialised mutualism between Tococa guianensis and ants housed in its leaf domatia is a well-known example of myrmecophily. A pollination study on this species revealed that flowers in the bud stage exude a sugary solution that is collected by ants. Given the presence of this unexpected nectar secretion, we investigated how, where, and when floral buds of T. guianensis secret nectar and what function it serves. We studied a population of T. guianensis occurring in a swampy area in the Cerrado of Brazil by analyzing the chemical composition and secretion dynamics of the floral-bud nectar and the distribution and ultrastructure of secretory tissues. We also measured flower damage using ant-exclusion experiments. Floral bud nectar was secreted at the tip of the petals, which lack a typical glandular structure but possess distinctive mesophyll due to the presence of numerous calcium oxalate crystals. The nectar, the production of which ceased after flower opening, was composed mainly of sucrose and low amounts of glucose and fructose. Nectar was consumed by generalist ants and sporadically by stingless bees. Ant exclusion experiments resulted in significantly increased flower damage. The floral nectar of T. guianensis is produced during the bud stage. This bud-nectar has the extranuptial function of attracting generalist ants that reduce florivory. Pollen is the unique floral resource attracting pollinators during anthesis. Tococa guianensis, thus, establishes relationships with two functional groups of ant species: specialist ants acting against herbivory and generalist ants acting against florivory.

RESUMO

Psychotria viridis Ruiz & Pav (Rubiaceae) occurs naturally throughout the Amazon and it is traditionally used by indigenous communities, being incorporated into religious use in urban contexts over the last few decades. It is known and cultivated in many regions of South America for possessing valuable bioactive alkaloids. In this paper, we described P. viridis leaf morphology, anatomy and histochemistry from three populations cultivated in the southeastern Brazil, in order to identify possible adaptations to local environment and management. All plants presented terminal stipules and basic morpho-anatomical patterns of leaves, consistent with most species of the genus, as heterogeneous dorsiventral mesophyll, uniseriate epidermis, presents large cells with prominent vacuoles and druses. Unicellular non-glandular trichomes and multicellular starry trichomes were present in the primary and secondary veins. Amphi-hypostomatic leaf pattern, not yet described for the species, was common in all studied plants. Variation in the presence of domatia in the same population indicates that this structure cannot be used for taxonomic determination of P. viridis, as already described for other species of the genus. Presence of secretory ducts and reduction in stomata density and leaf area represent the main morpho-anatomic adaptations of plants from drier and warmer climates. Histochemical tests were positive for alkaloids, polysaccharides, proteins and phenolic compounds, being negative for starch only in plants subjected to water stress. We concluded that the morpho-anatomical and histochemical alterations found in the plants of this study resulted from seasonal water deficit adaptations and to maintain or attract mutualistic organisms

Assuntos

RESUMO

Psychotria viridis Ruiz & Pav (Rubiaceae) occurs naturally throughout the Amazon and it is traditionally used by indigenous communities, being incorporated into religious use in urban contexts over the last few decades. It is known and cultivated in many regions of South America for possessing valuable bioactive alkaloids. In this paper, we described P. viridis leaf morphology, anatomy and histochemistry from three populations cultivated in the southeastern Brazil, in order to identify possible adaptations to local environment and management. All plants presented terminal stipules and basic morpho-anatomical patterns of leaves, consistent with most species of the genus, as heterogeneous dorsiventral mesophyll, uniseriate epidermis, presents large cells with prominent vacuoles and druses. Unicellular non-glandular trichomes and multicellular starry trichomes were present in the primary and secondary veins. Amphi-hypostomatic leaf pattern, not yet described for the species, was common in all studied plants. Variation in the presence of domatia in the same population indicates that this structure cannot be used for taxonomic determination of P. viridis, as already described for other species of the genus. Presence of secretory ducts and reduction in stomata density and leaf area represent the main morpho-anatomic adaptations of plants from drier and warmer climates. Histochemical tests were positive for alkaloids, polysaccharides, proteins and phenolic compounds, being negative for starch only in plants subjected to water stress. We concluded that the morpho-anatomical and histochemical alterations found in the plants of this study resulted from seasonal water deficit adaptations and to maintain or attract mutualistic organisms(AU)

Assuntos

RESUMO

Ant-associated microorganisms can play crucial and often overlooked roles, and given the diversity of interactions that ants have developed, the study of the associated microbiomes is of interest. We focused here on specialist plant-ant species of the genus Allomerus that grow a fungus to build galleries on their host-plant stems. Allomerus-inhabited domatia, thus, might be a rich arena for microbes associated with the ants, the plant, and the fungus. We investigated the microbial communities present in domatia colonised by four arboreal ants: Allomerus decemarticulatus, A. octoarticulatus, A. octoarticulatus var. demerarae, and the non-fungus growing plant-ant Azteca sp. cf. depilis, inhabiting Hirtella physophora or Cordia nodosa in French Guiana. We hypothesized that the microbial community will differ among these species. We isolated microorganisms from five colonies of each species, sequenced the 16S rRNA or Internal TranscribedSpacer (ITS) regions, and described both the alpha and beta diversities. We identified 69 microbial taxa, which belong to five bacterial and two fungal phyla. The most diverse phyla were Proteobacteria and Actinobacteria. The microbial community of Azteca cf. depilis and Allomerus spp. differed in composition and richness. Geographical distance affected microbial communities and richness but plant species did not. Actinobacteria were only associated with Allomerus spp.

RESUMO

Leaf domatia are cavity-shaped structures of different types or tufts of hairs located at the junction between ribs on the abaxial surface of the leaf blades of various families of angiosperms, serving as protection against phytophagous organisms by harboring beneficial mites, suggesting a mutualistic relationship. There is shortage of inventories of species with such structures; thus the present study examined native woody plant in two habitats of the backwoods of Pernambuco to identify the types of leaf domatia. 86 species were observed,43 inCaatinga area, out of which five had domatia, and43 inthe montane forest, 11 species with domatia. Four types of domatia were observed: hairtufts, pocket, pit and revolute margin. There was predominance of plant species with leaf domatia in the area Carro Quebrado in Triunfo,PernambucoState. These results corroborate the information available in the literature in which domatia are prevalent in more humid environments, and that these structures as micro-habitats influence the maintenance of diverse organisms.(AU)

Domلcias foliares sمo estruturas em forma de cavidades de diferentes tipos ou tufos de tricomas localizados na junçمo entre as nervuras, na face abaxial das lâminas foliares de diversas famيlias de angiospermas, servindo de defesa contra organismos fitَfagos por abrigarem لcaros benéficos, sugerindo uma relaçمo mutualيstica. Hل escassez de inventلrios de espécies apresentando essas estruturas; diante disso, o presente estudo analisou plantas lenhosas nativas em dois ambientes do sertمo de Pernambuco, visando identificar os tipos de domلcias foliares. Foram observadas 86 espécies, 43 em لrea de Caatinga em as quais cinco apresentaram domلcias e 43 no brejo de altitude, 11 espécies com domلcias. Foram encontrados quatro tipos de domلcias: tufo de pelos, bolso, cova e orla. Na لrea do Carro Quebrado, Triunfo, Estado do Pernambuco, as plantas com domلcias foliares foram predominantes. Estes resultados corroboram as informaçُes disponيveis na literatura de que domلcias sمo predominantes em ambientes mais ْmidos, e que essas estruturas como micro-habitats, influenciam a manutençمo de diversos organismos.(AU)

Assuntos

RESUMO

Leaf domatia are cavity-shaped structures of different types or tufts of hairs located at the junction between ribs on the abaxial surface of the leaf blades of various families of angiosperms, serving as protection against phytophagous organisms by harboring beneficial mites, suggesting a mutualistic relationship. There is shortage of inventories of species with such structures; thus the present study examined native woody plant in two habitats of the backwoods of Pernambuco to identify the types of leaf domatia. 86 species were observed, 43 in Caatinga area, out of which five had domatia, and 43 in the montane forest, 11 species with domatia. Four types of domatia were observed: hairtufts, pocket, pit and revolute margin. There was predominance of plant species with leaf domatia in the area Carro Quebrado in Triunfo, Pernambuco State. These results corroborate the information available in the literature in which domatia are prevalent in more humid environments, and that these structures as micro-habitats influence the maintenance of diverse organisms.

Domácias foliares são estruturas em forma de cavidades de diferentes tipos ou tufos de tricomas localizados na junção entre as nervuras, na face abaxial das lâminas foliares de diversas famílias de angiospermas, servindo de defesa contra organismos fitófagos por abrigarem ácaros benéficos, sugerindo uma relação mutualística. Há escassez de inventários de espécies apresentando essas estruturas; diante disso, o presente estudo analisou plantas lenhosas nativas em dois ambientes do sertão de Pernambuco, visando identificar os tipos de domácias foliares. Foram observadas 86 espécies, 43 em área de Caatinga em as quais cinco apresentaram domácias e 43 no brejo de altitude, 11 espécies com domácias. Foram encontrados quatro tipos de domácias: tufo de pelos, bolso, cova e orla. Na área do Carro Quebrado, Triunfo, Estado do Pernambuco, as plantas com domácias foliares foram predominantes. Estes resultados corroboram as informações disponíveis na literatura de que domácias são predominantes em ambientes mais úmidos, e que essas estruturas como micro-habitats, influenciam a manutenção de diversos organismos.

Assuntos