Evolution of the sexual reproduction in Veronica (Plantaginaceae) : phylogeny, phylogeography and invasion

Die geschlechtliche Fortpflanzung ist ein universelles Merkmal und erlaubt es genetische Variation innerhalb von Blütenpflanzen zu schaffen. Die Evolution der sexuellen und reproduktiven Systeme wurde hier auf mehreren zeitlichen Ebenen, in verschiedenen Arten von Lebensraum studiert und mit fast allen möglichen Methoden im Labor, im Gewächshaus sowie im Feld untersucht. Drei Hauptteile sind in dieser Arbeit enthalten und entsprechen jeweils einem unterschiedlichen Niveau der Zeit: Gattung, Untergattung und Arten. Der erste Teil zeigt, dass die PO-Verhältnisse Untersuchungen systematisch in jeder Pflanzen-Gattung oder Untergattung untersucht werden müssen. Dieses güngstige, schnelle und leistungsstarke Werkzeug kann eine Vielzahl von Informationen über die Modi der Pflanzenreproduktion produzieren, ohne die Verwendung von teuren und langen Experimenten. Darüber hinaus könnte diese Maßnahme auch ergänzende Daten über die Taxonomie dieser untersuchten Gruppen geben. Das zweite Kapitel befasst sich mehr mit der Taxonomie der Ehrenpreis(Veronica)-Arten als die beiden anderen und zeigt, dass verschiedene Ereignisse der interspezifischen Reproduktion in einem der Hotspots der Artenvielfalt in Europa (der Balkan-Halbinsel) auftreten. Die Ergebnisse zeigen, dass morphologische und genetische Daten inkongruent sind und die Analyse der Taxonomie dieser Arten oder Unterart schwierig ist. Das letzteKapitel erzählt die Geschichte einer erfolgreichen Invasion, die während des letzten Jahrhunderts in Europa ablief trotz der Tatsache, dass die Arten obligate Fremdbefruchter sind und dass keine Samen-Produktion in der Region beobachtet wurde. Dieses Manuskript erläutert den Weg der Pflanze, um die “Baker-Regel“ zu umgehen. Diese Regel besagt, dass selbst-inkompatible Arten erfolgloser bei der Invasion neuer Lebensräume sind. Dennoch schafft es die hier untersuchte Art einen großen Teil der europäischen Rasen zu bevölkern und zeigt dabei genetische und morphologische Veränderungen auf diesem Weg.rnSchließlich wird in diesen drei verschiedenen Papieren versucht, die Verbindung zwischen der Mikro-und Makroevolution in der geschlechtlichen Fortpflanzun in Ehrenpreis (Veronica) unter Betracht verschiedener sexueller Systeme und der Stammesgeschichte, sowie der Migration zu klären.

Analysis of the Nicotiana tabacum Stigma/Style Transcriptome Reveals Gene Expression Differences between Wet and Dry Stigma Species

The success of plant reproduction depends on pollen-pistil interactions occurring at the stigma/style. These interactions vary depending on the stigma type: wet or dry. Tobacco (Nicotiana tabacum) represents a model of wet stigma, and its stigmas/styles express genes to accomplish the appropriate functions. For a large-scale study of gene expression during tobacco pistil development and preparation for pollination, we generated 11,216 high-quality expressed sequence tags (ESTs) from stigmas/styles and created the TOBEST database. These ESTs were assembled in 6,177 clusters, from which 52.1% are pistil transcripts/genes of unknown function. The 21 clusters with the highest number of ESTs (putative higher expression levels) correspond to genes associated with defense mechanisms or pollen-pistil interactions. The database analysis unraveled tobacco sequences homologous to the Arabidopsis (Arabidopsis thaliana) genes involved in specifying pistil identity or determining normal pistil morphology and function. Additionally, 782 independent clusters were examined by macroarray, revealing 46 stigma/style preferentially expressed genes. Real-time reverse transcription-polymerase chain reaction experiments validated the pistil-preferential expression for nine out of 10 genes tested. A search for these 46 genes in the Arabidopsis pistil data sets demonstrated that only 11 sequences, with putative equivalent molecular functions, are expressed in this dry stigma species. The reverse search for the Arabidopsis pistil genes in the TOBEST exposed a partial overlap between these dry and wet stigma transcriptomes. The TOBEST represents the most extensive survey of gene expression in the stigmas/styles of wet stigma plants, and our results indicate that wet and dry stigmas/styles express common as well as distinct genes in preparation for the pollination process.

In vitro exposure of acer negundo pollen to atmospheric levels of SO2 and NO2: effects on allergenicity and germination

In the last years, a rising trend of pollen allergies in urban areas has been attributed to atmospheric pollution. In this work, we investigated the effects of SO2 and NO2 on the protein content, allergenicity, and germination rate of Acer negundo pollen. A novel environmental chamber was assembled to exposure pollen samples with SO2 or NO2 at two different levels: just below and two times the atmospheric hour-limit value acceptable for human health protection in Europe. Results showed that protein content was lower in SO2- exposed pollen samples and slightly higher in NO2-exposed pollen compared to the control sample. No different polypeptide profiles were revealed by SDSPAGE between exposed and nonexposed pollen, but the immunodetection assays indicated higher IgE recognition by all sera of sensitized patients to Acer negundo pollen extracts in all exposed samples in comparison to the nonexposed samples. A decrease in the germination rate of exposed in contrast to nonexposed pollen was verified, which was more pronounced for NO2-exposed samples. Our results indicated that in urban areas, concentrations of SO2 and NO2 below the limits established for human protection can indirectly aggravate pollen allergy on predisposed individuals and affect plant reproduction.

Reproductive ecology of the exotic tree Muntingia calabura L. (Muntingiaceae) in southeastern Brazil

The exotic tree Muntingia calabura L. (Muntingiaceae), a species native to Central America, is used as fish feed and fiber and cellulose production in Brazil. This study was carried out in urban areas and verified the reproductive biology of this plant species. Flower and fruit morphology, compatibility system, reproductive phenology, pollination and frugivore animals, and germination of disseminated seeds were recorded by standard field and laboratory procedures. This tree is self-compatible and autonomously self-pollinated, with its flowers being mainly visited by bees and its fruits consumed by birds and bats. Germination of its dispersed seeds is fast and occurs at a high rate. The results of this work suggest that M. calabura is very adaptable to cultivated areas,thus being an excellent choice for urban reforestation. However, its reproductive characteristics place this plant as an invasive species with significant potential in southeastern Brazil.

Sistemas reprodutivos de espécies de Melastomataceae da Serra do Japi, Jundiaí, São Paulo, Brasil

Neste trabalho foram investigados os sistemas reprodutivos de espécies de Melastomataceae ocorrentes em formações florestais da Serra do Japi. Esta investigação foi baseada em polinizações controladas e em análises de viabilidade de pólen e de crescimento de tubo polínico. Entre as populações de 13 espécies estudadas, sete mostraram produção de frutos apomíticos (Leandra australis, L. melastomoides, L. purpurascens, Miconia latecrenata, M. petropolitana, Ossaea amygdaloides e O. confertiflora). Entre as seis espécies não apomíticas, apenas uma apresentou mecanismo de auto-incompatibilidade (Miconia pusilliflora), enquanto que as demais se mostraram auto-compatíveis (Leandra dasytricha, L. regnellii, Tibouchina cerastifolia, T. sellowiana e T. semidecandra). A análise de pólen mostrou que as espécies apomíticas produzem uma proporção de grãos viáveis significativamente menor do que aquelas que não são apomíticas.

Rock outcrop vegetation in Brazil: a brief overview

This paper overviews the special issue of the Brazilian Journal of Botany dedicated to "Rock outcrop vegetation in Brazil". The main topics covered by this issue are phytogeography and vegetation ecology, plant life on shallow soils, plant reproduction and auto-ecology, morpho-physiology and plant adaptation, and finally conservation and global change. This collection of studies, in addition to other recent publications on Brazilian rocky outcrop vegetation, show that measurements of most of the relevant ecological and evolutionary parameters are under way and that scientific attention is now given to most Brazilian regions. However, there are still several gaps to be bridged: 1) inselbergs and high mountains in the Amazon and the Brazilian northeast, in particular, are still largely unknown to science; 2) long-term studies are almost totally unavailable, which hinders global change monitoring and assessment; 3) national and international networking are urgently needed to speed up scientific production about such habitats.

Implication du peptide ScRALF3 dans le développement du gamétophyte femelle chez Solanum chacoense

La coordination du développement par les communications intercellulaires est essentielle pour assurer la reproduction chez les plantes. Plusieurs études démontrent qu’une communication entre le sac embryonnaire et le tissu maternel, le sporophyte, est essentielle au bon développement des gamètes. Les molécules, peptides ou autres protagonistes impliqués dans ces voies de signalisation ainsi que leur mode d’action restent toutefois nébuleux. Les gènes de type RALF codent pour des petits peptides sécrétés retrouvés de manière spécifique ou ubiquitaire dans la plante. Leur structure en font de parfaits candidats pour permettre ces communications cellule-cellule entre les différents tissus. Treize gènes de type RALF ont été isolés actuellement chez la pomme de terre sauvage Solanum chacoense. Maintenant, nous montrons qu’un de ceux-ci, ScRALF3, est impliqué dans la polarisation du sac embryonnaire et dans la synchronicité des divisions mitotiques assurant la formation d’un gamétophyte femelle mature fonctionnel. Étant exprimé de manière spécifique au niveau des téguments de l’ovule, ScRALF3 est un candidat idéal pour réguler les communications cellule-cellule entre le sporophyte et le sac embryonnaire.

Analysis of the Nicotiana tabacum Stigma/Style Transcriptome Reveals Gene Expression Differences between Wet and Dry Stigma Species

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A tobacco cDNA reveals two different transcription patterns in vegetative and reproductive organs

In order to identify genes expressed in the pistil that may have a role in the reproduction process, we have established an expressed sequence tags project to randomly sequence clones from a Nicotiana tabacum stigma/style cDNA library. A cDNA clone (MTL-8) showing high sequence similarity to genes encoding glycine-rich RNA-binding proteins was chosen for further characterization. Based on the extensive identity of MTL-8 to the RGP-1a sequence of N. sylvestris, a primer was defined to extend the 5′ sequence of MTL-8 by RT-PCR from stigma/style RNAs. The amplification product was sequenced and it was confirmed that MTL-8 corresponds to an mRNA encoding a glycine-rich RNA-binding protein. Two transcripts of different sizes and expression patterns were identified when the MTL-8 cDNA insert was used as a probe in RNA blots. The largest is 1,100 nucleotides (nt) long and markedly predominant in ovaries. The smaller transcript, with 600 nt, is ubiquitous to the vegetative and reproductive organs analyzed (roots, stems, leaves, sepals, petals, stamens, stigmas/styles and ovaries). Plants submitted to stress (wounding, virus infection and ethylene treatment) presented an increased level of the 600-nt transcript in leaves, especially after tobacco necrosis virus infection. In contrast, the level of the 1,100-nt transcript seems to be unaffected by the stress conditions tested. Results of Southern blot experiments have suggested that MTL-8 is present in one or two copies in the tobacco genome. Our results suggest that the shorter transcript is related to stress while the larger one is a flower predominant and nonstress-inducible messenger.

Uso e conservação de Piper cernuum Vell. (Piperaceae) na Mata Atlântica: I. Fenologia reprodutiva e dispersão de sementes

The pariparoba (Piper cernuum Vell.), a native plant from the Atlantic Tropical Forest (ATF), has been commonly used in folk medicine. Works seeking the exploitation of P. cernuum natural populations need to be accomplished, seeking compatibility in obtaining income rates and preservation of ATF. The present work aimed to study the reproductive phenology and seed dispersal in P. cernuum natural population in the counties of Sete Barras/SP (Parque Estadual Intervales - PEI). The population of P. cernuum studied in PEI presented continuously bud-inflorescences, green-infrutescences and bud-inflorescence emission, with variation among individuals. Fruit-set average was of 9.1%, varying among individuals. Shading and foliar damage presented negative effect on the fruit-set. Three species of bats were identified as potential dispersors of the P. cernuum seeds: Carollia perspicillata, Anoura geoffroyi and Artibeus sp. The foragement strategy observed was the withdrawal of some seeds per infrutescence per flight. This strategy increases the potential in establishing new plants as well as in increase the potential of gene flow in comparison with the entire infrutescence plant eaten at the night perches. In consequence, the results of reproductive phenology and seed dispersal ecology presented in this work can help to establish management and conservation strategies of P. cernuum natural populations in the ATF.

Anthropogenic edges, isolation and the flowering time and fruit set of Anadenanthera peregrina, a cerrado savanna tree

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Fire and the reproductive phenology of endangered Madagascar sclerophyllous tapia woodlands

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Costs and benefits of reproducing under unfavorable conditions: an integrated view of ecological and physiological constraints in a cerrado shrub

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)