The flowers of the species belonging to the genus Passiflorashow a range of features that are thought to have arisen as adaptations to different pollinators. Some Passiflora species belonging to the subgenus Decaloba sect. Xerogona, show touch-sensitive motile androgynophores. We tested the role of auxin polar transport in the modulation of the androgynophore movement by applying auxin (IAA) or an inhibitor of auxin polar transport (NPA) in the flowers. We recorded the movement of the androgynophore during mechano-stimulation and analyzed the duration, speed, and the angle formed by the androgynophore before and after the movement, and found that both IAA and NPA increase the amplitude of the movement in P. sanguinolenta. We hypothesize that auxin might have a role in modulating the fitness of these Decaloba species to different pollination syndromes and demonstrate that an interspecific hybrid between insect- and hummingbird-pollinated Xerogona species present a heterosis effect on the speed of the androgynophore movement.

Citrus sinensis is a perennial woody species, for which genetic approaches to the study of reproductive development are not readily amenable. Here, the usefulness of the CitEST Expressed Sequence Tag (EST) database is demonstrated as a reliable new resource for identifying novel genes exclusively related to Citrus reproductive biology. We performed the analysis of an EST dataset of the CitEST Project containing 4,330 flower-derived cDNA sequences. Relying on bioinformatics tools, sequences exclusively present in this flower-derived sequence collection were selected and used for the identification of Citrus putative flower-specific genes. Our analysis revealed several Citrus sequences showing significant similarity to conserved genes known to have flower-specific expression and possessing functions related to flower metabolism and/or reproductive development in diverse plant species. Comparison of the Citrus flower-specific sequences with all available plant peptide sequences unraveled 247 unique transcripts not identified elsewhere within the plant kingdom. Additionally, 49 transcripts, for which no biological function could be attributed by means of sequence comparisons, were found to be conserved among plant species. These results allow further gene expression analysis and possibly novel approaches to the understanding of reproductive development in Citrus.

Floral transition is one the most drastic changes occurring during the life cycle of a plant. The shoot apical meristem switches from the production of leaves with associated secondary shoot meristems to the production of flower meristems. This transition is abrupt and generally irreversible, suggesting it is regulated by a robust gene regulatory network capable of driving sharp transitions. The moment at which this transition occurs is precisely determined by environmental and endogenous signals. A large number of genes acting within these pathways have been cloned in model herbaceous plants such as Arabidopsis thaliana. In this paper, we report the results of our search in the Citrus expressed sequence tag (CitEST) database for expressed sequence tags (ESTs) showing sequence homology with known elements of flowering-time pathways. We have searched all sequence clusters in the CitEST database and identified more than one hundred Citrus spp sequences that codify putative conserved elements of the autonomous, vernalization, photoperiod response and gibberelic acid-controlled flowering-time pathways. Additionally, we have characterized in silico putative members of the Citrus spp homologs to the Arabidopsis CONSTANS family of transcription factors.

Terpenes are a very large and structurally diverse group of secondary metabolites which are abundant in many essential oils, resins and floral scents. Additionally, some terpenes have roles as phytoalexins in plant-pathogen relationships, allelopathic inhibitors in plant-plant interactions, or as airborne molecules of plant-herbivore multitrophic signaling. Thus the elucidation of the biochemistry and molecular genetics of terpenoid biosynthesis has paramount importance in any crop species. With this aim, we searched the CitEST database for clusters of expressed sequence tags (ESTs) coding for terpene synthases. Herein is a report on the identification and in silico characterization of 49 putative members of the terpene synthase family in diverse Citrus species. The expression patterns and the possible physiological roles of the identified sequences are also discussed.

O trabalho científico seminal de Goethe, Versuch die Metamorphose der Pflanzen zu erklaren (Uma Tentativa de Interpretação da Metamorfose das Plantas), datado de 1790, criou a fundação para muitos domínios da biologia vegetal moderna. O conceito do arquétipo foliar, que considera os órgãos florais como folhas modificadas, é o mais conhecido e provou ser verdadeiro após a descrição molecular do modelo ABC para a determinação da identidade dos órgãos florais durante a última década. Todo o aparato teórico desse trabalho de Goethe de 1790 é analisado aqui e dois aspectos previamente desconsiderados da obra são reinterpretados: O conceito de ¨purificação da seiva¨ como um princípio direcional e os ¨ciclos de contração e retração¨ como ciclos de determinação diferencial do meristema apical caulinar. A reinterpretação desses conceitos concorda com a visão moderna de que redes de interações moleculares integram sinais endógenos e ambientais e regulam o desenvolvimento vegetal. Esta reanálise auxilia ainda na formalização de um arcabouço teórico que considera a conservação evolutiva dos mecanismos moleculares que regulam o desenvolvimento vegetal.

Goethe’s seminal scientific work, Versuch die Metamorphose der Pflanzen zu erklaren (An Attempt to Interpret the Metamorphosis of Plants) dated from 1790, has created the foundations for many domains of modern plant biology. The archetypal leaf concept, which considers floral organs as modified leaves, besides being the best known has been proven true, following the description of the ABC molecular model of floral organ identity determination during the last decade. Here we analyze the whole theoretical frame of Goethe’s 1790 publication and present two previously misconsidered aspects of this work: The "refinement of the sap" concept as a directional principle and the "cycles of contractions and expansions" as cycles of differential determination of the shoot apical meristem. The reinterpretation of these concepts are in line with the modern view that molecular networks integrate both environmental and endogenous cues and regulate plant development. This reassessment also helps to elaborate a theoretical frame that considers the evolutionary conservation of the molecular mechanisms that regulate plant development.

As decisões envolvidas na iniciação do processo de florescimento dependem da expressão equilibrada de uma rede complexa de genes, que é regulada por fatores endógenos e ambientais. A regulação correta da transição para o florescimento é crucial para o sucesso reprodutivo das plantas; dessa forma elas desenvolveram mecanismos moleculares conservados para integrar tanto indícios ambientais como endógenos para regular precisamente o tempo do florescimento. Avanços recentes na biologia molecular vegetal, incluindo o seqüenciamento completo de genomas, tornaram possível a comparação detalhada de genomas vegetais. Assim, estudos comparativos de genômica funcional estão emergindo como ferramentas poderosas para a identificação de genes envolvidos no regulamento das vias metabólicas relacionadas ao florescimento. Neste artigo são apresentados resultados da busca no banco de dados do Projeto FORESTS (Eucalyptus Genome Sequencing Project Consortium) para a obtenção de etiquetas de seqüências expressas (ESTs) mostrando homologia com elementos-chave das vias reguladoras do florescimento. Os 33.080 ¨clusters¨ de ESTs de Eucalyptus spp. disponíveis no banco de dados do FORESTS foram analisados, e identificaram-se elementos conservados, possivelmente envolvidos nas vias controladoras do florescimento, quer sejam as autônomas, quer as controladas por vernalização, por ácido giberélico ou por fotoperíodo. Adicionalmente, foram caracterizados in silico dez possíveis membros da família CONSTANS de fatores de transcrição de Arabidopsis, em Eucalyptus.

Flowering initiation depends on the balanced expression of a complex network of genes that is regulated by both endogenous and environmental factors. The timing of the initiation of flowering is crucial for the reproductive success of plants; therefore, they have developed conserved molecular mechanisms to integrate both environmental and endogenous cues to regulate flowering time precisely. Extensive advances in plant biology are possible now that the complete genome sequences of flowering plants is available and plant genomes can be comprehensively compared. Thus, association studies are emerging as powerful tools for the functional identification of genes involved on the regulation of flowering pathways. In this paper we report the results of our search in the Eucalyptus Genome Sequencing Project Consortium (FORESTS) database for expressed sequence tags (ESTs) showing sequence homology with known elements of flowering-time pathways. We have searched the 33,080 sequence clusters in the FORESTS database and identified Eucalyptus sequences that codify putative conserved elements of the autonomous, vernalization-, photoperiod response- and gibberellic acid-controlled flowering-time pathways. Additionally, we have characterized in silico ten putative members of the Eucalyptus homologs to the Arabidopsis CONSTANS family of transcription factors.

In angiosperms, flower formation is controlled by meristem identity genes, one of which, FLORICAULA (FLO)/LEAFY (LFY), plays a central role. It is not known if the formation of reproductive organs of pre-angiosperm species is similarly regulated. Here, we report the cloning of a conifer (Pinus caribaea var. caribaea) FLO/LFY homolog, named PcLFY. This gene has a large C-terminal region of high similarity to angiosperm FLO/LFY orthologs and shorter regions of local similarity. In contrast to angiosperms, conifers have two divergent genes resembling LFY. Gymnosperm FLO/LFY proteins constitute a separate clade, that can be divided into two divergent groups. Phylogenetic analysis of deduced protein sequences has shown that PcLFY belongs to the LFY-like clade. Northern hybridization analysis has revealed that PcLFY is preferentially expressed in developing female cones but not in developing male cones. This expression pattern was confirmed by in situ hybridization and is consistent with the hypothesis of PcLFY being involved in the determination of the female cone identity. Additionally, mutant complementation experiments have shown that the expression of the PcLFY coding region, driven by the Arabidopsis LFY promoter, can confer the wild-type phenotype to lfy-26 transgenic mutants, suggesting that both gymnosperm and angiosperm LFY homologs share the same biological role.

O gene EgLFY, clonado de Eucalyptus grandis, possui homologia de seqüência com o gene de identidade meristemática LEAFY (LFY) de Arabidopsis e FLORICAULA (FLO) de Antirrhinum. EgLFY é, preferencialmente, expresso nos órgãos florais em desenvolvimento de eucalipto, obedecendo a um padrão similar ao descrito para o gene LFY de Arabidopsis. Experimentos de hibridização in situ mostraram que o gene EgLFY é fortemente expresso em meristemas florais no início de seu desenvolvimento e, então, sucessivamente, durante a formação dos primórdios de sépalas, pétalas, estames e carpelos. Há expressão também nos primórdios foliares de árvores adultas. A expressão da região codificadora de EgLFY sob o controle do promotor do LFY de Arabidopsis pôde complementar mutantes lfy nulos em plantas de Arabidopsis transgênicas. Essas observações sugerem que o gene EgLFY possui um papel similar ao de LFY no desenvolvimento floral e que os mecanismos básicos envolvidos na iniciação e no desenvolvimento floral em Eucalyptus podem ser semelhantes aos de Arabidopsis.

The EgLFY gene cloned from Eucalyptus grandis has sequence homology to the floral meristem identity gene LEAFY (LFY) from Arabidopsis and FLORICAULA (FLO) from Antirrhinum. EgLFY is preferentially expressed in the developing eucalypt floral organs in a pattern similar to that described previously for the Arabidopsis LFY. In situ hybridization experiments have shown that EgLFY is strongly expressed in the early floral meristem and then successively in the primordia of sepals, petals, stamens and carpels. It is also expressed in the leaf primordia of adult trees. The expression of the EgLFY coding region under control of the Arabidopsis LFY promoter could complement strong lfy mutations in transgenic Arabidopsis plants. These data suggest that EgLFY plays a similar role to LFY in flower development and that the basic mechanisms involved in flower initiation and development in Eucalyptus may be similar to those occurring in Arabidopsis.

A elaboração da forma e função das plantas depende da habilidade de a célula vegetal dividir-se e diferenciar-se. As decisões tomadas por células individuais de entrar em divisão, manter a proliferação, tornarem-se quiescentes, expandir, diferenciar ou morrer, dependem da comunicação intercelular e da percepção de vários sinais. Esses podem incluir hormônios, nutrientes, luz, temperatura e/ou outros indicadores de posicionamento interno. Recentemente, têm sido alcançados progressos na compreensão do controle molecular da formação de padrões de desenvolvimento em plantas, especialmente na planta-modelo Arabidopsis thaliana. Adicionalmente, genes específicos têm sido identificados como necessários para a formação de padrões normais e para o controle das taxas de divisão e diferenciação. A clonagem de tais genes tem revelado a base molecular da formação de padrão em plantas e identificado os principais elementos nos sistemas de transdução em vegetais.

The elaboration of plant form and function depends on the ability of a plant cell to divide and differentiate. The decisions of individual cells to enter the cell cycle, maintain proliferation competence, become quiescent, expand, differentiate, or die depend on cell-to-cell communication and on the perception of various signals. These signals can include hormones, nutrients, light, temperature, and internal positional and developmental cues. In recent years, progress has been made in understanding the molecular control of plant pattern formation, especially in the model plant Arabidopsis thaliana. Furthermore, specific genes have been found that are necessary for normal pattern formation and the control of the rates of cell division and differentiation. Cloning of these genes is revealing the molecular basis of plant pattern formation and the key players on plant signal transduction systems.

Com o objetivo de estudar a organogênese in vitro em Passiflora edulis Sims f. flavicarpa Deg., o maracujá-amarelo, explantes derivados de folha foram cultivados em meio contendo NAA ou BAP, no escuro e na presença de luz. Foram descritos os eventos histológicos que levam à formação de novo de órgãos. Concluiu-se que o escuro induz a rizogênese, na presença de NAA, enquanto a regeneração de brotos é estimulada pela luz e BAP. Esta condição é recomendada para micropropagar o maracujá uma vez que vários brotos adventícios são formados a partir de meristemóides de origem parenquimática.

With the aim of studying the organogenesis in vitro in Passiflora edulis Sims f. flavicarpa Deg., the passionfruit, leaf-derived explants were cultured on media containing NAA or BAP and incubated either in continuous darkness or in light. The histological events leading to de novo organ formation were evaluated. Darkness induces rhizogenesis in the presence of NAA, whereas direct shoot regeneration is stimulated by light and BAP. This latter condition is recommended for passionfruit micropropagation as several adventitious shoot buds were formed from meristemoids of parenchymal origin.