Le déterminisme du sexe est un processus qui aboutit à la séparation physique des structures à l’origine des gamètes mâles et femelles, soit sur des fleurs séparées sur une même plante, pour les espèces monoïques, soit sur des individus séparés, dans le cas des espèces dioïques. Ce mécanisme favorise la fécondation croisée et augment ainsi la variabilité génétique. Il pourrait être influencé par les facteurs endogène (génétique ou hormonal) ou environnementaux. Chez le melon, le déterminisme du sexe est contrôlé par le gène A (andromonoecious) et le gène G (gynoecious). Le gène A code pour 1-aminocyclopropane-1-carboxylique acide synthase (ACS), un enzyme impliqué dans la voie de biosynthèse d’éthylène qui inhibe le développement des étamines dans les fleurs femelles. Le gène G code pour une protéine C2H2 à doigt de zinc appartenant à la famille WIP de facteurs de transcription qui inhibe le développement des capelles dans les fleurs mâles. Chez Arabidopsis thaliana, Il y a six gènes WIP et on en sait très peu sur leur fonction moléculaire. TT1/AtWIP1 est impliqué à l’accumulation de PA dans endothélium de graines. NTT/AtWIP2 est impliqué dans le développement de TRANSMITTING TRACT de carpelle. Dans cette thèse, nous avons essayé de mettre en évidence la fonction moléculaire de gènes WIP. Dans cette étude, nous avons montré que les gènes WIP des espèces différents partiellement restaurent le phénotype de graines jaune de tt1-3 mutants et régulent positivement les gènes tardifs de biosynthèse de flavonoïdes chez Arabidopsis thaliana La complémentation fonctionnelle de mutants tt1-3 par le gène WIP de melon et le gène WIP de la mousse montre que les gènes WIP ont la même fonction globale mais diffèrent à l’échelle spatio-temporelle. Il a été montré que le second motif conservé, à l’extrémité N-terminal, du gène TT1 était essentiel pour qu’il soit fonctionnel. La substitution d’acides aminés de ce motif (N2) par des alanines diminue l’accumulation de proanthocyanidines (PA) dans l’endothélium de la graine. TT1 perturbe également le développement des pétales, des étamines et des carpelles quand il est surexprimé de manière ectopique sous le contrôle des promoteurs d’AP3 et CRC. Il a été exprimé dans les racines secondaires sous le promoteur du gène SOLITARY ROOT (SLR/IAA14) ainsi que dans les stipules sous le promoteur du gène GLABROUS1 (GL1). TT1 inhibe le développement des racines secondaires et la formation des trichomes sur les feuilles. Dans cette étude, nous avons constaté que TT1 agit comme un inhibiteur de la formation d’organes quand il est exprimé de manière ectopique. On cherchera dans cette étude à comprendre les mécanismes mis en jeu lors de l’arrêt du développement de ces organes au cours du déterminisme du sexe et a évoqué de nouvelles pistes pour expliquer ce processus. / Sex determination in plants is a process that results the development of either male or female flower on the same or different individuals. This mechanism enhances the cross pollination and raises the genetic variability. It can be influenced by endogenous (genetic or hormonal) and/or external environmental factors. In melon, gene A arrests the stamen development in the female flowers and gene G arrests the development of carpel in the male flowers hence these two genes control the sex determination mechanism in melon. Gene A encodes 1-aminocyclopropane-1-carboxylic acid synthase (ACS), an enzyme which is involved in the ethylene biosynthesis pathway. Gene G encodes a C2H2 zinc finger proteins that belongs to WIP family of transcription factors. In Arabidopsis thaliana, there are six WIP genes and very little is known about their molecular function. TT1/AtWIP1 is involved in the accumulation of PA in the seed endothelium. NTT/AtWIP2 is involved in the development of transmitting tract in the carpel. In this thesis, we tried to highlight the molecular function of the WIP genes. Here we show that WIP genes from different species partially restore the yellow seed coat color phenotype of tt1-3 mutant and upregulate the late flavonoid biosynthetic genes. The functional complementation of tt1-3 mutants by WIPs from Cucumis melo and Physcomitrella patens indicates that WIP genes have the same global function but differ on the spatio-temporal level. Second conserved motif in the N-terminus of TT1 protein was found to be essential for its proper function as alanine scanning of N2 motif of TT1 decreased the accumulation of PAs in the seed endothelium. TT1 disturbed the development of petals, stamens and carpels in flower when ectopically expressed under AP3 and CRC promoter. TT1 was expressed in the lateral roots under the promoter of SOLITARY ROOT (SLR/IAA14) and in the stipules under the promoter of GLABROUS1 (GL1). TT1 was able to inhibit the development of the lateral roots and leaf trichomes. In this study, we found that TT1 can act as organ inhibitor when ectopically expressed. Our study will help us to understand the organ arrest during sex determination mechanism and will evoke new dimensions for further explanations of this process.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-04-13T14:28:14Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Versão definitiva dissertação.pdf: 2215795 bytes, checksum: 6ae1c11599069fa2b9b187adf1935e10 (MD5) / Made available in DSpace on 2016-04-13T14:28:15Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Versão definitiva dissertação.pdf: 2215795 bytes, checksum: 6ae1c11599069fa2b9b187adf1935e10 (MD5) Previous issue date: 2015-08-27 / CNPq / A maioria dos remanescentes de floresta Atlântica no Brasil são pequenas florestas secundárias em regeneração, muitas ocorrendo em áreas urbanas. Espécies arbóreas de remanescentes florestais indicam nível de perturbação, estágio sucessional e mudanças durante a regeneração. O objetivo dessa dissertação é conhecer a composição florística e fitossociológica arbórea de um fragmento urbano de floresta Atlântica em regeneração e verificar sua similaridade com remanescentes urbanos. Testou-se a hipótese de que remanescentes seriam menos similares quanto mais distantes fossem e que fragmentos de tamanhos semelhantes seriam mais similares que os de diferentes tamanhos. No remanescente em regeneração instalou-se 18 parcelas de 10 x 10m para a fitossociologia e realizaram-se expedições quinzenais de setembro de 2013 a dezembro de 2014 para coleta de espécies em estádio reprodutivo. Nos demais fragmentos, o levantamento florístico ocorreu mediante publicações florísticas e fitossociológicas. Médias de diâmetros e alturas das arbóreas do remanescente em regeneração foram de 15±14 cm e 9,54±3,5m, respectivamente e assemelham-se àquelas de florestas em estágio sucessional inicial. A maior similaridade foi encontrada entre a Mata da Guabiraba e o Parque Estadual de Dois Irmãos (0,43), que são fragmentos próximos e semelhantes em área. Na composição das comunidades desses remanescentes Tapirira guianensis Aubl e Eschweilera ovata Cambess. sobressaíram-se entre as espécies mais abundantes e frequentes, sendo que a primeira também se destacou com maior valor de importância e densidade. Outro objetivo dessa dissertação foi obter a diversidade funcional desses remanescentes, pois ela indica interações que os sustentam, a partir de atributos florais das arbóreas. Compararam-se atributos florais, síndromes de polinização e diversidade funcional desses remanescentes florestais urbanos. Testou-se a hipótese de que remanescentes diferem quanto a frequência dos atributos florais, síndromes de polinização e diversidade funcional. Nos demais fragmentos utilizaram-se publicações fitossociológicas e os dados de atributos florais obtidos em herbários e na literatura. Nos remanescentes predominaram flores generalistas, melitófilas (41% e 58%) e formaram-se grupos de fragmentos por atributos florais e síndromes de polinização, o que corrobora parcialmente a hipótese. Os remanescentes estudados não diferiram quanto à diversidade funcional de atributos florais (p = 0,99). Estudos como esse trazem contribuições para a compreensão sobre a diversidade e a estrutura das comunidades vegetais em remanescentes urbanos que devido às suas particularidades, sobretudo pela paisagem na qual se inserem podem apresentar uma dinâmica distinta do que ditam as teorias ecológicas. / The Atlantic forest remnants in Brazil mostly are small secondary forests in regeneration, many occurring in urban areas. Tree species of forest remnants indicate level of disturbance, successional stage and changes during regeneration. The goal of this dissertation is to know the floristic composition and phytosociology of tree of an urban fragment of Atlantic forest regeneration and verify its similarity to other urban forest remnants. The hypothesis tested was that remaining would present smaller the further away they were similarity and similar size fragments would be more similar than different sizes, they were installed 18 plots of 10 x 10m for the study phytosociological and held fortnightly expedition between September 2013 and December 2014 to collect of species in stage reproductive. In the remaining fragments, of the floristic survey occurred through floristic studies and published phytosociological. Average diameters and heights of the remaining tree regeneration were 15 ± 14 cm and 9,54 ± 3,5 m, respectively, and resemble those of forests in early successional stage. Similarity highest was found between the Forest Guabiraba and Parque Estaadual Dois Irmão (0,43), which are fragments near and similar in area. In community composition of these remaining Tapirira guianensis Aubl. and Eschweilera ovata Cambess. stood out among the most abundant and frequent species, with the first also excelled with highest importance value and density. Another aim of this thesis was to obtain the functional diversity of these remnants, as it indicates interactions that maintain them from floral traits of the tree. Compared to floral traits, pollination syndromes and functional diversity of these urban forest remnants. We tested the hypothesis that remaining differ in the frequency of floral attributes, pollination syndromes and functional diversity. In the remaining fragments were used in phytosociological publications and floral attributes of data from herbarium and literature. In general predominant remaining flowers, mellittophilous (41% and 58%) and were formed by groups of fragments and floral attributes pollination syndromes, which partially supports the hypothesis. The remaining studies did not differ in the functional diversity of floral traits (p = 0,99). Such studies bring contributions to the understanding of the diversity and structure of plant communities in urban remnants that because of their specific particularly the landscape in which they operate may have a different dynamic than dictate the ecological theories.

Observation of floral visitation is an accepted method to describe plant-pollinator interactions despite potential biases. Collecting pollen from pollinators offers new insights on the structure and function of plant-pollinator communities. Furthermore, the strength and frequency of plant-pollinator interactions can vary across temporal scales. However, within-season and within-day (morning vs. evening) variation in plant-pollinator networks has been little studied. By evaluating variation in network structure across these biologically relevant time scales, we will gain a better understanding of the factors that shape plant-pollinator communities. The objectives of this study are to 1) Compare the structure of plant-pollinator networks built on floral visitation and pollen transport data, 2) Evaluate intra-annual variation in plant-pollinator network structure and 3) Evaluate variation in plant-pollinator structure within a single day (i.e. morning vs. evening). Congruence and Temporal Variation of Floral Visitation and Pollen Transport Networks in Southern Appalachia

Increasing evidence documenting the decline of insect populations, resulting from increasing human disturbances has resulted in efforts to establish pollinator gardens to provide additional resources for insect populations. However, our understanding of biotic and abiotic garden characteristics important for attracting and sustaining pollinator diversity is limited. Here, we evaluated 17 pollinator gardens to evaluate the effect of five biotic and three abiotic garden characteristics on pollinator species richness, abundance, and proportional representation of four pollinator functional groups. Plant species richness positively influenced pollinator richness and negatively influenced flower visitation. Bombus proportional abundance responded to several variables (distance to vegetation, plant species richness, floral symmetry, floral native status, habitat type), and decreases in their proportional representation were accompanied by increasing proportions of other insect groups. Our results suggest any size, diverse, native pollinator gardens can improve pollinator diversity, and small-scale pollinator gardens should favor functional groups adapted for the habitat type.

The evolutionary relevance of homeotic alterations for the origin of new taxonomic entities is still a controversial objective in plant sciences. In this context, the discovery of a floral homeotic variant of Capsella bursa-pastoris in natural populations offers the unique opportunity to elucidate the evolutionary significance of homeotic mutants in the wild. Since all petals are transformed into additional stamens, the variant was termed Stamenoid petals (Spe). In this thesis, a combination of ecological and molecular characterisation of the variant was performed, to improve the understanding of evolutionary processes in plant populations. Molecular markers were used to analyze genetic differentiation among known provenances and also within a large sympatric population of wild-type and homeotic mutant. The results clearly suggest a repeated evolution of the novel flower morphology. Furthermore, genetic analyses provided substantial evidence, that the two floral variants are well-defined into flower-type dependent sub-samples within one population. The evaluation of phenotypic traits elucidated that the homeotic variant is not hampered in fitness. In greenhouse and field experiments, a significant ecological differentiation in the onset of flowering was detected among variants. Finally, the novel floral phenotype shows a co-dominant inheritance, and a marker-assisted mapping approach exposed a single locus in a genetic map. In conclusion, the comprehensive study of ecological and molecular aspects indicates that the floral homeotic variant may be treated as an established taxonomic entity and proved the predicted role as model for evolutionary objectives. Since morphological alterations like Spe are discussed as a result of macroevolution, the homeotic variant of C. bursa-pastoris provides the opportunity to survey a (macro)evolutionary novelty in association with continuous micro-evolutionary adaptation

Traditionally managed temperate semi-natural meadows are generally considered as one of the most diverse habitats worldwide. During the past decades, management changes and abandonment of meadows pose serious threats to communities of both flowering plants and pollinators. However, the extent to which are pollinators affected by changes in floral resources still remain unknown. To investigate the effect of floral resources on visitation specialization, species richness and abundance of hoverflies, pollination networks from 13 meadows in the Železné hory PLA were constructed and analysed. Moreover, patterns were recorded on two spatial scales, in transects and in the whole meadows. To specify the specialization of hoverfly pollinators, unvisited plant species and all resources present on a site (transect/meadow), offered by plants as floral abundance and nectar rewards, was added in the networks. Relationships between plant species richness, floral abundance and nectar sugar production were positively correlated with visitation specialization of hoverflies on the meadow scale. Species richness and abundance of hoverflies was affected by floral resources on the transect scale, unlike the specialization of hoverflies. The usage of extended network indices may act as an improvement towards the better...

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Natural selection mediated by pollinators has influenced the evolution of floral diversity of the flowering plants (angiosperms). The scope of this thesis was to study: 1) phenotypic selection, 2) mating systems, and 3) floral shifts involved in plant speciation. Model plant species were Platanthera bifolia and P. chlorantha (Orchidaceae). These orchids are moth-pollinated, strictly co-sexual (bisexual flowers), and produce a spike that displays 10-20 white flowers. I explored the influence of characters on plant fitness by using multiple linear regressions. Pollen removal (male fitness) and fruit set (female fitness) increased with more flowers per plant in three P. bifolia populations. There was selection towards longer spurs in a dry year when average spur length was shorter than in normal-wet years. Female function was sensitive to drought, which enabled an application of the male function hypothesis of floral evolution (Bateman's principle). The results show that selection may vary between populations, years, and sex-functions. I examined inbreeding by estimating levels of geitonogamy (self-pollination between flowers of an individual) with an emasculation method in two P. bifolia populations. Geitonogamy did not vary with inflorescence size. Levels of geitonogamy was 20-40% in the smaller, but non-significant in the larger population. This may relate to lower number of possible mates and pollinator activity in the smaller population. Platanthera bifolia exhibits the ancestral character state of tongue-attachment of pollinia on the pollinator. Its close relative P. chlorantha attaches its pollinia onto the pollinator's eyes. To explore the mechanism of a floral shift, pollination efficiency and speed was compared between the two species. The results showed no differences in pollination efficiency, but P. chlorantha had faster pollen export and import. Efficiency of pollination in terms of speed may cause floral shifts, and thus speciation.

"The area of study was restricted to those common flowering herbs of Denton County, Texas, which have conspicuous flowers or a conspicuous flower cluster. There were, however, many plants included in this flora which are common to several counties of north-central Texas. Since there has been no previous key devised for the herbs of Denton County, Texas, the purpose of this key was to provide a flora which could be used by elementary and high school instructors, as well as any other interested persons who lack an extensive knowledge of botanical nomenclature." -- leaf iv.