Les racines de la plupart des arbres forment des symbioses ectomycorhiziennes avec les champignons mutualistes du sol. Le basidiomycète L. bicolor (Maire) P.D. Orton secrète de petites protéines effectrices (MiSSP) afin d'établir les structures symbiotiques. Toutefois, les protéines de l'hôte ciblées par les MiSSPs ne sont pas connues. Dans notre étude, nous démontrons, à l'aide du système double hybride chez la levure (Y2H), que la protéine MiSSP7 interagit avec les co-récepteurs de l'acide jasmonique (AJ) JAZ5 et JAZ6 de P. trichocarpa. Cette interaction entraine un blocage de la voie de signalisation de l'AJ et favorise le développement symbiotique. Des transformants de L. bicolor, dont l'expression de MiSSP7 est fortement réduite, ne sont plus capables de mycorhizer les racines du peuplier. Une variation transgénique de la transcription de PtJAZ6 ou l'inhibition de la voie de signalisation de l'AJ complémente ce phénotype. Nous avons également montré que la protéine PtJAZ6 interagit avec une protéine de type 14-3-3 et un facteur de transcription de type MYC, formant un complexe de régulation. Deux autres protéines effectrices, MiSSP8 et MiSSP17, sont sécrétées et essentielles au développement symbiotique. Les résultats des analyses Y2H suggèrent que MiSSP8 et MiSSP17 pourraient aider au contournement des réactions de défense de la plante-hôte. Au cours du développement symbiotique, le champignon est le siège d'une reprogrammation génétique importante. Les facteurs de transcription (TFs) sont les principaux acteurs de ces changements génétiques. Nous avons donc étudié les TFs de L. bicolor afin d'obtenir un inventaire complet des TFs régulés par la mycorhization / Roots of most trees form symbiosis with mutualistic soil-borne fungi. The ectomycorrhizal basidiomycete L. bicolor (Maire) P.D. Orton relies on mycorrhizal-induced small secreted proteins (MiSSP) to establish symbiotic tissues in the host-plant. The host proteins targeted by these fungal effectors are yet unknown. In the present study, we used the binary yeast two-hybrid (Y2H) system to determine direct interactions between MiSSP7 and the plant proteins in the L. bicolor-P. trichocarpa ectomycorrhizae. We showed that MiSSP7 interact with the jasmonic acid (JA) co-receptors JAZ5 and JAZ6 of P. trichocarpa, blocking JA signaling and promoting mutualism. L. bicolor transformants with severely reduced expression of MiSSP7 did not enter into symbiosis with poplar roots, a phenotype that could be complemented by transgenically varying the transcription of PtJAZ6 or through inhibiting JA signalling. Additional Y2H assays showed that PtJAZ6 protein form a regulatory complex involving 14-3-3 protein(s) and MYC transcriptional factors. Two others L. bicolor effector-like proteins, MiSSP8 and MiSSP17, are secreted and are essential for the symbiosis development. Y2H assays suggested that these MiSSPs interact with plant proteins involved in plant defence signalling pathways. During symbiosis development, L. bicolor experiences important genetic reprogramming required for root colonization. Transcription factors (TFs) are key players of these genetic changes. Here, we developed high throughput analysis of TFs in L. bicolor to obtain a comprehensive inventory of significantly regulated transcription factors in ECM

A problem with the city is that urban development, for the last decades, has neglected the human scale. Since capitalism and modernism the focus has shifted towards the modern man, a new rational being separated from nature rather than nature being an ever present part of life. Adopting an architecture where form follows function. Focus is on designing for the market and economy which has generated a culture of consumption and capitalist cities plagued by environmental issues and social inequality and cities are not fulfilling essential needs of a big portion of the people living there. Our culture and cities have ecological ramifications that extend beyond its borders disrupting the very basic needs of human life.  Architecture must be designed for the collective rather than the ego. Rather than the few designing for the many, people should be a part of the making and remaking of the city and society. Design and architecture should rediscover our place in ecosystems and learn from nature how to adapt and be transformable. It should be inclusive, participatory and comprehensive to improve resilience.  Building laboratory explores how design and architecture can become mutalistic by including, teaching and learning from the inhabitants. Constructing by using simple strategies and local material.

Symbioses between microbes and multicellular eukaryotes are found in all biomes, and encompass a spectrum of symbiotic lifestyles that includes parasitism and disease, commensalism, and mutually beneficial interdependent host-microbe relationships. Regardless of outcome, these symbiotic lifestyles are governed by a complex molecular "courtship" between microbe and potential host. This courtship is the primary determinant of the host range of a given microsymbiont. Host immunity poses a formidable barrier to the establishment of host-microbe relationships, and the majority of microbial suitors will be thwarted by it. Only by successfully "wooing" the host cell's immune defenses with the appropriate molecular signals can a microsymbiont successfully colonize its host. A strategy common to microsymbionts across the spectrum of symbiotic lifestyles and host organisms is the delivery of microbial-encoded effector proteins into the cytoplasm of host cells to manipulate the host cell's molecular machinery for the purposes of subverting host immunity. Bacteria, in particular, have adapted a number of secretion systems for this purpose. The most well-characterized of these is the type III secretion system (T3SS), a molecular apparatus that specializes in injecting type III effector (T3Es) proteins directly into host cells. The work in this thesis focuses on T3Es of plant-associated bacteria, with particular emphasis on mutualistic bacteria. We present evidence that collections of T3Es from Sinorhizobium fredii and Bradyrhizobium japonicum are, in stark contrast to those of phytopathogenic bacteria, in a co-evolutionary equilibrium with their hosts. This equilibrium is characterized by highly conserved T3E collections consisting of many "core" T3Es with little variation in nucleotide sequence. The T3Es of Mesorhizobium loti MAFF303099 suggest a completely different picture of the evolution of T3Es. MAFF303099 recently acquired its T3SS locus, and the work in this thesis provides an evolutionary snapshot of a mutualist that is innovating a T3E collection primarily through horizontal gene transfer. Collectively, this work represents the first comprehensive catalog of T3Es of rhizobia and, in the case of Sinorhizobium and Bradyrhizobium, the first evidence of purifying selection for T3Es. / Graduation date: 2012

A subset of 199 Melissotarsus insularis and 130 Diaspididae specimens were analyzed to 1) determine the species status of M. insularis and 2) to explore the relative intimacy of the relationship between M. insularis and Diaspididae. An analysis of molecular variance and the observed lack of association between clades and distinct habitats on the M. insularis phylogeny suggested that while M. insularis exhibits isolation by distance, it does not apparently diversify by habitat. When cryptic COI pseudogenes were accounted for, the majority of the genetic diversity exhibited by M. insularis was limited to a divergence of 3% or less suggesting that M. insularis represents a single, albeit broadly distributed, species. A cophylogenetic reconstruction of the relationship between M. insularis and Diaspididae yielded 14 “cospeciation” events but was not significant unlike reconstructions of host-parasite relationships. Analyses of reduced datasets suggested that incomplete taxon sampling may significantly affect cophylogenetic reconstruction results. / National Science Foundation (grants No. DEB-0072713, DEB-0344731 to BLF and DEB-0842395 to BLF and MAS), a Natural Sciences and Engineering Research Council of Canada Discovery Grant to MAS and a Leaders Opportunity Fund grant from the Canada Foundation for Innovation to MAS

Fundação de Amparo a Pesquisa do Estado de Minas Gerais / Ants that collect nectar from plants bearing extrafloral nectaries (EFN) can defend them against the attacks of herbivores. Many cases of this food-for-protection mutualism have been described and the next step is to understand the mechanisms that structure these interactions. In this study, this issue was addressed through field observations and experiments on ant behaviour in studies compiled into five chapters. Specifically, we evaluated the plant\'s investment in attracting ants (nectar quality) and the competitive relationship between ants (resource dominance hierarchies) as structuring mechanisms of ant-plant interactions. The entire study took place in areas of the ecosystem known as Rupestrian Fields, located in Ouro Preto (Brazil), between June 2011 and March 2014. In Chapter 1, we observe that ant-plant interaction network in Rupestrian Fields is nested and generalized as expected for mutualisms, but differs from ant-hemipteran network, its ecological equivalent, despite both share ant species interactions. In Chapter 2, we delve into the study of the effect of resources in interaction frequency, and we showed that the quality more than quantity of nectar determines the pattern of interaction between plants (10 species) and ants (32 species), as well as the benefits of this interaction (conditional outcomes). In the Chapter 3, we focus on the ants to demonstrate, using paired encounters, that ants species are organized in dominance hierarchies based on aggressiveness. This hierarchies affects the numerical dominance based on territoriality and, more importantly, in the dominance of interactions and nectar. Keeping this line of thought, we demonstrated in Chapter 4 that not all ants that collect nectar really protect the plant against herbivores but only the ecological dominant and highly interacted species. Finally, we close the thesis demonstrating in Chapter 5 that the ant species interacted with plants during the day are not the same at night, but this diurnal-nocturnal turnover does not affect the structure of the interactions by only changing the dominant species. This study brings behavioural and empirical evidences on the importance of the identity of the ant species and its ecological dominance, as well the effect of the nectar quality, for the structure of ant-plant interactions and effectiveness of mutualisms. / As formigas que recolhem o néctar das plantas com nectários extraflorais (EFN) podem defendê-las contra ataques de herbívoros. Muitos casos desse tipo de mutualismo foram descritos mas ainda é preciso entender os mecanismos que estruturam essas interações. Neste estudo, esse problema foi abordado através de observações de campo e experimentos sobre o comportamento das formigas compilados em cinco capítulos. Especificamente, foi avaliado o investimento da planta em atrair formigas (qualidade do néctar) e a relação competitiva entre formigas pelo néctar (hierarquias de dominância) como mecanismos estruturadores das interações formiga-planta (partição das interações). Todo o estudo ocorreu em áreas do ecossistema Campo Rupestre, localizadas em Ouro Preto (Brasil), de junho de 2011 a março de 2014. No Capítulo 1, observamos que redes de interação formiga-planta em Campo rupestre é aninhada e generalizada como esperado para mutualismos, mas difere da rede formiga-hemíptero, seu equivalente ecológico, apesar de compartilharem as mesmas espécies de formigas interagentes. No Capítulo 2, nós aprofundamos no efeito dos recursos estruturando interações, e mostramos que a qualidade mais do que a quantidade de néctar determina o padrão de interação entre formigas (32 espécies) e plantas (10 espécies), bem como os benefícios desta interação (benefícios condicionais). No Capítulo 3, nós demonstramos através de encontros interespecíficos pareados que as formigas são organizadas em hierarquias de dominância comportamental baseadas em agressividade. Essa hierarquia afeta a dominância numérica por territorialidade e, mais importante, o domínio das interações e do néctar. Mantendo esta linha de pensamento, demonstramos no Capítulo 4 que nem todas as formigas que coletam néctar realmente protegem a planta contra herbívoros mas somente as espécies dominantes e altamente interagidas. Finalmente, fechamos a tese demonstrando no Capítulo 5 que as espécies de formiga que interagem com as plantas durante o dia não são o mesmo à noite, mas esta rotatividade diurno-noturno não afeta a estrutura das interações devido a troca específica da formiga dominante. Este estudo traz evidências comportamentais e empíricas sobre a importância da identidade de espécies de formiga e sua dominância ecológica, assim como da qualidade do recurso, para a estrutura de rede da formiga-planta e eficácia do mutualismo. / Doutor em Ecologia e Conservação de Recursos Naturais

Obligate nursery pollination mutualisms such as the fig–fig wasp system, with their central plant–pollinator mutualism associated with non-pollinating satellite wasp species, can function as closed system microcosms representative of tritrophic communities. In this system, enclosed inflorescences (syconia) function as sites of seed production, as well as brood-sites for the progeny of herbivorous mutualistic pollinators, non-pollinating gallers and parasitoids of the two. Plant reproductive traits such as inflorescence size (syconium volume) and within-plant phenology (within-tree asynchrony) as can affect inter-species relationships among the three trophic levels in such plant–herbivore–parasitoid systems. Induced or natural variations in such plant traits could influence various direct and indirect effects among the organisms in the community and could even lead to the formation of feedback cycles. Furthermore, changes in the abiotic environment could have major impacts on the biotic associations in the system either by affecting the community members directly, or through their effects on plant reproductive traits. Ficus racemosa with its fig wasp community comprised of a single herbivorous pollinator mutualist, three non-pollinating parasitic gallers and three non-pollinating parasitoids was used as a model to investigate: (1) the role of mutualistic and parasitic fig wasps in affecting within-tree phenology; (2) direct and indirect biotic associations between various groups of fig wasps (pollinators, gallers and parasitoids) and the influence of inflorescence size and within-tree phenology on them; and (3) variations in the reproduction of and the biotic associations between the organisms of the community under variable abiotic climatic conditions. Patterns of plant reproductive phenology are usually considered evolved responses directed at optimizing resource use, pollen receipt/donation schedules and seed dispersal for plant individuals. Within-plant reproductive synchrony or asynchrony can arise due to variation in floral initiation patterns, as well as from localised proximate mechanistic responses to interactants such as pollinators, parasites and herbivores which could affect floral longevity or fruit development time. The investigation was begun by exploring the role of a mutualistic pollinator, and for the first time in a brood-site mutualism, that of parasitic herbivores (gallers) and parasitoids in influencing within-plant reproductive phenology. Since a syconium functions as an inflorescence which develops into a fruit after pollination, investigations were carried out on the impact on syconium synchrony of fig wasps that began their development within the brood site syconium at pre-pollination, pollination, and post-pollination stages via their effects on the development time of individual syconia in Ficus racemosa. We found that syconium initiation patterns were not the only proximate mechanism for within-tree reproductive asynchrony, and that individual syconia (even within a tree) had highly plastic development times dependent on their sizes, pollination time and the species of wasp progeny developing within them. Syconium volume, pollination early in the pollen-receptive phase and presence of early-ovipositing galler progeny reduced syconium development time, whereas the presence of late-ovipositing parasitoid progeny or pollination late in the pollen-receptive phase increased syconium development time. These results suggest an ongoing tug-of-war between syconium inhabitants to modify syconium development times. Parasitic fig wasps pull in different directions to suit their own needs, such that final syconium development times are likely to be a compromise between conflicting demands from developing seeds and from different wasp species. Inter-species relationships among the three trophic levels in plant–herbivore–parasitoid systems can potentially include various direct and indirect effects possibly mediated by induced or natural variations in plant traits. Analysing the seed and fig wasp compositions of microcosm replicates, i.e. individual syconia, shows that besides direct competition for resources and predator–prey interactions, the F. racemosa community also displays exploitative or apparent competition and trait-mediated indirect interactions. Syconium volume and within-tree asynchrony were reproductive plant traits that not only affected plant–herbivore and plant–parasitoid associations, but also possibly modified herbivore–herbivore and herbivore–parasitoid interactions. Our results also indicated that the reciprocal effects of higher trophic level fauna on plant traits (and vice versa) within this system drive a positive feedback cycle between syconium inhabitants and within-tree reproductive asynchrony. In the F. racemosa system, abiotic environmental factors could affect the reproduction of mutualistic pollinators, non-mutualistic parasites and seed production via seasonal changes in plant reproductive traits such as syconium volume within-tree asynchrony. Temperature, relative humidity and rainfall defined four seasons: winter; hot days, cold nights; summer and wet seasons. Syconium volumes were highest in winter and lowest in summer, and affected syconium contents positively across all seasons. Greater transpiration from the nurseries was possibly responsible for smaller syconia in summer. The 3–5°C increase in mean temperatures between the cooler seasons and summer reduced fig wasp reproduction and increased seed production nearly two-fold. Yet, seed and pollinator progeny production were never negatively related in any season confirming the mutualistic fig–pollinator association across seasons. Parasites affected seed production negatively in some seasons, but had a surprisingly positive relationship with pollinators in most seasons. While within-tree reproductive phenology did not vary across seasons, its effect on syconium inhabitants varied with season. In all seasons, within-tree reproductive asynchrony affected parasite reproduction negatively, whereas it had a positive effect on pollinator reproduction in winter and a negative effect in summer. Seasonally variable syconium volumes probably caused the differential effect of within-tree reproductive phenology on pollinator reproduction. Within-tree reproductive asynchrony itself was positively affected by intra-tree variation in syconium contents and volume, creating a unique feedback loop which varied across seasons. Therefore, nursery size affected fig wasp reproduction, seed production and within-tree reproductive phenology via the feedback cycle in this system. Climatic factors affecting plant reproductive traits can cause biotic relationships between plants, mutualists and parasites to vary seasonally and must be accorded greater attention, especially in the context of climate change.

<p>  </p> <p>Plant roots form an intimate relationship with a diversity of soil microorganisms. Some soil-borne microbes cause harmful diseases on crops, but others promote plant growth and enhance host resilience against stressors. Beneficial bacteria have a high potential as a strategy for sustainable agricultural management, many of which have been recognized and commercialized for improving crop growth. Unfortunately, field inoculants of beneficial bacteria often give inconsistent results due to various environmental factors hindering their beneficial properties. Improving crop production utilizing beneficial bacteria requires two approaches: 1) breeding for crops with the enhanced association for beneficial bacteria and 2) improving formulation methods for producing more potent microbial products. To contribute to these goals, we address three critical questions utilizing the tomato root microbiome as a model system. First, we asked how beneficial root-associated bacteria could be efficiently identified. We developed a strategy to select beneficial bacteria from a novel collection of 183 bacterial endophytes isolated from roots of two field-grown tomato species. The results suggest that isolates with similar traits impact plant growth at the same levels, regardless of their taxonomic classification or host origin. Next, we asked whether host genetics contribute to the root microbiome assembly and response to beneficial microbes. An assessment of the root microbiome profile and plant binary interaction experiments suggested the role of host genetics in influencing root recruitment and response to beneficial bacteria. Subsequently, we asked whether root-associated bacteria induce physiological changes in root tissues in the host. We identified two isolates from our bacterial endophyte collection that significantly promoted the growth of tomato genotype H7996 (<em>Solanum lycopersicum</em>). Plant-binary interaction experiments suggested a significant increase of cell wall lignification in the root vasculature starting 96-hour post-inoculation with beneficial bacteria. Additional studies are needed to uncover a possible correlation between the induced vasculature lignification and the growth-promoting effects of the two isolates on H7996. Altogether, our findings highlight the multi-faceted role of root-associated bacteria in promoting plant growth and support the development of crop improvement strategies in optimizing host association with soil bacteria.</p>