Dans son environnement, la plante interagit sans cesse avec des microorganismes. Elle est confrontée à une variété de microorganismes bénéfiques, neutres ou pathogènes, qui sont fortement dépendants des ressources carbonées que la plante libère dans le sol, leur conférant ainsi un apport de nutriments et d’énergie nécessaire à leur développement. La mycorhize à arbuscules est une symbiose mutualiste formée par 80% des plantes terrestres datant de l’Ordovicien, i.e. environ 450 millions d’années avant notre ère. L’ensemble des travaux de recherche présenté au sein de ce manuscrit, s’inscrit dans le cadre de deux objectifs généraux : (i) acquérir une meilleure compréhension des mécanismes à l’origine des relations trophiques chez la plante mycorhizée, et (ii) étudier l’impact de la mycorhization sur la production végétale tant en terme de quantité que de qualité. Nous avons étudié la réponse à la mycorhization de variétés anciennes de blé afin d’appréhender s’il existait une différence dans un environnement semi-contrôlé (serres) ou dans un environnement non contrôlées (champ), et/ou en fonction de la communauté de champignons mycorhiziens à arbuscules présente. Nos résultats ont mis en évidence que la mycorhization et la nature des champignons mycorhiziens arbusculaires endogènes peuvent influer sur le rendement au stade tallage, même chez des variétés de blé ayant une faible capacité mycorhizogène. Nous avons aussi illustré l’importance de bien choisir les critères utilisés pour mesurer ce gain éventuel. Dans un deuxième axe de recherche nous nous sommes intéressés à l’impact de la mycorhize à arbuscules sur le développement de la tomate Micro-Tom, et les échanges trophiques au cours de l’interaction. Nous avons pu mettre en évidence, grâce à une analyse multivariée, à la fois des différences de comportement parmi les plantes particulièrement aux stades fruit vert mature et fruit rouge mature selon la nature des champignons mycorhiziens à arbuscules présents, et des potentiels phénomènes d’interaction entre deux souches de champignons mycorhiziens à arbuscules; nos résultats confirmant que les arbuscules ne sont pas les seules sites d’échanges dans la mycorhize à arbuscules. Le troisième axe de ce travail a porté sur l’impact potentiel des méthodes de production de semences de variétés anciennes de tomate en condition de sécheresse, à la fois sur la communauté endogène de champignons mycorhiziens au champ, sur la tolérance de la plante au stress hydrique et sur la production végétale en terme de rendement et de qualité des fruits. Le site d’expérimentation se situait au Potager de santé (ferme de production de semences gérée par Pascal Poot). Nos résultats ne montrent aucune différence, en conditions de stress hydrique au champ, entre des variétés cultivées régulièrement sur ce site et des variétés commerciales. Alors, on peut se demander si d’autres facteurs liés au site d’exploitation, tels que les microorganismes interagissant avec les racines de la plante pourraient être à l’origine de la tolérance accrue au stress hydrique. Des travaux sont en cours au laboratoire pour étudier cette hypothèse. L’ensemble de ces travaux ouvrent la voie à de nouvelles recherches visant à élucider les mécanismes moléculaires impliqués dans la régulation des échanges trophiques au cours de la mycorhize à arbuscules et à la valorisation des services écosystémiques rendus par la mycorhize à arbuscules au champ. / In its environment, the plant interacts constantly with microorganisms. It is confronted with a variety of beneficial, neutral or pathogenic microorganisms, which are highly dependent on the carbon resources that the plant releases into the soil, giving them a supply of nutrients and energy necessary for their development. The arbuscular mycorrhiza is a mutualistic symbiosis formed by 80% of terrestrial plants from the Ordovician period, i.e. about 450 million years ago. The research presented in this manuscript was focused on two main goals: (i) to gain a better understanding of the mechanisms underlying trophic relationships in the mycorrhizal plant, and (ii) to study the impact of mycorhization on plant production, both in terms of quantity and quality. We investigated the mycorrhizal response of wheat landraces in order to understand if there were differences in a semi-controlled environment (greenhouses) or in an uncontrolled environment (field), and / or depending on the community of mycorrhizal fungi. Our results showed that mycorrhization and the nature of endogenous arbuscular mycorrhizal fungi can affect yield, even in wheat varieties with low mycorrhizal ability. We also highlighted the importance of choosing the criteria used to measure this potential gain. In a second line of research, we were interested in the impact of arbuscular mycorrhiza on the development of Micro-Tom tomato, and the trophic exchanges during the interaction. Multivariate analysis revealed behavioral differences between plants at mature green fruit and red ripening stages depending on arbuscular mycorrhizal fungal strain, as well as potential interaction event between two arbuscular mycorrhiza fungus trains. Our results confirm that the arbuscules are not the only sites of exchange in arbuscular mycorrhiza. The third axis of this work focused on the potential impact of seed production methods of ancient tomato varieties in drought condition, both on the endogenous community of arbuscular mycorrhizal fungi in the field, on the tolerance of the plant to water stress and on crop production in terms of fruit yield and quality. The experimental site was located in the Potager de santé (seed farm managed by Pascal Poot). Our results show no difference, under conditions of water stress in the field, between varieties regularly cultivated on this site and commercial varieties. Then, one may wonder if other factors related to the exploitation site, such as the beneficial microorganisms interacting with the roots of the plants could be at the origin of the increased tolerance to water stress. Work is underway in the laboratory to study this hypothesis. All of this work paves the way for new research aimed at elucidating the molecular mechanisms involved in the regulation of trophic exchanges during arbuscular mycorrhizae and the valuation of the ecosystem services rendered by arbuscular mycorrhizae in the field.

L'étude de l'écologie des micro-organismes est récente malgré son importance pratique et théorique intrinsèque mais également son rôle central dans la niche des macro-organismes. Les interactions plantes-champignons, de par leur importance socio-écologique et de leur diversité -- du mutualisme au parasitisme en passant par le commensalisme --, offrent un modèle judicieux pour étudier l'écologie des communautés de micro-organismes en interaction avec des macro-organismes. À l'aide de techniques de séquençage à haut débit (NGS) et d'analyse des réseaux, nous explorons certains déterminants de la structure des champignons des forêts corses à travers trois guildes : les champignons ectomycorhiziens, endophytiques et saprotrophes. Ce travail considère les processus de dispersion, les perturbations (feux et chablis), les facteurs environnementaux (par ex. la profondeur du sol) et les contraintes dérivées de l'interaction avec les hôtes (par ex. taxinomie). Les assemblages des communautés des différentes guildes présentent des patrons communs qui pourraient être issus de mécanismes identiques. Ainsi, l'ensemble des guildes étudiées présentent des variations fortes à l’échelle des micro-régions de Corse et entre forêts ayant des histoires de feux différentes. En revanche, l'importance des différents processus d'assemblage et les échelles spatiales auxquelles ils s'appliquent varient selon les guildes. Nous discutons des implications que suscitent ce travail pour les écologues des communautés et pour les gestionnaires d'espaces naturels. / Study of micro-organisms ecology arose recently despite its intrinsic importance -- both practical and theoretical --, but also despite its overriding role in the niches of macro-organisms. Plant-fungi interactions offer a relevant model to study the ecology of micro-organisms interacting with macro-organisms because of their considerable ecological and economical values in addition to their high taxonomic and ecological diversity. Using next-generation sequencing (NGS) and network analysis, we explore some drivers of fungal community composition in Corsica, at various scales and through three guilds: ectomycorrhizal, endophytic and saprotrophic fungi. We investigate the effect of disturbance (e.g. fire and treefall), environmental variables (e.g. soil depth), constraints due to the interacting plants (e.g. taxonomy) and dispersion on fungal communities. Some community assembly rules are similar across guilds. For instance, forests in different micro-regions of Corsica harbor dissimilar fungal communities. However relative importance of processes and the scales at which they occur vary across guilds. In Corsican pine forests, fifteen years after fire occurrence, soil fungal diversity is close to the level of diversity in unburnt stand. Despite the absence of effect on diversity, fire induces marked shifts in soil fungal community composition, in particular for soil saprobic fungi. We discuss the implication of this work for ecologists -- both plant and fungal ecologist -- and stakeholders.

Increasing atmospheric CO2 and other greenhouse gasses coupled to the accelerated rate of global warming puts plants and ecosystems under the strain of a rapidly changing abiotic environment. Understanding the impacts of changing global climate is a strong focus of plant science and the establishment of more resilient crop variants is an important goal for breeding programs. Our understanding of plant responses and acclimation to abiotic conditions has improved substantially over the last decades but the combination of a complex abiotic environment and high biological diversity, both on molecular as well as on species level, leaves us still with a lot of uncertainties. The aim of this doctoral thesis was to establish a link between plant thermal responses and the carbon-nitrogen balance of plants. The work in this thesis focused on ecologically significant species of the boreal region: Picea abies, Pinus sylvestris and Betula pendula; and Betula utilis, which is one of the prominent tree species in the high altitudes of the Himalayas. The results presented demonstrate that sub-optimal temperatures combined with other abiotic factors can have additive effects that are not easily deducible from the effect of the two factors separately. Low nitrogen availability enhanced the negative effect of low temperature, while elevated CO2 enhanced plant growth under moderate increases in temperatures but under a more extreme temperature increase it exacerbated the negative effect of heat. I also show evidence that species, despite being grouped into the same functional group or inhabiting the same biome can have different thresholds to temperature and to shifts in the C/N balance of their environment and that these differences can, to some extent, be explained by their differential growth strategies. Furthermore, I demonstrate results supporting the hypothesis that the C-N fluxes between mycorrhizal fungi and tree are strongly dependent on the C and N in the environment, highlighting the significance of the tree-mycorrhiza associations in the C sequestration capacity of the boreal region. In this thesis I also present a generalised empirically based mathematical model that can describe the respiration-temperature response of plant functional types or biomes with high precision, giving a more accurate estimate of NPP when implemented in global climate models, and has the potential to incorporate the thermal acclimation of respiration, further increasing the precision of estimating carbon fluxes under future warming temperatures. My results provide novel insights into the interactive temperature-carbon-nitrogen responses of plants, taking a step towards better understanding the response of plants and forests to future climates. / Ökande atmosfäriskt CO2 och andra växthusgaser kopplade till den accelererande globala uppvärmningen utsätter växter och ekosystem för stressen av en snabbt förändrande abiotisk miljö. Att förstå påverkan av ett globalt klimat i förändring står i fokus inom växtforskning och utvecklandet av mer motståndskraftiga grödor är ett viktigt mål inom programmen för växtförädling. Vår förståelse av växters responser och acklimatisering till abiotiska förhållanden har förbättrats avsevärt under de senaste decennierna, men på grund av kombinationen av en komplex abiotisk miljö och stor biologisk mångfald, både på molekylär nivå såväl som på art-nivå, kvarstår en del frågetecken. Syftet med denna avhandling var att upprätta ett samband mellan växters responser på temperaturförändringar och kol-kvävebalansen hos växter. Arbetet i denna avhandling inriktades på ekologiskt betydande arter i den boreala regionen, Picea abies, Pinus sylvestris and Betula pendula; samt Betula utilis som är en av de framträdande trädarterna på höga höjder i Himalaya. Resultaten som presenteras visar att suboptimala temperaturer i kombination med andra abiotiska faktorer kan ha additiva effekter som inte enkelt kan härledas från effekten av de två faktorerna var för sig. Låg kvävetillgänglighet ökade den negativa effekten av låg temperatur, medan förhöjd CO2-halt förbättrade planttillväxt under måttliga temperaturökningar, men under en mer extrem temperaturökning förvärrades dock den negativa effekten av värme. Jag framför även bevis på att arter, trots att de grupperas i samma funktionella grupp eller finns inom samma biom, kan ha olika tröskelvärden beträffande temperatur och förskjutningar i C/N-balansen i sin miljö och att dessa skillnader, i viss utsträckning, kan förklaras av deras olika tillväxtstrategier. Vidare visar jag resultat som stöder hypotesen att C-N - flöden mellan mykorrhiza och träd är starkt beroende av C och N i miljön. Detta belyser i sin tur betydelsen av samarbetet mellan träd och mykorrhiza gällande kolbindningskapaciteten i den boreala regionen. I denna avhandling presenterar jag även en generaliserad empiriskt baserad matematisk modell som med hög precision kan beskriva respiration-temperatur svar av växtfunktionella typer eller biom, vilken ger en mer exakt uppskattning av NPP i globala klimatmodeller. Mina resultat åstadkommer nya insikter i de interaktiva temperatur-kol-kväve-responserna hos växter, och tar ett steg mot bättre förståelse för växters och skogars reaktion på framtida klimat.

Species prescriptions are developed for revegetating abandoned acidic coal overburden seepage sites in the Collie region of Western Australia. The research involved selecting appropriate plant species and determining successful methods of enhancing revegetation. Candidate species were screened for tolerance to acidic overburden materials, local climate conditions and metal toxicity. Methods tested included improving spoil conditions and trialing an alternative method for seeding.Twelve species of native plants were tested for tolerance in two acid overburden materials in pot and field trials. Eucalyptus robusta is the most tolerant, Eucalyptus camaldulensis and Eucalyptus cladocalyx are highly tolerant, Eucalyptus rudis and Melaleuca hamulosa demonstrate potential, provided adequate soil moisture is available.An important growth restriction factor in acid soils is the presence of free aluminium ions. A glasshouse trial performed on seven species for tolerance to aluminium toxicity revealed E. robusta as most tolerant and E. camaldulensis and Kunzea ericifolia a highly tolerant. E. rudis and M. hamulosa are moderately tolerant, but E. cladocalyx and Eucalyptus diversicolor are very sensitive to aluminium.Various methods were trialed to increase growth of seedlings transplanted on to acidic overburden sites. Both commercial cow manure and slow-release fertiliser tablets increase growth, whereas commercial potting mix and lime do not. Inoculation of plants with the ectomycorrhiza fungus Pisolithus tinctorius increases the amount of infection in roots but does not enhance plant growth.Supplementary fertilisation is necessary to maintain growth (nitrogen) and restore chlorophyll production (phosphorus) in fast growing eucalypt seedlings planted into typical acidic spoils. Poor levels of nutrient availability in such acidic sites appear to be the primary factor in ++ / retarding growth. In the absence of supplementation, foliage reddening is observed in several species.An alternative method of seeding dumps is fascining. Prepared dump surfaces may be covered with capsule-laden branchwood of myrtaceous species. Material of the locally available Kunzea ericifolia is effective in producing many seedlings. Subsequent seedling growth is enhanced with fertiliser and lime addition.

The Arbuscular mycorrhiza (AM) is an endosymbiont of higher plant roots. Most land plants and cultivated crops are concerned to AM symbiosis. This endosymbiosis is based on the mutual exchange of nutrients between plant and fungus. Therefore, AM symbiosis leads to an increased demand for photosynthetic products. The aim of this study was to investigate the pathway used by plants during AM symbiosis to increase photosynthetic performance. Therefore, we have carried out a systematic characterization of photosynthesis in Medicago truncatula (M. truncatula), which is a model legume. We observed colonization by the fungus in roots and that AM symbiosis increases the fresh and dry plant biomass. This could be attributed to an increase in both photosynthetic efficiency and capacity in AM plants. Consistent with these observations, AM symbiosis enhanced phosphorus uptake from the soil into roots, stems and leaves, as based on analyses of phosphorus content. Based on equal chl loading, no differences were found regarding D1, Lhcb1 and Lhcb2 protein content in four plant groups. This indicates similar ratio between chl and PSII proteins. Furthermore, AM symbiosis increases the amount of chlorophyll, steady state oxygen evolution activities, maximum quantum yield (Fv/Fm), and photosynthetic electron transport rate (about 5 fold). Nevertheless, photoprotection was not affected by AM symbiosis. We observed an increase in weight of seed/fruit and weight of seed/plant in AM plants (about 2 fold). Based on these results, we propose that AM symbiosis increases both the efficiency and the capacity of photosynthetic apparatus in the M. truncatula.

No description available.

The arbuscular mycorrhizal (AM) association results from a successful interaction between the genomes of the two symbiotic partners. In this context, the aim of my research was to better characterize the role of the late stage symbiosis-related pea genes PsSym36, PsSym33 and PsSym40 in the functional AM (i) by investigating the effect of mutations in the three genes on fungal and plant gene responses and (ii) by creating conditions for the localization of two of the genes, PsSym36 and PsSym40, on the pea genetic map for future map-based cloning. The expression of a subset of ten fungal and eight plant genes,previously reported to be activated during mycorrhiza development, was compared in Glomus intraradices-inoculated roots of wild type and Pssym36, Pssym33 and Pssym40 mutant pea plants. Most of the fungal genes were down-regulated in roots of the Pssym36 mutant where arbuscule formation is defective, and several were upregulated with more rapid fungal development in roots of the Pssym40 mutant. Microdissection of mycorrhizal PsSym40 roots corroborated preferential expression of the three G. intraradices genes SOD, DESAT and PEPISOM in arbuscule-containing cells. Inactivation of PsSym36 also resulted in down regulation of plant genes whilst mutation of the PsSym33 and PsSym40 genes affected plant gene responses in a more time-dependent way. Results thus indicate an implication of the investigated pea SYM genes in the modulation of plant and fungal molecular interactions linked to signaling, nutrient exchange or stress response regulation during AM symbiosis formation and functioning. Conditions for localization of the PsSym36 and PsSym40 genes on the pea genetic map were developed for their future map-based cloning. Based on the molecular markers obtained, it was possible to conclude that localization of the PsSym40 gene most likely resides outside the linkage groups I, II, III or V of the genetic map of pea.

Orientador: Ana Maria Rodrigues Cassiolato / Banca: Luiz Antonio Graciolli / Banca: Gilberto Colodro / Resumo: O solo é um meio que engloba diferentes substâncias químicas e colóides e uma alta diversidade biológica. Estes componentes apresentam íntima relação funcional para sustentabilidade dos ecossistemas e, sua degradação, geralmente causada pela ação antrópica, acarreta um grande prejuízos ambientais e socioeconômicos para as gerações atuais e um enorme risco para as gerações futuras. Para reverter um processo como este, são necessárias intervenções por meio de estratégias como a revegetação. O objetivo do trabalho foi avaliar crescimento e colonização micorrízica do pinhão manso em solo decaptado que recebeu inoculo de fungos micorrizicos arbusculares, hidrogel e materiais orgânicos. O experimento foi conduzido de maio de 2008 a maio 2009, na Fazenda de Ensino, Pesquisa e Extensão (FEPE) da UNESP - Universidade Estadual Paulista, Campus de Ilha Solteira, no município de Selvíria-MS. O delineamento experimental foi o em blocos casualizado, em esquema fatorial 4x2x2, ou seja, 3 tratamentos com material orgânico (aguapé, composto e aguapé+composto), 2 tratamentos com hidrogel (com e sem adição) e 2 tratamentos de inoculação (com e sem inoculação) empregando solo proveniente de uma área preservada de cerrado como fonte de microrganimos, incluíndo fungos micorrízicos arbusculares, com 4 repetições e 5 plantas por tratamentos. O composto foi preparado com materiais de poda e esterco de bovino. Avaliou-se: o crescimento das plantas em 7 épocas diferentes, a caracterização química e número de esporos em 4 épocas, além da porcentagem de colonização micorrízica, presença de flores, número de ramos e de folhas e peso fresco e seco da parte aérea. O tratamento com hidrogel não mostrou interferência no crescimento de plantas, mas, assim como o solo-inóculo, aumentou a esporulação, a colonização micorrízica e a produção de matéria seca... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The soil is a medium that contain different chemical substances and colloids and a high biological diversity. These components have functional relationship on the sustainability of ecosystems and their degradation, usually caused by human action, which causes great socio-economic damage to the present generations and an enormous risk for the future generations. To reverse such process, action is needed using strategies, such as, revegetation. The objective of this study was to evaluate the growth and mycorrhiza colonization of Jatropha on decapitated soil that received organic materials and hydrogel. The experiment was conducted from May 2008 to May 2009, the Farm Education, Research and Extension (FEPE), UNESP - Univ. Estadual Paulista, Ilha Solteira Campus, located at Selvíria city-MS, Brazil. The experimental design was randomized blocks in factorial scheme 3x2x2, i.e., 3 treatments with organic materials (water hyacinth, compost and water hyacinth + compost), 2 hydrogel treatments (with and without addition) and 2 inoculations treatments (with and without inoculation) using natural soil from a preserved 'cerrado' area as a source of microorganisms, including mycorrhizal fungi, with 4 replications and 5 plants per each. The compound was prepared with materials pruning and cow dung. The growth of plants in 7 different times, the chemical characterization and number of spores in 4 times, and the percentage of mycorrhizal colonization, presence of flowers, branches and leaves and fresh and dry weight of air part was evaluated. Treatment with hydrogel showed no interference with the growth of plants; however, as well as the soilinoculum, they increased sporulation, root colonization and production of dry matter. The organic materials treatments positively altered the condition of the ground, plant growth, mycorrhizal colonization and sporulation; the improved performances... (Complete abstract click electronic access below) / Mestre

Made available in DSpace on 2014-06-11T19:29:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-01-15Bitstream added on 2014-06-13T20:39:15Z : No. of bitstreams: 1 santos_aa_me_ilha.pdf: 676511 bytes, checksum: f49f6d1a9f6dfba6539f793f9e93426c (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O solo é um meio que engloba diferentes substâncias químicas e colóides e uma alta diversidade biológica. Estes componentes apresentam íntima relação funcional para sustentabilidade dos ecossistemas e, sua degradação, geralmente causada pela ação antrópica, acarreta um grande prejuízos ambientais e socioeconômicos para as gerações atuais e um enorme risco para as gerações futuras. Para reverter um processo como este, são necessárias intervenções por meio de estratégias como a revegetação. O objetivo do trabalho foi avaliar crescimento e colonização micorrízica do pinhão manso em solo decaptado que recebeu inoculo de fungos micorrizicos arbusculares, hidrogel e materiais orgânicos. O experimento foi conduzido de maio de 2008 a maio 2009, na Fazenda de Ensino, Pesquisa e Extensão (FEPE) da UNESP – Universidade Estadual Paulista, Campus de Ilha Solteira, no município de Selvíria-MS. O delineamento experimental foi o em blocos casualizado, em esquema fatorial 4x2x2, ou seja, 3 tratamentos com material orgânico (aguapé, composto e aguapé+composto), 2 tratamentos com hidrogel (com e sem adição) e 2 tratamentos de inoculação (com e sem inoculação) empregando solo proveniente de uma área preservada de cerrado como fonte de microrganimos, incluíndo fungos micorrízicos arbusculares, com 4 repetições e 5 plantas por tratamentos. O composto foi preparado com materiais de poda e esterco de bovino. Avaliou-se: o crescimento das plantas em 7 épocas diferentes, a caracterização química e número de esporos em 4 épocas, além da porcentagem de colonização micorrízica, presença de flores, número de ramos e de folhas e peso fresco e seco da parte aérea. O tratamento com hidrogel não mostrou interferência no crescimento de plantas, mas, assim como o solo-inóculo, aumentou a esporulação, a colonização micorrízica e a produção de matéria seca... / The soil is a medium that contain different chemical substances and colloids and a high biological diversity. These components have functional relationship on the sustainability of ecosystems and their degradation, usually caused by human action, which causes great socio-economic damage to the present generations and an enormous risk for the future generations. To reverse such process, action is needed using strategies, such as, revegetation. The objective of this study was to evaluate the growth and mycorrhiza colonization of Jatropha on decapitated soil that received organic materials and hydrogel. The experiment was conducted from May 2008 to May 2009, the Farm Education, Research and Extension (FEPE), UNESP - Univ. Estadual Paulista, Ilha Solteira Campus, located at Selvíria city-MS, Brazil. The experimental design was randomized blocks in factorial scheme 3x2x2, i.e., 3 treatments with organic materials (water hyacinth, compost and water hyacinth + compost), 2 hydrogel treatments (with and without addition) and 2 inoculations treatments (with and without inoculation) using natural soil from a preserved ‘cerrado’ area as a source of microorganisms, including mycorrhizal fungi, with 4 replications and 5 plants per each. The compound was prepared with materials pruning and cow dung. The growth of plants in 7 different times, the chemical characterization and number of spores in 4 times, and the percentage of mycorrhizal colonization, presence of flowers, branches and leaves and fresh and dry weight of air part was evaluated. Treatment with hydrogel showed no interference with the growth of plants; however, as well as the soilinoculum, they increased sporulation, root colonization and production of dry matter. The organic materials treatments positively altered the condition of the ground, plant growth, mycorrhizal colonization and sporulation; the improved performances... (Complete abstract click electronic access below)

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / Banco do Nordeste do Brasil / A regeneraÃÃo natural da vegetaÃÃo à o procedimento mais barato para reabilitar Ãreas degradadas, porÃm, à lento. O plantio de mudas de arbÃreas nativas pode ser uma soluÃÃo. Nesse contexto, conduziu-se o presente trabalho em casa de vegetaÃÃo por 120 dias, testando 5 doses de P (0, 75, 150, 300 e 600 mg L-1) com fosfato de rocha natural na colonizaÃÃo por FMA e por rizÃbio nativos, e no desenvolvimento de mudas de embaÃba (Cecropia pachystachya TrÃcul) e de sabià (Mimosa caesalpiniaefolia Benth), cultivadas em solo natural (SN), solo natural com 50 % esterilizado (SND) e solo natural adicionado de 25 % de material orgÃnico (SNM). Analisou-se o comprimento, massa da matÃria seca, teores de N, P, K da parte aÃrea e o diÃmetro do colo das plantas, nÃmero de esporos e colonizaÃÃo micorrÃzica, massa da matÃria seca dos nÃdulos de rizÃbios, carbono da biomassa microbiana, respiraÃÃo basal e quociente metabÃlico do solo. O crescimento em comprimento, o diÃmetro do colo e a produÃÃo de massa da matÃria seca da parte aÃrea das plantas de embaÃba nÃo sofreram efeito dos tratamentos. Os substratos SN e SND proporcionaram a maior esporulaÃÃo e colonizaÃÃo de FMA, favorecendo o aporte de P na parte aÃrea dessas plantas. Essa atividade foi reduzida nas maiores doses de P. A RespiraÃÃo Basal e o carbono da biomassa microbiana do solo (CBMS) foram menores no SND e nÃo sofreram influÃncia das doses de P. O substrato SND proporcionou maior aporte de N na parte aÃrea das plantas, mas sem influÃncia das doses de P. Enquanto que o SNM proporcionou maior aporte de P e K na parte aÃrea das plantas. Os FMA favoreceram o aporte de P na parte aÃrea das plantas de embaÃba, mas com reduÃÃo nas maiores doses de P. O crescimento em comprimento das plantas de sabià nÃo sofreu efeito dos tratamentos, porÃm o diÃmetro do colo e a massa da matÃria seca da parte aÃrea das plantas apresentaram melhores resultados no substrato SNM, mas sem influÃncia das doses de P. O SNM apresentou o menor nÃmero de esporos, maior colonizaÃÃo de FMA na dose de 75 mg de P, todavia com reduÃÃo nas maiores doses, e maior CBMS, mas sem influÃncia das doses de P. O SND e o rizÃbio nativo proporcionaram maior aporte de N na parte aÃrea e maior massa nodular nas plantas de sabiÃ, sendo influenciados pelas doses de P. O SNM proporcionou maior aporte de P e K na parte aÃrea das plantas de sabiÃ, tendo a dose de 600 mg de P favorecido os maiores valores desses nutrientes. Os FMA proporcionaram um discreto incremento no teor de P na parte aÃrea das plantas de sabiÃ. / Natural regeneration of vegetation is the procedure cheaper to rehabilitate degraded areas, however, is slow. The planting of native tree seedlings may be a solution. In this context, an experiment was carried out in a greenhouse for 120 days, testing 5 P rates (0, 75, 150, 300 and 600 mg L-1) with rock phosphate colonization by AMF and native rhizobia in development of seedlings embaÃba (Cecropia pachystachya TrÃcul) and sabià (Mimosa caesalpiniaefolia Benth), grown in natural soil (NS), natural soil sterilized with 50% (NSS) and natural soil added with 25% organic compost (NSC). We analyzed the length, dry matter weight, N, P, K aerial part and the stem diameter of the plant, number of spores and mycorrhizal colonization, dry matter weight of nodules rhizobia, microbial biomass carbon, basal respiration and metabolic quotient soil. The growth in length, stem diameter and dry matter weight of embaÃba not affected by the treatments. The substrates NS and NSS provided the greatest colonization and sporulation of AMF, favoring the input of P in shoots of these plants. This activity was reduced at the highest levels of P. The soil basal respiration and microbial biomass carbon (MBC) were lower in the NSS and not influenced by P fertilization. The substrate NSS provided major input of N in shoots, not influenced by P fertilization. Whereas the NSC provided major input of P and K in shoots of embaÃba plants. The AMF favored the input of P in shoots of embaÃba plants, but this activity was reduced at the highest levels of P. The growth of sabià was not affected by treatments, but stem diameter and dry mass weight showed better results in substrate NSC. However, were not affected by the rates of P. The NSC had the lowest number of spores, the highest colonization of AMF at rate of 75 mg of P, however with reduction in higher rates, and higher MBC, but without influence of P rates. The NSS and native rhizobia provided major input of N in shoots and increased nodular mass in sabià and levels of phosphorus influenced these parameters. The NSC provided major input of P and K in shoots of sabiÃ, in rate of 600 mg P, favored higher values of these nutrients. AMF provided a mild increase the levels of P in the shoots of sabià plants.