A seca é um dos principais problemas que afetam a produção do feijoeiro. A despeito da importância de caracteres fenotípicos radiculares, muitos dos esforços de melhoramento genético da cultura tem focado na seleção de cultivares com maior produção de grãos. A simbiose estabelecida entre plantas e FMA aumentam o potencial de captação de água no solo através das extensas redes formadas pelas hifas e alteram vias metabólicas vitais para a manutenção das relações hídricas da planta. O modelo de interação feijoeiro (BAT 477) colonizado por uma mistura de FMA (Glomus clarum, Acaulospora scrobiculata e Gigaspora rosea) foi submetido a um déficit hídrico de 96 h durante o pré-florescimento. O transcritoma global de raízes inoculadas e não-inoculadas, sujeitas ou não à seca, foi comparado por RNA-Seq. Um conjunto de 71 transcritos foram induzidos por FMA durante a seca. Comparando-se os tratamentos estresse e controle, 12.086 unigenes foram regulados em plantas inoculadas e 11.938 em não-inoculadas, refletindo o alto potencial de tolerância da linhagem BAT 477 e indicando que a presença de FMA produz uma regulação fina no perfil de expressão de genes regularmente envolvidos na resposta da planta ao estresse. Foram selecionados 15 fatores de transcrição e seus perfis de expressão foram caracterizados por RT-qPCR tomando-se três períodos, 48, 72 e 96 h de déficit hídrico. Plantas inoculadas ativaram a expressão destes genes mais tardiamente (após 72 h), refletindo melhorias nas condições hídricas da planta que adiam a percepção do estresse. Adicionalmente, a expressão de 23 transcritos foi avaliada em três amostras teciduais diferentes obtidas por microscopia de microdissecção a laser. Glucan 1,3 ?-Glucosidase e PIP2,3, foram detectados somente em células do córtex radicular contendo arbúsculos indicando uma possível indução tecido específica dependente da presença dos fungos. Análises complementares apontaram a regulação de 171 unigenes envolvidos na resposta das FMA ao estresse. Estes resultados validam a hipótese inicial de que a inoculação com FMA altera os perfis de expressão de genes vitais para a resposta da planta ao déficit hídrico / Drought is one of the main problems that affect common bean\'s production. Despite the importance of root fenological characters, breeding efforts for the culture have focused on the selection of cultivars for grain yield. The symbiosis stablished between AMF and plants enhances the potential of water absorption from the soil through an extensive net formed by hyphae and alters vital metabolic pathways involved in the maintenance of the water relations in plants. The interaction model common bean (BAT 477) colonized by a mixture of AMF (Glomus clarum, Acaulospora scrobiculata and Gigaspora rosea) was exposed to a water deficit regime of 96 h during pre-flowering. Global transcriptome from inoculated and non-inoculated roots, exposed or not to drought, were compared through RNA-Seq. A set of 71 transcripts was induced by AMF during drought. Comparing both stress and control treatments, 12,086 unigenes were regulated in inoculated plants, and 11,938 in non-inoculated, reflecting the great tolerance potencial of the lineage BAT 477 and indicating that the presence of AMF produces a fine tune regulation on the expression of genes regularly involved on the drought response of the plant. It was selected 15 transcription factors and their expression profiles were characterized through RT-qPCR taking 3 periods, 48, 72 and 96 h of water deficit. AM plants activated earlier (after 72 h) the expression of these genes, reflecting improvements on the water conditions of the plant that delay the stress perception. Additionally, the expression of 23 transcripts was evaluated on three different tissue samples obtained through laser microdissection microscopy. Glucan 1,3 ?-Glucosidase and PIP2,3, were detected only in cortical cells containing arbuscules, pointing to a possible tissue specific induction dependent of the presence of the fungus. Additional analysis point to the regulation of 171 unigenes involved on the response of the AMF to drought. These results corroborate the initial hypothesis that the inoculation with AMF alters the gene expression profiles of genes that are vital for water deficit response in plants

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No description available.

Os fungos micorrízicos arbusculares (FMAs, filo Glomeromycota) formam associações simbióticas com a maioria das plantas vasculares. Normalmente, as hifas dos FMAs crescem no solo e colonizam o interior das raízes. No entanto, não se sabe se as espécies mais abundantes detectadas no solo, por meio da identificação com base na morfologia dos esporos assexuais, são também as mais abundantes no interior das raízes, devido às dificuldades para a identificação dos FMAs com base nas estruturas intrarradiculares. Assim, o objetivo do presente trabalho foi avaliar a estrutura da comunidade de FMAs em cana-de-açúcar sob dois manejos de colheita por meio da identificação das espécies que estão no solo na forma de esporos assexuais e aquelas que estão nas raízes usando o sequenciamento de clones do gene rRNA 18S. Amostras de solo e raízes de cana-de-açúcar de três variedades e dois manejos de colheita: SEM QUEIMA prévia e COM QUEIMA prévia à colheita, foram coletadas em um experimento localizado no município de Novo Horizonte, SP. Foram utilizadas três abordagens para a identificação dos FMAs no interior das raízes: emprego de (1) iniciador específico para fungos em geral, (2) iniciador específico para FMAs e (3) iniciadores específicos para grupos de FMAs. O número de esporos por 50 g de solo, a riqueza de espécies observada e estimada e a diversidade de esporos não diferiram significativamente entre os manejos SEM QUEIMA e COM QUEIMA. Efeitos significativos de variedades de cana-de-açúcar ou na interação dos fatores manejo e variedade não foram observados. A análise de ordenação com base nos esporos identificados também não indicou separação das amostras em função dos tratamentos. Entretanto, plantas do tratamento sob manejo SEM QUEIMA apresentaram as maiores taxas de colonização micorrízica arbuscular, quando comparadas às plantas do tratamento sob manejo COM QUEIMA. Esses dados indicam que a taxa de colonização micorrízica arbuscular é um indicador mais sensível à mudança de manejo de colheita da cana-de-açúcar do que os outros indicadores avaliados. Após a extração de DNA das raízes, o uso dos iniciadores específicos para fungos em geral, para FMAs e iniciadores específicos para grupo de FMAs não resultou em sequências de Glomeromycota. Mesmo assim, a comunidade de fungos associados às raízes detectada por sequenciamento do gene rRNA 18S foi avaliada. Os resultados indicam que a estrutra da comunidade fúngica associada às raízes de cana-de-açúcar diferiu significativamente entre os manejos de colheita SEM QUEIMA e COM QUEIMA prévia, apesar de não haver diferenças na riqueza e índices de diversidade de unidades taxonômicas operacionais observadas. Em geral, estudos adicionais devem ser feitos para otimizar as condições para amplificação do gene rRNA 18S de FMAs para melhor entender a ecologia dos mesmos. / Arbuscular mycorrhizal fungi (AMF, Glomeromycota) form mutualistic symbioses with most land plants. AMF hypha generally grow through the soil and colonize the cortical tissue of the plant roots. However, it is not known whether the most abundant species in the soil, determined based on the morphology of asexual spores are the most abundant inside the roots, due the difficulties in identifying AMF based on intraradical structures. Therefore, the aim of this study was to evaluate the AMF community structure in sugarcane rhizosphere and roots under two harvesting managements, based on spores in the soil and sequencing of 18S rRNA gene clones, respectively. Sugarcane rhizosphere soil and roots were sampled from three varieties, under two harvesting managements: without pre-harvesting burning and with pre-harvesting burning, at an experimental field located in Novo Horizonte (São Paulo, Brazil). Three approaches were used to identify AMF inside the roots: (1) using fungi-specific primers, (2) using AMF-specific primers and (3) using AMF group-specific primers. The number of spores in the soil, the observed and estimated species richness and the diversity of AMF spores in the treatments without and with pre-harvesting burning were not statistically different. Statistically significant effects of sugarcane varieties or the interaction of the factors Harvesting Management and Varieties were not observed. Ordination analysis based on the identified spores did not show clustering by treatments. However, intraradical root colonization rates were higher in the treatment without pre-harvesting burning, as compared to the treatment with pre-harvesting burning. These data indicate that intraradical colonization rate may be used as a more sensitive indicator of environmental changes due to harvesting management, as compared to the other indicators evaluated. The use of fungi-specific, AMF-specific and AMF group-specific primers did not allow the detection of Glomeromycota in the sugarcane roots sampled from the field experiment. Nonetheless, the fungal communities associated with sugarcane roots detected by 18S rRNA gene clone sequencing were evaluated. The results indicate that the fungal communities associated with sugarcane roots from the treatments without and with pre-harvesting burning were statistically different, even though no differences in operational taxonomic unit richness and diversity indices were observed. In general, additional studies are necessary to optimize AMF 18S rRNA gene amplification for a better understanding of their ecology.

Low nutrition availability in the soil can be a major limitation of plant growth. To improve nutrient acquisition, the majority of land plants engage in symbiosis with arbuscular mycorrhizal (AM) fungi. The accommodation of fungal colonisation structures in the roots requires their radical reprogramming. This starts during pre-symbiotic communication, where signals are exchanged between the fungus and plant across the rhizosphere. The receptor D14-LIKE emerged as a vital component of this pre-symbiotic communication when it was found to be absolutely required for symbiosis in rice. However, the broader relevance of the receptor, both in terms of functional conservation across plant species and its relation to other pre-symbiotic plant signalling components, remained unclear. The aim of this thesis was to elucidate these two key points. To address the fragmented picture of fungal signals, plant receptors and signalling pathways, a large scale transcriptomic experiment in rice was conducted to tie D14L together with other distinct pre-symbiotic components. In the absence of D14L-mediated signalling, rice was found to be compromised in the perception of germinated spore exudates, as well as specific chitinaceous signals, meaning that normal transcriptional reprogramming could not be achieved in response to any of these treatments. In addition, the functional conservation of D14L signalling was explored using trans-species complementation experiments. It was found that the Arabidopsis homolog AtKAI2 could complement the developmental phenotype of the d14l rice mutant, but not symbiosis. Likewise, D14La from early diverging Marchantia polymorpha and Marachantia paleacea could rescue developmental phenotypes in d14l rice, but again failed to complement symbiosis. This demonstrated a functional separation between developmental and symbiotic signalling. The data generated during my PhD foster D14L as a central node for multiple inputs to pre-symbiotic reprogramming, and provides new insights into pre-symbiotic communication mechanisms which are required for the successful establishment of symbiosis.

Echinacea purpurea is a native herbaceous perennial with substantial economic value for its medicinal and ornamental qualities. Arbuscular mycorrhizae are symbiotic fungi that form relationships with plant roots and are known to enhance growth in the host. Mycorrhizae and other fungal endophytes often affect stress resistance and secondary metabolism in the host, as well as the ecology of other endophytes in the plant. A newly emerging paradigm in sustainable biotechnique is the targeted use of fungal endophytes to enhance growth and secondary metabolism in crops. Many of the therapeutic compounds in E. purpurea could be affected by fungal colonization. In this research the effects of inoculation of Echinacea purpurea with two classes of fungal endophytes: the arbuscular mycorrhizal fungi Glomus intraradices and Gigaspora margarita and the entomopathogenic endophyte Beauveria bassiana were evaluated . Endophyte colonization and impacts on plant growth and phytochemistry were tested in multiple greenhouse experiments. Arbuscular mycorrhizae and B. bassiana effectively colonized E. purpurea with some significant interactive effects. Consistent, substantial, and significant increases in all growth parameters were observed in mycorrhizal plants; mycorrhizal plants produced up to four times the biomass of controls in 12 weeks. Broad spectrum changes in fertilization were necessary to produce mycorrhizal and nonmycorrhizal samples of equal size, and severely nutrient-limited mycorrhizal E. purpurea seedlings maintained growth rates comparable to well fertilized samples. Treatment with B. bassiana had minor and inconsistent effects on some plant growth parameters, and there were significant interactive effects with arbuscular mycorrhizae. Phytochemical concentrations in all metabolite classes tested responded significantly to inoculation with both classes of fungal endophytes. Changes were observed in various pigments, caffeic acid derivatives, alkylamides, and terpenes. Many of the affected compounds have important roles in metabolism or have bioactive value as natural products. When considered from a net production perspective (concentration X dry weight), compared to controls, plants inoculated with endophytes produced as much as 30 times the content of some compounds in 12 weeks. This work effectively demonstrates that fungal endophytes can enhance the bioactivity of plant tissues and the production of natural products in E. purpurea.

Der Einfluss unterschiedlich aggressiver Fusarium culmorum- und F. graminearum-Isolate auf die Schadbildausprägung bei Winterweizen sowie die Möglichkeit der Befallskontrolle mit Mykorrhiza Die durch Pilzarten der Gattung Fusarium spp. hervorgerufene partielle Taubährigkeit ist ein ernstes Problem im weltweiten Weizenanbau. Eine für die Schaderreger günstige feuchte Witterung zum Zeitpunkt der Weizenblüte in Kombination mit befallsfördernden agrotechnischen Maßnahmen löst immer wieder Epidemien aus. Hauptsächlich verursacht durch F. culmorum und F. graminearum führt eine Erkrankung zu Ertrags- und Qualitätseinbußen sowie zu einer Belastung des Ernteguts mit Mykotoxinen, die bereits in niedrigen Konzentrationen toxisch auf den tierischen und menschlichen Organismus wirken. Die am häufigsten vorkommenden Fusarium-Toxine in Weizen sind Deoxynivalenol (DON) und Zearalenon (ZEA). Isolate von F. graminearum- und F. culmorum können in ihrem DON- und ZEA-Bildungsvermögen und ihrem Potential, Nekrosen zu verursachen, stark variieren. In Laborversuchen (in vitro) wurden F. graminearum- und F. culmorum-Isolate hinsichtlich dieser Eigenschaften (hier als Aggressivität bezeichnet) charakterisiert und anschließend wurde im Feldversuch überprüft, ob die in vitro-ermittelte Aggressivität die Schadbildausprägung bei Weizenpflanzen beeinflusst. Nur im ersten Versuchsjahr, das durch hohe Niederschläge gekennzeichnet war, konnte ein Einfluss der Aggressivität und einer zusätzlichen Beregnung im Feldversuch nachgewiesen werden. Die als hoch-aggressiv eingestuften Fusarium-Isolate reduzierten unter dem Einfluss der Beregnung den Ertrag und das Tausendkorngewicht. Die Beregnung führte zu einer Erhöhung des Pilzwachstums und der DON- und ZEA-Produktion. Ein extrem trockener Sommer verhinderte die Infektion der Weizenpflanzen durch die beimpften Fusarium-Isolate und ein anschließendes Pilzwachstum in den Ähren im zweiten Versuchsjahr. Um den Befall von Weizenpflanzen mit Fusarium spp. vorzubeugen, stehen verschiedene pflanzenbauliche Maßnahmen zur Verfügung. Eine Möglichkeit stellen in diesem Zusammenhang die symbiotischen Mykorrhizapilze (MP) dar. Die Pilze sind in der Lage, Pflanzen zu stärken und antagonistisch auf pilzliche Schaderreger zu wirken. Um zu überprüfen, ob MP dazu beitragen könnten, den Befall von Weizenpflanzen mit Fusarium spp. niedrig zu halten, wurden Weizenpflanzen mit MP und Fusarium spp. beimpft und die Auswirkungen der Interaktionen auf die Weizenpflanzen in einem Klimakammer- und einem Feldversuch getestet. In der Klimakammer wurde eine Reduzierung des Fusarium-Befalls nachgewiesen. Die mykorrhizierten Weizenpflanzen wiesen außerdem höhere Photosyntheseraten, höhere Sprosstrockenmassen und mehr Ähren im Vergleich zu den nicht-mykorrhizierten und mit Fusarium-beimpften Weizenpflanzen auf. Insgesamt wurde durch die Mykorrhizierung der negative Einfluss von Fusarium spp. kompensiert. Im Freiland konnte kein Einfluss der MP auf Fusarium spp. beobachtet werden. Im ersten Versuchsjahr führte das Beimpfen der Weizenpflanzen mit MP zu höheren Wurzel- und Sprosstrockenmassen sowie zu höheren Tausendkorngewichten im Vergleich zu den mit Fusarium spp.-beimpften Weizenpflanzen. Im zweiten Versuchsjahr konnte dieses Ergebnis nicht wiederholt werden. / Impact of aggressiveness of Fusarium culmorum and Fusarium graminearum isolates on the degree of symptoms as well as the possibility to control Fusarium spp. with mycorrhiza Fusarium Head Blight (FHB) is a serious problem worldwide and is mainly caused by Fusarium (F). culmorum and F. graminearum. Humid weather conditions, especially at anthesis and agricultural measures forcing pathogen attack cause epidemics repeatedly. FHB leads to yield and quality losses and also to contamination of harvest with mycotoxins that are toxic to humans and animals already in low concentrations. The most frequently occurring Fusarium toxins in wheat are deoxynivalenol (DON) and zearalenone (ZEA). F. culmorum and F. graminearum isolates can differ in their potential to produce mycotoxins and to cause necrosis. Isolates of these two species were assigned to three different groups of aggressiveness on the basis of mycotoxin production and necrotic activity. Afterwards these isolates were inoculated on wheat in fields to ascertain their aggressiveness on the degree of symptoms. Only in the first year of the trial that was characterized by high precipitation amounts an influence of the aggressiveness and of an additional irrigation could be determined. Influenced by irrigation isolates of high aggressiveness reduced yield and 1000-kernel-weight. Besides, irrigation led to an increase of fungal growth and DON and ZEA production. An extremely dry summer in the second year of the trial prevented wheat infection by Fusarium isolates and subsequent colonization of the ears. Various agricultural measures are available to prevent Fusarium infection. The release of mycorrhizal fungi is one possibility. These fungi are able to strengthen plants and affect fungal pathogens antagonistically. Mycorrhizal fungi and Fusarium isolates were inoculated on wheat plants in climate chamber and fields to determine their potential for pest management. The impact of the interactions of these two organisms on wheat plants was analyzed. In climate chamber a reduction of Fusarium colonization was observed. Furthermore a higher rate of photosynthesis, a higher shoot dry weight and a higher number of ears were detected for the mycorrhizal plants compared to the non-mycorrhizal Fusarium inoculated plants. Altogether the negative effects of Fusarium spp. on the wheat plants were compensated by mycorrhizal colonization. In fields no influence of mycorrhizal colonization on Fusarium spp. could be determined. In the first year of the trial inoculation of wheat plants with mycorrhiza led to higher root and shoot dry weight as well as to higher 1000-kernel-weight in comparison to the wheat plants inoculated with Fusarium spp. These results could not be reproduced in the second year of the trial.

Arbuscular mycorrhizas (AM) are the plant root-fungus interactions that are most widespread mycorrhiza in nature. As classically defined, there are two major AM morphologies named after the plant genera in which they were first described: Arum- (intercellular hyphae with arbuscules mainly in inner root cortex), Paris- (extensive hyphal coils in outer root cortex), as well as intermediate morphotypes. In this study, dandelions and chives harvested in Saskatoon (SK, Canada) were examined for AM colonization and morphological types. A Multiple Quantitation Method (MQM) was used for assessing fungal colonization intensity using magnified epifluorescence images of lactofuchsin stained roots, plus details analyzed by high-resolution confocal fluorescence imaging. The results showed that host plants harbored diverse endorhizal fungi, including arbuscular mycorrhizal fungi (AMF), septate endophytes (SE) and fine endophytes (FE), with varying abundances. The soil properties were assessed with respect to P status, organic matter and pH, but there was no correlation with the fungal abundance in this study. Both dandelion and chive roots had Arum- and Paris-type AM. In order to assess the applicability of a current model, I studied quantitative relationship between the cell packing pattern and AM morphotype. Cross sections of host roots were analyzed with Image J software to calculate the proportion of air spaces. The abundance of arbuscules (Arum-type) and hyphal coils (Paris-type) were significantly different in chive and dandelion roots. However, there was no difference in the proportion of air spaces in the inner or outer cortex. Therefore, host root cell packing does not appear to influence AM morphotype at least in the samples in this study. AM fungal diversity was preliminarily investigated by nested PCR with group specific primers, showing multiple PCR bands within root samples, and indicating the potential complexity of AMF groups. Further work to sequence the PCR products is needed to elucidate the AMF groups present.

There are no seeding rates established for organic production of field pea and lentil in Saskatchewan and organic producers must rely upon rates recommended for conventional production of these crops. These seeding rates may not be suitable for organic production as the two systems differ in the use of inputs and in pest management. The objectives of this study were to determine an optimal seeding rate for organic production of field pea and lentil in Saskatchewan considering a number of factors, including yield, weed suppression, soil nitrogen (N) and phosphorus (P) concentrations, soil water storage, colonization of crop roots by arbuscular mycorrhizal fungi (AMF), plant P uptake, and profitability. A field experiment was conducted to determine the optimal seeding rates of field pea and lentil. Field pea seeding rates were 10, 25, 62, 156 and 250 plants m-2 and lentil seeding rates were 15, 38, 94, 235 and 375 plants m-2. Sites were established at Vonda, Vanscoy and Delisle, SK using a randomized complete block designs with summerfallow and green manure treatments included for each crop. Seed yield increased with increasing seeding rate for both crops, up to 1725 kg ha-1 for field pea and 1290 kg ha-1 for lentil. Weed biomass at physiological maturity decreased with increasing seeding rate for both crops. In field pea, weeds were reduced in weight by 68%, while lentil reduced weed biomass by 59% between the lowest and highest seeding rates. <p>Post-harvest soil phosphate-P levels did not change consistently between treatments, indicating that there was no trend in soil P concentration with seeding rate. Post-harvest soil inorganic N, however, was higher for the summerfallow and green manure treatments than for the seeding rate treatments in both crops. Inorganic N was higher at some sites for the highest two seeding rates in field pea. Soil water storage following harvest was not affected by treatment.<p>Colonization of crop roots by AMF increased for lentil with increasing seeding rate, but the same trend was not observed in field pea. A growth chamber experiment to study the rate of colonization of field pea between 10 and 50 d after emergence did not show any differences in AMF colonization between seeding rates. Colonization levels were high (70 to 85%) for both crops in both the field and growth chamber. Arbuscular mycorrhizal fungi colonization and seeding rate had no effect on plant P concentration for either field pea or lentil. Both crops became increasingly profitable as seeding rate increased. Field pea reached a maximum return at 200 plants m-2 and lentil return increased to the highest seeding rate of 375 plants m-2. Organic farmers should increase seeding rates of these crops to increase returns and provide better weed suppression.

There is accumulating evidence that arbuscular mycorrhizal fungi (AMF) produce a glycoprotein called glomalin, which has the potential to increase soil carbon (C) and nitrogen (N) storage, thereby reducing soil emissions of carbon dioxide (CO2) and nitrous oxide (N2O) into the atmosphere. However, other soil microorganisms such as plant growth-promoting rhizobacteria (PGPR) that interact with AMF could indirectly influence glomalin production. The objectives of this study were to determine the effects of AMF and PGPR interactions on glomalin production and identify possible combinations of these organisms that could enhance C and N storage in the rhizosphere. The effects of AMF and PGPR interactions on pea (Pisum sativum L.) growth and correlations between glomalin production and plant growth also were assessed.<p> A series of growth chamber and laboratory experiments were conducted to examine the effect of fungal and host plant species on glomalin production by comparing the amounts of glomalin produced by Glomus clarum, G. intraradices, and G. mosseae in association with corn (Zea mays L.), in addition to examining differences in the ability of corn, pea, and wheat (Triticum aestivum L.) to support glomalin production by G. intraradices. There were no significant differences in glomalin production [measured in the rhizosphere as Bradford-reactive soil protein (BRSP)] by the three AMF species, whereas host plant significantly affected glomalin production. Specifically, higher BRSP concentrations were found in the rhizosphere of corn as compared to pea and wheat.<p> Additionally, the effect of long-term storage on the growth promoting traits of the PGPR strains selected; namely, Pseudomonas cepacia R55 and R85, P. aeruginosa R75, P. putida R105, and P. fluorescence R111 were investigated. These bacterial strains previously had been identified as PGPR, but had since undergone approximately twenty years of storage at -80¢ªC; thus, it was necessary to confirm that these strains had retained their plant growth promoting characteristics. Apparently, long-term storage had no significant adverse effect on the PGPR strains as all strains increased the total biomass of wheat significantly and demonstrated antagonism against fungal pathogens.<p> The possibility that spore-associated bacteria (SAB) could influence AMF associations, thereby affecting glomalin production, and subsequent crop yield potential was assessed. This was achieved by first isolating bacteria from disinfested spores of the AMF species and determining their potential as PGPR for wheat. According to fatty acid methyl ester (FAME) profiles, four genera of bacteria were isolated from AMF spores namely; Arthrobacter, Bacillus, Micrococcus, and Paenibacillus, of which Bacillus species were the most common SAB. None of these isolates, however, showed growth promoting abilities on wheat.<p> Based on the preliminary findings, the combined effects of the three AMF species and the five PGPR strains were examined on plant growth and glomalin production under gnotobiotic conditions using pea as the host plant. Interactions between G. intraradices and R75, R85, or R105 resulted in increased BRSP concentration in the mycorrhizosphere of pea. Additionally, significant interactions were observed between the AMF species and PGPR strains on BRSP concentration in pea rhizosphere under non-sterile conditions. As observed under sterile conditions, the co-inoculation of pea with G. intraradices and R75 or R85 increased BRSP concentrations in the rhizosphere of pea grown in non-sterile soil, although interaction effects were not significantly different from the control or when G. intraradices was applied alone. Significant AMF and PGPR interactions were observed to affect AMF colonization; however, the combination of these organisms did not significantly affect pea growth, nutrient uptake, and C and N storage in the plant rhizosphere. No correlations were detected between glomalin-related soil protein (GRSP), pea growth, nutrient concentrations in the plant tissue, and soil organic C and N content. This study demonstrated that although the potential exists to manipulate certain AMF and PGPR to enhance glomalin production, co-inoculation of AMF and PGPR did not enhance plant growth or C and N storage beyond that achieved by inoculation of either organism.