Triclosan (TCS) is an antimicrobial compound found in several types of common household products. After being washed down the drain, TCS will then end up in the local watershed. Although numerous studies have been conducted to evaluate the fate and effects of TCS in aquatic environments, there have been no studies evaluating the role arbuscular mycorrhizal fungi (AM) play in a plants response to TCS exposure. Three species of wetland plants native North Texas were inoculated with AM spores and exposed to 0, 0.4 g/L and 4.0 g/L TCS concentrations. Root morphology of E. prostrata and S. herbacea showed AM and exposure responses. S. herbacea produced the greatest amounts biomass and TCS bioaccumulation, in all but one treatment. It also displayed opposing results to E. prostrata in measures of root length, root surface area, relative root mass, relative shoot mass and shoot:root ratio. TCS root tissue concentrations increased with increased exposures for both E. prostrata and S. herbacea. Even though E. prostrata had the lowest levels in each measure of biomass production, it had the highest amount of root TCS bioaccumulation in the AM inoculated 4.0 g/L treatment. H. laevis was between the other two species in terms of biomass production, and did not demonstrate any exposure or inoculation effects in morphology or TCS accumulation. Overall, no clear patterns were detected, which highlights the fact that further study is required to completely understand the effects compounds like TCS can have on plant community structure, and ultimately ecosystem function.

In this thesis I investigated the mutualism between Kunzea ericoides (kanuka) and two groups of soil fungi, ectomycorrhizae (ECM) and arbuscular mycorrhizae (AMF). Mycorrhizal mutualisms, which are considered globally ubiquitous, are poorly understood over changing abiotic gradients. A field survey of K. ericoides assessed how the relationship with the soil fungi varieties altered over a hydrologic gradient. Arbuscular mycorrhizal colonisation was significantly improved by increasing rainfall levels and amount of surrounding kanuka, and negatively affected by increasing altitude. Ectomycorrhizal colonisation was not significantly affected by any measured variables and remained relatively constant across all circumstances, suggesting that it is the preferred fungal mutualist for this tree species. A glasshouse experiment was done to measure the effect of ECM inoculation on the growth and water usage of K. ericoides over varying moisture availability. The seedlings were planted in soil inoculated with both ECM and AMF (experimental) or AMF only (control) and then grown under varying levels of water stress. The experiment was replicated with two soil types, with soil from beneath adult manuka (Leptospermum scoparium) and soil from beneath adult kanuka (K. ericoides). ECM colonisation significantly increased as soil moisture decreased for both soil types. ECM inoculation also increased the root:shoot ratio, and drastically decreased water usage under drought conditions. There were some soil effects as the seedlings grown in manuka-soil achieving greater biomass than seedlings grown in kanuka-soil. This is possibly due to presence of pathogens or some type of legacy competition which the seedlings would experience growing near conspecifics. Overall, K. ericoides formed a dominant mutualism with ectomycorrhizae. These two both thrive in dry environmental conditions and have a suite of complementing abilities which possibly allow K. ericoides to expand it range into these dry habitat types. The increased benefit of these mutualisms at the hydrologic range limit of the species supports the importance of biotic interaction mediating environmental stress. Understanding the effects and response of mycorrhizal mutualisms are especially significant considering current climate change issues in New Zealand and worldwide.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2006. / Härtill 4 uppsatser.

La Tara (Caesalpinia spinosa) est une espèce forestière d’une grande importance en raison d’une forte demande sur le marché international pour les tanins présents dans ses gousses, et pour les gommes provenant de ses graines. Malgré son importance économique pour le Pérou, la majeure partie de la production provient de forêts naturelles non aménagées. Ces forêts présentent des problèmes de sol (érosion, faible fertilité, présence d’agents pathogènes, manque d'irrigation), qui conduisent à des rendements faibles. C’est pourquoi dans le présent travail, nous étudions les composantes microbiologiques du sol associé à cette culture, telles que les mycorhizes et les bactéries dont l’utilisation, selon de nombreuses études, s’est révélée être une alternative à l'utilisation d'engrais chimiques. Pour cela, nous avons procédé à l'analyse moléculaire de la diversité des champignons mycorhiziens arbusculaires par la technique de Miseq Illumina, ce qui nous a permis de mettre en évidence une prépondérance de Gloméracées parmi lesquelles les Rhizophagus spp. étaient retrouvés dans 70% des séquences. En outre, la dépendance de la Tara vis-à-vis de la mycorhization a été démontrée car, après avoir testé la mycorhization contrôlée de la Tara par Rhizophagus irregularis, il a été constaté que la croissance de Caesalpinia spinosa était considérablement améliorée, ainsi que l'absorption d'éléments nutritifs tels que l'azote (N) et le phosphore (P). Pour vérifier la capacité à noduler de la Tara, différents milieux de culture ont été utilisés ainsi que différentes conditions de croissance, en serre et in vitro. Ces expérimentations ont toutes montré que les racines de Tara ne présentaient pas de nodules, confirmant que cette légumineuse de la sous-famille des Caesalpinioideae est non nodulante. Par conséquent et afin d’étudier la diversité des rhizobia présents dans le sol de la plantation de Tara, nous avons utilisé en serre une plante-piège, le pois (Pisum sativum) car c’est une légumineuse nodulante et de plus est traditionnellement associée à la culture de Tara. Les rhizobia identifiés moléculairement se sont révélés très spécifiques et différents des rhizobia présents dans les sols extérieurs à la plantation de Tara. Plus particulièrement, ces rhizobia se sont révélés être phylogénétiquement proches de R. etli, R. phaseoli, R. pisi et R. leguminosarum. Enfin, un test d'inoculation contrôlée (in vitro) a été réalisé sur des plantules de pois, avec ces bactéries préalablement piégées et isolées du pois. Il a été observé que les rhizobia piégés à partir des sols collectés entre deux lignes de Tara et sur la ligne de plantation de Tara, ont stimulé la croissance du pois par rapport aux rhizobia présents dans les sols collectés à l'extérieur de la plantation. / The Tara (Caesalpinia spinosa) is a forest species of great importance due to its high demand in the international market for the tannins present in its pods and its seeds’ gum. Despite its great importance for Peru, most of the production comes from unmanaged natural forests. These forests present soil problems (e.g., erosion, low fertility, pathogens, lack of irrigation), which cause low yields. Therefore, in the present work we seek to study the soil components associated with Tara plantation , such as mycorrhizae and bacteria that have proved to be an alternative for reducing the use of chemical fertilizers in similar context (Aboubacar et al., Flores Chavez 20015, E and Saif 1987, Dia et al. 2010; Bilgo et al., 2013) . We used molecular analysis of the arbuscular diversity by the Miseq Illumina technique that allowed to verify the arbuscular diversity with a preponderance of Glomeraceae among which the Rhizophagus spp were found to be present in 70% of the sequences. In addition, the dependence of the Tara on obligatory mycorrhization was demonstrated, after testing the controlled mycorrhization of the Tara by the Rhizophagus irregularis. We found that the growth of this crop was significantly improved, as well as the absorption of nutrients such as nitrogen (N) and phosphorus (P).To check the nodulation of the Tara, different culture media were used (JenSen, sand mixture with Tara plantation soil, attapulgite mixture with Tara plantation soils) in greenhouse and in vitro condition. We did not manage to find rhizobial nodules in the roots which let us think that Tara is a non-nodular legume. Therefore, we used Pisum sativum as a trap plant to study the diversity of rhizobia present in the soil of the Tara plantation since this legume is often associated with Tara crop. The rhizobia found in the trap plant were very specific and different from the rhizobia present in soils outside the Tara plantation. Likewise, these rhizobia found to be phylogenetically close to R. etli, R. phaseoli, R. pisi and R. leguminosarum. Finally, we inoculated the trapped bacterias (in vitro) in Pisum sativum with the bacterias previously trapped and isolated from the pea (which grew in the green house); where it was observed that the rhizospheric bacteria of the zones IL (soil collected between two lines) and L (soil collected from the same line) from the plantation of Tara stimulated the growth of this crop with respect to the bacteria present in soils collected outside of the plantation (OP zone).

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.

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.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2007. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2007. / Härtill 4 uppsatser.

The study of arbuscular mycorrhizal symbiosis (AMS) - the mutualist relationship between the most of land plants and evolutionary old fungal group Glomeromycota - is becoming a prestigious topic. The prevalence of and extent of physiological action of AMS on plants is very interesting for the plant biology itself, but its importance grows, notably in time of global climate change, frequent soil degradation and ascending exhaustion of mineral fertilizer reserves. Although the flows in AMS of some minerals, like of phosphorus was enlightened, carbon exchange between the symbionts is still poorly understood. In this experimental work, I utilized the boom of molecular and bioinformatic methods in the quest for completely unexplained carbon flows. The organisms used include barrel medic (Medicago truncatula), the model legume for symbiotic relationships, biotic, and abiotic stresses; Rhizophagus irregularis, the widely used fungus for such experimental studies of AMS; and Sinorhizobium meliloti, the nodulating nitrogen-fixing bacterium compatible with the barrel medic. Two variants - mycorrhizal (M+) and non-mycorrhizal (NM) plants were subjected to several levels of analysis. I have checked the variants, did the measurements of phosphorus and nitrogen contents, as well as I probed the plants with...