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Made available in DSpace on 2014-06-12T15:54:38Z (GMT). No. of bitstreams: 2 arquivo5245_1.pdf: 1717033 bytes, checksum: 35f1239c38c5377c844bcfff660ab161 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2006 / Foi analisada a influência da atividade gesseira sobre a ocorrência, a diversidade, o potencial de infectividade de fungos micorrízicos arbusculares (FMA), e o estado biológico dos solos. Além disso, utilizou-se a técnica ARDRA na tentativa de diferenciar espécies de FMA encontradas nas áreas de estudo. Coletas de solo foram realizadas nos períodos chuvoso (Dez/2003) e seco (Set/2004), em quatro áreas: uma com caatinga nativa preservada (AN) e três em mineradora de gesso: interface entre o depósito de rejeito e área de caatinga degradada pela mineração (AI); arredores da mina (AM) e rejeito (AR). A mineração diminuiu a diversidade de FMA e de plantas nas três subáreas, em relação à caatinga nativa preservada. Foram identificadas 27 e 29 espécies de plantas e 29 e 28 espécies de FMA respectivamente nos períodos chuvoso e seco. Entre os FMA, Glomus intraradices e Paraglomus occultum foram os melhores representados tolerando as condições edáficas das subáreas impactadas e desse modo mostraram potencial para utilização em programas de revegetação em áreas similares. Baixos índices de similaridade vegetal e de FMA foram verificados entre a área nativa e as afetadas pela mineração. Maior esporulação dos FMA ocorreu no período chuvoso, enquanto o número mais provável (NMP) de propágulos de fungo (incluindo FMA) e a colonização radicular foram maiores no período seco. Houve correlação positiva entre o NMP de FMA e o número de esporos nos dois períodos de coleta. No período chuvoso, o NMP de FMA foi negativamente correlacionado com a colonização radicular. A atividade antrópica exercida nas áreas em estudo teve forte impacto negativo sobre a microbiota do solo, reduzindo o número de bactérias, actinomicetos e fungos, a atividade e a biomassa microbianas. A atividade gesseira reduziu a produção de glomalina facilmente extraível (GFE) e total (GT) em relação ao encontrado na área de caatinga nativa. Esta glicoproteína pode ser utilizada como indicador da qualidade edáfica, considerando que apontou diferenças entre os solos impactados e o nativo, preservado. Alguns FMA obtidos nas áreas de estudo foram distinguidos pela técnica ARDRA-ITS, que mostrou potencial como marcador capaz de diferenciar espécies com elevada afinidade filogenética

Three studies were conducted on VA mycorrhiza in Wanagama Forest Research Center, Yogyakarta, Indonesia. The first was on VA mycorrhizal status of four forest species (Acacia mangium, Acacia holosericea, Tectona grandis, and Swietenia macrophylla) plantations and nurseries of Acacia mangium and Tectona grandis. Samples from the field were only taken during the dry season, June 1988. These four six-year old forestry species were mycorrhizal. Nursery plants had higher VAM colonization than the plantation roots and both Acacia species have higher percent colonization than the other two species. Available phosphorus in calcareous soils is low and seems not to be a major contribution to the variation of VAM colonization. Potassium and sodium were more important in this case even though their role could not be determined in this study. The second study was conducted to determine VAM fungal species associated with the plant species. There were 16 different spore types belonging to the genera Glomus, (the most common found), Sclerocystis, Scutellispora, and probably Acaulospora. Type of inoculum and host compatibility were suggested as important factors in the success of pot culture study. The third study was carried out in a growth chamber to determine Acacia spp. response to single VAM fungal species and mixed species inoculum. Single species inoculum in both Acacia was observed to improve biomass and plant growth better than the mixed inoculum. Acacia mangium performed better with Glomus versiforme than did A. holosericea. Host compatibility, effectiveness of VAM spore inoculant, infectivity and environmental factors have major effects on plant growth responses. Study of tropical VAM requires further basic research, including taxonomy. Experimental procedures such as pot culture technique, type of inoculum, growth media and host plant specificity along with evaluation of appropriate soil chemical analysis also requirefurther elaboration. These types of studies are needed to understand the relationship between VAM and the environment and in the application studies in agriculture and forestry. This information is especially important in tropical countries, where little research results and limited resources, such as for fertilizers, are available. / Land and Food Systems, Faculty of / Graduate

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.

Arbuscular mycorrhizal fungi (AMF) form a mutually beneficial symbiotic relationship with a majority of land plants through an exchange of nutrients. Despite the importance of AM symbiosis in agricultural and ecological settings, relatively little is known about how the fungal symbiont actively promotes symbiosis. To overcome a host’s immune response, plant pathogens secrete effector proteins that modify a host to suppress an immune response. Few effectors have been identified in AMF, as bioinformatics methods have failed to accurately predict their sequences. To successfully colonize a plant, AMF form structures called arbuscules within plant root cortical cells. Arbuscules are a primary site of nutrient exchange during AMF symbiosis. This work is built on the hypothesis that AMF produce effector proteins to promote symbiosis, and that arbuscules are a site of effector secretion. Using Rhizophagus irregularis, Glomus versiforme and Medicago truncatula this work applies a proteomics-based approach using a new biotechnology to identify fungal proteins secreted by AMF. This novel approach using proteomics and proximity labelling to identify proteins by mass spectrometry is the first time this system has been used to study the plant-AMF relationship. In this work, mass spectrometry identifies a total of 24 R. irregularis proteins and two G. versiforme proteins that are candidate effectors involved in the plant-AMF symbiosis.

"June 2002" / Bibliography: leaves 179-194. / 194 leaves : ill. (col.), plates (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The overall aim of the research presented in this thesis was to determine if the growth and function of external hyphae of Arbuscular Mycorrhizal (AM) fungi is affected by changes in soil pore size. / Thesis (Ph.D.)--University of Adelaide, Dept. of Soil and Water, 2002

Numerous soils have been contaminated by radiocaesium (Cs) as a result of nuclear weapon testing and accidents at nuclear power-plant facilities. Management of the areas, which have been exposed to either intense or diffuse Cs pollution, has therefore become a major environmental concern. Strategies orientated toward the use of plants and microorganisms, or both in combination, have been proposed in the recent years as potential players in removing or stabilizing Cs in contaminated soils. Among these microorganisms, arbuscular mycorrhizal (AM) fungi are of particular interest due to their unique position at the soil/root interface and their recognized role in element transport and immobilization. In the recent years, contradictory results have been published on the impact of AM fungi on Cs accumulation by plants, failing to ascertain whether AM fungi could effectively transport this radionuclide to their host. Therefore, the objective of this work was to determine the role of AM fungi in plant Cs acquisition and accumulation. Using in vitro compartmented systems, we unambiguously demonstrated that AM fungi could transport Cs to their host, while its accumulation within the extraradical mycelium was rather limited. Our results also suggested that AM fungi could have an effect on Cs distribution within their host. Indeed, it appeared that AM fungi could potentially limit the translocation of Cs from roots to shoot. However, if the results obtained during this research project have shown that AM fungi could influence the acquisition and accumulation of Cs by plants, their capacity to take part in phytoremediation strategies remains questionable and would need additional investigations. In particular, attention should be focused on the mechanisms behind Cs transport by AM fungi, their influence on Cs root to shoot translocation and the subsequent validation of the findings obtained to in situ conditions.

The Arbuscular mycorrhiza (AM) symbiosis is a mutual association formed by plant roots and soil fungi. Most vascular flowering plants have the ability to form AM associations, which show significant impact on ecosystem function and plant health. This association is based on the mutual exchange of nutrients between plant and fungus. Therefore, AM association leads to increased demands for photosynthesis. The main aim of this study was to investigate the pathway used by plants during AM to increase the photosynthetic performance. To achieve this aim, we used the model legume Medicago truncatula. We have found out that AM symbiosis develops in roots, where AM fungi colonize the roots, leading to better plant growth and more biomass. Furthermore, AM symbiosis increases chlorophyll content and photosynthetic electron transport rate in leaves. Based on these results we suggest that AM symbiosis increases both efficiency and capacity of photosynthetic apparatus in Medicago truncatula

"June 2002" / Bibliography: leaves 179-194. / 194 leaves : ill. (col.), plates (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The overall aim of the research presented in this thesis was to determine if the growth and function of external hyphae of Arbuscular Mycorrhizal (AM) fungi is affected by changes in soil pore size. / Thesis (Ph.D.)--University of Adelaide, Dept. of Soil and Water, 2002

Thesis (Ph. D.)--University of Adelaide, Dept. of Soil Science, 1995? / Copies of author's previously published articles inserted. Includes bibliographical references (leaves 184-197).