Made available in DSpace on 2014-06-11T19:35:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-09-23Bitstream added on 2014-06-13T20:26:13Z : No. of bitstreams: 1 scabora_mh_dr_ilha.pdf: 1356809 bytes, checksum: 1945cc637998450974f2829ff790aafa (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Com a construção da barragem da Usina Hidrelétrica de Ilha Solteira (SP), ocorreu a degradação do solo, expondo o subsolo e dando origem às áreas de empréstimo. Com o objetivo de melhor compreender a associação entre fungos micorrízicos arbusculares (FMA) e espécies arbóreas na recuperação de áreas degradadas, foram avaliados a produção de esporos e a diversificação das comunidades de FMA nativos após inoculação em dez espécies arbóreas nativas do cerrado, implantadas em duas áreas, uma vegetada com pastagem e outra com subsolo exposto, bem como avaliar a ocupação destas por espécies herbáceas co-ocorrentes e as alterações da fertilidade do solo ao longo de quatro anos de revegetação. O experimento foi conduzido na Fazenda de Ensino, Pesquisa e Extensão da Universidade Estadual Paulista, Faculdade de Engenharia, Campus de Ilha Solteira, localizada no município de Selvíria-MS. O delineamento experimental foi o fatorial 2x4x10 em blocos, ou seja, duas áreas (pastagem e subsolo exposto), quatro anos e 10 espécies arbóreas, com quatro repetições, sendo cada repetição constituída por cinco plantas. Após a instalação do experimento, amostras do solo e do subsolo foram coletadas na profundidade de 0- 0,10 cm, no 1, 2, 3 e 4o ano e utilizadas para avaliação das características químicas e das comunidades de FMA. O número de esporos, a riqueza de espécies, a diversidade e a equabilidade foram comparados e relacionados com as propriedades químicas do solo e com a ocupação das espécies herbáceas co-ocorrentes. Houve incrementos nos teores de matéria orgânica ao longo do anos na área de subsolo. Na diversificação de FMA foram identificadas 52 espécies, das quais 19 pertencem ao gênero Glomus, 14 pertencem à Acaulospora, 10 à Scutellospora, seis à Gigaspora... / Due the construction of the Ilha Solteira Hydroelectric plant (SP), soil degradation has occurred, exposing the subsoil and giving rise to the “soil landing” areas. In order to better understand the association between arbuscular mycorrhizal fungi (AMF) and tree species in the recovery of degraded areas, were assessed the spores production and diversification of native communities of AMF by evaluating ten species of cerrado native tree after the inoculation, introduced in two areas, one vegetated with grass and the other with exposed subsoil, as well as, by evaluating the occupation by the co-occurring plant species and changes in soil fertility, over the four years of restoration. The experiment was conducted at the Education, Research and Extension Farm of the UNESP-Universidade Estadual Paulista, Engineering Faculty, Ilha Solteira Campus, located in the city of Selvíria-MS. The experimental design was a complete randomized block design in a 2 x 4 x 10 factorial, i.e., two areas (pasture and subsoil exposed), four years and 10 tree species, with four replicates, each replicate consisting of five plants. The soil and subsoil, sampled at the depth of 0 to 0.10 m, after 12, 24, 36 and 48 months after the experiment installation, were used to evaluate the soil chemical and AMF communities characteristics... (Complete abstract click electronic access below)

Resumo: Com a construção da barragem da Usina Hidrelétrica de Ilha Solteira (SP), ocorreu a degradação do solo, expondo o subsolo e dando origem às áreas de empréstimo. Com o objetivo de melhor compreender a associação entre fungos micorrízicos arbusculares (FMA) e espécies arbóreas na recuperação de áreas degradadas, foram avaliados a produção de esporos e a diversificação das comunidades de FMA nativos após inoculação em dez espécies arbóreas nativas do cerrado, implantadas em duas áreas, uma vegetada com pastagem e outra com subsolo exposto, bem como avaliar a ocupação destas por espécies herbáceas co-ocorrentes e as alterações da fertilidade do solo ao longo de quatro anos de revegetação. O experimento foi conduzido na Fazenda de Ensino, Pesquisa e Extensão da Universidade Estadual Paulista, Faculdade de Engenharia, Campus de Ilha Solteira, localizada no município de Selvíria-MS. O delineamento experimental foi o fatorial 2x4x10 em blocos, ou seja, duas áreas (pastagem e subsolo exposto), quatro anos e 10 espécies arbóreas, com quatro repetições, sendo cada repetição constituída por cinco plantas. Após a instalação do experimento, amostras do solo e do subsolo foram coletadas na profundidade de 0- 0,10 cm, no 1, 2, 3 e 4o ano e utilizadas para avaliação das características químicas e das comunidades de FMA. O número de esporos, a riqueza de espécies, a diversidade e a equabilidade foram comparados e relacionados com as propriedades químicas do solo e com a ocupação das espécies herbáceas co-ocorrentes. Houve incrementos nos teores de matéria orgânica ao longo do anos na área de subsolo. Na diversificação de FMA foram identificadas 52 espécies, das quais 19 pertencem ao gênero Glomus, 14 pertencem à Acaulospora, 10 à Scutellospora, seis à Gigaspora... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Due the construction of the Ilha Solteira Hydroelectric plant (SP), soil degradation has occurred, exposing the subsoil and giving rise to the "soil landing" areas. In order to better understand the association between arbuscular mycorrhizal fungi (AMF) and tree species in the recovery of degraded areas, were assessed the spores production and diversification of native communities of AMF by evaluating ten species of cerrado native tree after the inoculation, introduced in two areas, one vegetated with grass and the other with exposed subsoil, as well as, by evaluating the occupation by the co-occurring plant species and changes in soil fertility, over the four years of restoration. The experiment was conducted at the Education, Research and Extension Farm of the UNESP-Universidade Estadual Paulista, Engineering Faculty, Ilha Solteira Campus, located in the city of Selvíria-MS. The experimental design was a complete randomized block design in a 2 x 4 x 10 factorial, i.e., two areas (pasture and subsoil exposed), four years and 10 tree species, with four replicates, each replicate consisting of five plants. The soil and subsoil, sampled at the depth of 0 to 0.10 m, after 12, 24, 36 and 48 months after the experiment installation, were used to evaluate the soil chemical and AMF communities characteristics... (Complete abstract click electronic access below) / Orientador: Ana Maria Rodrigues Cassiolato / Coorientador: Rosilaine Carrenho / Banca: Katia Luciene Maltoni / Banca: Franscisco Maximino Fernandes / Banca: Daniela Tiago da Silva Campos / banca: Waldeamar Zangaro Filho / Doutor

abstract: Mycorrhizal fungi form symbiotic relationships with plant roots, increasing nutrient and water availability to plants and improving soil stability. Mechanical disturbance of soil has been found to reduce mycorrhizal inoculum in soils, but findings have been inconsistent. To examine the impact of restoration practices on riparian mycorrhizal inoculum potential, soil samples were collected at the Tres Rios Ecosystem Restoration and Flood Control Project located at the confluence of the Salt, Gila, and Agua Fria rivers in central Arizona. The project involved the mechanical removal of invasive Tamarix spp.( tamarisk, salt cedar) and grading prior to revegetation. Soil samples were collected from three stages of restoration: pre-restoration, soil banks with chipped vegetation, and in areas that had been graded in preparation for revegetation. Bioassay plants were grown in the soil samples and roots analyzed for arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) infection percentages. Vegetations measurements were also taken for woody vegetation at the site. The mean number of AM and EM fungal propagules did not differ between the three treatment area, but inoculum levels did differ between AM and EM fungi with AM fungal propagules detected at moderate levels and EM fungi at very low levels. These differences may have been related to availability of host plants since AM fungi form associations with a variety of desert riparian forbs and grasses and EM fungi only form associations with Populus spp. and Salix spp. which were present at the site but at low density and canopy cover. Prior studies have also found that EM fungi may be more affected by tamarisk invasions than AM fungi. Our results were similar to other restoration projects for AM fungi suggesting that it may not be necessary to add AM fungi to soil prior to planting native vegetation because of the moderate presence of AM fungi even in soils dominated by tamarisk and exposed to soil disturbance during the restoration process. In contrast when planting trees that form EM associations, it may be beneficial to augment soil with EM fungi collected from riparian areas or to pre-inoculate plants prior to planting. / Dissertation/Thesis / M.S. Applied Biological Sciences 2012

Arbuscular mycorrhizas (AM) are mutually beneficial symbiotic associations between the roots of plants and certain Zygomycetous fungi. The role of AM fungi in coastal sand dunes has been explored in many parts of the world, though little work has been conducted in South African dune systems. This study aimed to investigate the presence and extent of mycorrhizal colonisation of a coastal sand dune in South Africa. The roots of five plant species (Scaevola plumieri, Arctotheca populifolia, Ipomoea pes-caprae, Ehrharta villosa and Chrysanthemoides monilifera) were sampled along a foredune profile at Old Woman's River in the Eastern Cape. These roots were assessed for the percentage mycorrhizal colonisation they supported. Spores extracted from the rhizosphere sand of each plant species were counted and identified to genus level. Results were related to seasonality and the position of the plants along the profile. All plant species were found to be mycorrhizal. Percentage colonisation ranged from 0-92%, depending on plant species and season. Mycorrhizal colonisation was generally highest in the winter months, and especially so in I pes-caprae and E. villosa. The extent of various mycorrhizal structures in root tissue varied between plant species. Spore numbers ranged from 0-48 spores 100g-1 sand with highest numbers occurring in winter. S. plumieri and A. populifolia were associated with greatest spore abundance. Four fungal genera (Glomus, Acaulospora, Scutellospora and Gigaspora) were identified. Distribution of these genera showed seasonal variations between plant species. A bioassay, using Sorghum, was conducted to test the inoculum potentials of sand from the Scaevola hummock and the IpomoealEhrharta dune. Highest percentage colonisation occurred in plants grown in the Scaevola sand, which also had the lowest root and shoot measurements. The bioassay confirmed that AM propagules are present and viable, even in the mobile sand of the foredune. This study showed that mycorrhizal colonisation and spore numbers varied seasonally, but that the extent of this was dependent on plant species. The position of plants along the foredune profile tended to be less important than plant species. It is thought that the growth cycle and rooting system of each plant species determines seasonal cycles and abundance of AM fungi. Variation within fungal populations probably also impacts on this. Knowledge of the presence and distribution of AM fungi in this system paves the way for more detailed studies which need to examine the role of these endophytes in South African sand dunes.

Existing evidence suggested that nursery inoculation with Trichoderma harzianum and arbuscular mycorrhizal fungi (AMF) could reduce deleterious effects of biotic and abiotic stresses and improve seedling quality, fruit yield and quality of tomato (Solanum lycopersicum L.). However, studies of their combined inoculation on seedling growth, fruit yield and quality of tomato plants are not well-documented. Experiments were carried out to investigate the combined effect of T. harzianum and AMF on tomato crop performance under various conditions. When combined with a T. harzianum and AMF mixture, seaweed extract from Ecklonia maxiama inhibited AMF root colonisation of tomato seedlings. Treating seedlings with a mixture of T. harzianum and AMF reduced the incidence of Verticillium wilt in tomato grown in a nethouse at early season, with negligible effect on fruit yield. Further investigations were initiated to find out whether T. harzianum and AMF were efficient when applied as a mixture or alone, at different inoculation times. Co-inoculation with T. harzianum and AMF (Glomus mosseae) improved seedling growth and development, except when both fungi were simultaneously applied two weeks after sowing. When the seedlings were allowed to grow up until full harvest in a greenhouse, both fungal inoculants increased total yield and marketable yield, but these increases were not significant. Furthermore, inoculation with AMF increased the percentage of extra-large fruit. Field experiments conducted under commercial tomato production confirmed greenhouse studies. Inoculation of tomato with T. harzianum and AMF, either alone or in combination increased early fruit yield (four first harvesting weeks). Throughout the studies, percentage AMF root colonisation in seedlings and plants remained low, despite nursery inoculation. Field experiments investigated the effects of AMF-inoculated transplants combined with biochar-amended soils on AMF root colonisation and their resultant effects on overall crop performance and microbial community structure. Biochar had no effect on AMF root colonisation, and also when combined with AMF, it had no influence on tomato productivity. Interestingly, biochar altered the fungal community while AMF might have influenced the bacterial community such as plant-growth promoting rhizobacteria, which are associated with improved plant growth, nutrient uptake and disease control in the rhizosphere. These benefits could contribute to improved yield and fruit quality. In conclusion, although the results were variable, there was a clear indication that T. harzianum and AMF can play an important role in tomato production. / Thesis (PhD)--University of Pretoria, 2012. / Plant Production and Soil Science / unrestricted

Mycorrhizal networks (MNs) are fungal hyphae that connect the roots of at least two plants, potentially providing a conduit for interplant resource transfer. Interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) is an obligate ectomycorrhizal (EM) tree species that has high potential to form MNs with neighboring trees because of its receptivity to a diverse community of EM fungi. This MN potential is expected to be greatest among conspecific trees. In this thesis, I determined the influence of MNs formed by residual Douglas-fir trees on interplant carbon transfer and survival, growth, physiology, and EM status of neighboring naturally regenerated and planted Douglas-fir seedlings. To do this, I used MN-restricting treatments and isotope gas-labeling techniques on sites harvested with variable tree retention to investigate how varying: i) proximity to conspecific trees affects EM colonization and performance of planted seedlings; ii) ‘donor’ tree size affects seedling establishment and carbon or nitrogen transfer, and; iii) soil disturbance stress affects net carbon transfer between established seedlings. Because I used physical barriers (i.e., mesh bags) to control for the presence and characteristics of the MN, I also verified the effectiveness of different-sized mesh pores at reducing hyphal connections between plants in the greenhouse. In my experiments, I found that MN-mediated colonization was not the dominant mechanism responsible for EM colonization of planted seedlings; other sources of inoculm (e.g., spores, sclerotia, hyphal fragments) were more important. I found that mature trees not only competed for resources with seedlings but offered some facilitative effects at intermediate distances within their rooting zones. My key finding was that access to a MN with residual trees benefited seedling survival and that this corresponded with increased carbon and nitrogen transfer to seedlings. In addition, I found that there was consistently a net gain in carbon by one seedling in a MN and this net transfer increased with relative growth rate of the receiver seedling. These results indicate that MNs can facilitate interplant carbon transfer and be important in regeneration dynamics in dry Douglas-fir forests. / Forestry, Faculty of / Graduate

Arbuscular mycorrhizal (AM) fungi are obligate biotrophs that formsymbiosis with plants by colonizing their roots. The fungus supplies thehost plant with various nutrients, including phosphorus. Phosphorus iscrucial for the development of plants and is hard to acquire in soilsince it can be scarce and has a slow motility. The fungus utilizes itslong hyphal threads to contact more soil to obtain phosphorus andtransport it back to the plant. It does so with its use of differentphosphorus transporters (PTs) located in its membranes. Here we havedone a phylogenetic analysis of different PTs from a variety of fungifrom different phyla together with plants and new sequence data from AMfungi. In total, 955 genomes were screened, 26 of which belong to AMfungi. This work resulted in a database of 1351 PT sequences, 907 fromfungi (243 from AM) and 444 from plants, and two phylogenetic trees tovisualize the data. One phylogeny was made of the branch of the PT Pho87which was selected for building a Hidden Markov model, which canfacilitate future searches of PTs.

Arbuscular mycorrhizal fungi (AMF) are a group of root obligate symbionts that are part of the fungal sub-phylum Glomeromycotina, which provide water, nutrients, and pathogen protection to about 80% of land plants in exchange for their photosynthetic products. AMF thus act as “biofertilizers”, have a profound effect and influence on the biodiversity of plants, and play a major role in life on land. From an evolutionary point of view, AMF are a puzzling group of organisms, thought to have propagated for over 400 million years without sexual reproduction, a rarity among eukaryotes. However, this assumption is largely based on the absence of definitive observations of sexual reproduction through microscopic tools. One clue into the sexual activity of AMF is evidence of a dikaryotic-like genome organization in their multi-nucleated mycelium. The recent identification of multi-allelic mating-type loci (MAT locus) potentially places AMF among other heterothallic or bipolar species, who’s mating compatibility is determined by their MAT locus. The presence of a hidden sexual cycle in AMF is still a possibility, and recent findings on the meiotic gene content of AMF suggests an alternative narrative to how these fungi have escaped extinction for so long. Seven meiosis-specific genes (MSG) were found to exist in AMF, indicating that these fungi are likely undergoing a cryptic sexual cycle. The main goal of this research is to determine if/when MSG are expressed in an in-vitro model of AMF. To build onto this research, we established crossings between isolates with hypothetically compatible mating types, in order to determine if fusion of their hyphae can trigger the expression of MSG. Together, these experiments will assess expression at varying stages of the putative cycle of sexual reproduction and give further insight into the elusive sexual life of AMF.

Thickets of Rhododendron maximum (Rm) in the southern Appalachians impose severe limitations on the regeneration of hardwood and coniferous seedlings. Interactions between Rm thickets and ectomycorrhizal colonization were examined to explain seedling inhibition. Experimental blocks were established in and out of Rm thickets in a mature, mixed hardwood/conifer forest in Macon County, North Carolina. Planted seedlings of red oak (Quercus rubra) and hemlock (Tsuga canadensis) were harvested at the end of the first and second growing seasons. Litter manipulation had no effect on total mycorrhizal colonization. Mycorrhizal colonization and ramification index (# mycorrhizae cm-1) were depressed and colonization by Cenococcum geophilum increased in blocks with versus without Rm. After the first year, percent colonization of T. canadensis not in Rm thickets (62 %) was three times higher than in Rm thickets (19%), and the ramification index was increased by more than a factor of four (2.83 versus 0.61). Mycorrhizal colonization levels were correlated with root weight and shoot weight in both hemlock and oak seedlings, but did not explain most of the variation observed. Sporocarps of 69 putatively ectomycorrhizal species were collected on the blocks. Species diversity and overall community structure was similar in and out of Rm thickets. Individual species, i.e. Lactarius speciosus and Russula krombholzii, were significant indicators of forest without Rm thickets. Rhododendron maximum thickets probably affect the process of mycorrhization. The reduced level of mycorrhizal capacity under Rm thickets could be a factor in the increased seedling failure in Rm thickets. / Master of Science

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