Tomato (Solanum lycopersicum L.) produces an array of volatile secondary metabolites that act as constitutive and induced defenses against a variety of insect pests and diseases. We studied the effect of beneficial microorganisms, an arbuscular mycorrhiza fungus (AM), Glomus intraradices, an entomopathogenic fungus (Bb), Beauveria bassiana and a combination of both (AM+Bb), as well as, pests, such as rootknot nematode (RKN) (Meloidogyne incognita) and beet armyworm (BAW) (Spodoptera exiguae H.) on the production of volatile compounds in the leaves and roots of tomato. Benzyl alcohol, 3-hexenoic acid, total other compounds and β-myrcene were significantly increased (P<0.05) in the leaves by AM and Bb colonization. Upon herbivory, control plants showed a trend for high volatile contents among all four treatment groups contrary to the trend observed without herbivory, when control showed low volatile contents. Herbivory significantly decreased all the volatiles in the leaves compared to those without herbivory. Pest bioassay revealed that these two fungi together can significantly induce resistance against BAW. In the experiment with RKN, a trend was observed with low production of most volatile compounds in the leaves from the RKN plants. Varying durations of herbivory exposure had significant effects on many leaf volatile compounds compared to those without herbivory. Effect of RKN was significant (P<0.05) on the production of methyl salicylate, and (Z)-geraniol in the roots. Interaction effect of RKN with 18 hours of herbivory was significant for (Z)-geraniol, and with 42 hours of herbivory, it was significant for (Z)-geraniol, benzyl alcohol, and total volatiles in the roots. Beet armyworm preferred RKN plants and caused greater damage to them compared to the control plants. Semi-quantitative RT-PCR showed higher expression of the SlSAMT gene in the roots colonized with RKN, compared to the control roots and those from a resistant line. The experiments demonstrated that interaction with these organisms can change the volatile compounds in the leaves and roots of tomato plant, can alter herbivore preference, and can upregulate defense genes such as SlSAMT.

AM plants acquire Pi via two pathways; the direct uptake pathway via plant roots and the AM pathway via external fungal hyphae and colonised cortical cells. It has been assumed that these two pathways are additive and therefore in non-responsive plants the AM pathway is often considered to be non-functional. However, data from ³²P uptake studies indicates that the AM pathway is functional in many non-responsive symbioses and in some instances supplies the majority of plant P. In recent years the high-affinity Pi transporters involved in both direct and AM Pi uptake pathways have been identified. They are expressed at the root epidermis and the symbiotic interface of colonised cortical cells and respond to the P and AM status of the plant. The overall objective of the work described in this thesis was to characterise Pi uptake via the AM pathway in barley, a non-responsive AM host, using an approach which integrated physiological measurements of plant responsiveness and AM contribution with investigations of gene expression and functional characterisation of the plant Pi transporters. A preliminary survey of field-grown barley demonstrated the persistence of AM colonisation under commercial cropping regimes in southern Australia and highlighted the relevance of AM studies to commercial agriculture. Under glasshouse conditions AM colonisation of barley induced depressions in growth and P uptake compared to NM controls. Growth depressions were unrelated to percent colonisation by two AM fungal species and could not readily be explained by fungal C demand; the strong correlation between growth and P content suggested that P was the limiting factor in these experiments. However, a compartmented pot system incorporating ³²P-labelling demonstrated that the AM pathway is functional in colonised barley and, in the interaction with G. intraradices, contributed 48% of total P. This suggested that P flux via the direct uptake pathway is decreased in AM barley. The expression of three Pi transporters, HvPT1, HvPT2 and HvPT8 was investigated in colonised roots. HvPT1 and HvPT2 have previously been localised to the root epidermis and root hairs and are involved in Pi uptake via the direct pathway whilst HvPT8 is an AM-inducible Pi transporter which was localised by in-situ hybridisation to colonised cortical cells. Using promoter::GFP gene fusions the localisation of HvPT8 to arbuscule-containing cortical cells was confirmed in living roots from transgenic barley. Quantitative real-time PCR analysis of the expression of these three Pi transporters indicated that HvPT1 and HvPT2 were expressed constantly, under all conditions regardless of AM colonisation status and indicated that decreased P flux via the direct pathway is not related to expression of these transporters. HvPT8 was induced in AM colonised roots. However, the level of expression was not related to flux via the AM pathway or arbuscular colonisation. The HvPT8 transporter was further characterised by constitutive over-expression in transgenic barley. ³²P uptake assays in excised roots demonstrated increased Pi uptake from low P solution compared to wild-type roots and confirmed that HvPT8 is a functional Pi transporter with high-affinity transport properties. This is the first report of characterisation of an AM-inducible Pi transporter in planta. When these transgenic plants were grown in solution culture there was no increase in growth or P uptake relative to wild-type or transgenic controls and growth in soil and AM colonisation were also unaffected in these transgenic lines. The data presented in this thesis highlights the importance of combined physiological and molecular approaches to characterising plant AM interactions. The persistence of AM colonisation in barley in the field indicates the importance of improving our understanding of symbiotic function in non-responsive plants. Future efforts should be directed towards understanding the signals which regulate P flux via both the direct and AM pathways with the ultimate aim of enhancing AM responsiveness of non-responsive species. Making the direct and AM pathways additive in nonresponsive species should be a key aim of future research. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1313311 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2008

AM plants acquire Pi via two pathways; the direct uptake pathway via plant roots and the AM pathway via external fungal hyphae and colonised cortical cells. It has been assumed that these two pathways are additive and therefore in non-responsive plants the AM pathway is often considered to be non-functional. However, data from ³²P uptake studies indicates that the AM pathway is functional in many non-responsive symbioses and in some instances supplies the majority of plant P. In recent years the high-affinity Pi transporters involved in both direct and AM Pi uptake pathways have been identified. They are expressed at the root epidermis and the symbiotic interface of colonised cortical cells and respond to the P and AM status of the plant. The overall objective of the work described in this thesis was to characterise Pi uptake via the AM pathway in barley, a non-responsive AM host, using an approach which integrated physiological measurements of plant responsiveness and AM contribution with investigations of gene expression and functional characterisation of the plant Pi transporters. A preliminary survey of field-grown barley demonstrated the persistence of AM colonisation under commercial cropping regimes in southern Australia and highlighted the relevance of AM studies to commercial agriculture. Under glasshouse conditions AM colonisation of barley induced depressions in growth and P uptake compared to NM controls. Growth depressions were unrelated to percent colonisation by two AM fungal species and could not readily be explained by fungal C demand; the strong correlation between growth and P content suggested that P was the limiting factor in these experiments. However, a compartmented pot system incorporating ³²P-labelling demonstrated that the AM pathway is functional in colonised barley and, in the interaction with G. intraradices, contributed 48% of total P. This suggested that P flux via the direct uptake pathway is decreased in AM barley. The expression of three Pi transporters, HvPT1, HvPT2 and HvPT8 was investigated in colonised roots. HvPT1 and HvPT2 have previously been localised to the root epidermis and root hairs and are involved in Pi uptake via the direct pathway whilst HvPT8 is an AM-inducible Pi transporter which was localised by in-situ hybridisation to colonised cortical cells. Using promoter::GFP gene fusions the localisation of HvPT8 to arbuscule-containing cortical cells was confirmed in living roots from transgenic barley. Quantitative real-time PCR analysis of the expression of these three Pi transporters indicated that HvPT1 and HvPT2 were expressed constantly, under all conditions regardless of AM colonisation status and indicated that decreased P flux via the direct pathway is not related to expression of these transporters. HvPT8 was induced in AM colonised roots. However, the level of expression was not related to flux via the AM pathway or arbuscular colonisation. The HvPT8 transporter was further characterised by constitutive over-expression in transgenic barley. ³²P uptake assays in excised roots demonstrated increased Pi uptake from low P solution compared to wild-type roots and confirmed that HvPT8 is a functional Pi transporter with high-affinity transport properties. This is the first report of characterisation of an AM-inducible Pi transporter in planta. When these transgenic plants were grown in solution culture there was no increase in growth or P uptake relative to wild-type or transgenic controls and growth in soil and AM colonisation were also unaffected in these transgenic lines. The data presented in this thesis highlights the importance of combined physiological and molecular approaches to characterising plant AM interactions. The persistence of AM colonisation in barley in the field indicates the importance of improving our understanding of symbiotic function in non-responsive plants. Future efforts should be directed towards understanding the signals which regulate P flux via both the direct and AM pathways with the ultimate aim of enhancing AM responsiveness of non-responsive species. Making the direct and AM pathways additive in nonresponsive species should be a key aim of future research. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1313311 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2008

?rea de concentra??o: Produ??o vegetal. / Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2017-01-03T16:10:54Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) debora_cintia_santos_avelar.pdf: 1075322 bytes, checksum: 956aee85f03869781bc0c12ae661e4f7 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2017-01-31T16:25:33Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) debora_cintia_santos_avelar.pdf: 1075322 bytes, checksum: 956aee85f03869781bc0c12ae661e4f7 (MD5) / Made available in DSpace on 2017-01-31T16:25:33Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) debora_cintia_santos_avelar.pdf: 1075322 bytes, checksum: 956aee85f03869781bc0c12ae661e4f7 (MD5) Previous issue date: 2016 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / A determina??o da dose de inoculante ? essencial para a obten??o de benef?cios da utiliza??o de fungos ectomicorr?zicos (FEM) em mudas de eucalipto. O objetivo deste estudo foi avaliar a melhor dose de inoculante miceliano de isolados de Pisolithus sp., encapsulados em gel de alginato de c?lcio, visando a promo??o da coloniza??o, nutri??o e do crescimento das mudas de clones de eucalipto em viveiro comercial. Em experimentos independentes e utilizando aduba??o fosfatada reduzida, foram produzidas mudas de dois clones de eucalipto (AEC 2034 e AEC 2233) inoculados com 9, 18 e 36 esferas de inoculante miceliano dos isolados f?ngicos D17, D216, D5 e D95 e um tratamento N?o-inoculado (fatorial 3x5). Al?m disso, foram feitos mais dois tratamentos adicionais com (Controle) e sem (Comercial) redu??o da aduba??o fosfatada do substrato e sem adi??o dos inoculantes. A dose de 36 esferas de inoculante, em geral, promoveu maiores ganhos para as mudas de eucalipto, como maior coloniza??o, massa seca da parte a?rea (MSPA) e de ra?zes (MSR) e teores de K, sendo algumas vezes maior que nas mudas do Controle e Comercial. A maior altura da parte a?rea e di?metro do coleto foram observados com o uso de 18 esferas. A coloniza??o ectomicorr?zica foi maior nas mudas inoculadas e considerada m?dia para os dois clones. A inocula??o pr?via nos dois clones n?o promoveu aumento nos teores de P em rela??o ao Comercial, no entanto para o clone AEC 2233 com a utiliza??o do D216, houve aumento nos teores de P em rela??o ao N?o-inoculado, sendo este isolado o mesmo que proporcionou uma das maiores porcentagens de coloniza??o, contribuindo para maior absor??o desse nutriente. Em rela??o aos isolados, a inocula??o com o D17 em geral aumentou a sobreviv?ncia, altura, MSPA, MSR e teores de K no AEC 2034 e a altura e di?metro no AEC 2233, mas isto foi dependente da dose e do clone de eucalipto. A dose de 18 esferas foi mais apropriada, pois, na maioria dos casos, os maiores benef?cios como sobreviv?ncia, altura, di?metro, MSPA, MSR, coloniza??o, teores de N e K foram obtidos com a adi??o de 18 ou mais esferas por mini-estaca e, em alguns casos, os par?metros altura e coloniza??o foram reduzidos nas maiores doses. O isolado D17 ? promissor para uso em programas de micorriza??o controlada em viveiros comerciais de mudas clonais de eucalipto e a dose de 18 esferas por mini-estaca ? a mais recomendada. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Produ??o Vegetal, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2016. / The determination of the inoculum dose is essential for obtaining the benefits from the utilization of ectomycorrhizal fungi (EMF) in eucalypt saplings. The aim of this study was to evaluate the best dose of inoculum consists of mycelium from isolates Pisolithus sp., encapsulated in calcium alginate gel, aiming at promoting the colonization, nutrition and growth of the eucalypt rooted cuttings in commercial nursery. In independent experiments and using reduced phosphorus fertilization, were produced rooted cuttings from two eucalypts clones (AEC 2034 e AEC 2233) inoculated with 9, 8 and 36 beads of inoculum from fungal isolates D17, D216, D5 e D95 and one Non-inoculated treatment (factorial 3x5). Furthermore, two more additional treatments were performed with (Control) and without (Commercial) reduction of phosphorus fertilization of the substrate and without the addition of the inoculum.The dose of 36 inoculum beads, in general, has promoted higher benefits for the saplings, such as greater colonization, dry mass of shoot (DMS) and of roots (DMR) and K concentrations, sometimes being higher than in the saplings from Control and Commercial. The greater height of the shoot and collar diameter were observed with the use of 18 beads of inoculum. The ectomycorrhizal colonization was higher in inoculated saplings and considered average for the two clones. The previous inoculation in both clones did not promote an increase in P concentrations in relation to Commercial, however for the AEC 2233 clone with the utilization of D216, there was an increase in the P concentrations in relation to Non-inoculated, this being the same isolate that provided one of the greatest percentages of colonization, contributing to a higher absorption of this nutrient. Regarding the isolates, the inoculation with D17 in general increased the survival, height, DMS, DMR and K concentrations in AEC 2034, and height and diameter in AEC 2233, but this was dependent on the dose and on the eucalypt clone. The dose of 18 beads of inoculum was most appropriate, because in most cases, the greatest benefits as survival, height, diameter, DMS, DMR, colonization, N and K concentrations were obtained with addition of 18 or more beads of inoculum by mini-cutting and, in some cases, the parameters height and colonization were reduced with the highest doses. The isolate D17 is promising for its use in controlled mycorrization programs in commercial nurseries of eucalypt rooted cuttings and the dose of 18 beads by mini-cutting is the most recommended.

Germination course and mycorrhizal partners during germination and adulthood were studied in Neottia ovata and N. cordata. Neottia ovata was studied in two different biotops: meadows and forests. Research was conducted in in situ conditions in the Šumava and the Smrčiny mountains.

I have studied arbuscular mycorrhizal symbiosis of 44 herbaceous invasive neophytes occuring in the Czech Republic. My results show that about 70% of the examined species are capable to form symbiotic association with arbuscular mycorrhizal fungi (AMF) in the field. To my knowledge, mycorrhizal status of 23 invasive species is reported here for the first time. I predicted, based on the hypothesis of Urcelay & Díaz (2003), that the intensity of AMF in the roots of invasive species will be correlated with that of the native dominant species of invaded plant community, but collected data did not support this hypothesis. In addition, the effects of habitat and community characteristics on the intensity of AMF colonization of the invasive species{\crq} roots were tested. My results show that, at the within-species level, plants in the habitats with higher light and temperature conditions have less colonized roots whereas intensity of mycorrhizal colonization increases with habitat moisture. At the among-species level, invasive species occurring in the habitats with elevated nitrogen availability have higher mycorrhizal colonization of their roots. The effect of nitrogen availability is revealed at the among-species level and stays significant even after phylogenetic correction, suggesting this is an evolutionary adaptation rather than a phenotypic plasticity.

Os fungos representam cerca de 75% da biomassa microbiana em áreas florestais, desempenhando funções importantes, desde a mineralização dos resíduos orgânicos até a disponibilização de nutrientes para plantas por meio das associações micorrízicas, o que influencia a ciclagem de nutrientes e, consequentemente, o crescimento das árvores. O objetivo desse trabalho foi avaliar a comunidade de fungos do solo, da rizosfera e do sistema radicular de Eucalyptus grandis e Acacia mangium plantados em monocultivos e em consórcio, e encontrar respostas para os padrões observados por meio da correlação com os atributos físicos, químicos, biológicos e a profundidade do solo. A coleta das amostras foi realizada na Estação Experimental de Ciências Florestais de Itatinga, em 2016, quando as plantas estavam com 2 anos de idade. Foram coletadas amostras em quatro tratamentos: monoculturas de E. grandis e de A. mangium e consórcios de E. grandis e de A. mangium, nos quais foram construídas trincheiras para coleta das amostras nas camadas de 0-10, 10-20, 20-50 e 50-100 cm de profundidade. Foram caracterizados os atributos físicos e biológicos do solo e os atributos químicos do solo, da rizosfera e das raízes. Para a avaliação micorrízica, foi quantificado o número de esporos de fungos micorrízicos arbusculares (FMA) e as taxas de colonização radicular por FMA e por fungos ectomicorrízicos. Foi avaliada a morfologia das estruturas das micorrizas arbusculares e ectomicorriza (ECM). A estrutura da comunidade de fungos do solo e da rizosfera foi avaliada por meio da técnica de Terminal restriction fragment length polymorphism (T-RFLP). Para isso, o DNA foi amplificado utilizando os primers ITS1f-FAM e ITS4 e a restrição dos fragmentos foi realizada com a enzima HaeIII. A abundância de cópias do gene ITS do solo e da rizosfera foi quantificada por PCR quantitativo (qPCR), utilizando os primers ITS1f e 5.8s. Os atributos físicos, químicos e biológicos tiveram poucas variações entre os tratamentos avaliados, sendo as maiores diferenças encontradas entre as profundidades. O número de esporos (<29) e as taxas de colonização micorrízica (<48%) foram baixos em todos os tratamentos, e se reduziram com o aumento da profundidade. As plantas de A. mangium não formaram micorrizas arbusculares. Nas raízes de E. grandis, não houve a formação de arbúsculos, mas foi verificada a presença de hifas enroladas (hyphal coils), estrutura de micorriza do tipo Paris. A anatomia das ECM confirmou a colonização destes fungos nas raízes das plantas estudadas. O qPCR mostrou maior abundância de genes ITS na rizosfera em relação ao solo, assim como nas camadas superficiais (0-10 cm) em relação às mais profundas (10 cm abaixo). A Análise de Coordenadas Principais revelou diferenças na estrutura das comunidades de fungos nos tratamentos estudados, principalmente para a região da rizosfera, diferenciando o perfil de fungos do monocultivo de E. grandis dos demais tratamentos, assim como a influência da A. mangium na estruturação da comunidade. A análise de redundância mostrou a influência de alguns atributos químicos nas taxas de colonização e estruturação da comunidade. Dessa forma, conclui-se que em sistema de consórcio, uma espécie de planta parece ser mais influente do que a outra na estruturação da comunidade de fungos e essa influência é mais evidente na rizosfera. Além disso, os atributos químicos são fatores importantes na organização da comunidade fúngica. / The fungi represent about 75% of the microbial biomass in forest areas, performing important functions, from the mineralization of the organic residues to the availability of nutrients to plants through mycorrhizal associations, which influences the nutrient cycling and, consequently, the growth of trees. The objective of this work was to evaluate the community of fungi of the soil, rhizosphere and root system of Eucalyptus grandis and Acacia mangium planted in monocultures and consortium, and to find explanations for the observed patterns through the correlation with physical and chemical soil attributes and soil depth. The samples were collected at the Experimental Station of Forest Sciences of Itatinga in 2016, when the plants were 2 years old. Samples were collected in four treatments: monocultures of E. grandis and A. mangium and consortia of E. grandis and A. mangium, in which trenches were constructed to collect samples in the 0-10, 10-20, 20 -50 and 50-100 cm deep. The physical and biological attributes of the soil and the chemical attributes of soil, rhizosphere and roots were characterized. For the mycorrhizal evaluation, the number of spores of arbuscular mycorrhizal fungi (AMF) and the rates of root colonization by AMF and ectomycorrhizal fungi were quantified. The morphology of arbuscular mycorrhizal and ectomycorrhizal (ECM) structures was evaluated. The structure of the soil and rhizosphere fungi community by was evaluated by the technique of Terminal restriction fragment length polymorphism (T-RFLP). For this, the DNA was amplified using primers ITS1f-FAM and ITS4 and restriction of the fragments was performed with the enzyme HaeIII. The abundance of ITS gene copies of soil and rhizosphere was quantified by quantitative PCR (qPCR), using primers ITS1f and 5.8s. The physical, chemical and biological attributes had few variations among the evaluated treatments, being the greatest differences found between the depths. The number of spores (<29) and mycorrhizal colonization rates (<48%) were low in all treatments, and reduced with increasing depth. A. mangium plants did not form FMA. In the roots of E. grandis, there was no formation of arbuscules, but we found the presence of hyphal coils, mycorrhizal structures of the Paris type. The anatomy of the ECM confirmed the colonization of these fungi in the roots of the studied plants. The qPCR showed higher abundance of ITS genes in the rhizosphere in relation to the soil, as well as in the superficial layers (0-10 cm) in relation to the deeper ones (10 cm below). The Principal Coordinates Analysis revealed differences in the structure of the fungal communities in the treatments studied, especially for the rhizosphere region, differentiating the fungal profile of the E. grandis monoculture from the other treatments, as well as the influence of A. mangium on the structure of the community. The redundancy analysis showed the influence of some chemical soil attributes on the rates of colonization and community structuring. Thus, it is concluded that in a consortium system, one plant species seems to be more influential than the other in structuring the fungal community, and this influence is more evident in the rhizosphere. In addition, chemical attributes are important factors in the organization of the fungal community.

Os solos brasileiros são predominantemente ácidos, ocorrência comum nas regiões tropicais. Esta condição, aliada a outros fatores abióticos e bióticos, pode resultar em toxicidade de manganês (Mn) às plantas, o que limita o seu desenvolvimento. A utilização de práticas agrícolas convencionais propicia o aumento da toxidez de Mn, à medida que reduz o teor de matéria orgânica. Para atenuar este problema, algumas práticas como a calagem e o melhoramento genético são amplamente utilizados. Entretanto, a utilização de alternativas de manejo da cultura através do uso da simbiose micorrízica, para induzir maior resistência das plantas a altos níveis de Mn, parece bastante promissora. Para investigar possíveis mecanismos de indução da resistência e interações de nutrientes no controle da toxicidade de Mn em soja, foram avaliados o crescimento, a absorção e a acumulação de Mn, Fe, P e Ca e a atividade de catalase, peroxidase, superóxido dismutase e oxidase de AIA, nas folhas e raízes das plantas micorrizadas e não micorrizadas, além do nível de colonização de raízes pelo fungo micorrízico arbuscular (FMA). A planta teste foi a soja (Glycine max L. Merr. CV. IAC 8-2). O experimento foi executado em casa de vegetação, em vasos preenchidos com 4 Kg de solo classificado como Neossolo Quartzarênico típico, previamente autoclavado para eliminar fungos micorrízicos arbusculares. O delineamento foi inteiramente casualizado, em esquema fatorial, 4x5: dois isolados de FMA, Glomus etunicatum e Glomus macrocarpum, cada qual com 30 mg kg –1 de P adicionado ao substrato e dois controles não inoculados, sendo um com 30 mg kg –1 e outro com 50 mg kg –1 de P, 5 níveis de Mn (0, 5, 10, 20, 40 mg kg -1 ). Foram realizadas duas épocas distintas de colheita, aos 45 e 90 dias. As atividades enzimáticas foram avaliadas pelo método PAGE não-denaturante através de análise visual. Os resultados demonstram que níveis de Mn entre 10 e 40 mg kg -1 no substrato podem induzir respostas de toxidez de Mn em plantas de soja, acompanhadas de redução de crescimento e alterações no padrão de absorção de vários nutrientes vegetais. O aumento da dose de P e a presença da micorriza são fatores de atenuação da toxidez de Mn em soja, visto que plantas micorrizadas contêm menor concentração de Mn em seus tecidos e, de uma maneira geral, menor atividade enzimática de peroxidase (PO) e oxidase do ácido-indolacético (AIA) do que as plantas controles. Aumentos no nível de Mn do substrato podem causar um aumento da atividade de PO e de oxidase de AIA nas plantas, sendo que as plantas mais estressadas quase sempre apresentam maior atividade dessas enzimas. Apesar da superóxido dismutase (SOD) ser também enzima antioxidativa, apresenta um padrão eletroforético diferenciado da PO, sendo que na raiz sua maior atividade está correlacionada com a presença do FMA. / Brazilian soils are predominantly acid, which is considered a common incident in tropical regions. Soil acidity in combination with biotic and non-biotic factors can result manganese toxicity in plants, limiting their development. The use of conventional agricultural practices promotes an increase in Mn toxicity, as it reduces the soil content of organic matter. This problem can be minimized by the use of some tilling practicies like liming and breeding, which are widely used. However, crop management alternatives through the use of mycorrhizae to induce greater Mn tolerance in plants under high levels of Mn seem to be promising. In this work, plant growth, the absorption, distibution of Mn, Fe, P, Ca and activity of catalase, peroxidase, superoxide dismutase and indolacetic acid oxidase were evaluated in leaves and roots of plants inoculated with mycorrhizal fungi and non-inoculated ones, to invetigate a possible resistance induction mechanism and nutrient interactions in control of toxic levels of Mn. A greenhouse experiment was conducted with soybean plant (Glycine max L. Merr. CV. IAC 8-2) in a completely randomized factorial design 4x5: inoculation of two different arbuscular mycorrhizal fungi (AMF): Glomus etunicatum and Glomus macrocarpum, which received 30 mg kg –1 of P, and two non-inoculated controls, one that received 30 mg kg –1 and the other with 50 mg kg –1 of P; 5 levels of Mn (0, 5, 10, 20, 40 mg kg -1 ). There were two harvest periods, 45 and 90 days. The enzymatic activities were evaluated in non-denaturing polyacrilamyde gel eletrophoresis (PAGE). Manganese levels between 10 and 40 mg kg -1 in the substrate can induce Mn toxicity in soybean plants, that results in a growth reduction and in alterations in the nuttrient absorption alterations of the plants. The increase of P and the presence of mycorrhizae result in the alleviation of Mn toxicity in soybean plants. Micorrhizal plants present lower Mn concentration and generally less enzymatic activity of indolacetic acid oxidase and peroxidase than control plants. Although both, peroxidase and superoxide dismutase are antioxidant enzymes, they present differentiated electrophoretic standards. Most of the time peroxidase and indolacetic acid oxidase activities increase due to increasing Mn levels. Superoxide dismutase activity, however, is higher in the shoots of micorrhizal plants when compared to control plants.

Abstract In this thesis I studied responses of three biennial, monocarpic plants Erysimum strictum, Gentianella amarella, and G. campestris, to various aspects in resource availability (i.e. competition, mineral nutrition, neighbor removal) and environmental stress (early frost) at adult or rosette stages and how these effects are related to grazing tolerance. I also studied how manipulations in resource availability affected arbuscular mycorrhizal colonization of the roots. All three species were relatively tolerant to simulated grazing and in most cases plants were able to compensate quite well for minor biomass losses. According to the compensatory continuum hypothesis, tolerance is most pronounced in resource-rich conditions, but this was not always the case in the present experiments. Erysimum strictum compensated for defoliation at the rosette stage but the reproductive output of adult plants was reduced markedly in the next year. This reduction was strongest among fertilized plants. Moreover, apex removal at the adult stage resulted in overcompensation (i.e. clipped plants were more productive) but only in the absence of fertilization and in the presence of competition, which is against the compensatory continuum hypothesis. In E. strictum a potential cost of compensation appeared as delayed flowering and fruit maturation among clipped plants. However, in spite of early frost treatment clipped plants were still able to overcompensate. In Gentianella amarella and G. campestris, apex removal reduced growth and reproductive performance in most cases. Effects on root fungal parameters were positive or neutral. This pattern suggests that simulated above-ground herbivory tends to increase carbon limitation, and therefore regrowing shoots and the fungal symbionts may appear as alternative, competing sinks for the limited carbon reserves of the host plant. Both shoot architecture and resource availability modify the responses of the study plants to apical damage at both rosette and adult stages. In addition, different environmental stress factors affect success in compensatory growth.

Thesis (M.Sc. (Horticulture)) -- University of Limpopo, 2017 / Refer to document / National Research Foundation of South Africa, and Agricultural Research Council-Universities Collaboration Centreꞌ for scholarship and research