ABSTRACT Canga ecosystems develop over superficial iron crusts with shallow and nutrient-poor soils. Under these conditions, arbuscular mycorrhizal fungi (AMF) play an important role in helping plants to overcome abiotic and biotic stresses. Canga can suffer periodic burning and yet it is unknown what the impacts of fire are to AMF communities. We aimed to compare AMF in Canga areas affected by burning (BC) with those with no previous history of burning (NC). We compared AMF species composition, spore numbers, species richness, and mycorrhizal inoculum potential. The total number of spores, AMF species richness and mycorrhizal colonization measured in the infectivity bioassay were not significantly different between areas. A total of 23 species in 10 genera were recovered, with most species belonging to Gigasporaceae and Acaulosporaceae. BC and NC shared 52 % of AMF species. Gigaspora albida, Gigaspora gigantea, and Dentiscutata heterogama sporulated exclusively in trap cultures. We concluded that AMF spore communities were not affected by burning in Canga soils as measured by spore abundance, species richness and infectivity. Our data contribute to the inventory of soil biodiversity associated with Canga, a high biodiverse and threatened Brazilian ecosystem.

ABSTRACT High rates of agricultural gypsum, above the recommended levels, have been used on a regular basis to deepen plant roots and to alleviate recurrent water stress in Cerrado areas. However, very little is known about the consequences of this practice to arbuscular mycorrhizal fungi (AMF). Therefore, the objective of this study was to evaluate whether or not applying high rates of agricultural gypsum affects the mycorrhizal fungi community, glomalin content and coffee yield. The study rates were: 0; 3.5; 7.0; 14 and 56 t·ha-1 of agricultural gypsum applied in the planting row of the coffee plantation on top of the previous recommended gypsum application. Samples were collected for analysis at the depths of 0-20, 20-40 and 40-60 cm at the end of dry and rainy seasons of the year. In the coffee plantation, 16 AMF species were identified. Gigaspora sp. and Glomus macrocarpum were dominant in all situations. The rate of 7 t·ha-1 favored greater diversity of AMF species and the rate of 56 t·ha-1 reduced AMF diversity and mycorrhizal colonization in deeper layers. In the rainy season, there was a linear decrease of easily extractable glomalin-related soil protein (EE-GRSP) levels as the agricultural gypsum rate was increased. Coffee yield was reduced with the highest gypsum rate (56 t·ha-1), even though the coffee plantation had higher phosphorus contents in beans and leaves. This may have resulted from a number of reasons, including a negative effect on the AMF community.

ABSTRACT In this work, we hypothesized that two spore-based methods, direct analysis of field samples and trap cultures, simultaneously used for assessment of occurrence and species richness of arbuscular mycorrhizal fungi (AMF) may vary in their efficiency according to the environmental conditions and the total AMF species richness of the evaluated ecosystem. The performance of both methods was analyzed based on two datasets: 1) a complete site x species matrix compiled from two studies in different land uses in the Amazon using direct analysis of field samples and trap cultures. 2) Total number of AMF morphotypes detected by both methods in published manuscripts across several ecosystems. From dataset 1, direct analysis of field samples revealed 57 morphotypes, whereas only 21 of these were detected by trap culture. Community variation (beta diversity) analysis revealed that field samples are far more sensitive in detecting shifts in AMF community composition among land uses than trap cultures in the Amazon region, with the combined results of both methods being not better than that obtained only by direct analysis of field samples. Analysis of dataset 2 showed that the relative performance of trap cultures, using direct analysis of field sample as reference, was inversely related to the total observed AMF species richness.

ABSTRACT: Arbuscular mycorrhizal fungi (AMF), which live in symbiosis with 80 % of plants, are not able to grow when separated from their hosts. Spore germination is not host-regulated and germling growth is shortly arrested in the absence of host roots. Germling survival chances may be increased by hyphal fusions (anastomoses), which allow access to nutrients flowing in the extraradical mycelium (ERM). Perfect anastomoses, occurring with high frequency among germlings and the ERM of the same isolate, show protoplasm continuity and disappearance of hyphal walls. A low frequency of perfect fusions has been detected among co-specific genetically different isolates, although fungal nuclei have been consistently detected in all perfect fusions, suggesting active nuclear migration. When plants of different taxa establish symbioses with the same AMF species, anastomoses between ERM spreading from single root systems establish a common mycelium, which is an essential element to plant nutrition and communication. The interaction among mycelia produced by different isolates may also lead to pre-fusion incompatibility which hinders anastomosis formation, or to incompatibility after fusion, which separates the hyphal compartments. Results reported here, obtained by analyses of hyphal compatibility/incompatibility in AMF, suggest that anastomosis formation and establishment of protoplasm flow, fundamental to the maintenance of mycelial physiological and genetic continuity, may affect the fitness of these ecologically important biotrophic fungi.

RESUMO No manejo da fertilidade de Latossolos brasileiros altamente intemperizados e lixiviados, o P é o macronutriente mais limitante. Assim, conduziu-se um experimento em casa de vegetação, objetivando-se avaliar a influência da interação entre doses de P, inoculação micorrízica e histórico de uso do solo no crescimento de Urochloa decumbens e absorção de P, em quatro Latossolos com atributos químicos, físicos e mineralógicos contrastantes. As plantas foram cultivadas em vasos contendo 4 kg de solo, dispostos em um delineamento inteiramente casualizado, com quatro repetições e esquema fatorial 2x2x2: duas doses de P; com e sem inoculação micorrízica; solos cultivados por longos períodos e não cultivados (sob vegetação nativa). Realizaram-se dois cultivos com duração de 10 semanas cada. Após cada cultivo avaliaram-se a matéria seca da parte aérea, teor e acúmulo de P na parte aérea. No primeiro cultivo, maior resposta ao P aconteceu nos solos sob vegetação nativa em associação à inoculação e adição de P. No segundo cultivo, a inoculação teve maior efeito em todos os solos, associada à menor dose de P. O aumento do P no solo aumenta a concentração desse nutriente na parte aérea. A inoculação não teve efeito na concentração e no acúmulo de P na parte aérea de Urochloa. O crescimento de Urochloa decumbens foi fortemente influenciado pela interação entre classe de solo x histórico de uso da terra x dose de P x inoculação.

ABSTRACT In the fertility management of highly weathered-leached Brazilian Oxisols, P is the most limiting macronutrient. A greenhouse experiment was conducted with the objective to evaluate the influence of the interaction between P doses, mycorrhizal inoculation and historical land use on Urochloa decumbens growth and P uptake in four Oxisols with contrasting chemical, physical and mineralogical properties. The plants were cultivated in plastic pots containing 4 kg of soil in a completely randomized design, four replications and 2x2x2 factorial scheme: with two P doses; with and without mycorrhizal inoculation; soils cultivated for long periods and non-cultivated (under native vegetation). There were two plantings of ten weeks each. Shoot dry mater, concentration and accumulation of P in the shoot were evaluated. In the first planting, the Urochloa response was greater in non-cultivated soils associated with inoculation and P addition. However, in the second planting, the inoculation had a greater effect in all soils compared to the first planting associated with the lowest P dose. As the P concentration in the soil increased, P in the shoot dry matter increases. The inoculation did not affect the P concentration and accumulation in the shoot of Urochloa. The growth of Urochloa decumbens was strongly influenced by the interaction among soil class x history of land use x dose of P x inoculation.

RESUMO: O objetivo deste estudo foi avaliar os efeitos da inoculação com diferentes fungos micorrízicos arbusculares nativos do Cerrado, associados à aplicação de estimulante de colonização (7-hidroxi, 4’-metoxi-isoflavona) no crescimento inicial de plantas de algodão e milho em casa de vegetação. O experimento foi conduzido em delineamento inteiramente casualizado e esquema fatorial 7x2, com cinco espécies de fungos micorrízicos arbusculares e inoculação combinada (unindo todas as espécies em proporção igual) e fungos nativos, na presença e ausência de estimulante de colonização em culturas de milho e algodão. Avaliou-se a massa de matéria seca (SDM), matéria seca de raízes (RDM), colonização micorrízica e acúmulo de cálcio, zinco e fósforo na SDM. A inoculação com fungos micorrízicos arbusculares e o uso de estimulante de colonização em baixa densidade de propágulos de fungos micorrízicos arbusculares foi benéfico para o desenvolvimento da planta. A inoculação com fungos micorrízicos mostrou efeitos diferentes para os vários parâmetros avaliados no algodão e no milho, e a aplicação de estimulante de colonização promoveu maior colonização micorrízica e crescimento inicial no algodão quando associado à fungos micorrízicos arbusculares nativa e no milho quando associado à inoculação com Dentiscutata heterogama, Gigaspora margarita e Rhizophagus clarus.

ABSTRACT: The objective of this study was to evaluate the effects of inoculation with different arbuscular mycorrhizal fungi native to Cerrado, associated with the application of colonization stimulant (7-hydroxy, 4’-methoxy-isoflavone) at the initial growth of cotton and maize plants in a greenhouse. The experiment was carried out in a completely randomized design and 7x2 factorial scheme, with five species of arbuscular mycorrhizal fungi and combined inoculation (uniting all species in equal proportion) and native fungi, in the presence and absence of colonization stimulant in maize and cotton crops. Shoots dry matter (SDM), roots dry matter (RDM), mycorrhizal colonization and accumulation of calcium, zinc and phosphorus in the SDM were evaluated at flowering. Inoculation of arbuscular mycorrhizal fungi and the use of colonization stimulant at low density of arbuscular mycorrhizal fungi propagules was beneficial to plant development. Inoculation with mycorrhizal fungi demonstrated different effects for the various parameters evaluated in cotton and maize, and the application of colonization stimulant promoted higher mycorrhizal colonization and initial growth in cotton, when associated with native AMF, and in corn, when associated with inoculation with Dentiscutata heterogama, Gigaspora margarita and Rhizophagus clarus.

Resumo Com base em espécimes de herbários do Brasil e exterior, complementado pela literatura pertinente e buscas em sites de biodiversidade, foram identificados 66 táxons de Eriocaulaceae para a Amazônia brasileira, definida pelos estados do Acre, Amapá, Amazonas, Pará, Rondônia e Roraima. Seis gêneros de Eriocaulaceae foram encontrados na Amazônia com os seguintes números de táxons: Comanthera (3 táxons), Eriocaulon (10), Paepalanthus (15), Rondonanthus (2), Syngonanthus (35) e Tonina (1). Desse total, 25 táxons foram considerados como de distribuição ampla e os restantes 41 táxons são restritos ao bioma Floresta Amazônica. Os dados de distribuição para apenas 31 táxons foram utilizados para Modelagem de Distribuição de Espécies, devido ao baixo número de pontos de ocorrência reportados para os outros táxons, 17 dos quais conhecidos de uma só localidade. A sobreposição desses modelos mostrou áreas do Amapá, Amazonas, Pará e Roraima como tendo maior probabilidade de ocorrência para as espécies modeladas. Os dados obtidos permitirão a localização de novas populações das espécies de Eriocaulaceae. Novas detecções das espécies de Eriocaulaceae podem ajudar a preencher as lacunas sobre sua distribuição geográfica e ecologia, contribuindo para a proteção ou restauração de áreas prioritárias para sua conservação.

Abstract Following a survey in herbaria in Brazil and abroad, complemented by a survey of the literature and searches of biodiversity data, 66 taxa of Eriocaulaceae have been identified in the Brazilian Amazon, as defined by the states of Acre, Amapá, Amazonas, Pará, Rondônia and Roraima. Six genera of Eriocaulaceae were found in the Amazon with the following taxon numbers: Comanthera (3 taxa), Eriocaulon (10), Paepalanthus (15), Rondonanthus (2), Syngonanthus (35) and Tonina (1). Of this total, 25 taxa present distributions in the states of the Amazon and other Brazilian states (considered as widely distributed) and the remaining 41 taxa are restricted to the Amazon Rainforest biome. The distribution data for 31 species were used for Species Distribution Modelling, due to the low number of occurrence points reported for the other taxa, 17 of those are known from a single location. The overlap of these models indicates areas from Amapá, Amazonas, Pará and Roraima where modelled species are most likely to occur. These data can further contribute to the location of new populations of species of Eriocaulaceae. New detection of Eriocaulaceae species can assist in filling the gaps on their geographic distribution and ecology, contributing to the protection or restoration of priority areas set aside for their conservation.

Abstract Spore counts, species composition and richness of arbuscular mycorrhizal fungi, and soil glomalin contents were evaluated in a soil contaminated with Zn, Cu, Cd and Pb after rehabilitation by partial replacement of the contaminated soil with non-contaminated soil, and by Eucalyptus camaldulensis planting with and without Brachiaria decumbens sowing. These rehabilitation procedures were compared with soils from contaminated non-rehabilitated area and non-contaminated adjacent soils. Arbuscular mycorrhizal fungi communities attributes were assessed by direct field sampling, trap culture technique, and by glomalin contents estimate. Arbuscular mycorrhizal fungi was markedly favored by rehabilitation, and a total of 15 arbuscular mycorrhizal fungi morphotypes were detected in the studied area. Species from the Glomus and Acaulospora genera were the most common mycorrhizal fungi. Number of spores was increased by as much as 300-fold, and species richness almost doubled in areas rehabilitated by planting Eucalyptus in rows and sowing B. decumbens in inter-rows. Contents of heavy metals in the soil were negatively correlated with both species richness and glomalin contents. Introduction of B. decumbens together with Eucalyptus causes enrichment of arbuscular mycorrhizal fungi species and a more balanced community of arbuscular mycorrhizal fungi spores in contaminated soil.

RESUMO A adoção de recursos biológicos na agricultura pode permitir menor dependência e melhor aproveitamento de recursos finitos. Objetivou-se avaliar os efeitos da inoculação com fungos micorrízicos arbusculares nativos do Cerrado associados à aplicação de estimulante micorrízico (7-hidroxi, 4'-metoxi-isoflavona), no crescimento inicial de plantas de feijoeiro e soja. O experimento foi conduzido em casa-de-vegetação, em delineamento inteiramente casualizado e esquema fatorial 7 x 2, sendo cinco espécies de fungos micorrízicos arbusculares, inoculação conjunta (junção de todas as espécies em igual proporção) e fungos nativos (sem inoculação), na presença e ausência de estimulante. Foram avaliados a massa seca da parte aérea, massa seca da raiz, colonização micorrízica, massa de nódulos e acúmulo de cálcio, zinco e fósforo na massa seca da parte aérea. O aumento proporcionado pelos fungos micorrízicos arbuculares e a utilização de estimulante chegou a mais de 200 % no feijoeiro e a mais de 80 % na soja. Os fungos Acaulospora scrobiculata, Dentiscutata heterogama, Gigaspora margarita e Rhizophagus clarus, para o feijoeiro, e Claroideoglomus etunicatus, Dentiscutata heterogama, Rhizophagus clarus e a inoculação conjunta, para a soja, se mostraram promissores no incremento de massa e acúmulo de nutrientes.

ABSTRACT The adoption of biological resources in agriculture may allow less dependence and better use of finite resources. This study aimed at evaluating the effects of inoculation with arbuscular mycorrhizal fungi native to the Brazilian Savannah associated with the application of mycorrhizal stimulant (7-hydroxy, 4'-methoxy-isoflavone), in the early growth of common bean and soybean. The experiment was carried out in a greenhouse, in a completely randomized design, with a 7 x 2 factorial arrangement, consisting of five arbuscular mycorrhizal fungi species, joint inoculation (junction of all species in equal proportions) and native fungi (without inoculation), in the presence and absence of stimulant. The following traits were evaluated: shoot dry matter, root dry matter, mycorrhizal colonization, nodules dry matter and accumulation of calcium, zinc and phosphorus in the shoot dry matter. The increase provided by the arbuscular mycorrhizal fungi and the use of stimulant reached over 200 % in bean and over 80 % in soybean plants. The fungi Acaulospora scrobiculata, Dentiscutata heterogama, Gigaspora margarita and Rhizophagus clarus, for bean, and Claroideoglomus etunicatum, Dentiscutata heterogama, Rhizophagus clarus and the joint inoculation, for soybean, increased the dry matter and nutrients accumulation.

RESUMO O P é um nutriente chave no manejo da fertilidade de solos tropicais altamente intemperizados. Este trabalho foi conduzido com o objetivo de avaliar a influência da interação entre doses de P, inoculação micorrízica e histórico de uso do solo no crescimento da soja e absorção de P em cinco Latossolos com atributos físicos, químicos e mineralógicos contrastantes recebendo adubação fosfatada por longo período (> 15 anos). As plantas foram cultivadas em potes plásticos (4,5 L) contendo 4 kg de solo em um delineamento inteiramente casualizado, quatro repetições e esquema fatorial 2x2x2 correspondente a: duas doses de P; com e sem inoculação micorrízica; solos previamente cultivados e não cultivados (sob vegetação nativa). Foram realizados dois cultivos de dez semanas cada. Após cada um dos cultivos, avaliaram-se a massa seca da parte aérea, concentração e acúmulo de P na parte aérea. O cultivo do solo reduziu a resposta à aplicação de P e inoculação. A resposta da soja à inoculação foi maior nos solos cultivados e quando a menor dose de P foi aplicada. A magnitude dessas respostas foi diferente entre os Latossolos estudados, sendo os atributos mineralógicos e químicos dos Latossolos determinantes.

ABSTRACT Phosphorus is a key-nutrient in the fertility management of highly weathered tropical soils. So, this work was carried out with the objective of evaluating the influence of the interaction between P doses, mycorrhizal inoculation and historical land use on soybean growth and P uptake in five Latosols (Oxisols) with contrasting chemical, physical and mineralogical properties under a continuous long-term phosphate fertilization (more than 15 years). The plants were cultivated in 4.5L-plastic pots containing 4 kg of soil in a completely randomized design, four replications and 2x2x2 factorial scheme with two P doses; and with or without mycorrhizal inoculation; and soils cultivated for long periods and non-cultivated (under native vegetation). There were two cultivations of ten weeks each. Shoot dry mass, P content and accumulation in the shoot dry mass were evaluated after each cultivation period. The cultivation history reduced the response to P application and inoculation. The soybean response to inoculation was greater in cultivated soils and when the lower P dose was applied. The soybean response magnitude to these variables was different among the studied Latosols. The mineralogical and chemical attributes of the Latosols were determinants.

O objetivo deste trabalho foi avaliar a densidade e a diversidade de esporos de fungos micorrízicos arbusculares (FMA) nos agregados do solo de campos de murundus, em áreas convertidas e não convertidas para agricultura. O experimento foi conduzido em delineamento inteiramente casualizado com cinco repetições, em arranjo fatorial 5x3: cinco áreas e três classes de agregados (macro, meso e microagregados). As variáveis avaliadas foram: densidade e diversidade de esporos de FMA, glomalina total, carbono orgânico total (COT), micélio extrarradicular total (MET) e diâmetro médio geométrico (DMG) dos agregados do solo. Foram identificadas 21 espécies de FMA. A densidade de esporos variou de 29 a 606 por 50 mL de solo e foi maior nos microagregados e na área com 6 anos de conversão para agricultura. A glomalina total foi maior entre os murundus em todas as classes de agregados em estudo. A área com 6 anos apresentou menor concentração de COT nos macroagregados (8,6 g kg-1) e nos microagregados (10,1 g kg-1). O MET foi maior no topo dos murundus em todas as classes de agregados. O DMG aumentou com o tempo de conversão para agricultura. A densidade e a diversidade de esporos de fungos micorrízicos arbusculares mudam com a conversão dos campos de murrundus em agricultura.

The objective of this work was to evaluate the spore density and diversity of arbuscular mycorrhizal fungi (AMF) in soil aggregates from fields of "murundus" (large mounds of soil) in areas converted and not converted to agriculture. The experiment was conducted in a completely randomized design with five replicates, in a 5x3 factorial arrangement: five areas and three aggregate classes (macro-, meso-, and microaggregates). The evaluated variables were: spore density and diversity of AMF, total glomalin, total organic carbon (TOC), total extraradical mycelium (TEM), and geometric mean diameter (GMD) of soil aggregates. A total of 21 AMF species was identified. Spore density varied from 29 to 606 spores per 50 mL of soil and was higher in microaggregates and in the area with 6 years of conversion to agriculture. Total glomalin was higher between murundus in all studied aggregate classes. The area with 6 years showed lower concentration of TOC in macroaggregates (8.6 g kg-1) and in microaggregates (10.1 g kg-1). TEM was greater at the top of the murundus in all aggregate classes. GMD increased with the conversion time to agriculture. The density and diversity of arbuscular mycorrhizal spores change with the conversion of fields of murundus into agriculture.

Os campos de murundus são fitofisionomias de ocorrência no bioma Cerrado com funções ecológicas importantes para a manutenção da sustentabilidade do solo; e a conversão para sistemas agrícolas pode provocar alterações nos atributos físicos, químicos e biológicos do solo ainda não avaliados, como a redução da biodiversidade de fungos micorrízicos arbusculares. O objetivo deste estudo foi avaliar como a conversão dos campos de murundus em áreas de sistema agrícola altera a comunidade de fungos micorrízicos arbusculares (FMAs). Os tratamentos constituíram-se de três áreas agrícolas submetidas ao mesmo manejo e uso agrícola em uma cronossequência (7, 11 e 14 anos) e duas na área referência [campo de murundus, em topo (TM) e entre os murundus (EM)]. Os esporos de FMAs foram extraídos, contados, e as espécies de FMAs identificadas pelas características morfológicas. O total de FMAs recuperado foi de 27 espécies, sendo nove espécies da família Acaulosporaceae, uma Ambisporaceae, sete Glomeraceae, duas Claroideoglomeraceae e oito Gigasporaceae. Desse total, as espécies Acaulospora scrobiculata, Glomus macrocarpum, e Gigaspora sp. ocorreram em todas as áreas nos dois anos estudados. As espécies Acaulospora mellea, Acaulospora cavernata, Acaulospora colombiana, Glomus diaphanum, Scutellospora reticulata e Scutellospora sp. só foram encontradas nos campos de murundus. A conversão de campos de murundus em área agrícola modificou a ocorrência e composição da comunidade de FMAs; as espécies Acaulospora scrobiculata, Glomus macrocarpum, Claroideoglomus etunicatus e Gigaspora sp ocorreram em todas as áreas e a não ocorrência de algumas espécies nas áreas de cultivo, como as espécies Acaulospora cavernata, Acaulospora colombiana, Rhizophagus diaphanus, Scutellospora reticulata e Scutellospora sp. representa perda de diversidade desses fungos. Portanto, este estudo tratou-se do primeiro relato da ocorrência e da estrutura da comunidade de FMAs em fitofisionomia de campos de murundus, contribuiu para o maior entendimento dos FMAs no bioma Cerrado e demonstrou que as alterações promovidas pela conversão da área alteraram a ocorrência e a diversidade dos fungos micorrízicos arbusculares.

The murundu fields (Campos de Murundus) are characterized by mounds occurring in some parts of the Cerrado (Brazilian tropical savanna) biome with important ecological functions for the maintenance of soil sustainability. Conversion to agricultural systems may lead to changes in physical, chemical, and biological soil properties not yet assessed, such as reduction in the biodiversity of arbuscular mycorrhizal fungi. The aim of this study was to evaluate how the conversion of mound fields into agricultural areas changes the community of arbuscular mycorrhizal fungi (AMF). Treatments consisted of three agricultural areas subjected to the same agricultural management and use in a chronosequence (seven, 11, and 14 years) and two in the mound fields, sampling at the top (TM) and between the mounds (EM)). AMF spores were extracted and counted, and AMF species were identified by morphological characteristics. The total AMF recovered was 27 species, made up of nine species of the Acaulosporaceae family, one Ambisporaceae, seven Glomeraceae, two Claroideoglomeraceae, and eight Gigasporaceae. Of this total, the species Acaulospora scrobiculata , Glomus macrocarpum , and Gigaspora sp occurred in all areas in the two years studied. The species Acaulospora melle a, Acaulospora cavernata , Acaulospora colombiana , Glomus diaphanum , Scutellospora reticulata , and Scutellospora sp only occurred in the mound fields. The conversion of mound fields into an agricultural area modified the occurrence and composition of the arbuscular mycorrhizal fungi community, and the species Acaulospora scrobiculata , Glomus macrocarpum , Gigaspora sp, and Claroideoglomus etunicatus occurred in all areas. The non-occurrence of some species in the crop areas, such as the species Acaulospora cavernata , Acaulospora columbiana , Rhizophagus diaphanus , Scutellospora reticulata , and Scutellospora sp, represents a loss of diversity of these fungi. Therefore, this study is the first report of the occurrence and community structure of AMF in the mound field vegetation type. It contributes to better understanding of AMF in the Cerrado biome and shows that the changes introduced by conversion of the area alter the occurrence and diversity of arbuscular mycorrhizal fungi.

A estrutura do solo exerce importante influência na sustentabilidade dos ecossistemas e no crescimento de plantas. Os fungos micorrízicos arbusculares (FMAs) constituem um importante grupo funcional da microbiota do solo, atuando diretamente nos processos de agregação, principalmente em agroecossistemas e têm relação direta com a produção e diversidade vegetal. Esses estão amplamente distribuídos no agroecossistemas tropicais e são extremamente importantes para o crescimento de várias espécies vegetais agrícolas. No presente estudo, avaliou-se o efeito da inoculação com Glomus macrocarpum e diferentes sucessões de culturas no crescimento vegetal, na atividade microbiana e na agregação de um Latossolo Vermelho de Cerrado. O estudo foi conduzido em delineamento inteiramente casualizado com arranjo fatorial 4 x 4. Os tratamentos constituíram da combinação entre quatro condições de eliminação e/ou introdução de FMA (NS-NI: não autoclavado-não inoculado; NS-I: não autoclavado-inoculado; S-NI: autoclavado-não inoculado; S-I: autoclavado-inoculado) e quatro sucessões de culturas (Panicum maximum/Panicum maximum; Brachiaria ruziziensis/soja; sorgo/soja; Stylosanthes spp./soja). A inoculação com FMAs favoreceu o crescimento do estilosantes, apresentando aumento de até 91% na produção de massa seca quando inoculado. Nenhumas das gramíneas beneficiaram-se com a introdução de G. macrocarpum. Nós observamos que a inoculação com G. macrocarpum associado aos FMAs indígenas incrementou a biomassa microbiana, atividade da fosfatase ácida, diâmetro médio geométrico e o ponderado. Os resultados indicam os efeitos benéficos da inoculação que reflete na melhoria da estrutura do solo, contribuindo para a sustentabilidade.

Soil structure has major influence on ecosystem sustainability and plant growth. Arbuscular mycorrhizal fungi (AMF) are an important functional group of soil microbiota, acting in the process of aggregation, especially in agroecosystems and related to the production and plant diversity. AMF are widely distributed in tropical agroecosystems and are extremely important for development of many agricultural crops. The present study evaluated the effect of inoculation with Glomus macrocarpum in different crop sequences on plant growth, microbial activity and aggregation of a Cerrado Oxisol. The study was conducted in a completely randomized design in a4 x 4 factorial scheme. Treatments consisted of four conditions of elimination and/or introduction of AMF (NS-NI: non-sterilized and non-inoculated; NS-I: non-sterilized and inoculated; S-NI: sterilized and non-inoculated; andS-I: sterilized and inoculated) and four crop sequences (Panicum maximum/Panicum maximum, Brachiaria ruziziensis/ soybean, sorghum/soybean and Stylosanthes spp./soybean). Inoculation favored growth of Stylosanthes spp. by increasing plant growth in up to 91% when inoculated. None of the grasses benefited from G. macrocarpum introduction. We observed that G. macrocarpum inoculation associated with indigenous AMF increased microbial biomass, phosphatase activity, mean geometric diameter and mean weighted diameter. The results indicated the beneficial effects of inoculation, which reflected in soil structure improvement and, hence, to agroecosystems sustainability.

O objetivo deste trabalho foi caracterizar fenotípica e genotipicamente isolados de espécies de fungos micorrízicos arbusculares (FMA) mantidos em cultura pura e avaliar a aplicabilidade da técnica PCR-DGGE desenvolvida para Gigaspora, na identificação molecular de espécies de FMA pertencentes a outros gêneros. A caracterização fenotípica das espécies foi realizada de acordo com critérios morfológicos, descritos pela taxonomia, e com uso de descrições originais das espécies presentes na literatura especializada. A análise genotípica foi feita com base na discriminação específica da região V9 do 18S rDNA, que permitiu a diferenciação das espécies e não revelou qualquer diferença entre os isolados geográficos de Glomus clarum, e entre os de Glomus etunicatum. Isto indica a aplicabilidade da técnica para a avaliação da pureza genética e discriminação de espécies de FMA.

The objective of this work was to characterize phenotypically and genotypically isolates of arbuscular mycorrhizal fungi (AMF) maintained in pure culture and to evaluate the applicability of PCR-DGGE analysis, developed for Gigaspora, for molecular identification of AMF species belonging to other genres. The species phenotypic characterization was done according to morphological criteria, as described by taxonomy, and according to original descriptions of species published in the specialized literature. The genotypic analysis was made through specific discrimination of the V9 region in the 18S rDNA, which allowed the distinction of species and showed no difference among geographical isolates of Glomus clarum, and among those of Glomus etunicatum. This indicates the applicability of this technique for assessment of genetic purity and discrimination of AMF species.

This work evaluated the kinetics as well as the retention capacity of Cu, Zn, Cd, and Pb by arbuscular mycorrhizal fungi (AMF) mycelium. The metal retention is a fast process with Cu being retained 3, 30, and 60 times faster than Zn, Cd, and Pb, respectively. Metal retention capacity varied amongst the different tested AMF species and decreased in the following order: Cu>Zn>>Cd>Pb. The Glomus clarum mycelium showed the highest retention capacity for Cu, Cd and Pb, whereas Zn was mostly retained by Gigaspora gigantea mycelium. The simultaneous application of all tested metals in solution decreased Cu and Zn retention by AMF mycelium. The high retention capacity of Cu and Zn by mycelium of G. clarum and G. gigantea suggests a promising use of these isolates in phytoremediation.