Descripción morfológica y caracterización molecular de los hongos asociados a la raíz de Masdevallia coccinea Linden ex Lindl / Morphological description and molecular characterization of fungi associated with the root of Masdevallia coccinea Linden ex Lindl

RESUMEN Masdevallia coccinea es una orquídea llamativa, endémica de Colombia, empleada en la generación de híbridos ornamentales con más de una década, clasificada como una especie en peligro de extinción. Entre las técnicas usadas para la propagación in vitro y ex situ de especies de la familia Orchidaceae, se estudia la simbiosis micorrízica, debido a que esta familia micoheterótrofa depende de una correlación con estos hongos para subsistir en las primeras etapas de desarrollo en estado silvestre. Con el objetivo de caracterizar e identificar los hongos asociados a las raíces de M. coccinea, se realizó un estudio histológico en raíces y, a partir de micropreparados, se caracterizó morfológicamente micro, macroscópica y molecularmente diez aislamientos. Se identificó a M. coccinea como una orquídea que presenta diferentes patrones de colonización micorrízicos y con posibles efectos endófitos de los géneros Aspergillus, Scopulariopsis, Trichoderma, Ilyonectria y del orden Xylariales en condiciones ex situ.

ABSTRACT Masdevallia coccinea is a striking orchid, endemic to Colombia, used in the generation of ornamental hybrids, with more than a decade classified as an endangered species. Among the techniques used for in vitro and ex situ propagation of species of the Orchidaceae family, mycorrhizal symbiosis is studied, because this mycoheterotrophic family depends on a correlation with these fungi to survive in the early stages of development in the wild. In order to characterize and identify the fungi associated with the roots of M. coccinea, a histological study was carried out on roots and 10 isolates were morphologically, macroscopically and molecularly characterized from micropreparations. M. coccinea is identified as an orchid with different mycorrhizal colonization patterns and with possible endophytic effects of the genera Aspergillus, Scopulariopsis, Trichoderma, Ilyonectria and the order Xylariales under ex situ conditions.

Microbial biostimulants as alternatives for the rooting of olive tree cuttings

Currently, southern Minas Gerais (MG) state is an important producer of different olive tree (Olea europaea L.) cultivars because, in this region, the plants can differentiate the buds to produce flowers and fruit. To stimulate the rooting of cuttings, the synthetic hormone indole-3-butyric acid (IBA) at a concentration of 3 g L−1 is used commercially. However, few studies have investigated arbuscular mycorrhizal fungi (AMF), isolated or combined with rhizobacteria, as a biotechnological tool to produce hormones that function in the rooting of olive tree cuttings. The aim of this study was to evaluate the capacity of different AMF species (Rhizophagus clarus, Gigaspora rosea, or Acaulospora scrobiculata), combined or not with IBA or rhizobacteria, to promote the rooting of three olive tree cuttings (Arbequina, Grappolo 541, and Maria da Fé) with potential for cultivation in this region. For this, three experiments were conducted at the Experimental Farm of EPAMIG in Maria da Fé (MG), and the rooting potential of the olive tree cuttings inoculated with I) AMF, II) AMF combined with increasing doses of IBA, and III) AMF combined with three isolates of rhizobacteria was evaluated. The inoculation of olive tree cuttings of cultivars Arbequina, Grappolo 541, and Maria da Fé with Rhizophagus clarus, Gigaspora rosea, or Acaulospora scrobiculata combined or not with IBA or rhizobacteria did not significantly promote rooting. Alternative forms of rooting olive tree cuttings are still a challenge, and further studies for standardizing methodologies and experimental conditions are required.

Effect of Field Inoculation with Arbuscular Mycorrhizal Fungi on Rhizosphere Soil Structure of Paris polyphylla var. yunnanensis / 中国实验方剂学杂志

Objective:To investigate the effects of arbuscular mycorrhiza（AM） fungi inoculation on the rhizosphere soil of Paris polyphylla var. yunnanensis under field conditions，so as to provide a reference for the standardized cultivation and development of high-quality varieties of P. polyphylla var. yunnanensis. Method:The effects of inoculation with mycorrhizal fungi on the rhizosphere soil structure of P. polyphylla var. yunnanensis were observed through a combination of small-scale field inoculation test and laboratory analysis. Soil indexes were determined by soil agrochemical methods. Result:The treatment groups inoculated with exogenous AM fungi showed a regulatory effect on the infection rate and intensity of AM fungi infection in the root system of P. polyphylla var. yunnanensis. After treatment with AM fungi，the soil pH was basically not affected，and the contents of organic matter，available nitrogen，available phosphorus，and available potassium increased. Moreover，the number of fungi decreased，the number of bacteria and actinomycetes increased，and soil enzyme activities increased. The results of correlation analysis showed that there was a significant positive correlation among the soil physical and chemical indexes，especially the bacterial number and the three types of phosphatases showed extremely significant correlation （r=0.849，0.800，0.804，P<0.01）. Conclusion:The application of the two mixed fungicides could increase the number of microorganisms and enzyme activities in the rhizosphere of P. polyphylla var. yunnanensis， and there was a certain synergy effect among the soil factors. Among the three field trials，the effects in Anshun，Guizhou and Wanzhou，Chongqing were more ideal，which provided a theoretical and practical basis for large-scale promotion of P. polyphylla var. yunnanensis in the field.

Effect of Arbuscular Mycorrhizal Fungi Inoculation on Physical and Chemical Properties of Rhizosphere Soil of Paris polyphylla var. yunnanensis / 中国实验方剂学杂志

Objective:To investigate the infection rate of Paris polyphylla var. yunnanensis at different periods，the changes of mineral nutrients in rhizosphere soil and the correlation among the factors under different arbuscular mycorrhizal （AM） fungi conditions. Method:28 kinds of AM fungi were inoculated into the seedlings of P. polyphylla var. yunnanensis by single factor pot experiment. The samples were collected in August （fruit ripening period） and November （senescence period） to analyze the infection rate and the physical and chemical properties of rhizosphere soil. Result:The mycorrhizal infection rate of each treatment group was 75%-100% in the fruit ripening period and senescence period. The contents of easily extracted glomalin and total glomalin in rhizosphere soil increased to different degrees in these two periods as compared with CK group， the pH of rhizosphere soil in the two treatment groups showed an increasing trend， the content of organic matter in rhizosphere soil decreased significantly in the fruit ripening period in all the treatment groups，and the organic matter in rhizosphere soil in the senescence period showed no significant differences. The total N and K contents in rhizosphere soil decreased in both periods， and the other physical and chemical properties of rhizosphere soil increased or decreased without significant change regularity. Correlation analysis showed that the infection rate was correlated with the physical and chemical properties of rhizosphere soil to a certain degree. Conclusion:Inoculation of AM fungi can affect the physical and chemical properties of rhizosphere soil of P. polyphylla var. yunnanensis to some extent，and provide reference value for the application of AM fungi in the cultivation of traditional Chinese medicine.

Efectividad de hongos micorrizo-arbusculares nativos en suelos con diferentes usos agropecuarios / Native arbuscular mycorrhizal fungi effectiveness in soils with different agricultural uses

RESUMEN Objetivo. Determinar la efectividad de hongos micorrizo-arbusculares (HMA) de suelos con diferentes usos agropecuarios, en el valle medio del río Sinú, Colombia. Materiales y métodos. Bajo condiciones de invernadero se realizó el experimento, donde se utilizó como planta indicadora Leucaena leucocephala, la cual se sembró en materos con suelo de un Andisol (horizonte B) usado como sustrato. Este sustrato, se inoculó separadamente con muestras de siete suelos (horizonte Ap), como fuente de HMA, provenientes del Centro de Investigación Turipaná de Agrosavia. Como controles se incluyeron inoculación con HMA Glomus fasciculatum y uno no-inoculado El efecto de la inoculación micorrizal se evaluó mediante el monitoreo del contenido de P foliar en las plantas de L. leucocephala, en función del tiempo hasta 64 días cuando se determinó la masa seca de su parte aérea y la colonización micorrizal. Resultados. El crecimiento de L. leucocephala y el contenido de P foliar fue significativamente superior cuando el suelo se inoculó con G. fasciculatum, en comparación a aquel observado con los demás tratamientos. De igual forma, la colonización micorrizal fue muy alta en las raíces de L. leucocephala que crecieron en el suelo inoculado con G. fasciculatum e inferior en los otros tratamientos. Conclusiones. Los resultados indican que los HMA nativos de suelos con diferentes usos, provenientes del C.I Turipaná de Agrosavia, exhibieron bajo potencial para desarrollar simbiosis micorrizal, lo que limitó el crecimiento y la concentración de P foliar en la planta hospedera.

ABSTRACT Objective. To determine the effectiveness of mycorrhizal-arbuscular fungi (AMF) of soils with different agricultural uses, in the middle valley of the Sinú river, Colombia. Materials and methods. The experiment was carried out under greenhouse conditions, where Leucaena leucocephala was used as the indicator plant, which was planted in masons with an Andisol soil (horizon B) used as a substrate. This substrate was inoculated separately with samples from seven soils (Ap horizon), as a source of AMF, from the Turipaná Research Center in Agrosavia. As controls we included inoculation with HMA Glomus fasciculatum and one non-inoculated one. The effect of mycorrhizal inoculation was evaluated by monitoring the foliar P content in L. leucocephala plants, as a function of time to 64 days, when the dry mass of its aerial part and mycorrhizal colonization was determined. Results. The growth of L. leucocephala and the foliar P content was significantly higher when the soil was inoculated with G. fasciculatum, in comparison to that observed with the other treatments. Likewise, mycorrhizal colonization was very high in the roots of L. leucocephala that grew in the soil inoculated with G. fasciculatum and lower in the other treatments. Conclusions. The results indicate that the native AMF of soils with different uses, from Turipaná, exhibited low potential to develop mycorrhizal symbiosis, which limited the growth and concentration of leaf P in the host plant.

The arbuscular mycorrhizal fungi colonizing the roots of pre-nursery stage of oil palm seedlings: Elaeis guineensis in Malaysia

Aims@#Arbuscular mycorrhizal is an obligate mutualistic symbiosis fungus which survives by forming endomycorrhizal on plant roots. The arbuscular mycorrhizal fungi are not host-specific, allowing them to form a mutualistic symbiosis with a wide range of host plants including oil palm. In Malaysia, the arbuscular mycorrhizal fungi are used as a growth enhancer for the oil palm: Elaeis guineensis. The arbuscular mycorrhizal fungi are introduced only during transplantation to the field when the ages of the seedlings are approximately one year old. As such, this study is designed to investigate the ability of the arbuscular mycorrhizal fungi to form colonisation with pre-nursery oil palm seedlings. @*Methodology and results@#Here, the arbuscular mycorrhizal fungi were introduced at the pre-nursery stage oil palm seedlings. After inoculation, the seedlings were harvested on different days, i.e. on day-3, day-7, day-14, day-21, day-40 and day-60 to determine the colonisation of arbuscular mycorrhizal fungi. We found that the arbuscular mycorrhizal fungi are able to form a mycorrhizal association with the oil palm seedling at the pre-nursery stage after 40 days of inoculation, and the arbuscular mycorrhizal fungi that formed the association are Glomus sp. and Scutellospora sp. @*Conclusion, significance and impact of study@#This study suggested that the oil palm seedling can be made into a mycorrhizal plant as early as the nursery stage before transplanting them into the plantation.

Maize Productivity, Mycorrhizal Assessment, Chemical and Microbiological Soil Attributes Influenced by Maize-Forage Grasses Intercropping

Abstract Mycorrhizae are important components of agroecosystems and the diversification of crops stimulates the abundance of arbuscular mycorrhizal fungi and the participation of symbiosis in plant growth. This experiment examined mycorrhizal assessment, chemical and microbiological soil attributes in a maize-forage grasses intercropping compared to a maize-monocropping system. A complete randomized block design was used with crop systems installed under no-till management with three replicates, as follow: Maize (Zea mays L.); Panicum maximum Jacq. cv. Aruana; Urochloa humidicola (Rendle.) Schweickerdt.; Maize-P. maximum intercropping and Maize-U. humidicola intercropping. In 2015/2016 season, intercropping maize with Panicum maximum Jacq. cv. Aruana or Urochloa humidicola (Rendle.) Schweickerdt. promoted similar effects (Tukey test, p<0.05) to monocropped maize under no-till system on soil chemical and biochemical parameters related to carbon cycling in the soil surface layer, as well as the dynamics of arbuscular mycorrhizal symbiosis in tropical soils, managed for a period of more than six years. Similar grain yield was verified among maize crop systems. This result indicates that intercropping maize-tropical forage grasses represents an alternative for monocropped grains, a very common practice that is used in intensive management, being able to guarantee equivalent productivities and to combine grain production with crop-livestock systems. As a result, intercropping promotes the diversification of the property's income source, adding environmental gains, such as more efficient land use by cultivated plants, keeping soil constantly cultivated, storing carbon and contributing to minimize the impact of climate change on agricultural systems and the sustainability of food production.

ESTIMULACIÓN DE GERMINACIÓN Y COLONIZACIÓN RADICULAR DE Diversispora trimulares POR FLAVONOIDES DE EXUDADOS RADICULARES DE Nicotiana glauca / STIMULATION OF GERMINATION OF SPORES AND ROOT COLONIZATION OF Diversispora trimulares BY FLAVONOIDS IN Nicotiana glauca ROOT EXUDATES

Los metabolitos secundarios son señales importantes en la interacción planta-microrganismos; sin embargo, los datos que corroboran el rol de los flavonoides como señales entre plantas y la simbiosis micorrízica arbuscular son limitados y aún recientes. Este estudio tiene por objetivo evaluar el efecto de flavonoides presentes en exudados radiculares de Allium porrum L., Nicotiana gluaca y Brassica oleracea var. Itálica, en la germinación de esporas y establecimiento de colonización radicular de Diversispora trimulares. Se detectaron miricetina y canferol en exudados de A. porrum, con un contenido total de flavonoides de 23,80µg g-1, de raíz seca; quercetina, en N. glauca, con 23,35µg g-1 y crisina, en B. oleracea, con 14,71µg g-1. Quercetina estimuló la germinación y la vitalidad de esporas (24%, 40%), a diferencia de crisina, que presentó un efecto inhibitorio (4%, 20%). A. porrum y N. glauca incrementaron la germinación de esporas (54%, 56%) y porcentaje de colonización de micorriza arbuscular (72%, 75%). Los resultados de la investigación mostraron una evidencia sólida del efecto de los flavonoides como moléculas estimulantes en los procesos de germinación de esporas y colonización de micorriza arbuscular.

Secondary metabolites are important signals that could determine the outcome of the plant soil microbial interactions, however, the data available that support the leading role of flavonoids in the communication of arbuscular mycorrhizal symbiosis are recent and limited. The present study examines the effect of flavonoids detected in root exudates from Allium porrum, Nicotiana glauca y Brassica oleracea var. italica on spore germination and mycorrhizal root colonization of Diversispora trimulares. Myricetin and kaempferol were detected in A. porrum root exudates with a total flavonoid content of 23.80µg g-1 dried root, quercetin in N. glauca with 23,35µg g-1 and chrysin in B. Oleracea with 14.71 µg g-1. Quercetin increased the spore germination and vitality (24%, 40%). In contrast, chrysin showed an inhibitory effect (4%, 20%). A. porrum and N. glauca increased spore germination (54%, 56%) and root mycorrhizal colonization (72%, 75%). This results evidence the effect of flavonoids on the stimulization of spore germination and stablishment of root colonization of arbuscular mycorrhizal fungi.

Dos registros de Agaricales (Basidiomycota) exóticos en bosques nativos de la Patagonia argentina / Two records of exotic Agaricales (Basidiomycota) in native forests of the Argentinean Patagonia

Inocybe sindonia (Fr.) P. Karst. y Amanita rubescens Pers. son especies típicamente asociadas a bosques de Pseudotsuga menziesii (Mirb.) Franco y Pinus radiata D. Don respectivamente. Se reporta por primera vez su presencia en Argentina en bosques de Nothofagus de la Patagonia andina como resultado de la invasión de especies forestales introducidas como recurso maderero. I. sindonia fue colectado en bosques de N. dombeyi (Mirb.) Oerst. y A. rubescens en bosques de N. pumilio (Poepp. & Endl.) Krasser en áreas protegidas con invasión evidente de coníferas exóticas.

Inocybe sindonia (Fr.) P. Karst. and Amanita rubescens Pers. are species typically associated to Pseudotsuga menziesii (Mirb.) Franco and Pinus radiata D. Don respectively. Both species have been introduced in South America together with timber species plantations. Basidiomes of I. sindonia were found occurring under Nothofagus dombeyi (Mirb.) Oerst., while basidiomes of A. rubescens were found under N. pumilio (Poepp. & Endl.) Krasser in protected areas that are under invasion of exotic conifers.

Symbiotic compatibility between arbuscular mycorrhizal fungi (autoctone or exotic) and three native species of the Caatinga in different phosphorus levels / Compatibilidade simbiótica entre fungos micorrízicos arbusculares (autóctone ou exótico) e três espécies nativas da Caatinga em diferentes níveis de fósforo

The aim of this study was to evaluate three plant species native to Caatinga (Aspidosperma pyrifolium, Ziziphus joazeiro and Pseudobombax simplicifolium) in response to inoculation with two arbuscular mycorrhizal fungi (autoctone: Claroideoglomus etunicatum or exotic: Acaulospora longula) and phosphate fertilization. The experiment was conducted in a greenhouse with a completely randomized design involving a factorial arrangement of three inoculation treatments (control, C. etunicatum or A. longula) and 4 levels of single superphosphate (0 - no added P2O5, 12, 24 and 48 mg dm-3) in 10 repetitions. Under the conditions of this study, the inoculum of C. etunicatum, autoctone to the semi-arid region, showed great compatibility and efficiency in promoting plant growth and nutrient intake when compared to the exotic inoculum of A. longula. Plants of A. pyrifolium were not responsive to mycorrhization and phosphate fertilization. In soil with low phosphorus content, mycorrhized plants of Z. joazeiro and P. simplicifolium presented better vegetative development with high shoot dry weight. Mycorrhized plants of Z. joazeiro had a proportional increase in the levels of macro- and micronutrients at the phosphorus doses applied. Mycorrhizal symbiosis may have a fundamental role in the development of these species from the Caatinga.

O objetivo do trabalho foi avaliar o desenvolvimento de três espécies vegetais nativas da Caatinga (Aspidosperma pyrifolium, Ziziphus joazeiro e Pseudobombax simplicifolium) em resposta à inoculação com dois fungos micorrízicos arbusculares (autóctone: Claroideoglomus etunicatum ou exótico: Acaulospora longula) e adubação fosfatada. O experimento foi realizado em casa de vegetação em delineamento inteiramente casualizado em arranjo fatorial com três tratamentos de inoculação (Controle, C. etunicatum ou A. longula) e quatro doses de superfosfato simples (0 - sem adição de P2O5, 12, 24 e 48 mg dm -3), em dez repetições. Nas condições deste estudo, o inóculo de C. etunicatum, autóctone da região semiárida, demonstrou maior compatibilidade e eficiência na promoção do crescimento e nutrição das plantas quando comparado ao inóculo exótico de A. longula. Plantas de A. pyrifolium não foram responsivas à micorrização e adubação fosfatada. Em solo com menor teor de fósforo as plantas de Z. joazeiro e P. simplicifolium micorrizadas apresentaram melhor desenvolvimento vegetativo, com elevada produção de biomassa seca da parte aérea. Plantas de Z. joazeiro micorrizadas tiveram aumento nos teores de macro e micronutrientes proporcional às doses de fósforo aplicadas. Conclui-se que simbiose micorrízica pode ter papel fundamental no desenvolvimento destas espécies nativas da Caatinga

Arbuscular mycorrhizal fungi and colonization stimulant in cotton and maize / Fungos micorrízicos arbusculares e estimulante da colonização na cultura do algodoeiro e do milho

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: 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.

Enrichment of arbuscular mycorrhizal fungi in a contaminated soil after rehabilitation

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.

Formononetin associated with phosphorus influences soybean symbiosis with mycorrhizal fungi and Bradyrhizobium / Formononetina associada com fósforo influencia a simbiose de soja com fungos micorrízicos e Bradyrhizobium

Arbuscular mycorrhizal fungi play an important role on nutrient supply to plants, specially P. However, the availability of inoculants for large-scale usage in agriculture is still limited because these organisms are obligatory symbionts. The use of symbiosis stimulants such as flavonoids can be an alternative to improve the beneficial effects of mycorrhiza for plant nutrition. The aim of this study was to evaluate the effect of the isoflavonoid biostimulant formononetin (7-hydroxy, 4'-methoxy isoflavone) in combination with three levels of phosphorus fertilization on mycorrhizal colonization, nodulation, and productivity of soybean, under field conditions. A 3 x 4 factorial scheme (levels of P: 0, 60 and 120 kg ha-1 P2O5 and doses of formononetin: 0, 25, 50 and 100 g ha-1) was used with five replicates. The following parameters were quantified at full bloom: plant height, shoot dry weight, nodule number, nodule dry weight, mycorrhizal colonization, and shoot N and P concentrations. Productivity was also evaluated at the end of the crop cycle. Formononetin stimulated mycorrhizal colonization at lower levels of P (0 and 60 kg ha-1), with colonization increasing from 56 to 64%. When applied with 60 kg ha-1 P2O5, formononetin increased soybean productivity to values similar to those observed when 120 kg ha-1 de P2O5, was applied. At doses above 50 g ha-1, formononetin applied to the seeds can reduce the need of P fertilization by 50%.

Os Fungos micorrízicos arbusculares desempenham papel importante no fornecimento de nutrientes para as plantas, especialmente P. No entanto, a disponibilidade de inoculantes com esses fungos, para o uso em larga escala na agricultura é ainda limitada, porque estes organismos são simbiontes obrigatórios. O uso de estimulantes simbióticos, como os flavonóides, podem ser uma alternativa para melhorar os efeitos benéficos da micorrrização na nutrição das plantas. O objetivo neste estudo foi avaliar o efeito do isoflavonóide bioestimulante formononetina (7-hidroxi, 4'-metoxi isoflavona) em combinação com três níveis de adubação fosfatada sobre a colonização micorrízica, a nodulação e a produtividade da soja, em condições de campo. Um esquema fatorial 3 x 4 (níveis de P: 0, 60 e 120 kg ha-1 de P2O5 e doses de formononetina: 0, 25, 50 e 100 g ha-1) foi utilizado, com cinco repetições. Os seguintes parâmetros foram quantificados em plena floração: altura da planta, matéria seca da parte aérea, número e matéria seca de nódulos, colonização micorrízica, e concentrações de N e P na parte aérea das plantas. A produtividade também foi avaliada no final do ciclo da cultura. A Formononetina estimulou a colonização micorrízica em níveis mais baixos de P (0 e 60 kg ha- 1), com aumentos de 56-64%. Quando aplicado com 60 kg ha-1 de P2O5, a formononetina aumentou a produtividade da soja, alcançando valores semelhantes aos observados quando foi aplicado 120 kg ha-1 de P2O5. Em doses acima de 50 g ha- 1, a formononetina aplicada na semente pode reduzir a necessidade de fertilização fosfatada em 50%.

Effects of Arbuscular Mycorrhiza on Osmotic Adjustment and Photosynthetic Physiology of Maize Seedlings in Black Soils Region of Northeast China

ABSTRACT To investigate the effect of arbuscular mycorrhiza fungi on maize growth, osmoregulation substances and photosynthetic physiology, a popular maize variety ZD 958 was measured under potted condition. Arbuscular mycorrhiza (AM) symbiosis promoted plant growth, and enhanced plant height, leaf length, mean leaf width and dry weight. Higher soluble sugar and protein, but lower proline concentrations were detected in AM seedlings than corresponding non-AM seedlings. Quantum yield of PSII photochemistry and potential photochemical efficiency increased by arbuscular mycorrhiza fungi, meanwhile, AM plants had lower primary fluorescence but higher maximal fluorescence and variable fluorescence than non-AM plants. AM enhanced apparent quantum efficiency, maximum net photosynthetic rate, dark respiration rate and light saturation point, but reduced light compensation point. The conclusion was that, after the seedling inoculated with Glomus. tortuosum, AM symbioses could protect cell from being hurt through regulating substances related to osmotic adjustment, besides, the efficiency of light utilization, the capacity of using low light and the capacity of fitting and using high light were all increased by AM symbiosis.

Mycorrhizal fungi isolated from native terrestrial orchids of pristine regions in Córdoba (Argentina) / Hongos micorrízicos aislados de orquídeas terrestres nativas de regiones pristinas en Córdoba (Argentina)

Orchidaceae is a highly dependent group on the Rhizoctonia complex that includes Ceratorhiza, Moniliopsis, Epulorhiza and Rhizoctonia, for seed germination and the development of new orchid plants. Thus, the isolation and identification of orchid mycorrhizal fungi are important to understand the orchid-fungus relationship, which can lead to the development of efficient conservation strategies by in vivo germination of seeds from endangered orchid plants. The aim of our work was to isolate and characterize the different mycorrhizal fungi found in roots of terrestrial orchids from Córdoba (Argentina), and, to learn about the natural habit and fungal associations in the Chaco Serrano woodland pristine region. In this study, bloomed orchid root and rhizosphere soil samples were obtained in two times from Valle de Punilla during spring of 2007; samples were kept in plastic bags until processed within 48 hours, and mycorrhizal condition confirmed assessing peloton presence. A total of 23 isolates of the orchideous mycorrhizal Rhizoctonia complex were obtained. The isolates were studied based on morphological characters and ITS-rDNA sequences. Morphological characteristics as color of colonies, texture, growth rate, hyphal diameter and length and presence of sclerotia were observed on culture media. To define the number of nuclei per cell, the isolates were grown in Petri dishes containing water-agar (WA) for three days at 25°C and stained with Safranine-O solution. The mycorrhizal fungi were grouped into binucleate (MSGib, 10 isolates) and multinucleate (MSGim, 13 isolates) based on morphological characteristics of the colonies. We obtained the ITS1-5.8s-ITS4 region that was amplified using primers ITS1 and ITS4. Based on DNA sequencing, isolates Q23 and Q29 were found to be related to species of Ceratobasidium. Isolates Q24 and Q4 were related to the binucleated anastomosis group AG-C of Rhizoctonia sp. The rest of the isolates grouped in the Ceratobasidium clade without grouping. From our knowledge this is the first report of the association of the AG-C testers with terrestrial orchids. A high specificity was observed in the symbiotic relationship. As the mycorrhizal fungal isolates were obtained from native orchids, they could be incorporated in conservation programes of endangered orchids in Argentina.

La Familia Orchidaceae se encuentra estrechamente relacionada con hongos micorrízicos que pertenecen al complejo Rhizoctonia, e incluyen los géneros Ceratorhiza, Moniliopsis, Epulorhiza y Rhizoctonia. Esta asociación es esencial para el desarrollo de nuevas plantas ya que favorecen el proceso de germinación de las semillas. Por lo tanto, el conocimiento de la naturaleza de esta interacción es importante para que los resultados de los programas de conservación de orquídeas sean efectivos. La fragmentación del bosque Chaqueño Serrano en el centro de Argentina, ha alcanzado un punto crítico en los últimos años, afectando el funcionamiento del ecosistema. El objetivo de este trabajo fue: a) aislar y caracterizar hongos micorrízicos presentes en orquídeas terrestres de la provincia de Córdoba (Argentina) y b) conocer el hábitat natural y las asociaciones fúngicas que se establecen en esta región prístina. A partir de las raíces de orquídeas terrestres, se obtuvieron 23 aislamientos de hongos micorrízicos que pertenecen al complejo Rhizoctonia. Estos aislamientos fueron caracterizados con base en caracteres morfológicos y moleculares. Las características morfológicas (color y textura de las colonias, cinética de crecimiento, diámetro y largo de la hifa y presencia de esclerocios) fueron observados en PDA y MEA a 25ºC. El número de núcleos por célula se observó en cultivos crecidos en AA (agar-agua) y teñidos con una solución de Safranine-O. La región ITS se amplificó usando los primers ITS1 e ITS4. Con base en las características morfológicas de la colonia, los aislamientos fueron agrupados en binucleados (MSGib) y multinucleados (MSGim). De acuerdo al cladograma obtenido con las secuencias de ADN, los aislamientos Q23 y Q29 están relacionados a especies de Ceratobasidium, aisladas de raíces de orquídeas. Los aislamientos Q24 y Q4 se asocian con el grupo de anastomosis de Rhizoctonia AG-C. Finalmente, se observó una alta variabilidad en el grado de especificidad existente en la simbiosis que se establece entre las raíces de estas orquídeas terrestres y los aislamientos obtenidos a partir de ellas. Este es el primer reporte de la asociación entre el grupo de anastomosis AG-C y orquídeas terrestres. Dado que estos aislamientos se obtuvieron de orquídeas terrestres nativas, podrían ser incorporados como nuevos patrones para micorrizas de orquídeas terrestres en Argentina. Este trabajo contribuye al conocimiento de la relación simbiótica que se establece entre orquídeas y hongos micorrízicos, así como también al desarrollo de estrategias de conservación de orquídeas terrestres nativas del bosque Chaco Serrano.

Use of the arbuscular mycorrhizal fungus Glomus intraradices as biological control agent of the nematode Nacobbus aberrans parasitizing tomato

The plant-parasitic nematode Nacobbus aberrans is an endoparasite that induces gall formation in the roots and causes severe losses to diverse crops. Some populations of this nematode show preference for certain hosts, revealing the existence of "races/groups" with different behaviour and making nematode management difficult. A possible biological control alternative to reduce the damage caused by this species may be the use of arbuscular mycorrhizal fungi (AMF). In the present work, the effect of Glomus intraradices on tomato plants inoculated with the nematode at transplanting and three weeks later was tested. At 60 days, the following parameters were estimated: percentage of AMF colonization, root and aerial dry weight, number of galls and egg masses, and reproduction factor (RF=final population/initial population) of N. aberrans. AMF colonization was higher in the presence of the nematode. The use of AMF favoured tomato biomass and reduced the number of galls and RF on the plants inoculated with the nematode at transplanting.

Resposta do cafeeiro à inoculação de fungos micorrízicos arbusculares, em latossolo vermelho, do cerrado / Response of coffee plants colonized inoculation with arbuscular mucorrhizal fungi, red latosol, in cerrado

O objetivo deste trabalho foi verificar a resposta de dois cultivares de café (sensível e tolerante ao alumínio - Al), à inoculação de Gigaspora margarita e Glomus etunicatum, em Latossolo Vermelho do cerrado, com diferentes saturações por bases (30, 45 e 53 %). O experimento foi realizado em casa de vegetação, com delineamento inteiramente casualizado e em esquema fatorial 2x3x3, consistindo de 2 cultivares de (tolerante e sensível a Al), 3 tratamentos com micorriza (com inoculação de duas espécies de FMA e sem inoculação) e 3 níveis de saturação por bases do solo (V%), com cinco repetições por tratamento. As variáveis foram: altura da planta, diâmetro do caule, área foliar, massa da matéria seca da parte aérea, massa da matéria fresca de raiz, atividade da redutase do nitrato, teor de clorofila, colonização micorrízica e número de esporos. Os isolados de micorrizas proporcionaram maior crescimento do cafeeiro em solo ácido com alta concentração de Al, porém esta resposta foi verificada para ambos os cultivares quando colonizados por G. margarita. Os cultivares avaliados não mostraram diferenças quanto à tolerância ao Al quando não micorrizados.

The aim of this study was evaluate the response of two coffee cultivars (tolerant and sensitive to aluminum - Al), inoculated or not by two arbuscular mycorriza fungi (AMF), Gigaspora margarita and Glomus etunicatum, in cerrado Oxisol, with different base saturation. This experiment was conducted under greenhouse conditions, with a complete randomized design, in a 2x3x2 factorial scheme, consisting of 2 cultivars (tolerante and sensitive to Al), 3 treatments with mycorrhizal (inoculated with two species of AMF and without inoculation) and 3 levels of soil base saturation (30, 45 and 53 V%), with five replicates per treatment. The variables were: plant height, stem diameter, leaf area, shoot dry weight, root fresh weight, nitrate reductase activity, chlorophyll concentration, root colonization and number of AMF spores. Mycorrhizae isolates promoted greater response of coffee plants, in acid soil with high concentration of Al, but this response was observed for both cultivars when plants were colonized by G. margarita. The cultivars evaluated showed no differences in Al tolerance when non inoculated.

Arbuscular mycorrhizal fungi in saline soils: vertical distribution at different soil depth

Arbuscular mycorrhizal fungi (AMF) colonize land plants in every ecosystem, even extreme conditions such as saline soils. In the present work we report for the first time the mycorrhizal status and the vertical fungal distribution of AMF spores present in the rhizospheric soil samples of four species of Chenopodiaceae (Allenrolfea patagonica, Atriplex argentina, Heterostachys ritteriana and Suaeda divaricata) at five different depths in two saline of central Argentina. Roots showed medium, low or no colonization (0-50%). Nineteen morphologically distinctive AMF species were recovered. The number of AMF spores ranged between 3 and 1162 per 100 g dry soil, and AMF spore number decreased as depth increased at both sites. The highest spore number was recorded in the upper soil depth (0-10 cm) and in S. divaricata. Depending of the host plant, some AMF species sporulated mainly in the deep soil layers (Glomus magnicaule in Allenrolfea patagonica, Septoglomus aff. constrictum in Atriplex argentina), others mainly in the top layers (G. brohultti in Atriplex argentina and Septoglomus aff. constrictum in Allenrolfea patagonica). Although the low percentages of colonization or lack of it, our results show a moderate diversity of AMF associated to the species of Chenopodiaceae investigated in this study. The taxonomical diversity reveals that AMF are adapted to extreme environmental conditions from saline soils of central Argentina.

Soil fungal and bacterial biomass determined by epifluorescence microscopy and mycorrhizal spore density in different sugarcane managements / Biomassa fúngica e bacteriana do solo determinada por microscopia de epifluorescência e densidade de esporos micorrízicos em diferentes manejos de cana de açúcar

Crop productivity and sustainability have often been related to soil organic matter and soil microbial biomass, especially because of their role in soil nutrient cycling. This study aimed at measuring fungal and bacterial biomass by epifluorescence microscopy and arbuscular mycorrhizal fungal (AMF) spore density in sugarcane (Saccharum officinarum L.) fields under different managements. We collected soil samples of sugarcane fields managed with or without burning, with or without mechanized harvest, with or without application of vinasse and from nearby riparian native forest. The soil samples were collected at 10cm depth and storage at 4°C until analysis. Fungal biomass varied from 25 to 37µg C g-1 dry soil and bacterial from 178 to 263µg C g-1 dry soil. The average fungal/bacterial ratio of fields was 0.14. The AMF spore density varied from 9 to 13 spores g-1 dry soil. The different sugarcane managements did not affect AMF spore density. In general, there were no significant changes of microbial biomass with crop management and riparian forest. However, the sum of fungal and bacterial biomass measured by epifluorescence microscopy (i.e. 208-301µg C g-1 dry soil) was very close to values of total soil microbial biomass observed in other studies with traditional techniques (e.g. fumigation-extraction). Therefore, determination of fungal/bacterial ratios by epifluorescence microscopy, associated with other parameters, appears to be a promising methodology to understand microbial functionality and nutrient cycling under different soil and crop managements.

A produtividade e sustentabilidade das culturas têm sido frequentemente relacionadas com a matéria orgânica e a biomassa microbiana do solo, especialmente devido ao seu papel na ciclagem de nutrientes do solo. Este trabalho teve como objetivo avaliar a biomassa de fungos e bactérias do solo por microscopia de epifluorescência e a densidade de esporos de fungos micorrízicos arbusculares (FMAs) em lavouras de cana de açúcar (Saccharum officinarum L.) sob diferentes manejos. Foram coletadas amostras de solo de lavouras manejadas com ou sem queima, com ou sem colheita mecanizada, com ou sem aplicação de vinhaça e de matas ciliares adjacentes. As amostras de solo foram coletadas a 10 cm de profundidade e mantidas a 4°C até o momento das análises. A biomassa fúngica variou de 25 a 37µg C g-1 de solo seco e a bacteriana, de 178 to 263µg C g-1 de solo seco. A razão média entre a biomassa fúngica e bacteriana do solo nos diferentes manejos de canaviais foi de 0,14. A densidade de esporos de FMAs variou de 9 a 13 esporos g-1 de solo seco. Os diferentes manejos da cana de açúcar não afetaram significativamente a densidade de esporos de FMAs. Em geral, não foram encontradas mudanças significativas na biomassa microbiana nos diferentes manejos de solo com cana de açúcar em comparação com a mata ciliar. Todavia, a soma das biomassas fúngicas e bacterianas (208 a 301µg C g-1 de solo seco) determinadas por microscopia de epifluorescência foram similares a resultados da biomassa total do solo encontrados em outros estudos com métodos tradicionais (e.g. fumigação-extração). Os resultados evidenciam que a determinação da razão fungo/bactéria por microscopia de epifluorescência, associada a outros parâmetros, é uma metodologia promissora para compreender a funcionalidade microbiana e ciclagem de nutrientes sob diferentes manejos do solo.

Role of arbuscular mycorrhiza fungi on tolerance to salinity of the tree legume Albizia lebbeck (L.) inoculated by Rhizobium.

Myrica esculenta (Myricaceae) and Syzygium cumini(Myrtaceae), the Indian traditional fruits The effect of different level of salinity on growth, nodulation and Nitrogen fixation of single and dual inoculated tree legumes which help arbascular mycorrhizal fungi (AMF) Acaulospora laevis Gerd. and Trappe with Rhizobium bacteria in the presence of different levels of salinity (concentration of NaCl) conducted in earthen pots in a completely randomized block design with three replications resulted in effective plant growth, shoot and root biomasses, nodulation and N2 fixation. The effect of different levels of salinity (concentration of NaCl) on growth, nodulation and N2 fixation of single (Rhizobium or AMF alone) and dual inoculated (Rhizobium + AMF ) tree legume has a pot culture experiment using The parameter growth , nodulation, nitrogen fixation and % AMF colonization of roots were considerable influenced with the increase in salt concentration from 0.5 % to 4.0 % NaCl. It was observed that the mycorrhizal tree legume (inoculated with the most preferred AMF Acaulospora laevis) performed better in the increasing levels of salinity in comparison to non-mycorrhozal ones. These investigations suggested a protective role play by AMF in providing resistance to the tree legume against injurious effects of salinity. Inoculation of efficient strain of AMF (Acaulospora laevis) during the course of study, prevented the injurious effects of salinity in the test plants due to enhanced water and sustainable nutrient uptake thereby promoting growth, nodulation and biogeochemical N2 cycle (fixation of nitrogen) of the tree legume under investigation.