Arbuscular mycorrhizal fungi activity in the rhizosphere of tree seedlings subjected to residual herbicides / Atividade de fungos micorrízicos arbusculares na rizosfera de mudas de árvores submetidas a herbicidas residuais

Abstract Trees occurring on the margins of agricultural areas can mitigate damage from residual herbicides. Rhizospheric microbial activity associated with trees is one of the main remedial capacity indicators. The objective of this study was to evaluate the rhizospheric microbiological activity in tree species subjected to the herbicides atrazine and sulfentrazone via the rhizosphere. The experiment was designed in four blocks and a 6 × 3 factorial scheme. The first factor consisted of six tree species from Brazil and the second of atrazine, sulfentrazone, and water solutions. Four herbicide applications were performed via irrigation. The total dry mass of the plants, mycorrhizal colonization, number of spores, basal respiration of the rhizospheric soil, and survival rate of bioindicator plants after phytoremediation were determined. Trichilia hirta had higher biomass when treated with atrazine and sulfentrazone. Herbicides decreased the microbial activity in Triplaris americana and did not affect the microbiological indicators of Myrsine gardneriana, Schizolobium parahyba, and Toona ciliata. Fewer bioindicator plants survived in soil with Triplaris americana and sulfentrazone. Microbiological indicators were influenced in different ways between species by the presence of herbicides in the rhizosphere.

Resumo As árvores que ocorrem nas margens das áreas agrícolas podem mitigar os danos dos herbicidas residuais. A atividade microbiana rizosférica associada às árvores é um dos principais indicadores de capacidade corretiva. O objetivo deste trabalho foi avaliar a atividade microbiológica rizosférica em espécies arbóreas submetidas aos herbicidas atrazina e sulfentrazone via rizosfera. O experimento foi estruturado em quatro blocos e esquema fatorial 6 × 3. O primeiro fator consistiu em seis espécies de árvores do Brasil e o segundo em soluções de atrazine, sulfentrazone e água. Quatro aplicações de herbicidas foram realizadas via irrigação. Foram determinados a massa seca total das plantas, colonização micorrízica, número de esporos, respiração basal do solo rizosférico e taxa de sobrevivência de plantas bioindicadoras após fitorremediação. Trichilia hirta apresentou maior biomassa quando tratada com atrazina e sulfentrazone. Os herbicidas diminuíram a atividade microbiana em Triplaris americana e não afetaram os indicadores microbiológicos de Myrsine gardneriana, Schizolobium parahyba e Toona ciliata. Menos plantas bioindicadoras sobreviveram no solo com Triplaris americana e sulfentrazone. Os indicadores microbiológicos foram influenciados de formas distintas entre as espécies pela presença dos herbicidas na rizosfera.

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.

Revisión: Distribución y efecto de los hongos micorrízicos en el agroecosistema de café / Distribution and effect of mycorrhizal fungi in the coffee agroecosystem: A review

Resumen Introducción: El café es una planta altamente micotrófica, por lo que la interacción con los hongos micorrízicos arbusculares (HMA) se ha estudiado en distintos países tropicales. La mayoría de los trabajos publicados indican que el café se beneficia de la asociación micorrízica, donde los HMA confieren protección ante patógenos y enfermedades, incrementa la absorción de agua, así como la adaptación de la planta durante el trasplante de vivero al campo. Objetivo: Se realizó una revisión donde se resumieron y analizaron trabajos reportados por la asociación de HMA y café de los últimos 10 años, enfocada en la distribución global de especies de HMA, beneficio nutricional de la asociación y su interacción con patógenos. Métodos: Se revisaron diferentes bases de datos que reportaron trabajos realizados en los principales países productores de café. La revisión se centró principalmente en los trabajos publicados entre el 2000 y el 2019, sin embargo, en algunos casos se incluyeron artículos clásicos en el tema, que no corresponden al periodo señalado, principalmente los realizados en Brasil desde 1986. Se organizó el número de especies reportadas por país, se buscaron sinonimias y agruparon por familia, género y especie. Los trabajos donde solo se reportan géneros o las especies presentaron ambigüedad, se usaron como referencia, pero no se incluyeron en el análisis final. Se resumieron los reportes de los beneficios de la interacción de HMA con café, así como la tolerancia a patógenos. Resultados: Los datos recabados muestran que hay más de 100 especies de HMA asociadas con el café, lo cual representa más de la tercera parte del total de las especies reportadas en el mundo. En Colombia se reportó la mayor riqueza de especies de HMA, lo cual puede deberse a que es el país con más reportes en el tema. Conclusiones: Esta información muestra los beneficios de la incorporación de HMA en los programas de replantación de fincas de café, pues estos hongos son un elemento clave en la nutrición de los cafetos, sin embargo, se debe considerar la variedad de café cultivada y la introducción de HMA, pues no en todas hay una asociación exitosa.

Abstract Introduction: Coffee is a highly mycotrophic plant, its interaction with arbuscular mycorrhizal fungi has been studied among different tropical countries. The majority of the published works indicates that coffee is benefited from the mycorrhizal association, where the AMF confers protection against pathogens and diseases, increases water absorption, as well as it increases the adaptation of the plant at transplant from nurseries to the main plantation. Objective: A review was made where we summarized and analyze the research reports of AMF with coffee from at least the past 10 years, focused on AMF global species distribution, nutritional benefits of the association and interaction with pathogens. Methods: We retrieved available bibliographic data from coffee producer countries in public databases. We considered published works from 2000 to 2019, nevertheless, we included classic papers on the topic, outside that period, mainly the ones performed in Brazil since 1986. We organized the number of reported species per country, we look for synonyms, grouped them by family, genera and species. The reports that only reported genera or where ambiguous were used as reference but not considered for the final analysis. We summarized the reports of the benefits of the AMF interaction in coffee, as well as pathogen tolerance. Results: The collected data shows that there are more than 100 AMF species associated with coffee, which represents more than a third part of the total of reported species worldwide. We found that Colombia has the highest richness, but it also has the highest number of published reports. Conclusions: This information shows the benefits of the incorporation of AMF to coffee plantation programs, because these fungi are a key element in coffee plant nutrition, nevertheless, the coffee variety should be considered when introducing AMF, as not all associations has been efficient.

Inoculation of arbuscular mycorrhizal fungi as a strategy to improve annatto (Bixa orellana L. ) growth

This study aimed to assess the occurrence of arbuscular mycorrhizal fungi (AMF) in annatto (Bixa orellana L.) cultivars and their response to AMF inoculation using biometric parameters. The occurrence surveys were conducted in annatto fields in three municipalities from Pernambuco Forest Zone: Lagoa de Itaenga, Gloria de Goitá, and Vitoria de Santo Antão, and in four cultivars (Red Piave, Green Piave, Red Peruvian Paulista, and Green Peruvian Paulista). In a greenhouse, biometric parameters of annatto seedlings of Red Piave, Red Peruvian Paulista, Embrapa-36, and Embrapa-37 cultivars inoculated with AMF isolated from annatto fields. The Red Piave cultivar exhibited greater root colonization than the Green Peruvian Paulista in the Lagoa de Itaenga and Vitoria de Santo Antão municipalities. The cultivar Red Piave showed a more beneficial association with AMF in plants and soil than cultivar Green Peruvian Paulista did, in both Lagoa de Itaenga and Vitoria de Santo Antão. AMF inoculation was effective in promoting the growth of annatto plants, particularly those inoculants with S. heterogama and C. etunicatum.

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.

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.

Arbuscular mycorrhizal fungi associated with the babassu palm (Attalea speciosa) in the eastern periphery of Amazonia, Brazil / Fungos micorrízicos arbusculares associados com a palmeira babaçu (Attalea speciosa) na periferia leste da Amazônia, Brasil

Babassu, Attalea speciosa (Arecaceae) is a ruderal palm native to Amazonia, which turned dominant in frequently burned lands throughout the arc of deforestation and other degraded lands, in extreme cases attaining complete dominance. This study investigated arbuscular mycorrhizal fungi (AMF) as one possible explanation for the outstanding ecological success of this exceptional palm. We explored the relationships between the babassu palm and native arbuscular mycorrhizal fungi and babassu effects on the AMF richness and mycorrhizal inoculum potential (MIP) in the eastern periphery of Amazonia. For this purpose, we sampled topsoil (0-20 cm) at the onset of the rainy season from a 5-year-old secondary forest regrowth (SEC) area with three levels of babassu dominance (sites with 10, 50 and 70% babassu biomass shares), and at three distances (0, 2.5 and 4 m) from isolated babassu patches within a degraded pasture (PAS), both with five replications per treatment. Glomerospore density varied from 100 to 302 per gram of soil, 56% higher in SEC than PAS. We identified a total of 16 AMF species, with dominance of Acaulospora (six species) followed by Glomus (three species). AMF richness increased with babassu dominance in SEC sites, and reduced with distance from babassu patches within the PAS. The colonization rate of babassu roots was higher in SEC than in PAS, whereas MIP was similar in both areas and without treatment differences. Our study points to strong mycorrhizal association of the babassu palm as a potential mechanism for its outstanding ecological success in degraded lands.

Babaçu, Attalea speciosa (Arecaceae) é uma palmeira ruderal nativa da Amazônia, dominante em terras frequentemente queimadas ao longo do arco de desmatamento e outras áreas degradadas, em casos extremos atingindo domínio completo. Este estudo investigou os fungos micorrízicos arbusculares (FMA) como possível explicação do sucesso ecológico desta palmeira. Nós exploramos as relações entre o babaçu e glomerosporos, efeitos do babaçu na riqueza destes fungos e o potencial do inóculo micorrízico (PIM) na periferia oriental da Amazônia. Amostras de solo (0-20 cm) foram coletadas no início da estação chuvosa em uma área de floresta secundária (SEC) de cinco anos de idade e três níveis de dominância do babaçu (10, 50 e 70% de biomassa de babaçu) e a três distâncias (0; 2,5 e 4 m) de ilhas de babaçu isoladas em uma pastagem degradada (PAS), ambas com cinco repetições por tratamento. A densidade de esporos de FMA variou de 100 a 302 por grama de solo, sendo 56% maior em SEC do que em PAS. Dezesseis espécies de FMA foram identificadas, com predominância de Acaulospora (seis espécies) seguidos do gênero Glomus (três espécies). A riqueza destes fungos aumentou com o domínio da palmeira em SEC e reduziu com a distância das ilhas de babaçu em PAS. A taxa de colonização das raízes de babaçu foi superior nas áreas de SEC enquanto o PIM não apresentou diferenças entre os tratamentos. Nosso estudo aponta a uma forte associação micorrhízica da palmeira babaçu, um possível mecanismo central no seu sucesso ecológico em áreas degradadas.

Dinámica de la diversidad temporal de los hongos micorrícicos arbusculares de Larrea tridentata (Sesse & Mocino ex DC) Coville en un ecosistema semiárido / Temporal diversity dynamics of the arbuscular mycorrhizal fungi of Larrea tridentata (Sesse & Mocino ex DC) Coville in a semi-arid ecosystem

Los hongos micorrícicos arbusculares (HMA) de los ambientes áridos y semiáridos son importantes para el desarrollo de las plantas que crecen bajo estrés biótico y abiótico en áreas naturales o en agroecosistemas. Existe poca información sobre la diversidad temporal de los HMA en plantas perennes de ecosistemas áridos en el norte de México. En este estudiose evaluaron la colonización micorrícica y la diversidad temporal de los HMA en la rizosfera de Larrea tridentata, planta perenne de amplia distribución en el Desierto Chihuahuense. Se obtuvieron muestras de la rizosfera y de raíces de 15 plantas, en 3 fechas de muestreo del año 2015. Se encontró un total de 17 especies de HMA, distribuidas en 12 géneros y 7 familias dentro del phylum Glomeromycota. La especie más abundante fue Funneliformis geosporum. Esta especie pertenece a la familia Glomeraceae, la única que estuvo representada con varios géneros en L. tridentata. El mayor porcentaje de micorrización se presentó en febrero, con un 83,22%, en septiembre fue del 75,27% y en mayo del 65,27%. El muestreo realizado en febrero presentó el mayor número de especies (16), seguido por el de mayo (15) y el de septiembre (12). El análisis estadístico mostró diferencias significativas en el número de esporas entre los muestreos de febrero y los de mayo y septiembre.

Arbuscular mycorrhizal fungi (AMF) of arid and semiarid ecosystems are important for the development of plants that grow under biotic stress in wild or in agro-ecosystems. There is little information on the temporal diversity of these organisms in perennial plants from arid ecosystems in northern Mexico. On this study, the mycorrhizal colonization and the temporal diversity of AMF in the rhizosphere of Larrea tridentata, perennial plant abundant in the Chihuahuan Desert region were explored. Samples of the rhizosphere and roots of fifteen plants in each of the three sampling dates during the 2015 year were obtained. A total of 17 species of HMA belonging to 12 genera and 7 families within the phylum Glomeromycota in all three sampling dates were found. Funneliformis geosporum was the dominant species belonging to the family Glomeraceae which possess the highest genera number on L. tridentata.The highest mycorrhization percentage was in February with 83.22, followed by September and May with 75.27 and 65.27%, respectively. A maximum of 16 AM fungal species were isolated and identified from L. tridentata rhizosphere in February, 15 species in May and 12 species in September. Statistical analysis showed significant differences between sampling dates in the spores number.

Arbuscular mycorrhizal fungal communities in the rhizosphere of a continuous cropping soybean system at the seedling stage

Abstract Arbuscular mycorrhizae (AM) fungi play a crucial role in the growth of soybean; however, the planting system employed is thought to have an effect on AM fungal communities in the rhizosphere. This study was performed to explore the influence of continuous soybean cropping on the diversity of Arbuscular mycorrhizal (AM) fungi, and to identify the dominant AM fungus during the seedling stage. Three soybean cultivars were planted under two and three years continuous cropping, respectively. The diversity of AM fungi in the rhizosphere soil at the seedling stage was subsequently analyzed using polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE). The results showed that an increase in cropping years improved the colonization rate of AM in all three soybean cultivars. Moreover, the dominant species were found to be Funneliformis mosseae and Glomus species. The results of cluster analysis further confirmed that the number of years of continuous cropping significantly affected the composition of rhizospheric AM fungal communities in different soybean cultivars.

Crecimiento y eficiencia fotoquímica del fotosistema II en plántulas de 2 variedades de Capsicum annuum L. inoculadas con rizobacterias u hongos micorrícicos arbusculares / Growth and photochemical efficiency of photosystem II in seedlings of two varieties of Capsicum annuum L. inoculated with rhizobacteria and arbuscular mycorrhizal fungi

Una alternativa para el manejo sustentable en el cultivo de Capsicum annuum L. se ha enfocado en el uso de bacterias promotoras del crecimiento vegetal (BPCV) y hongos micorrícicos arbusculares (HMA). Esta investigación seleccionó BPCV y HMA sobre la base de su efecto en plantas de chile Bell Pepper y jalapeño. Se utilizaron 5 cepas bacterianas aisladas de diferentes localidades del estado de México (P61 [Pseudomonas tolaasii], A46 [P. tolaasii], R44 [Bacillus pumilus], BSP1.1 [Paenibacillus sp.] y OLs-Sf5 [Pseudomonas sp.]) y 3 tratamientos con HMA (H1 [consorcio aislado de la rizosfera de chile en el estado de Puebla], H2 [Rhizophagus intraradices]y H3 [consorcio aislado de la rizosfera de limón del estado de Tabasco]). Además, se incluyó un tratamiento fertilizado (solución Steiner 25%) y un testigo absoluto. Plántulas de chile jalapeño «Caloro¼ y pimiento Bell Pepper «California Wonder¼ fueron inoculadas con HMA en el momento de la siembra y con BPCV 15 días después de emerger, y crecidas bajo condiciones de cámara de ambiente controlado. En chile jalapenño, la mejor cepa bacteriana fue P61 y el mejor tratamiento de HMA fue el H1; en Bell Pepper la mejor cepa fue R44 y los mejores HMA fueron el H3 y el H1. Estos microorganismos incrementaron el crecimiento de plántulas de chile jalapenño y Bell Pepper en comparación con el testigo sin fertilizar. Asimismo, P61 y R44 beneficiaron positivamente la capacidad fotosintética del PSII.

Plant growth promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi (AMF) are a biological alternative for the sustainable management of Capsicum annuum L. This research work evaluated the effects of both PGPR and AMF on bell pepper and jalapeno pepper plants. Five bacterial strains isolated from several locations in Estado de Mexico were used: [P61 (Pseudomonas tolaasii), A46 (P. tolaasii), R44 (Bacillus pumilus), BSP1.1 (Paenibacillus sp.), and OLs-Sf5 (Pseudomonas sp.)], and three treatments with AMF [H1 (consortium isolated from pepper crops in the State of Puebla), H2 (Rhizophagus intraradices), and H3 (consortium isolated from the rhizosphere of lemon trees, State of Tabasco)]. In addition, a fertilized treatment (Steiner nutrient solution at 25%) and an unfertilized control were included. Seedlings of "Caloro" jalapeno pepper and "California Wonder" bell pepper were inoculated with AMF at seed sowing, and PGPR were inoculated after 15 days of seedling emergence; seedlings were grown under plant growth chamber conditions. P61 bacterium and H1 AMF consortia were the most effective microorganisms for jalapeno pepper whereas R44 bacterium and AMF H3 and H1 were the most effective for bell peppers, when compared to the unfertilized control. Furthermore, P61 and R44 bacteria showed beneficial effects on PSII efficiency.

Diversity and growth-effects of ectomycorrhizal fungi of a Nothofagus pumilio forest in the Andes of Southern Chile / (Diversidad y efectos de crecimiento de hongos ectomicorrízicos en un bosque de Nothofagus pumilio en los andes del sur de Chile

Chilean temperate rainforests have unique climatic, edaphic and biotic conditions, constituting pre-industrial blueprint ecosystems. Mycorrhizal associations play a central role in the biogeochemical processes of these ecosystems´ functioning. Baseline forest ecology studies are necessary in order to better understand diversity patterns, specifically regarding mycorrhizal symbiosis. Therefore, here we describe the vegetation characteristics and the mycorrhizal relationships of vascular plants in a Nothofagus pumilio forest. We also describe, via morphological methods, the ectomycorrhizal diversity present in this forest. Additionally, we determined whether ectomycorrhizal inoculation confers positive growth effects on N. pumilio seedlings. We found that from 46 vascular plant species identified in this study, 42 (91%) were mycorrhizal and of these 33 (72%) were associated with arbuscular mycorrhizae (AM), two (the dominant trees N. pumilio and N. dombeyi) were forming ectomycorrhizae (EM), five were associated with ericoid mycorrhizae, two with orchid mycorrhizae, and four were nonmycorrhizal. Additionally, 26 EM species were detected of which 15 belong to Cortinarius. Finally, there were clear differences in the growth of N. pumilio seedlings inoculated with the ectomycorrhizal fungus Laccaria laccata compared to noninoculated plants. We suggest that mycorrhizal fungi play a key role in seedling colonization of harsh environments such as the Andean treeline.

Los bosques templados lluviosos de Chile tienen condiciones climáticas, edáficas y bióticas únicas, constituyendo ecosistemas preindustriales modelo. Las asociaciones micorrízicas juegan un rol central en los procesos biogeoquímicos del funcionamiento de estos ecosistemas. Por lo tanto, en este estudio describimos las características de la vegetación y las relaciones micorrízicas de las plantas vasculares de un bosque de Nothofagus pumilio. También describimos, vía métodos morfológicos, la diversidad ectomicorrízica presente en este bosque. Adicionalmente, determinamos si inoculaciones ectomicorrízicas confieren efectos de crecimiento positivos a semilleros de N. pumilio. Encontramos que, de 46 especies de plantas vasculares identificadas en este estudio, 42 (91%) son micorrízicas, y de estas, 33 (72%) están formando micorrizas arbusculares (AM), dos (los árboles dominantes N. pumilio y N. dombeyi) están asociados con ectomicorrizas (EM), cinco están asociadas con micorrizas ericoides, dos con micorrizas orquioides, y cuatro fueron nomicorrizadas. Adicionalmente, 26 especies de EM fueron detectadas, de las cuales 15 pertenecen a Cortinarius. Finalmente, hubo claras diferencias en el crecimiento de los semilleros de N. pumilio inoculados con el hongo ectomicorrízico Laccaria laccata, comparados a plantas no inoculadas. Sugerimos que los hongos micorrízicos juegan un rol clave en la colonización de ambientes severos por juveniles, como en el límite altitudinal andino.

Conceptos fundamentales en ecología de hongos del suelo: una propuesta pedagógica y de divulgación / Fundamental concepts in ecology of soil fungi: a pedagogic and outreach proposal

El estudio de los procesos biogeoquímicos implica entender cómo los macro y micro nutrientes que componen los seres vivos se mueven de un componente a otro del ecosistema (incluyendo la atmósfera, organismos, suelo, cuerpos de agua, etc.). Usualmente, una mayor diversidad biótica y una mayor complejidad de las interacciones bióticas y abióticas, resultan en una mayor estabilidad ecosistémica. El rol de los hongos en los ciclos biogeoquímicos se suele estudiar superficialmente, no mucho más allá de sus funciones ecosistémicas generales: descomposición, simbiosis mutualista, y parasitismo. Esta revisión tiene por objetivo ilustrar los conceptos base de los roles ecológicos de los hongos del suelo, que debieran enseñarse en tres públicos objetivo: universitario, tomadores de decisiones, y estudiantes de educación secundaria/público general. En estos públicos, se propone abordar cuatro áreas temáticas: introducción al suelo, ecología de comunidades, interacciones de hongos con otros organismos, y biogeoquímica. Aunque los roles ecosistémicos de los hongos del suelo están bien documentados, su estudio debería partir de la base de que estos afectan y son afectados tanto por variables climáticas, como por características físico-químicas del suelo, y por flujos biogeoquímicos. Los roles ecológicos de los hongos del suelo debieran entenderse en un contexto holístico de integración multidisciplinar, y el nivel de especialización del conocimiento debiera darse hacia niveles superiores de la jerarquía biológica, es decir, conocer más en detalle la ecología de ecosistemas y comunidades de hongos que la de poblaciones y organismos, o que sus procesos bioquímicos y edáficos específicos.

The study of biogeochemical processes involves understanding how the macro and micro nutrients that make up living things move from one ecosystem component to another (including the atmosphere, organisms, soil, waterbodies, etc.). Usually, a greater diversity of biotic diversity and a greater complexity of biotic and abiotic interactions, result in a greater ecosystemic stability. The role of fungi in biogeochemical cycles is usually studied superficially, not much beyond their general ecosystem functions: decomposition, mutualistic symbiosis, and parasitism. The objective of this review is to illustrate the basic concepts of the ecological roles of soil fungi, which should be taught in three target audiences: university students, decision makers, and secondary school students / general public. In these audiences, it is proposed to address four thematic areas: introduction to soil, community ecology, interactions of fungi with other organisms, and biogeochemistry. Although the ecosystemic roles of soil fungi are well documented, their study should be based on the fact that they affect and are affected by climatic variables, physical-chemical soil characteristics, and biogeochemical flows. The ecological roles of soil fungi should be understood in an holistic context of multidisciplinary integration, and the level of specialization of knowledge should be given to higher levels of the biological hierarchy, that is, to know more in detail the ecology of ecosystems and communities of fungi than that of populations and organisms, or than that of their specific biochemical and edaphic processes.

Effectiveness of Arbuscular Mycorrhizal Fungal Isolates from the Land Uses of Amazon Region in Symbiosis with Cowpea

ABSTRACT Arbuscular mycorrhizal fungi provide several ecosystem services, including increase in plant growth and nutrition. The occurrence, richness, and structure of arbuscular mycorrhizal fungi communities are influenced by human activities, which may affect the functional benefits of these components of the soil biota. In this study, 13 arbuscular mycorrhizal fungi isolates originating from soils with different land uses in the Alto Solimões-Amazon region were evaluated regarding their effect on growth, nutrition, and cowpea yield in controlled conditions using two soils. Comparisons with reference isolates and a mixture of isolates were also performed. Fungal isolates exhibited a wide variability associated with colonization, sporulation, production of aboveground biomass, nitrogen and phosphorus uptake, and grain yield, indicating high functional diversity within and among fungal species. A generalized effect of isolates in promoting phosphorus uptake, increase in biomass, and cowpea yield was observed in both soils. The isolates of Glomus were the most efficient and are promising isolates for practical inoculation programs. No relationship was found between the origin of fungal isolate (i.e. land use) and their symbiotic performance in cowpea.

Physiological response of Cucurbita pepo var. pepo mycorrhized by Sonoran desert native arbuscular fungi to drought and salinity stresses

ABSTRACT Plants response to symbiosis with arbuscular mycorrhizal fungi (AMF) under water stress is important to agriculture. Under abiotic stress conditions native fungi are more effective than exotics in improving plant growth and water status. Mycorrhization efficiency is related to soil fungi development and energy cost-benefit ratio. In this study, we assessed the effect on growth, water status and energy metabolism of Cucurbita pepo var. pepo when inoculated with native AMF from the Sonoran desert Mexico (mixed isolate and field consortium), and compared with an exotic species from a temperate region, under drought, low and high salinity conditions. Dry weights, leaf water content, water and osmotic potentials, construction costs, photochemistry and mycorrhization features were quantified. Under drought and low salinity conditions, the mixed isolate increased plant growth and leaf water content. Leaf water potential was increased only by the field consortium under drought conditions (0.5-0.9 MPa). Under high salinity, the field consortium increased aerial dry weight (more than 1 g) and osmotic potential (0.54 MPa), as compared to non-mycorrhized controls. Plants inoculated with native AMF, which supposedly diminish the effects of stress, exhibited low construction costs, increased photochemical capacity, and grew larger external mycelia in comparison to the exotic inoculum.

Tripartite symbiosis of Sophora tomentosa, rhizobia and arbuscular mycorhizal fungi

ABSTRACT Sophora tomentosa is a pantropical legume species with potential for recovery of areas degraded by salinization, and for stabilization of sand dunes. However, few studies on this species have been carried out, and none regarding its symbiotic relationship with beneficial soil microorganisms. Therefore, this study aimed to evaluate the diversity of nitrogen-fixing bacteria isolated from nodules of Sophora tomentosa, and to analyze the occurrence of colonization of arbuscular mycorrhizal fungi on the roots of this legume in seafront soil. Thus, seeds, root nodules, and soil from the rhizosphere of Sophora tomentosa were collected. From the soil samples, trap cultures with this species were established to extract spores and to evaluate arbuscular mycorhizal fungi colonization in legume roots, as well as to capture rhizobia. Rhizobia strains were isolated from nodules collected in the field or from the trap cultures. Representative isolates of the groups obtained in the similarity dendrogram, based on phenotypic characteristics, had their 16S rRNA genes sequenced. The legume species showed nodules with indeterminate growth, and reddish color, distributed throughout the root. Fifty-one strains of these nodules were isolated, of which 21 were classified in the genus Bacillus, Brevibacillus, Paenibacillus, Rhizobium and especially Sinorhizobium. Strains closely related to Sinorhizobium adhaerens were the predominant bacteria in nodules. The other genera found, with the exception of Rhizobium, are probably endophytic bacteria in the nodules. Arbuscular mycorrhizal fungi was observed colonizing the roots, but arbuscular mycorhizal fungi spores were not found in the trap cultures. Therefore Sophora tomentosa is associated with both arbuscular mycorhizal fungi and nodulating nitrogen-fixing bacteria.

Identificación de Scleroderma citrinum Pers en una plantación de almendros de la ciudad de Villa Alemana, Chile / Identification of Scleroderma citrinum Pers in an almond tree plantation from Villa Alemana city, Chile

Las micorrizas son una asociación mutualista fundamental para el desarrollo tanto de las plantas como para los hongos que la establecen. Son comunes en bosques y existen muchas especies de hongos que realizan esta asociación. Las ectomicorrizas son hifas de un hongo que penetran las raíces secundarias de la planta para desarrollarse, rodeando las células de la corteza de las raices. En este trabajo se reporta el hallazgo de la ectomicorriza Scleroderma citrinum en un predio con almendros en la ciudad de Villa Alemana, Quinta región de Chile, lugar donde no había sido descrita. Tanto las condiciones ambientales, como las características del suelo del lugar no son las más favorables para el desarrollo de esta especie.

Micorrhizae are mutualistic association between plants and fungus, which is fundamental for the both of them. They are common in forest and many species of fungus are involved in this association. Ectomicorrhizae are a group of hyphae that penetrate the secondary roots of a plant, surrounding the cortex cells to develop. In the present report we inform the ectomicorrhizae Scleroderma citrinum finding in a location with almond tree plantation at Villa Alemana city V region of Chile, place where it never been found out before. Both the environmental condition and the soil characteristics are not the best for the development of this specie.

Combinación de hongos movilizadores y solubilizadores de fósforo con rocas fosfóricas y materiales volcánicos para la promoción del crecimiento de plantas de lechuga (Lactuca sativa L.) / Combination of phosphorus solubilizing and mobilizing fungi with phosphate rocks and volcanic materials to promote plant growth of lettuce (Lactuca sativa L.)

Los hongos micorrícicos arbusculares (HMA) incrementan la toma de fosfatos solubles, mientras que los hongos solubilizadores de fósforo (S) promueven la solubilización de complejos insolubles de fosfato, en conjunto benefician la nutrición de las plantas. La utilización de estos organismos en combinación con minerales o rocas que aportan nutrientes es otra alternativa para mantener la productividad de los cultivos. El objetivo de este trabajo fue combinar HMA y S con materiales piroclásticos (cenizas y pumicitas) del volcán Puyehue y rocas fosfóricas (RP) del Grupo Río Chico (Chubut) y evaluar el desempeno de estas mezclas como sustratos para la producción en maceta de Lactuca sativa. Para formular los sustratos, se utilizó como base una mezcla de Terrafertil® con cenizas. Penicillium thomii fue el S y esporas del hongo Rhizophagus intraradices (AEGIS® Irriga) sirvieron de fuente del HMA. Se evaluaron diversas combinaciones de microorganismos y la adición o no de RP. Los tratamientos fueron: 1) sustrato; 2) sustrato + HMA; 3) sustrato + S; 4) sustrato + HMA + S; 5) sustrato: RP; 6) sustrato: RP + HMA; 7) sustrato: RP + S, y 8) sustrato: RP+ HMA + S. Se efectuaron 3 repeticiones por tratamiento. Los parámetros evaluados fueron el contenido de P total y asimilable en el sustrato, el P en el tejido vegetal y la biomasa seca. Todos ellos fueron significativamente mayores en las plantas que crecieron en el sustrato adicionado con RP e inoculadas con S y HMA. Este trabajo confirma que la combinación S/HMA con cenizas volcánicas del Puyehue y las RP del Grupo Río Chico formuladas con un sustrato comercial promueven el crecimiento de L. sativa. De este modo es posible incrementar el valor agregado de geomateriales de origen nacional.

Arbuscular mycorrhizal fungi (AMF) increase the uptake of soluble phosphates, while phosphorus solubilizing fungi (S) promote solubilization of insoluble phosphates complexes, favoring plant nutrition. Another alternative to maintaining crop productivity is to combine minerals and rocks that provide nutrients and other desirable properties. The aim of this work was to combine AMF and S with pyroclastic materials (ashes and pumices) from Puyehue volcano and phosphate rocks (PR) from Rio Chico Group (Chubut) - to formulate a substrate for the production of potted Lactuca sativa. A mixture of Terrafertil®:ashes was used as substrate. Penicillium thomii was the solubilizing fungus and Rhizophagus intraradices spores (AMF) was the P mobilizer (AEGIS® Irriga). The treatments were: 1) Substrate; 2) Substrate + AMF; 3) Substrate+S; 4) Substrate + AMF+ S; 5) Substrate: PR; 6) Substrate: PR + AMF; 7) Substrate: PR + S and 8) Substrate: PR + AMF + S. Three replicates were performed per treatment. All parameters evaluated (total and assimilable P content in substrate, P in plant tissue and plant dry biomass) were significantly higher in plants grown in substrate containing PR and inoculas with S and AMF. This work confirms that the combination of S/AMF with Puyehue volcanic ashes, PR from the Río Chico Group and a commercial substrate promote the growth of L. sativa, thus increasing the added value of national geomaterials.

Occurrence of arbuscular mycorrhizal fungi on King George Island, South Shetland Islands, Antarctica

ABSTRACT Arbuscular mycorrhizal fungi make up an important ecological niche in ecosystems, and knowledge of their diversity in extreme environments is still incipient. The objective of this work was to evaluate the density and diversity of arbuscular mycorrhizal fungi in the soil of King George Island in the South Shetland Islands archipelago, Antarctica. For that, soil and roots of Deschampsia antarctica were collected at the brazilian research station in Antarctica. The spore density, species diversity and mycorrhizal colonization in the roots were evaluated. There was a low density of spores (27.4 ± 17.7) and root mycorrhizal colonization (6 ± 5.1%), which did not present statistical difference. Four species of arbuscular mycorrhizal fungi were identified, distributed in two genera: three species of the genus Glomus (Glomus sp1, Glomus sp2 and Glomus sp3) and one of the genus Acaulospora, which was identified at species level (Acaulospora mellea). Greater soil diversity was verified with pH 5.9 and phosphorus concentration of 111 mg dm-3, occurring two species of genus Glomus and A. mellea. Based on literature data, this may be the first record of this species of Acaulospora mellea in Antarctic soils, colonizing D. antarctica plants.

Crescimento de Ruta graveolens l. Inoculada com micorrizas sob doses de fósforo / Growth of Ruta graveolens l. Inoculated with arbuscular mycorrhizal fungi under levels of phosphorus / Crecimiento del Ruta graveolens l. Inoculada con micorrizas bajo dosis de fósforo

Os fungos micorrízicos arbusculares (FMAs) são micro-organismos que fazem simbiose com raízes da maioria das plantas. O objetivo deste trabalho foi avaliar a influência dos FMAs Rhizophagus clarus e Claroideoglomus etunicatum em substrato sob baixa e ou alta dose de fósforo (P), na produção de biomassa e na acumulação de P na arruda (Ruta graveolens L.). O experimento foi conduzido no laboratório de botânica da Universidade Paranaense - UNIPAR, município de Umuarama - PR. O delineamento experimental foi inteiramente ao acaso, em fatorial 3x2, sendo os fatores: FMAs (sem FMA, com R. clarus e ou com C. etunicatum); duas doses de P (20 e 200 mg kg-1) com 8 repetições por tratamento, num total de 48 unidades experimentais (vasos de 3 L). Avaliou-se a produção de massa seca das raízes (MSR), massa seca da parte aérea (MSPA), massa seca total (MST) e o acúmulo de P na parte aérea da planta (PPA). A produção de MSR, MSPA e MST pela planta não foram significativamente afetadas apenas pela adição de P ao substrato, porém sim, pela inoculação com o FMA C. etunicatum, sob baixo e ou alto P. O acúmulo de P na parte aérea da planta foi aumentado significativamente no tratamento sem a inoculação com FMAs. Conclui-se que a inoculação com C. etunicatum é indicada para aumentar a produtividade da arruda.(AU)

Arbuscular mycorrhizal fungi (AMF) are microorganisms that present symbiosis with the roots of most plants. The purpose of this work was to evaluate the influence of AMF Rhizophagus clarus and Claroideoglomus etunicatum on low and high doses of phosphorus (P) on plant biomass and P accumulation in rue (Ruta graveolens L.). The experiment was performed in the botanical laboratory at Universidade Paranaense ­ UNIPAR in the city of Umuarama, in the state of Paraná, Brazil. It used a completely randomized 3x2 experimental design, being: AMFs (without AMF, with R. clarus and/or with C. etunicatum); two levels of P (20 and 200 mg kg-1) with 8 repetitions per treatment, totaling 48 experimental units (3 L pots). Root dry matter (RDM), shoot dry matter (SDM), total dry matter (TDM) and P accumulation in the aerial part of the plant were evaluated. The production of RDM, SDM and TDM by the plant was not significantly affected by the addition of P to the substrate, but by the inoculation with AMF C. etunicatum under low and/or high P. The accumulation of P in the aerial part of the plant significantly increased in the treatment without AMF inoculation. It was concluded that inoculation with C. etunicatum is indicated to increase the productivity of rue.(AU)

Los hongos micorrícicos arbusculares (HMA) son microorganismos que forman simbiosis con las raíces de la mayoría de las plantas. El objetivo de este estudio fue evaluar la influencia del HMA Rhizophagus clarus y Claroideoglomus etunicatum en substrato so baja y/o alta dosis de fósforo (P), en la producción de biomasa y en la acumulación de P en la ruda (Ruta graveolens L.). El experimento se llevó a cabo en el laboratorio de botánica de la Universidad Paranaense - Unipar, municipio de Umuarama - PR. El diseño experimental fue completamente al azar, en un 3x2 factorial, con los factores: HMA (Sin HMA, con R. clarus y C. etunicatum); dos dosis de P (20 y 200 mg kg-1) con 8 repeticiones por tratamiento de un total de 48 unidades experimentales (vasos de 3 L). Se evaluó la producción de materia seca de las raíces (MSR), materia seca de la parte aérea (MSPA), materia seca total (MST) y la acumulación de P en la parte aérea de la planta (PPA). La producción de MSR, MSPA y MST por la planta no se vieron afectados significativamente sólo mediante la adición de P al sustrato, sino por inoculación con HMA C. etunicatum so bajo y/o alto P. El acúmulo de P en parte aérea de la planta se incrementó significativamente en el tratamiento sin inoculación con HMA. Se concluye que la inoculación con C. etunicatum está indicada para aumentar la productividad de la ruda.(AU)