Endophytic fungi from the genus Colletotrichum are abundant in the Phaseolus vulgaris and have high genetic diversity

To evaluate the diversity of endophytic fungi from the leaves of the common bean and the genetic diversity of endophytic fungi from the genus Colletotrichum using IRAP (inter-retrotransposon amplified polymorphism) and REMAP (retrotransposon-microsatellite amplified polymorphism) analyses. The fungi were isolated by tissue fragmentation and identified by analysing the morphological features and sequencing the internal transcribed spacer (ITS) regions and the rDNA large subunit (LSU). Twenty-seven different taxa were identified. Colletotrichum was the most commonly isolated genera from the common bean (32.69% and 24.29% of the total isolates from the Ouro Negro and Talismã varieties, respectively). The IRAP and REMAP analyses revealed a high genetic diversity in the Colletotrichum endophytic isolates and were able to discriminate these isolates from the phytopathogen Colletotrichum lindemuthianum. Fungi from the genus Colletotrichum are abundant in the Phaseolus vulgaris endophytic community, and the IRAP and REMAP markers can be used to rapidly distinguish between C. lindemuthianum and other Colletotrichum members that are frequently found as endophytes. This is the first report of the diversity of endophytic fungi present in the common bean and the use of IRAP and REMAP markers to assess the genetic diversity of endophytic fungi from the genus Colletotrichum

Qualidade física de neossolo quartzarênico submetido a diferentes sistemas de uso agrícola Physical quality of quartzarenic neosol submitted to different systems of agricultural use

Apesar da existência de informações descritivas sobre solos arenosos das regiões tropicais, àquelas referentes ao manejo e conservação são escassas. No presente estudo, objetivou-se avaliar as alterações dos atributos físico-hídricos de um Neossolo Quartzarênico Órtico em função do uso e manejo com vistas à definição de sistemas de manejo sustentáveis. O estudo foi conduzido no município de Mineiros, GO, em áreas submetidas a cinco sistemas de uso e manejo do solo, sendo: Pastagem (PAS), Plantio direto de Soja (PDS) e de milho (PDM), Integração agricultura-pecuária (IAP) e cerrado nativo (CER). Coletaram-se cinco amostras por sistema nas camadas de 0 a 10 e 10 a 20 cm no inverno de 2005 e verão de 2006, para avaliação da densidade do solo, micro e macroporosidade e condutividade hidráulica do solo saturado. Os atributos físico-hídricos avaliados não variaram com a época de amostragem. Os valores de microporosidade indicam baixa retenção da água disponível às plantas. O uso agrícola do solo promoveu alterações em todos os atributos avaliados. A macroporosidade do solo foi o atributo mais sensível às alterações estruturais decorrentes do manejo, contudo, sem apresentar valores considerados limitantes ao crescimento das plantas. A redução da condutividade hidráulica do solo saturado em áreas de atividade antrópica comprometeu a qualidade do solo e pode afetar a recarga do lençol freático e aumentar o processo erosivo. A manutenção da cobertura vegetal do solo é considerada medida-chave para exploração agropecuária nessas áreas.<br>In spite of the existence of descriptive information on sandy soils in tropical areas, information regarding management and conservation is scarce. The present study aimed at evaluating changes in the physical-hydric attributes of Orthic Quartzarenic Neosol resulting from use and management having in view the definition of sustainable management systems. The study was carried out in the municipal district of Mineiros, GO, in areas submitted to five systems of use and management of the soil: pasture (PAS), soybeans under no-till (PDS), corn under no-till (PDM), agriculture-livestock integration (IAP), and native savannah (NSAV). Five samples were collected per area, at the depths of 0-10 and 10-20 cm, in the winter of 2005 and in the summer of 2006, for evaluation of bulk density, micro and macroporosity, and saturated soil hydraulic conductivity. The physical-hydric attributes evaluated did not vary within the sampling period. Microporosity values indicate low retention of the water available to the plants. Agricultural land use of the soil promoted alterations in all the appraised attributes. The macroporosity of the soil was the attribute most sensitive to structural changes resulting from management, but it did not, however, present values considered limiting to plant growth. The reduction of saturated soil hydraulic conductivity in human activity areas endangered the quality of the soil and it can affect the recharge of the water table and increase the erosive process. Maintenance of the soil covering is considered the key measure for agricultural exploration in these areas