ABSTRACT: Fungal endophytes of Brachiaria, a nonhost of Sclerotinia sclerotiorum, may harbor species with antagonistic effects against this plant pathogen. The objective of this work was to investigate the diversity of endophytic fungi associated with different Brachiaria species and hybrids and evaluate their potential to inhibit the plant pathogen S. sclerotiorum. Stem samples from 39 Brachiaria spp. plants were collected in pasture fields and experimental areas of three states of Brazil resulting in 74 endophytes isolated. Twenty-eight species were identified by sequences of the Internal Transcribed Spacer (ITS) and 18S rDNA regions. Paraconiothyrium sp. was the most abundant endophyte, accounting for 24 % (14 isolates) of total, and it was isolated from B. ruziziensis, B. decumbens, B. humidicola, and B. brizantha. Phoma sorghina was the second most abundant taxon, followed by Sarocladium strictum, and Plenodomus sp. In vitro analyses showed that Paraconiothyrium sp., Sarocladium kiliense, Acremonium curvulum, Setophoma terrestris, Dissoconium sp., and Cladosporium flabelliforme exhibited antagonistic activity against S. sclerotiorum, with percentages of growth inhibition ranging from 25 to 60 (p < 0.05). Paraconiothyrium sp. BBXE1 (60 %), BBPB4.1 (60 %), BCMT4.1 (54 %), and S. kiliense (54 %) showed the highest values of Antagonism Percentages (AP). Therefore, fungi with inhibitory activity against S. sclerotiorum such as Paraconiothyrium sp. are naturally endophytic in Brachiaria grasses.

ABSTRACT It is know that many plants live in symbiosis with microorganisms that can be found on their interior, the endophytes. Environment and tissue type are modulating factors of this community, in which most of these microorganisms produce important antimicrobial molecules and they may be powerful biocontrol agents in agriculture. Thus, the aim of this study was to evaluate the community of Endophytic fungi from Eremanthus erythropappus in anthropogenic and natural areas (with human interaction, natural habitat and planned planting) of Minas Gerais State, Brazil, through cultivation-based approach and verify their antimicrobial activity against phytopathogenic fungal and pathogenic bacteria. The endophytic fungi isolated were identified by sequencing of the ITS region and subjected an in vitro antagonism test. The antagonisms that show antibiosis were submitted to tests on split plates to verify the volatile compound production. In the pairing testes, the endophytic fungi of the genera Cryptosporiopsis, Diaporthe, Xylaria, Paraconiothyrium and Camarosporium presented antibiosis against phytopathogenic fungi by releasing compounds in the medium. To our knowledge, this paper is the first report on the isolation of twelve genera fungi in E. erythropappus besides verifying their antagonist capacity, which opens the way for discovery of bioactive substances produced by endophytic fungi that inhibit pathogens.

RESUMO A seleção de rizóbios eficientes para inoculação em mucuna preta pode aumentar o uso dessa leguminosa como adubo verde, maximizando o incremento de nitrogênio (N) na cultura. O objetivo deste trabalho foi selecionar rizóbios que nodulam mucuna preta com eficiência superior às estirpes atualmente recomendadas, com potencial para compor um inoculante. Um experimento em casa de vegetação avaliou 39 estirpes em solo não esterilizado, seguido de um experimento de campo com as cinco estirpes mais efetivas sob condições de campo em um argisolo amarelo distrocoeso. Ambos os experimentos incluíram a inoculação com as estirpes atualmente recomendadas, sem inoculação e os controles fertilizados com N, avaliando-se assim os nódulos, a massa seca da raiz e da parte aérea, a concentração e acúmulo de N da parte aérea e eficiência relativa. A dose de N correspondente ao ganho de massa seca da parte aérea das plantas inoculadas foi também estimada. Em condições de campo, as plantas inoculadas com os isolados T2.19A e T1.17M tiveram concentração de N na parte aérea similar a aplicação de 80 kg ha-1 de N e significativamente superior aos demais tratamentos. Além disso, o acúmulo de N foi significativamente superior ao controle (112 e 104%), à inoculação com a mistura das estirpes recomendadas (99 e 91%) e à aplicação de nitrogênio mineral (58 e 52%), respectivamente. A inoculação com as estirpes T2.19A e T1.17M apresentou resultados promissores, mostrando o seu potencial para recomendação e inoculação em mucuna preta.

ABSTRACT The selection of efficient rhizobia for the inoculation of velvet bean may increase the use of this plant as green manure, maximizing the addition of nitrogen (N) to the crop. This study aimed to select rhizobia that nodulate velvet bean more efficiently than do strains currently recommended and for the potential of rhizobia to compose an inoculant. A greenhouse experiment evaluated 39 strains using non-sterile soil and was followed by a field experiment with the five most effective strains under field conditions on a dystrocohesive Yellow Argisol. Both experiments included non-inoculated and inoculated treatments with currently recommended strains and N-fertilized controls. Nodules, root and shoot dry mass, shoot N concentration and accumulation and relative efficiency were evaluated. The N dose corresponding to the shoot dry mass increase of the inoculated plants was also estimated. Under field conditions, the plants inoculated with the strains T2.19A and T1.17M had a shoot N concentration similar to that from the application of 80 kg ha-1 N, and the N concentration was significantly higher that of the other treatments; additionally, the N accumulation was significantly higher than that of the control (112 and 104% for the two strains, respectively), the recommended strain mixture inoculation (99 and 91%, respectively) and the mineral N application (58 and 52%, respectively). Inoculation with T2.19A and T1.17M presented promising results, showing the potential of these strains for recommendation and inoculation of velvet bean.