Caryota mitis Lour. is a species of palm tree of Asian origin, adapted to the tropical climate, that is economically important in culinary, landscaping, in addition to anti-allergenic properties an...

Arcopilus is a genus recently proposed after the taxonomic restructuring of Chaetomium with only seven described species so far. During the characterization of the microbiome of the Amazonian guarana plant (Paullinia cupana var. sorbilis), nine red pigment-producing strains of fungi were isolated. These strains were identified through morphological characterization and phylogenetic analysis based on the internal transcribed spacer (ITS), 28S large subunit (LSU), partial second largest subunit of RNA polymerase II (RPB2) and β-tubulin (TUB2) regions. Moreover, chemical profiles were obtained via high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS), in which the isolated strains were able to produce significant amounts of the polyketide oosporein. The obtained results indicate the occurrence of a new fungal species, A. amazonicus. Chemical analyses showed that oosporein is overproduced by these strains under laboratory culture conditions.

The aim of this study was to molecularly identify different species of Aeromonas isolated from farmed tambaqui (Colossoma macropomum) from North Brazil, and evaluate their pathogenic potential by the presence of virulence genes. From the extraction of bacterial DNA, PCR (polymerase chain reaction) of the primers 16S rDNA, aerA (cytolytic enterotoxin), ast (cytotoxic enterotoxin) and act (cytotoxic enterotoxin) were performed. Of 24 isolates evaluated, eight amplified the ast gene, one amplified the act gene, but the areA gene was not amplified in any isolate. Sequencing of the 16S rRNA primer revealed a predominance of Aeromonas jandaei specie (92%). Aeromonas taiwanensis (4%), for the first time isolated from fish in Brazil, and Aeromonas hydrophila (4%) each appeared as just one isolate. Results showed that 32% of Aeromonas isolated from farmed tambaqui have considerable pathogenic potential for systemic damage, since the selected PCR primers are encoding the most common virulence genes in Aeromonas with high pathogenic intensity.

Guaraná is indigenous to the Brazilian Amazon where it has cultural and agroeconomic significance. However, its cultivation is constrained by a disease termed oversprouting of guaraná caused by Fusarium decemcellulare, with yield losses reaching as high as 100%. The disease can affect different parts of the plant, causing floral hypertrophy and hyperplasia, stem galls, and oversprouting of vegetative buds. To date, no study has been conducted characterizing the genetic diversity and population structure of this pathogen. Here, we report genetic diversity and genetic structure among 224 isolates from eight guaraná production areas of Amazonas State, Brazil, that were genotyped using a set of 10 inter-simple-sequence repeat (ISSR) markers. Despite moderate gene diversity (Hexp = 0.21 to 0.32), genotypic diversity was at or near maximum (223 multilocus genotypes among 224 isolates). Population genetic analysis of the 10 ISSR marker fragments with STRUCTURE software identified two populations designated C1 and C2 within the F. decemcellulare collection from the eight sites. Likewise, UPGMA hierarchical clustering and discriminant analysis of principal components of the strains from guaraná resolved these same two groups. Analysis of molecular variance demonstrated that 71% of genetic diversity occurred within the C1 and C2 populations. A pairwise comparison of sampling sites for both genetic populations revealed that 59 of 66 were differentiated from one another (P < 0.05), and high and significant gene flow was detected only between sampling sites assigned to the same genetic population. The presence of MAT1-1 and MAT1-2 strains, in conjunction with the high genotypic diversity and no significant linkage disequilibrium, suggests that each population of F. decemcellulare might be undergoing sexual reproduction. Isolation by distance was not observed (R² = 0.02885, P > 0.05), which suggests that human-mediated movement of seedlings may have played a role in shaping the F. decemcellulare genetic structure in Amazonas State, Brazil.

Sclerotium rot, caused by Agroathelia rolfsii, is one of the main soilborne diseases that limit plant growth and tomato yield. This study evaluated the efficacy of Amazonian Trichoderma species to control sclerotium rot, and promote plant growth under field conditions, in Manaus, Brazil. We used six species (isolates) of Trichoderma based on their previously assessed performance in field trials. The incidence of sclerotium rot, tomato fruit yield and the production of indoleacetic acid (IAA) and siderophores were evaluated. The isolates reduced the incidence of sclerotium rot by up to 75% and also increased fruit yield. T. rugulosum had the best performance, as it greatly reduced sclerotium rot incidence and improved fruit yield. Although no differences were found in biomass allocation to plant organs, T. endophyticum, T. agriamazonicum, and T. asperelloides showed high production of IAA. The results highlight the potential of Amazonian Trichoderma isolates as bio fungicides to be used in sustainable cultivation of tomato. Furthermore, we show the potential of Amazonian species of Trichoderma to both reduce the incidence of sclerotium rot, and to increase the production of bioactive compounds that stimulate plant growth. By reducing the use of synthetic agrochemicals, the use of Trichoderma promotes healthier and more sustainable agricultural practices.