ABSTRACT
Endophytes are growth-promoting agents capable of synthesizing phytohormones, uptaking nutrients, and controlling pathogens. There is a strong potential to exploit them in the agriculture field like biofertilizers and biocontrol agents. In this work, we aimed to evaluate endophytic fungi isolated from Pachystachys lutea for their potential to solubilize phosphate, synthesise indole acetic acid (IAA), antagonize phytopathogens, and promote plant growth under greenhouse conditions. The phosphate solubilization efficiency was assessed on Pikovskayas agar medium. For analysis of IAA production, mycelia plugs of endophytes were cultured in Potato Dextrose Broth medium supplemented with L-tryptophan, with Salkowski Reagent, and the absorbance of the culture was measured. The antagonism evaluation of strain Alternaria sp. PL75 against phytopathogens was performed using the paired-culture technique. The promotion of plant growth provided by Alternaria sp. PL75 was evaluated in tomato plants. All strains evaluated were able to solubilize phosphate; however, the strain Alternaria sp. PL75 was the most effective (4.29). Two strains, Nemania sp. PL27 and Alternaria sp. PL75, produced 1.86 and 1.73 & 956;g mL-1 of IAA, respectively. In the antagonism assay, the endophyte Alternaria sp. PL75 and its fungal extract showed the best results against the pathogen Moniliophthora perniciosa. The greenhouse experiment result showed the endophyte Alternaria sp. PL75 increased the plantlets emergency speed index and the percentage of germination from 60 to 81.63%. It was also observed a statistical significance in the shoot length of the treated plants with the endophyte suspension (55.38 cm) compared to the control (41.67 cm).
Subject(s)
Endophytes , Phosphates , Lamiales/growth & development , Acetic Acid/analysisABSTRACT
A non-linear mixed-effects model is proposed to assess the impact of acarbose over time on postprandial glycaemia in a single rat. The model is based on two compartments, one representing the entry of glucose in the blood and the other its exit. The rat was submitted to two treatments: ingestion of starch and ingestion of starch plus acarbose. The model showed great suitability, with inferences on the behavior of glucose levels in response to treatments and supplying a richer description than just the area under the curve. The marginal curves for the two treatments are similar during the first moments; however, after reaching the peak of glucose concentration, they progressively became separate due to acarbose treatment and reached the initial levels more quickly. The proposed model, albeit with a single sample unit, showed similar results to those with larger samples; in other words, acarbose significantly attenuates glycaemia after ingestion of starch.
Neste estudo, foi proposto um modelo não linear de efeitos mistos para verificar o impacto da acarbose ao longo do tempo na glicemia pós -prandial de um único rato. Adotou-se um modelo de dois compartimentos: um representando a entrada de glicose no sangue e outro, a saída. O rato foi submetido a dois tratamentos: ingestão de amido e de amido com adição de acarbose. O modelo proposto apresentou um ótimo ajuste, permitindo fazer inferências do comportamento da glicose para os tratamentos e fornecendo uma descrição muito mais rica do que simplesmente a área sob a curva. As curvas marginais para os dois tratamentos foram semelhantes nos primeiros tempos observados, porém, após o pico de concentração de glicose, elas se distanciaram progressivamente com o tratamento da acarbose atingindo os níveis iniciais mais rapidamente. O modelo adotado, com uma única unidade amostral, mostrou resultados similares a outros estudos com maior número de unidades amostrais, isto é, a acarbose pode atenuar consideravelmente a glicemia após ingestão de amido.