Biomarkers of pollution by glyphosate in the lichens, Parmotrema tinctorium and Usnea barbata.

Glyphosate is a herbicide commonly used in agriculture for weed control. Current agricultural production demands vast amounts of this product, which are applied by ground or aerial spraying. The concomitant aerial currents promote glyphosate drift to vegetated or urban areas. In this context, we hypothesized that the lichens, Parmotrema tinctorum and Usnea barbata, could be sensitive to the action of glyphosate and therefore be used to bio-indicate the presence of this herbicide in areas affected by drift. Since living organisms respond in different ways to the action of herbicides, our interest was also to indicate biological markers responsive to the action of glyphosate, through concentrations and exposure times of the thallus, besides identifying the most sensitive species. We evaluated the effect of different concentrations (0.0, 4.8, 9.6, and 19.2 mg L-1) and exposure times (24, 48, and 72 hours) to glyphosate on the morphoanatomy, photobiont vitality, photosynthetic efficiency, and oxidative metabolism of the thalli. We found that the lichens, P. tinctorum and U. barbata, respond to glyphosate stress, with prospects for use in the biomonitoring of pollutant dispersal from plantation areas. When using P. tinctorum as a bioindicator, lichen morphoanatomy, photobiont vitality, and photosynthetic pigment concentration were efficient biomarkers for the effect of concentration and exposure time. For U. barbata, the lichenic morphoanatomy and the activity of SOD and APX enzymes were essential tools to indicate the herbicide action. Parmotrema tinctotum, however, was characterized as more sensitive in bio-indicating the presence of this herbicide to diagnose the air quality in urban areas or vegetation sectors adjacent to agricultural environments.

Dissimilarity between Mouriri elliptica (Mart.) plants cultivated in vitro and in situ through anatomic parameters.

Mouriri elliptica (Mart.) is a genetic resource of the Cerrado domain, which has potential for food and medicinal use. A few studies have been performed on its in vitro propagation, and no studies have examined dissimilarities between plants of this species when cultivated in situ or in vitro. Therefore, the objective of the present study was to identify in vitro cultivation conditions that permit the formation of plantlets with leaf anatomical features that are less dissimilar to those of plants grown in situ. Thus, an anatomical study of the leaves was conducted to investigate the adaxial epidermis thickness, abaxial epidermis thickness, chlorenchyma thickness, stomatal crypt depth, stomatal crypt density, and leaf surface stomatal crypt aperture area. The distance between phenotypes was determined based on micromorphometric data, and unweighted pair group mean arithmetic clustering was performed. Four different groups were tested, and cultivation with sucrose and 50 and 75 µmol⋅m-2⋅s-1 irradiance was found to promote plantlet development and maximize similarity to plants cultivated in situ. The most important anatomical parameters in this study were the stomatal crypt aperture area and the crypt density. This study is of importance for the anatomical characterization of M. elliptica (Mart.) leaves, as it identifies plasticity as a function of in vitro culture conditions.

Dormancy break in seeds of quina (Strychnos pseudoquina A. St.-Hil.) / Superação da dormência de sementes de quina (Strychnos pseudoquina A. St.-Hil.)

"Quina" (Strychnos pseudoquina A. St. Hil) is a medicinal plant species from the Brazilian Cerrado. As its seeds show dormancy, they were subjected to the treatments pre-cooling at 5ºC during 7 days, pre-heating at 40ºC during 7 days, pre-soaking in sulfuric acid PA during 5 and 15 min, pre-soaking in boiling water during 5 and 15 min, pre-soaking in 100 and 200 ppm gibberellic acid during 48 h, pre-soaking in distilled water during 24 and 48 h, and mechanical scarification to break dormancy. Counts were daily conducted from the 2nd day after the experiment implementation until the germination stabilization at the 65th day. The germination speed index (GSI) and the germination percentage were evaluated. Germination rates above 96 percent were reached in seeds pre-soaked in water during 48 h and substrate moistened with water or KNO3.

A quina (Strychnos pseudoquina A. St.-Hil) é espécie medicinal do Cerrado Brasileiro. As sementes apresentam dormência e, por isso, foram submetidas aos tratamentos pré-resfriamento a 5ºC durante 7 dias, pré-aquecimento a 40ºC durante 7 dias, pré-embebição em ácido sulfúrico P.A. durante 5 e 15 minutos, pré-embebição em água fervente durante 5 e 15 minutos, pré-embebição em ácido giberélico a 100 e 200 ppm, durante 48 horas, pré-embebição em água destilada durante 24 e 48 horas e escarificação mecânica, visando à superação da dormência. Foram realizadas contagens diárias entre o 2º dia após a implantação do experimento até a estabilização da germinação, que ocorreu no 65º dia. Foram avaliados o índice de velocidade de germinação (IVG) e a porcentagem de germinação. Taxas de germinação acima de 96 por cento foram atingidas em sementes pré-embebidas em água durante 48 horas e substrato umedecido com água ou KNO3.