Acetylcholine (Ach) is a common neurotransmitter in animals, also synthesized in plants, which can have an influence on plant response to stress, also acting as a signaling molecule between root and shoot. The objective of this study was to analyze the possible mitigating effects of exogenous application of Ach on soybean germination under different levels of osmotic potential. The experiments were conducted with soybean [Glycine max (L.) Merrill] genotype Intacta. The seeds were first treated with Ach solutions with the following concentrations: 0.0 (control); 0.5; 1. 0 and 2.0 mM. Then, the seeds were subjected to two water potentials,-0.5 and-1.0 MPa, reached by using mannitol solutions, for the induction of osmotic stress, and a control condition with distilled water. Thus, 12 treatments were established in a double factorial 4 9 3, with 4 levels of Ach and 3 osmotic potential treatments (0.0,-0.5 and-1.0 MPa) with four replicates per treatment. The results showed that the concentration of 1.0 mM Ach, without osmotic stress, presented higher values for total dry mass of the seedlings compared to the control treatment (without Ach supply). In the treatments conducted to test the effectiveness of Ach on the mitigation of severe osmotic stress effects (-1.0 MPa), results showed that the concentration of 0.5 mM Ach showed positive results for the following parameters; dry weight of shoot, root dry weight, total dry mass, which were significantly higher than treatment under 1.0 MPa.
Approximately 80-90% of cultivated grassland areas in Brazil are covered by Urochloa brizantha [syn. Brachiaria brizantha (Hochst. ex A. Rich.) Stapf.]. Some genotypes of Urochloa have being widely used with a wrong nomenclature, like species and cultivars. In this way, the Urochloa cultivar identification is primordial for breeding programs and seed production. Considering the importance of genetic purity in commercialized seed lots, the present work aimed to evaluate the use of inter-simple sequence repeat (ISSR) markers in six cultivars of U. brizantha (Xaraés; Piatã; Basilisk; MG4; MG5 and Marandu) to discriminate and determine the contamination in seed batches. Results showed that it is possible to discriminate all cultivar with only two primers in pure samples. Basilisk was confirmed as a U. brizantha cultivar. ISSR markers showed a low polymorphism level. It was not possible to separate samples intentionally contaminated even at 5%.
Aim of study: Soils contaminated by heavy metals, such as cadmium, may reduce plant development. Exogenous application of plant growth regulators (PGR), are used for optimizing the crops production in stressful environments. The aim of this study was to evaluate the effects of Cd concentrations on the development of soybean seedlings under exogenous application of a commercial PGR.Area of study: Presidente Prudente, São Paulo, Brazil.Material and methods: Soybean seeds were pre-treated in distilled water (control treatment) and in solution with plant growth regulator (PGR treatment) and then germinated with distillated water. The germinated seeds were transferred to different levels of Cd (0, 100, 500 and 900 mg of Cd).Main results: Cd exposure at increasing concentrations, decreased root development, (area, length and volume of roots) and activity of enzymatic antioxidants (SOD, CAT and APX) and enhanced MDA. These responses were accentuated by the PGR exposition. The root morphology and activity of antioxidant enzymes presented "hormesis" responses until 500 mg L-1 of Cd, and the proline content may have played a fundamental role in the maintenance of metabolic activities and biomass.Research highlights: The results indicate that the use of PGR intensified the toxicity responses caused by exposure to increased Cd level. In addition, stress indicators such as MDA content and antioxidant activity in different organs (root and shoot) of soybean seedlings, responded differently according with the use of PGR under exposure of Cd.
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