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Evaluation of the nitrogen cycling in soybean mutants eu3-a (urease-negative) and non-mutant using nitrate or N2 from biological fixation as nitrogen sources

Grant number: 13/25094-8
Support type:Scholarships in Brazil - Post-Doctorate
Effective date (Start): April 01, 2014
Effective date (End): March 31, 2017
Field of knowledge:Biological Sciences - Botany
Principal Investigator:Paulo Mazzafera
Grantee:Sarah Caroline Ribeiro de Souza
Home Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

Soybean is a legume that has been used as a model plant in studies involving the metabolism of nitrogen (N), by its rapid growth, economic importance, and for their successful symbiotic relationship with rhizobia. Nitrogen is the nutrient required in largest amounts by plants, and is acquired by them as minerals, nitrate and ammonia, and organic form, urea and amino acids. In the case of urea, in addition to that provided to the roots, the plant produces urea in the cycling cell N. Some studies have also shown that the degradation of ureides as a source of urea, but no concrete evidence that this occurs in plants. Urea is degraded to ammonia by the urease a Ni -dependent enzyme. Ni is considered an essential mineral to plants for their role as an activator of this enzyme. Several mutants were designed to elucidate the mechanisms involved in the synthesis and activation of urease in soybean. The mutant eu3-a, urease-negative, for example, is unable to metabolize urea. Thus, in order to better understand the mechanism of cycling of nitrogen through the metabolism of urea, and as Ni can actually control the process, eu3-a mutant and non-mutants plants will be used in assays of this project, using two different sources of N from NO3- or from biological fixation. The tests shall be conducted in growth chambers with controlled conditions of light and temperature, and will involve addition of biochemical and molecular approaches, the use of 15N to study the routes involved in the cycling of N. It is hoped that this study the better understanding of N cycling in soybean and generate data that can improve the efficiency in the use of N.