The high input of nitrogen fertilizers in order to increase crop productivity of tomato (Solanum lycopersicum) is required to attend the increasing world demand for flesh tomatoes. However, the accumulation / excess of organic or inorganic nitrogen (N) in the soil are associated with several environmental problems. An alternative to overcome this limitation is the identification of genetic variability for N uptake, ensuring high productivity and a possible improvement in N use efficiency (NUE). Therefore, the genotypes S. lycopersicum cv Santa Clara, S. pimpinellifolium and S. habrochaites, which were previously identified with greater N acquisition capacity will be used in assays with 15N tracer in short term kinetics experiments. Furthermore, the relative quantification of gene expression related to the AMMONIUM TRANSPORTERS (AMTs) and NITRATE TRANSPORTERS (NRTs) will confirm whether the increased uptake capacity correlates with transporters expression and activity. Based on the genetic and physiological characterization of genotypes mentioned above, it is intended to isolate the factors responsible for genetic differences, creating near isogenic lines (NILS) by introgression through successive crosses of greater capacity for N uptake in miniature tomato cultivar 'micro-Tom '. The availability of such Nils, coupled with the existence of large collection of mutants in cv 'Micro-Tom' (www.esalq.usp.br / tomato) will contribute to future functional studies of higher N uptake, using the gene mapping to search for candidate gene in the genome of tomato.
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