Brazil is one of the major agriculture producers in the world and imports 7 % (a deficit of U$ 700 million) of phosphate rock to supply the low phosphate quality and the agriculture growth. A further limitation is the reduced water viability to irrigation practice and investment needed on northern region, which suffer from water scarcity and soil salinization. The use of microorganisms can be a biotechnological tool to reduce agriculture production costs and stimulate agriculture on saline soils. More than solubilize phosphate; some rhizospheric bacteria are able to stimulate plant growth by hormone production and to protect plant against pathogen and osmotic stress. The phosphate solubilization by bacteria occurs, in general, by gluconic acid production. This mechanism has been genetically enhanced to stimulate rock phosphate solubilization by bacteria, focusing on bio-fertilizer development. However, plasmid have been used, and insertion of phosphate solubilization gene on genome have not been tested in order reduce the use of selection marker and loss of the inserted gene. Unlike phosphate solubilizaton genes, those involved with the salinity resistance still need further study. The second generation sequencing technology and bioinformatics improvements turn genome comparison possible, enable search of gene of biotechnological interest and facilitate recombinant bacteria development. Those techniques also help the search for promoters (eg. rap - root-activated promoters) involved in plant x microorganisms interaction that can be used as tool to control gene expression, like pqq gene of phosphate rock solubilization. This can be useful to develop greater competitiveness recombinant bacteria in rhizospheric region. The aim of this work is: I- study the genome of the Pseudomonas putida (strain 103) resistant to high salt concentration, isolated from mangrove region and corn promoter growth in saline soils and II- develop a recombinant capable of expressing pqq gene and solubilize rock phosphate, adapted to colonize and compete in the rhizosphere environment and able to promote plant growth in saline soils with low phosphorus availability.
News published in Agência FAPESP Newsletter about the scholarship: