Effect of agrochemical application on peanut (arachis hypogaea l.) associated phosphate solubilizing soil bacteria

ANZUAY, MARÍA SOLEDAD; ANGELINI, JORGE; FABRA, ADRIANA; TAURIAN, TANIA

La Falda

Workshop; II LATIN AMERICAN PGPR WORKSHOP; 2014

Effect of agrochemical application on peanut (Arachishypogaea L.) associated phosphate solubilizing soil bacteria Anzuay, M.S.1, Angelini, J.G., Fabra, A.1 and Taurián, T.1 1Universidad Nacional de Río Cuarto, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Departamento de Ciencias Naturales. Argentina. Contact: ttaurian@exa.unrc.edu.ar In the peanut production area of Córdoba, Argentina, herbicides and fungicides application is a common practice. The main mechanism of mineral phosphate solubilization by bacteria is associated with the production of gluconic and 2-cetogluconic acids. These acids are produced by a direct oxidation pathway of glucose catalyzed by the glucose dehydrogenase whichrequires the pirroquinolinquinone (PQQ) protein. The rol of PQQ has been described to be essential for the phosphate solubilizing phenotype in several bacteria. The objective of this research was to evaluate the effect of agrochemicals on the diversity of soil phosphate solubilizing bacteria from peanut-growing area in Argentina, by using the pqqE gene as molecular marker. The experimental field was divided into two plots; ?control plot? in which no agrochemicals were applied and ?treated plot? in which agrochemicals commonly used for peanut were applied. Soil DNA was extracted from both soil samples 63 days after planting the seeds and used as template for pqqE-PCR. PCR product was ligated in pGEM-T vector and used to transform competent E. coli DH5α strain. The amplification products of pqqE-colonyPCR were digested with the enzymes CfoI, MspI and NdeII. Analyses of the clone libraries were followed by calculation of coverage and the quantitative estimation of pqqE gene sequence diversity was analyzed by Shannon?Wiener and Simpson indexes.The expected amplification product was obtained in 72 pqqE clones (37 clones from treated soil samples and 35 from control soil samples). Coverage values higher than 70% were observed in both control and treated samples. Values of Simpson index were 0.13 and 0.12 and the values of Shannon-Wiener index were 2.75 and 3.10 in the libraries of clones obtained from control and treated soil samples, respectively indicating an increase in diversity. Results obtained indicated an increase in the diversity of pqqE gene sequence from phosphate solubilizing bacteria obtained from soil samples treated with agrochemicals.