Characterization of Azotobacter isolates from Argentinean soils. Assessment of the role of auxins in the early growth of wheat.

RUBIO, ESTEBAN; MONTECHIA, MARCELA; CASSAN, FABRICIO; PERTICARI, ALEJANDRO; CORREA, OLGA

EUROPEAN JOURNAL OF SOIL BIOLOGY

ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER

Lugar: Paris; Año: 2014

1164-5563

The genetic diversity among 31 Azotobacter isolates obtained from agricultural and non-agricultural soils was assessed by rep-PCR genomic fingerprinting. Isolates were identified to species level by ARDRA and partial 16S rRNA gene sequence analysis. The genotypic characterization revealed a high level of genomic diversity among the isolates identified to species level as A. chroococcum, A. salinestris and A. armeniacus, being the former two the most frequently isolated species. Inoculation experiments were performed with the selected strains based on their in vitro phytohormone production and nitrogenase activity as plant growth-promoting traits. Wheat seedlings whose seeds were inoculated with A. chroococcum and A. salinestris showed significant increases in the number of seminal roots, shoot dry weight and production of root hairs. A direct and positive correlation was found between the in vitro production of indole-3-acetic acid (IAA) and the capacity of these strains to stimulate the early growth of roots of wheat seedlings. Our results suggest that auxin production may be a useful tool in a preliminary selection of strains of Azotobacter to be used as biofertilizer. To ourknowledge, this is the first report of phytohormone production in A. salinestris.