Effect of Azospirillum brasilense coinoculated with Rhizobium on Phaseolus vulgaris flavonoids and Nod factor production under salt stress

DARDANELLI, M.S.; F.J. FERNÁNDEZ; M.R. ESPUNY; M.A. RODRÍGUEZ; M.E. SORIA; A.M. GIL SERRANO; Y. OKON; M. MEGÍAS

SOIL BIOLOGY AND BIOCHEMISTRY

Elsevier

Lugar: Amsterdam; Año: 2008 vol. 40 p. 2713 - 2721

0038-0717

The effects of Azospirillum brasilense strain Cd on plant growth, nodulation, flavonoid and lipochitooligosaccharides (LCOs-Nod factors) production, were sequentially followed after 4, 7 and 14 days during the Rhizobium-Phaseolus vulgaris cv. Negro Jamapa interaction, in a hydroponics growth system, with or without salt. Azospirillum brasilense promoted root branching in bean seedling roots and increased secretion of nod gene-inducing flavonoids species, as detected by high-performance liquid chromatography (HPLC). The results also support that A. brasilense allows a longer, more persistent exudation of flavonoids by bean roots. A general positive effect of Azospirillum-Rhizobium coinoculation on the expression of nod genes by Rhizobium tropici CIAT899 and Rhizobium etli ISP42, and on nodulation factors patterns, was observed in the presence of root exudates. The negative effects obtained under salt stress on nod gene expression and on Nod factors’ appearance were relieved in coinoculated plants. To the best of our knowledge this is one among few studies on the effect of A. brasilense on the early events of the Rhizobium-legume symbiotic interaction, under abiotic stress.