The pattern of secreted molecules during the co-inoculation of alfalfa plants with Sinorhizobium meliloti and Delftia sp. JD2: an interaction that improves plant yield

MOREL MA; CAGIDE C; MINTEGUIAGA MA; DARDANELLI MS; CASTRO-SOWINSKI S

MOLECULAR PLANT-MICROBE INTERACTIONS

AMER PHYTOPATHOLOGICAL SOC

Año: 2015 vol. 28 p. 134 - 142

0894-0282

Delftia sp. JD2 is a plant-growth-promoting bacterium that enhances legume nodulation and growth, acting as nodule-assisting bacterium during the co-inoculation of plants with rhizobial strains. In this work we evaluate how the co-inoculation of alfalfa with Sinorhizobium meliloti U143 and JD2 increases plant yield under greenhouse conditions and we analyze the pattern of secreted bioactive compounds which may be involved in the microbe-plant communication. The chemical composition of extracellular cultures (ECs) produced in hydroponic conditions (collected 4, 7 and 14 days after bacterial treatment) were characterized using different chromatographic and elucidation techniques. In addition, we assessed the effect that plant irrigation with cell-free ECs, produced during co-inoculation experiments, would have on plant yield. Results showed increased alfalfa shoot and root matter suggesting that U143-JD2 co-inoculation might be a beneficial agricultural practice. The pattern of secreted secondary metabolites among treatments showed important differences. Qualitative and quantitative changes in phenolic compounds (including flavonoids), organic acids and volatile compounds were detected during the early microbe-plant interaction, suggesting that the production of some molecules positively affect the microbe-plant association. Finally, the irrigation of co-inoculated plants with cell free ECs, under greenhouse conditions, increased plant yield over agronomic expectations. This effect might be attributed to the bioactive secondary metabolites incorporated during the irrigation.