CHANGES IN THE PRODUCTION OF MOLECULAR SIGNALS INVOLVED IN THE RHIZOBIAL COLONIZATION OF LEGUMES ROOTS IN PLANTS INOCULATED WITH A MICROBIAL CONSORTIUM

TONELLI, MARÍA LAURA; MAGALLANES-NOGUERA, CYNTHIA; FABRA, ADRIANA

Córdoba

Congreso; XI Congreso Argentino de Microbiología General-SAMIGE; 2015

Asociación Civil de MIcrobiología General

CHANGES IN THE PRODUCTION OF MOLECULAR SIGNALS INVOLVED IN THE RHIZOBIAL COLONIZATION OF LEGUMES ROOTS IN PLANTS INOCULATED WITH A MICROBIAL CONSORTIUM Tonelli María Laura*, Magallanes-Noguera Cynthia, Fabra AdrianaUniversidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Físico-Químicas y Naturales. Dpto. de Ciencias Naturales. Ruta 36 Km 601, Río Cuarto, Córdoba, Argentina. *mtonelli@exa.unrc.edu.ar.In previous studies we demonstrated that in peanut and soybean plants inoculated with the microbial consortium composed by a biocontrol agent (Bacillus sp. CHEP5) and a microsymbiont (Bradyrhizobium sp. SEMIA 6144 or Bradyrhizobium japonicum E109) in presence or absence of Sclerotium rolfsii and Cercospora sojina, respectively, the symbiotic behavior of both microsymbionts was improved. Moreover, the disease incidence or severity caused by the fungal pathogens was reduced when plants were inoculated simultaneously with the microsymbiont and the biocontrol bacteria. Taking into account these results, the objectives of this work were a) to determine changes in the composition of flavonoids secreted by roots when the legumes grow in presence of fungal pathogens and beneficial bacteria, b) to evaluate the ability of bacterial mixed cultures to form biofilms.The flavonoids profiles from the legume root exudates were determined by HPLC. Preliminary results indicated differences in peanut root exudates composition, revealing an important production of daidzein and crysin in control plants. Meanwhile, in root exudates from plants inoculated with the microsymbiont or the microbial consortium it was detected the production of genistein. In root exudates from soybean plants challenged with the pathogen it was detected the production of crysin and luteolin, while in those inoculated only with the microsymbiont or the microbial consortium it was identified crysin. On the other hand, results obtained from the in vitro biofilm formation assay revealed that the bacterial consortium showed a greater biofilm formation index compared to pure microsymbiont culture. However, the biofilm formation index of Bacillus sp. CHEP5 growing in pure culture was higher than in mixed cultures.From these results it is suggested that legumes flavonoids production is affected by the presence of the microbial consortia. Moreover, the ability to form biofilms appears to be increased in bacterial mixed cultures, compared to microsymbionts pure cultures. Since the production of biofilm confers a greater capability to colonize plant roots, this could turn in higher root microsymbiont colonization, explaining the improved symbiotic behavior under this condition. Suported by: ANPCyT, CONICET, SECyT-UNRC, FUNDACIÓN MANÍ.