Induced systemic resistance and symbiotic performance of peanut plants challenged with fungal pathogens and co-inoculated with the biocontrol agent Bacillus sp. CHEP5 and Bradyrhizobium sp. SEMIA6144

FIGUEREDO, MARÍA SOLEDAD; TONELLI, MARÍA LAURA; IBAÑEZ, FERNANDO; MORLA, FEDERICO; CERIONI, GUILLERMO; TORDABLE, MARÍA DEL CARMEN; FABRA, ADRIANA

MICROBIOLOGICAL RESEARCH

ELSEVIER GMBH

Año: 2017 vol. 197 p. 65 - 73

0944-5013

Synergism between beneficial rhizobacteria and fungal pathogens is poorly understood. Therefore, eval-uation of co-inoculation of bacteria that promote plant growth by different mechanisms in pathogenchallenged plants would contribute to increase the knowledge about how plants manage interactionswith different microorganisms. The goals of this work were a) to elucidate, in greenhouse experiments,the effect of co-inoculation of peanut with Bradyrhizobium sp. SEMIA6144 and the biocontrol agent Bacillussp. CHEP5 on growth and symbiotic performance of Sclerotium rolfsii challenged plants, and b) toevaluate field performance of these bacteria in co-inoculated peanut plants. The capacity of Bacillus sp.CHEP5 to induce systemic resistance against S. rolfsii was not affected by the inoculation of Bradyrhizobiumsp. SEMIA6144. This microsymbiont, protected peanut plants from the S. rolfsii detrimental effect, reducingthe stem wilt incidence. However, disease incidence in plants inoculated with the isogenic mutantBradyrhizobium sp. SEMIA6144 V2 (unable to produce Nod factors) was as high as in pathogen challengedplants. Therefore, Bradyrhizobium sp. SEMIA6144 Nod factors play a role in the systemic resistanceagainst S. rolfsii. Bacillus sp. CHEP5 enhanced Bradyrhizobium sp. SEMIA6144 root surface colonization andimproved its symbiotic behavior, even in S. rolfsii challenged plants. Results of field trials confirmed theBacillus sp. CHEP5 ability to protect against fungal pathogens and to improve the yield of extra-largepeanut seeds from 2.15% (in Río Cuarto) to 16.69% (in Las Vertientes), indicating that co-inoculation ofbeneficial rhizobacteria could be a useful strategy for the peanut production under sustainable agriculturesystem.