THE FOLIAR APPLICATION OF Bacillus sp. CHEP5 PROTECTS PEANUT PLANTS AGAINST PHYTOPATHOGENS BY INDUCING SYSTEMIC RESISTANCE

FIGUEREDO, MARÍA SOLEDAD; TONELLI MARÍA LAURA; LOSER, URSULA; FABRA ADRIANA

Congreso; Reunión de la Sociedad Argentina de Fisiología Vegetal: RAFV Conference; 2023

Diseases caused by fungi represent an important limitation in peanut production in Córdoba, Argentina. In order to revert this problem, producers apply synthetic fungicides more than once during the crop cycle. However, the incidence of fungal diseases, especially of the rhizoplane, is still causing significant economic losses in peanut cultivation. Among them are wilt and smut caused by Sclerotium rolfsii and Thecaphora frezii, respectively. Previous works of our laboratory demonstrated that the native biocontrol strain, Bacillus sp. CHEP5, induces systemic resistance in peanut plants against the phytopathogens S. rolfsii and T. frezii when is inoculated in root or seed. The objective of this work was to evaluate the ability of Bacillus sp. CHEP5 to induce systemic resistance when applied by foliar spray on peanut, both in assays done under controlled conditions and in the field. Quantification of soluble phenolic compounds was used as a defensive response marker. Plants growing under controlled conditions and inoculated with Bacillus sp. CHEP5 (4 L ha-1) in leaves showed a reduction (88%) in the incidence of the wilt caused by S. rolfsii. In addition, it was observed an increase in their aerial and root dry weight (80% and 44%, respectively). On the other hands, an increment of soluble phenolic compounds, was found at 48 hours post pathogen inoculation. Under field conditions, only peanut smut caused by T. frezii was detected. Our assay revealed a reduction in the incidence and severity of this disease (32% and 33% respectively) when Bacillus sp. CHEP5 (4 L ha-1) was applied by foliar spray at 70 days post-sowing. In addition, an increment in yield around of 11 % was observed in plots treated with biocontrol strain respect to control plots. Our results demonstrate that the native biocontrol strain, Bacillus sp. CHEP5, protects peanut plants against phytopathogens S. rolfsii and T. frezii by inducing systemic resistance when is inoculated by foliar spray.