Modifications in the lipid metabolism of F. graminearum and barley roots in response to B. subtilis ATC 6633

REYNA, M; MACOR, E P; VILCHEZ, A C; VILLASUSO, A L

Congreso; IV Reunión Conjunta de Sociedades de Biología de la República Argentina y XXIII Reunión Anual de la Sociedad de Biología de Córdoba; 2020

Fusarium graminearum (Fg) is a plant pathogen that produces significant economic losses in the agricultural sector of the province ofCórdoba. The establishment of the pathogen is given by its asexual propagation structure, "the macroconidia", when they come intocontact with the different plant organs. Current agricultural practices and consumer demands for agrochemical-free food drive thedevelopment of microbial formulations capable of controlling pests as well as improving food quality. The use of biological controlagents is an important strategy for the integrated management of fungal diseases and strains of Bacillus sp. They could suppress soildiseases due to their antagonistic properties regarding competitiveness with pathogens in the rhizosphere and the production of toxicmetabolites. The objective of the work was to analyze the inhibitory action of Bacillus subtilis ATCC 6633 (Bs) as a biocontrol agenton Fg, its effect at the lipid, structural level and its implication in the lipid signaling mechanism for this pathogen in barley. Thus,plaque inhibition and recovery assays, lipid profile analysis by TLC, measurement of phospholipase A2 (PLA2) and phospholipase D(PLD) activity, EROS production and free proline content were carried out. The results showed that the inhibition of Bs on Fg givenby compounds released to the medium was independent of the concentration of Bs used in the inhibition tests. While the recovery ofFg after the inhibition was dependent on the concentration of Bs. The macroconidia obtained from inhibited colonies showed alterationsin their length, foot cell angle and number of septa. Likewise, these structures presented alterations in the lipid pattern with a decreasein the content of triacylglycerides (TAG), free fatty acids (AGL), ergosterol (ERG), phosphatidylcholine (PC) andphosphatidylglycerol (PG) and an increase in phosphatidylethanolamine (PE). In the presence of Bs, the PLD activity and the EROSproduction previously described for the barley-Fg pathosystem showed no changes. However, the activity of PLA2 was differentbetween Bs and Fg, but similar between Bs and Bs / Fg. This latter behavior was also observed in the accumulation of free proline.Thus, the antagonistic action of Bs on Fg affects its optimal development, preventing its establishment. Concomitantly, Bs + Fg wouldinduce mobilization or metabolism of proline in the plant by modulating, by a mechanism not yet elucidated, the recognition of thepathogen. Thus, the barley seedling in the presence of Bs does not recognize the pathogen, avoiding activating various immunitymechanisms.