The native strain Paenibacillus sp. A224 induces systemic tolerance and mitigates stresses caused in peanut plants by high temperatures and the pathogen Sclerotium rolfsii

Abstract

Background and Aim: Models predicting climate change suggest that the frequency of occurrence of combined biotic and abiotic stresses is likely to increase in the future. Plant growth promoting bacteria increase the defensive response of plants against these stresses. The main objective of this study was to identify, in the available collection of bacteria isolated from the peanut rhizosphere or phyllosphere, those whose inoculation protects against the effects of both high temperature (35 °C for 6 days) and Sclerotium rolfsii occurring simultaneously through induced systemic tolerance (IST). Methods: The trials were carried out in pots containing a peanut plant growing under optimal conditions or under combined biotic and abiotic stress (high temperatures and Sclerotium rolfsii). Ninenative bacterial strains were tested to mitigate stress caused by such combined stressors by IST. Finally, systemic protection was confirmed by quantifying biochemical markers of plant defense. Results: The native strain Paenibacillus sp. A224 was able to reverse the deleterious effect of both stresses on the growth and health of peanut plants. Furthermore, peroxidase activity and phenolic compound content were induced earlier in plants inoculated with Paenibacillus sp. A224 than in uninoculated ones exposed to both stresses, in concordance with their higher tolerance to S. rolfsii and high temperature. Conclusion: The results indicate that inoculation of Paenibacillus sp. A224 could be a useful strategy to increase peanut tolerance against biotic and abiotic stresses that occur simultaneously, through a mechanism that involves the induction of systemic defense responses.