Enhancing Botrytis disease management in tomato plants: insights from a Pseudomonas putida strain with biocontrol activity.

AIMS: This study explores the biocontrol potential of Pseudomonas putida Z13 against Botrytis cinerea in tomato plants, addressing challenges posed by the pathogen's fungicide resistance. The aims of the study were to investigate the in vitro and in silico biocontrol traits of Z13, identify its plant-colonizing efficacy, evaluate the efficacy of different application strategies against B. cinerea in planta, and assess the capacity of Z13 to trigger induced systemic resistance (ISR) in plants. METHODS AND RESULTS: The in vitro experiments revealed that Z13 inhibits the growth of B. cinerea, produces siderophores, and exhibits swimming and swarming activity. Additionally, the Z13 genome harbors genes that encode compounds triggering ISR, such as pyoverdine and pyrroloquinoline quinone. The in planta experiments demonstrated Z13's efficacy in effectively colonizing the rhizosphere and leaves of tomato plants. Therefore, three application strategies of Z13 were evaluated against B. cinerea: root drenching, foliar spray, and the combination of root drenching and foliar spray. It was demonstrated that the most effective treatment of Z13 against B. cinerea was the combination of root drenching and foliar spray. Transcriptomic analysis showed that Z13 upregulates the expression of the plant defense-related genes PR1 and PIN2 upon B. cinerea inoculation. CONCLUSION: The results of the study demonstrated that Z13 possesses significant biocontrol traits, such as the production of siderophores, resulting in significant plant protection against B. cinerea when applied as a single treatment to the rhizosphere or in combination with leaf spraying. Additionally, it was shown that Z13 root colonization primes plant defenses against the pathogen.

Bacillus species: factories of plant protective volatile organic compounds.

Several studies have described the potential use of volatile organic compounds (VOCs) emitted by soil microorganisms, specifically of the genus Bacillus, as a sustainable solution for disease management in plants. The Bacillus species have been extensively studied as biocontrol agents (BCAs) due to their ability to inhibit pathogens, trigger induced systemic resistance (ISR) in plants, and enhance plant growth. The ability of the Bacillus species to produce long-lasting resting structures, such as endospores, makes them particularly appealing as BCAs. In recent years, there has been a growing body of research on the effects of Bacillus-emitted VOCs on plant pathogen growth and the triggering of ISR. This review aims to highlight recent advances in the understanding of the biological activities of Bacillus-emitted VOCs, identify new subjects for VOCs research, and stimulate interest in the academic and agri-business sectors for developing pre- and post-harvest application methods.