Crop protection against Botrytis cinerea by rhizhosphere biological control agent Bacillus velezensis XT1 Toral Navarro, Laura Rodríguez González, Miguel Ángel Béjar Luque, María Victoria Sampedro Quesada, María Inmaculada Biocontrol Botrytis Bacillus PGPR Phytohormones Callose H2O2 MDA Tomato Strawberry The study was funded by Xtrem Biotech S.L (Granada, Spain), the Ramón y Cajal MINECO program (RYC-2014-15532) in Spain, the H2020 European Industrial Doctorates Project (UGR-Ref. 4726) and the Spanish Ministry of Economy (MINECO) Challenges—Collaboration Project (2015, RTC-2015-4121-2). This study aims to evaluate the use of Bacillus velezensis strain XT1 as a plant growth-promoting rhizobacterium (PGPR) and biocontrol agent against B. cinerea in tomato and strawberry plants. Foliar and radicular applications of strain XT1 increased plant total biomass as compared to the control and B. cinerea-infected plants, with root applications being, on the whole, the most e ective mode of treatment. Applications of the bacterium were found to reduce infection parameters such as disease incidence and severity by 50% and 60%, respectively. We analyzed stress parameters and phytohormone content in order to evaluate the capacity of XT1 to activate the defense system through phytohormonal regulation. Overall, the application of XT1 reduced oxidative damage, while the H2O2 and malondialdehyde (MDA) content was lower in XT1-treated and B. cinerea-infected plants as compared to non-XT1-treated plants. Moreover, treatment with XT1 induced callose deposition, thus boosting the response to pathogenic infection. The results of this study suggest that the signaling and activation pathways involved in defense mechanisms are mediated by jasmonic acid (JA) and ethylene hormones, which are induced by preventive treatment with XT1. The study also highlights the potential of preventive applications of strain XT1 to activate defense mechanisms in strawberry and tomato plants through hormone regulation. 2024-07-01T11:04:51Z 2024-07-01T11:04:51Z 2020-06-03 journal article Toral Navarro, L. Crop protection against Botrytis cinerea by rhizhosphere biological control agent Bacillus velezensis XT1. Microorganisms 2020, 8, 992; doi:10.3390/microorganisms8070992 https://hdl.handle.net/10481/92901 10.3390/microorganisms8070992 eng info:eu-repo/grantAgreement/EC/H2020/4726 http://creativecommons.org/licenses/by-nc-nd/4.0/ open access Attribution-NonCommercial-NoDerivatives 4.0 Internacional MDPI