Exploration of a multifunctional biocontrol agent Streptomyces sp. JCK-8055 for the management of apple fire blight

Abstract

Phytopathogenic microorganisms have detrimental impacts on crop production as well as the economic and political stability of countries (Ristaino et al. 2021 ). Fire blight caused by the bacterial pathogen Erwinia amylovora was first noted in Hudson Valley, New York (USA) in 1780 (Bonn and Van der Zwet 2000 ). Since its discovery, fire blight has been recognized as a devastating disease of pome fruit trees, leading to substantial economic losses worldwide (Zhao et al. 2019 ). Traditionally, fire blight has been managed through cultural practices and preventative sprays containing copper and antibiotics (Norelli et al. 2003 ). Streptomycin, an aminoglycoside antibiotic, is the most effective chemical in fire blight management, reducing disease incidence by more than 90% in clinical trials conducted in the northeastern states of the USA (Aldwinckle et al. 2001 ; Norelli et al. 2003 ). Nevertheless, considering pesticide spray drift with antibiotics may induce the spread of antibiotic-resistant bacteria, the use of antibiotics for plant protection is under scrutiny (McManus 2014 ). Therefore, various strategies have been implemented to find alternative antibiotics by inducing plant resistance through breeding, genetic engineering, and biological control (Adhikari et al. 2020 ). Among these strategies, biological control is an eco-economic and evolutionary approach that enhances plant immunity and/or modifies the environment by utilizing beneficial microbes, substances, or healthy cropping practices (He et al. 2021 ). Numerous bacterial isolates taken from diverse environmental samples have been examined to discover appropriate candidates that exhibit antagonistic properties toward E. amylovora (Dagher et al. 2020 ; Esteban-Herrero et al. 2023 ; Mechan Llontop et al. 2020 ). It is essential that candidate bacteria survive well on or in plants, are non-phytotoxic, possess a broad range of effectiveness, synthesize various hydrolases associated with biocontrol, and induce plant defense (Dagher et al. 2020 ; Esteban-Herrero et al. 2023 ; Mechan Llontop et al. 2020 ; Zeng et al. 2023 ). However, the exploration of bacteria possessing all these traits in the control of E. amylovora is quite limited.