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

Abstract

Apple fire blight, caused by the bacterium Erwinia amylovora, is a devastating disease of apple and pear trees. Biological control methods have attracted much attention from researchers to manage plant diseases as they are eco-friendly and viable alternatives to synthetic pesticides. Herein, we isolated Streptomyces sp. JCK-8055 from the root of pepper and investigated its mechanisms of action against E. amylovora. Streptomyces sp. JCK-8055 produced aureothricin and thiolutin, which antagonistically affect E. amylovora. JCK-8055 and its two active metabolites have a broad-spectrum in vitro activity against various phytopathogenic bacteria and fungi. They also effectively suppressed tomato bacterial wilt and apple fire blight in in vivo experiments. Interestingly, JCK-8055 colonizes roots as a tomato seed coating and induces apple leaf shedding at the abscission zone, ultimately halting the growth of pathogenic bacteria. Additionally, JCK-8055 can produce the plant growth regulation hormone indole-3-acetic acid (IAA) and hydrolytic enzymes, including protease, gelatinase, and cellulase. JCK-8055 treatment also triggered the expression of salicylate (SA) and jasmonate (JA) signaling pathway marker genes, such as PR1, PR2, and PR3. Overall, our findings demonstrate that Streptomyces sp. JCK-8055 can control a wide range of plant diseases, particularly apple fire blight, through a combination of mechanisms such as antibiosis and induced resistance, highlighting its excellent potential as a biocontrol agent. Key points• JCK-8055 produces the systemic antimicrobial metabolites, aureothricin, and thiolutin.• JCK-8055 treatment upregulates PR gene expression in apple plants against E. amylovora.• JCK-8055 controls plant diseases with antibiotics and induced resistance.

Hibiscus acid and hydroxycitric acid dimethyl esters from Hibiscus flowers induce production of dithiolopyrrolone antibiotics by Streptomyces Strain MBN2-2

“…This class of compounds are known for their wide range of activities against several human pathogens, including S. aureus , E. coli , Klebsiella pneumoniae , Listeria monocytogenes , Candida albicans , Aspergillus carbonarius , and Fusarium culmorum [ 14 , 16 , 19 ]. They also have broad-spectrum activity against phytopathogenic bacteria and fungi; for example, compounds 1 and 2 have shown strong activity against Erwinia amylovora , a bacterium that is responsible for apple fire blight [ 20 ]. Furthermore, in in vivo experiments they have been effective in suppressing tomato bacterial wilt and apple fire blight [ 20 ].…”

“…They also have broad-spectrum activity against phytopathogenic bacteria and fungi; for example, compounds 1 and 2 have shown strong activity against Erwinia amylovora , a bacterium that is responsible for apple fire blight [ 20 ]. Furthermore, in in vivo experiments they have been effective in suppressing tomato bacterial wilt and apple fire blight [ 20 ]. The antibiotic mode of action of thiolutin is attributed to interruption of diverse cellular pathways [ 21 ].…”