Bacillus subtilis SL18r Induces Tomato Resistance Against Botrytis cinerea, Involving Activation of Long Non-coding RNA, MSTRG18363, to Decoy miR1918

Abstract

Mounting evidence has indicated that beneficial rhizobacteria can suppress foliar pathogen invasion via elicitation of induced systemic resistance (ISR). However, it remains elusive whether long non-coding RNAs (lncRNAs) are involved in the mediation of the rhizobacteria-primed ISR processes in plants. Herein, we demonstrated the ability of the rhizobacterial strain Bacillus subtilis SL18r to trigger ISR in tomato plants against the foliar pathogen Botrytis cinerea. Comparative transcriptome analysis was conducted to screen differentially expressed lncRNAs (DELs) between the non-inoculated and SL18r-inoculated plants. Among these DELs, four variants of MSTRG18363 possessed conserved binding sites for miR1918, which negatively regulates immune systems in tomato plants. The expression of MSTRG18363 in tomato leaves was significantly induced by SL18r inoculation. The transcription of MSTRG18363 was negatively correlated with the expression of miR1918, but displayed a positive correlation with the transcription of the RING-H2 finger gene SlATL20 (a target gene of miR1918). Moreover, MSTRG18363-overexpressing plants exhibited the enhanced disease resistance, reduction of miR1918 transcripts, and marked increases of SlATL20 expression. However, the SL18r-induced disease resistance was largely impaired in the MSTRG18363-silenced plants. VIGS-mediated SlATL20 silencing also greatly weakened the SL18r-induced disease resistance. Collectively, our results suggested that induction of MSTRG18363 expression in tomato plants by SL18r was conducive to promoting the decoy of miR1918 and regulating the expression of SlATL20, thereby provoking the ISR responses against foliar pathogen infection.

Mechanisms of Action of Microbial Biocontrol Agents against Botrytis cinerea

“…Plants possess their own defense system that includes physical, chemical, and induced defenses [182]. The latter is defined as "the process of active resistance dependent on the host plant's physical or chemical barriers, activated by biotic or abiotic inducing agents" [186].…”

“…Induced resistance is usually divided in two main groups, systemic acquired resistance (SAR) and inducible systemic resistance (ISR) [182]. The former can be defined as the inherent immunity of the plant, and it is activated either by direct exposure to biotic triggers, both pathogens and non-pathogens, or by abiotic factors, including a number of chemical compounds [1,199].…”

In Vitro Evaluation and Genome Mining of Bacillus subtilis Strain RS10 Reveals Its Biocontrol and Plant Growth-Promoting Potential

“…Similarly, B. velezensis strain FZB42 produces bacilysin, bacillaene, and diffcidin which suppress fire blight disease in plants [8]. Recently, it was reported that B. subtilis SL18r and B. simplex Sneb545 elicit induce systemic resistance in plants against Botrytis cinerea and Heterodera glycines, respectively [9,10]. Furthermore, volatile organic compounds such as acetoin and 2,3-butanediol have also been reported to trigger systemic resistance in plants [11].…”

Foliar pathogen-induced assemblage of beneficial rhizosphere consortia increases plant defense against Setosphaeria turcica

“…It has been well demonstrated that several rhizobacterial strains can effectively prevent the infection of foliar and soil-borne pathogens by activating the induced systemic resistance (ISR) [3,4]. The rhizobacteriainduced ISR responses are widely present in various plant species, conferring the increased broad-spectrum resistance against pathogenic microbes such as viruses, bacteria and fungi [5][6][7][8]. The defense responses of plants triggered by rhizobacteria are not associated with direct activation of defense-related pathways, but precisely perceive bacteriaderived elicitors to provoke more efficient defense actions against pathogen infection [9].…”