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Small RNAs play an important role in plant innate immunity. However, their regulatory function in induced systemic resistance (ISR) triggered by plant growth‐promoting rhizobacteria remains unclear. Here, using Arabidopsis as a model system, one plant endogenous small RNA, miR472, was identified as an important regulator involved in the process of Bacillus cereus AR156 ISR against Pseudomonas syringae pv. tomato (Pst) DC3000. The results revealed that miR472 was down‐regulated with B. cereus AR156 treatment by comparing small RNA profiles and northern blot analysis of Arabidopsis with or without B. cereus AR156 treatment. Plants overexpressing miR472 showed higher susceptibility to Pst DC3000; by contrast, plant lines with miR472 knocked down/out showed the opposite. The transcriptome sequencing revealed thousands of differentially expressed genes in the transgenic plants. Target prediction showed that miR472 targets lots of coiled coil nucleotide‐binding site (NBS) and leucine‐rich repeat (LRR) type resistance genes and the expression of these targets was negatively correlated with the expression of miR472. In addition, transgenic plants with knocked‐out target genes exhibited decreased resistance to Pst DC3000 invasion. Quantitative reverse transcription PCR results indicated that target genes of miR472 were expressed during the process of B. cereus AR156‐triggered ISR. Taken together, our results demonstrate that the miR472‐mediated silencing pathway is an important regulatory checkpoint occurring via post‐transcriptional control of NBS‐LRR genes during B. cereus AR156‐triggered ISR in Arabidopsis., The plant miR472‐mediated silencing pathway is an important regulatory checkpoint occurring via post‐transcriptional control of nucleotide‐binding site and leucine‐rich repeat genes during Bacillus cereus AR156‐triggered induced systemic resistance in Arabidopsis.

Plant gray mold disease caused by necrotrophic pathogen Botrytis cinerea, has been a serious threat to many important crops. It is urgent and necessary to seek an effective and environmentally friendly control strategy to control grey mold disease during the crop production. Moreover, it is also urgently needed to clear understand how the strategy works. To screening an efficient biocontrol agent in control of gray mold disease caused by B. cinerea, one hundred strains, which have the potential in controlling plant diseases, were selected from our laboratory’s strain library, and employed to our research. The results in the study indicated that Bacillus velezensis could act as a potential and efficient biocontrol agent (BCA), and two B. velezensis strains 5YN8 and DSN012 were screened out with high antagonistic and hydrolase activity, which could significantly control pepper gray mold disease and promote the pepper growth. Further deeply study on biocontrol mechanism indicated that B. velezensis could suppress the growth and spore formation of B. cinerea by secreting some secondary metabolites or releasing numbers of volatile organic compounds (VOCs). In the other hand, we also found that B. velezensis could trigger plant basal immunity. The BCA could increase the expression of SA signal markers and plant defense related genes. It was able to induce hydrogen peroxide accumulation and plant related enzyme activities in leaves of pepper as well. This study provides another high-efficiency, and potential strategies for the biological control of gray mold disease. It is the first report of B. velezensis strain which can control gray mold disease, In addition, it is also the first to comprehensively illustrate how the strains can efficiently protect pepper from B. cinerea attacking.