Comparative transcriptome analysis of Sclerotinia sclerotiorum revealed its response mechanisms to the biological control agent, Bacillus amyloliquefaciens

Xiaoxiang Yang,Yong Liu,Lei Du,Lei Zhang,Xiaoqin Huang,Yunjia Xiang

doi:10.1038/s41598-020-69434-9

Abstract

Biological control mechanisms of plant diseases have been intensively studied. However, how plant pathogens respond to and resist or alleviate biocontrol agents remains largely unknown. In this study, a comparative transcriptome analysis was performed to elucidate how the pathogen of sclerotinia stem rot, Sclerotinia sclerotiorum, responds and resists to the biocontrol agent, Bacillus amyloliquefaciens. Results revealed that a total of 2,373 genes were differentially expressed in S. sclerotiorum samples treated with B. amyloliquefaciens fermentation broth (TS) when compared to control samples (CS). Among these genes, 2,017 were upregulated and 356 were downregulated. Further analyses indicated that various genes related to fungal cell wall and cell membrane synthesis, antioxidants, and the autophagy pathway were significantly upregulated, including glucan synthesis, ergosterol biosynthesis pathway, fatty acid synthase, heme-binding peroxidase related to oxidative stress, glutathione S-transferase, ABC transporter, and autophagy-related genes. These results suggest that S. sclerotiorum recruits numerous genes to respond to or resist the biocontrol of B. amyloliquefaciens. Thus, this study serves as a valuable resource regarding the mechanisms of fungal pathogen resistance to biocontrol agents.

Highlights

Biological control is an effective way by using beneficial microorganisms or microbial metabolites to control plant diseases
In order to decipher the changes of S. sclerotiorum gene expression characteristics under B. amyloliquefaciens stress, the total RNA from S. sclerotiorum samples treated with the fermentation broth of B. amyloliquefaciens (TS) and control samples (CS) were extracted for transcriptome sequencing
Based on the comparative analysis of the Fragments Per Kilobase of transcript per Million (FPKM) mapped reads distribution and FPKM density distribution (Fig. 2), there were differences in the dispersion and population distribution of gene expression between TS and CS samples, indicating that the expression of some S. sclerotiorum genes were changed in response to B. amyloliquefaciens stress

Summary

Introduction

Biological control is an effective way by using beneficial microorganisms or microbial metabolites to control plant diseases. As an excellent biocontrol agent, Bacillus amyloliquefaciens exhibits a broad spectrum of antifungal activities with the ability to produce different types of cyclic lipopeptides. Cyclic lipopeptides produced by B. amyloliquefaciens are catalyzed by non-ribosomal peptide synthase[3], which inhibit the growth of various plant pathogenic bacteria and fungi 4–7. The development of environmentally friendly biological control measures is ideal for managing sclerotinia stem rot on oilseed rape, and is in line with the national policy of "reducing fertilizer and reducing pesticide" and the national strategic demand of building ecological civilization in China. B. amyloliquefaciens strain Bam[22] was isolated from oilseed rape rhizosphere in Sichuan province, China, which exhibited the strong ability to inhibit the growth of S. sclerotiorum. B. amyloliquefaciens and S. sclerotiorum were used to explore the response of plant pathogens against biocontrol agents. The goal of this study was to decipher the response mechanisms of S. sclerotiorum to B. amyloliquefaciens stress at the transcriptome level

Objectives

Methods

Results

Conclusion