An increase in the number of peroxisomes is coupled to the initial infection stage and stress response of Botrytis cinerea

Abstract Peroxisomes are very important organelles in eukaryotic cells and participate in various biological processes, including pathogen–host interactions. A variety of proteins involved in peroxisome proliferation and metabolic activity within peroxisomes have been shown to be essential for full virulence of several phytopathogenic fungi. However, the effects of changes in the number of peroxisomes and proteins involved in the peroxisome pathway on the pathogenicity of Botrytis cinerea have rarely been reported. In this study, by analysing transcriptome data and RT-qPCR validation, we found that more than half of the genes annotated to the peroxisome pathway in B. cinerea were upregulated more than twofold between mycelial samples cultured in medium with tomato leaves and without tomato leaves. A strain of B. cinerea with fluorescently labelled peroxisomes was obtained by overexpression of GFP fused to peroxisomal targeting signal 1 (the tripeptide ‘SKL’). The addition of tomato leaves to the liquid medium induced a significant increase in the number of peroxisomes, β-oxidation level, H2O2 content, and acetyl-CoA level in B. cinerea mycelia. When B. cinerea was cultured with oleic acid as the sole carbon source, the formation of infection-related structures and their penetration into plant cells were found to be associated with peroxisome pathway activity. Furthermore, peroxisome proliferation and lipid metabolism increased in response to different extracellular stresses in B. cinerea. Taken together, our results confirmed that activation of the peroxisome pathway in B. cinerea contributes to the initial infection and the ability to cope with environmental stress.