Bio-priming with a hypovirulent phytopathogenic fungus enhances the connection and strength of microbial interaction network in rapeseed.

Plant disease is one of the most important causes of crop losses worldwide. The effective control of plant disease is related to food security. Sclerotinia stem rot (SSR) caused by Sclerotinia sclerotiorum leads to serious yield losses in rapeseed (Brassica napus) production. Hypovirulent strain DT-8 of S. sclerotiorum, infected with Sclerotinia sclerotiorum hypovirulence-associated DNA virus 1 (SsHADV-1), has the potential to control SSR. In this study, we found rapeseed bio-priming with strain DT-8 could significantly decrease the disease severity of SSR and increase yield in the field. After bio-priming, strain DT-8 could be detected on the aerial part of the rapeseed plant. By 16S rRNA gene and internal transcribed spacer (ITS) sequencing technique, the microbiome on different parts of the SSR lesion on bioprimed and non-bioprimed rapeseed stem was determined. The results indicated that SSR and bio-priming treatment could influence the structure and composition of fungal and bacterial communities. Bio-priming treatment could reduce the total abundance of possible plant pathogens and enhance the connectivity and robustness of the interaction network at the genus level. This might be one of the mechanisms that rapeseed bioprimed with strain DT-8 had excellent tolerance on SSR. It might be another possible mechanism of biocontrol and will provide a theoretical guide for agricultural practical production.