Involvement of MdWRKY40 in the defense of mycorrhizal apple against fusarium solani

Background Apple (Malus domestica Borkh.) is an important economic crop. The pathological effects of Fusarium solani, a species complex of soilborne pathogens, on the root systems of apple plants was unknown. It was unclear how mycorrhizal apple seedlings resist infection by F. solani. The transcriptional profiles of mycorrhizal and non-mycorrhizal plants infected by F. solani were compared using RNA-Seq. Results Infection with F. solani significantly reduced the dry weight of apple roots, and the roots of mycorrhizal apple plants were less damaged when the plants were infected with F. solani. They also had enhanced activity of antioxidant enzymes and a reduction in the oxidation of membrane lipids. A total of 1839 differentially expressed genes (DEGs) were obtained after mycorrhizal and non-mycorrhizal apple plants were infected with F. solani. A gene ontogeny (GO) analysis showed that most of the DEGs were involved in the binding of ADP and calcium ions. In addition, based on a MapMan analysis, a large number of DEGs were found to be involved in the response of mycorrhizal plants to stress. Among them, the overexpressed transcription factor MdWRKY40 significantly improved the resistance of the apple 'Orin' callus to F. solani and the expression of the resistance gene MdGLU by binding the promoter of MdGLU. Conclusion This paper outlines how the inoculation of apple seedlings roots by arbuscular mycorrhizal fungi responded to infection with F. solani at the transcriptional level. In addition, MdWRKY40 played an important role in the resistance of mycorrhizal apple seedlings to infection with F. solani.

Automated summary

This study investigated the transcriptional response of apple seedlings inoculated with arbuscular mycorrhizal fungi to infection with F. solani. The results showed that mycorrhizal apple plants had less damage to their roots when infected with F. solani, along with enhanced activity of antioxidant enzymes and reduced lipid oxidation. A total of 1839 differentially expressed genes (DEGs) were identified after infection, with most of the DEGs involved in the binding of ADP and calcium ions. Furthermore, a large number of DEGs were found to be involved in the stress response of mycorrhizal plants based on MapMan analysis. Among them, MdWRKY40 transcription factor significantly improved the resistance of apple callus to F. solani by binding the promoter of the resistance gene MdGLU.