Essential Oil from Lavandula Angustifolia Elicits Expression of Three SbWRKY Transcription Factors Against Sorghum Damping-off and Induces Ultrastructural Alterations in Fusarium Solani

Abstract Sorghum damping-off, caused by Fusarium solani (Mart.) Sacc., is a momentous disease which causes economic loss in sorghum production. In this study, antagonistic activity of lavender essential oil (EO) against F. solani was studied in vitro. Their effects on regulation of three transcription factors SbWRKY, the response factor JERF3 and eight defense-related genes, which mediate different signaling pathways, in sorghum were investigated. Their application under greenhouse conditions was also evaluated. The obtained results showed that lavender EO possessed potent antifungal activity against F. solani. Gas chromatography-mass spectrometric analysis revealed that their antifungal activity is mainly attributed to linalyl anthranilate, α-terpineol, eucalyptol, α-Pinene, and limonene. Observations using transmission electron microscope exhibited many abnormalities in the fungal ultrastructures as a response to treating with lavender EO indicating that multi-mechanisms were contributed to their antagonistic behavior. Results obtained from the Real-time PCR investigation demonstrated that all studied genes were overexpressed, at varying extents, in response to lavender EO, however, SbWRKY1 was the highest expressed gene followed by JERF3, which suggest their probable primary role(s) in synchronously organizing the transcription-regulatory-networks enhancing the plant resistance. Under greenhouse conditions, treating of sorghum grains with lavender EO at 1.5% prior to the infection significantly reduced the disease severity. Moreover, the evaluated growth parameters, activities of the antioxidant enzymes, and total phenolic and flavonoid contents were enhanced. In contrast, lipid peroxidation was highly reduced. Results obtained from this study results support the high possibility of using lavender EO for control of sorghum damping-off, however, the field evaluation was highly needed prior to the usage recommendation.