Down-regulatory effect of essential oils on fungal growth and Tri4 gene expression for some Fusarium oxysporum strains: GC-MS analysis of essential oils

Abstract

The objectives of this work were to evaluate the efficacy of Eucalyptus camaldulensis green branches (GB) and Origanum majorana whole plant (WP) essential oils (EOs) on Tri4 gene expression and Fusarium oxysporum strains growth In vitro. Five strains of Fusarium oxysporum were identified molecularly through polymerase chain reaction (PCR) amplification of the internal transcript spacer (ITS) region. The efficacy of the EOs from Eucalyptus camaldulensis GB and Origanum majorana WP on Tri4 gene expression and F. oxysporum strains growth were evaluated In vitro. GC-MS analysis of the EOs referred that 1,8-cineole, and spathulenol were presented in E. camaldulensis GB, while in O. majorana WP were tricyclene, and p-cymene as abundant compounds. E. camaldulensis and O. majorana EOs showed MIC of 32–64 µg/mL and 32 µg/mL, respectively. E. camaldulensis EO was more suppressive against all the F. oxysporum strains. Both EOs reduced Tri4 gene expression significantly compared with control. qRT-PCR results revealed a down-regulation in Tri4 gene expression of all of F. oxysporum strains exposed to both EOs at the MIC values. The results suggest that both EOs can be used as safe and green bio-pesticide.