Foliar application of Moringa oleifera leaves extract altered stress-responsive gene expression and enhanced bioactive compounds composition in Ocimum basilicum

Moringa oleifera leaves extract (MLE) contains a mixture of essential elements, which promotes the growth and yield of many plant species. In this study, the effects from foliar application of MLE on the plant growth parameters as well as phytochemical composition of Ocimum basilicum plants cultivated under 1000 ppm salt stress were investigated. In addition, the effect of MLE on gene expression was examined by monitoring the expression of a multi-stresses' responsive gene, ObOLP. MLE displayed similar bio-stimulant effects on Ocimum plants growth and yield as for other plant species. Furthermore, our study also indicated that MLE has altered the expression of ObOLP gene and the alteration trend was positively correlated with the plant growth and yield enhancement. Therefore, it is suggested that MLE might directly or indirectly affects gene expression in the Ocimum plants. The phytochemical composition analyses have implicated that MLE is a potential biofertilizer to modify the composition of major bioactive compounds, such as estragole and eucalyptol in the Ocimum plants. Among the three concentrations of MLE tested, the 5 g/L of MLE was the most effective concentration for growth and yield enhancement, as well as induction of the highest estragole and eucalyptol contents (approximately 5 times higher) as compared to non-treated plants.