Plant Extracts Inducing Enzyme Activity in Grains Against Loose Smut Disease

Abstract This study investigated the role of endogenous Palestinian plant extracts in inducing wheat and barley resistance systems against loose smut disease with the aim to alternate the chemical pest control with natural fungicides. Twenty indigenous herbal plant extracts and essential oils were assessed for their biological and antifungal properties against Ustilago tritici and Ustilago nuda. Their potential role in inducing resistance pathways was studied on four different cultivars of wheat and barley. Two common enzyme indicators – guaiacol peroxidase (POX) and polyphenol oxidase (PPO) – are expressed in plants only after physical or chemical induction. The antifungal activity of the plant extracts was investigated in vitro. Totally 70 % of the plant extracts showed antifungal activity against Ustilago tritici and Ustilago nuda. Coridothyme extracts ranked first (61 %) in the fungal growth inhibition, followed by varthemia, salvia, ambrosia, artemisia, and lemon thyme. Some plant extracts significantly increased the POX and PPO effect compared to control for all the wheat and barley cultivars tested. The study revealed that oregano, clove or lavender and pomegranate, common yarrow or chamomile oil effectively induced the resistance indicator enzymes in wheat and barley.