Green Tea (Camellia sinensis) Extract Induces Systemic Acquired Resistance against Witches’ Broom Diseases of Citrus aurantifolia

Witches’ broom disease of Citrus aurantifolia (Christm.) Swingle, caused by ‘Candidatus Phytoplasma aurantifolia’, is a big threat to Citrus aurantifolia production in South of Iran. Accumulation of defense-related enzymes is defense reactions against pathogens in infected plant tissues. Herein, the effect of ethyl acetate extract of Camellia sinensis (L.) Kuntze was investigated on induced resistance against phytoplasma in the leaves of Citrus aurantifolia. The leaves were pretreated with different concentration of the extract, and then study on the defense enzymes and phenolic compounds was done.  The results indicated that the pre-treatment of the leaves with low concentration of Camellia sinensis extract induced resistance through the accumulation of various phenolic compounds and phytoalexins, as well as the activation of peroxidases (POD), catalase (CAT) and key enzymes in phenylpropanoid pathways i.e., phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), and stilbene synthase (STS). Thus, applying low concentration of Camellia sinensis extract induces resistance against disease and can be a novel strategy in plant disease management.