Essential oils in pathogen resistance induction of Eucalyptus benthamii Maiden et Cambage

ABSTRACT: This study evaluated the essential oils of Melaleuca alternifolia, Casearia sylvestris and Eugenia uniflora as inducers of defense mechanisms in Eucalyptus benthamii seedlings. Four mL of each oil, with a concentration of 0.75% were sprayed in E. benthamii seedlings and two bioassays were performed, in the first, the essential oils were sprayed and after 30 days, sugars, proteins, peroxidases, phenylalanine ammonia (PAL), and phenols were evaluated and; in the second, seven days after the first analysis, the essential oils were again sprayed and after three days, the same variables were evaluated. The essential oils of M. alternifolia, C. sylvestris, and E. uniflora sprayed had no significant effects on E. benthamii seedlings after 30 days in terms of total sugars, proteins, peroxidase, PAL activity, and phenols. However, when M. alternifolia and E. uniflora essential oils were sprayed seven days after the first analysis with evaluation after 3 days, an increase in total sugars was observed. After these days, all essential oils promoted an increase in protein levels. The oils of E. uniflora and C. sylvestris also increased peroxidase levels. The PAL defense enzyme not showed increased when essential oils were used. The essential oils of M. alternifolia and C. sylvestris had potential as inducers of defense mechanisms on E. benthamii seedlings after 3 days of their application, what it demonstrated not be permanent.