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.

Óleo essencial de guaçatonga no controle alternativo de fungos causadores do mofo cinzento e alternarioses

“…A guaçatonga (Casearia sylvestris), também conhecida como erva-de-bugre ou cafezinho-do-mato, está entre as espécies vegetais brasileiras de uso medicinal, indicada para várias enfermidades humanas, e tem despertado grande interesse no ramo de fitoquímicos (FERREIRA et al, 2011). Na agricultura, a guaçatonga demonstrou ter efeito inseticida sobre o ácaro rajado Tetranychus urticae que ataca várias culturas (BECKER, 2008), além de reduzir o crescimento in vitro dos fungos deterioradores de madeira Trametes villosa, Ganoderma australe e Pycnoporus sanguineus (BENTO et al, 2016), apresentando também potencial como indutor de mecanismos de defesa das plantas (STENGER et al, 2021;VISMARA et al, 2022). Embora os resultados de estudos utilizando os extratos e o óleo essencial da planta sejam promissores, pesquisas para uso no controle de fitopatógenos ainda são raros.…”

Epidemiology and management of Fusarium wilt of Eucalyptus camaldulensis through systemic acquired resistance

“…The use of macro and micro nutrients is another strategy to manage the Fusarium wilt of eucalyptus ( Asma et al, 2009 ). Deficiency or excessive use of nutrients is responsible for causing ill effects on the plants by causing a disturbance in the metabolism and physiology of the host plants, which makes the plants vulnerable to pathogens ( Asma et al, 2009 ; Stenger et al, 2021 ). The deficiency of nutrients in plants is the prime cause of the deteriorating defense system of the plants, which makes the plants susceptible to various diseases ( Shrestha et al, 2020 ).…”