Tolerância de espécies de Metarhizium a estresse oxidativo induzido por Menadiona

Abstract

Oxidative stress is caused by reactive oxygen species (ROS) such as superoxide ion, hydrogen peroxide and hydroxyl radicals. Various types of stress conditions including heat, UV-A radiation and chemicals such as diamide, paraquat, menadione, sodium chloride are potent inducers of ROS. Entomopathogenic fungi are predisposed to ROS induced by heat and UV-A radiation when outside the insect host and when inside the host, they are subject to phagocytic cells that generate ROS to eliminate invading pathogens. This work aimed to evaluate the tolerance levels of Metarhizium species to oxidative stress induced by menadione and to analyze the viability of Metarhizium species to oxidative stress in different concentrations of menadione. Conidial germination was evaluated 24 h after inoculation on potato dextrose agar (BDA) (control) or PDA supplemented with 0.05 menadione; 0.07; 0.09; 0.11; 0.13; 0.15 and 0.17 mM. The plates were kept at 26°C in the dark. The fungi most resistant to oxidative stress were M. anisopliae (ARSEF 4570) from Macquarie Island in Australia located in the Antarctic Circle and M. brunneum (ARSEF 5626) from Finland, probably because they evolved under intense ultraviolet radiation, cold and others. stresses, with M. album (ARSEF 2082) being the fungus most susceptible to oxidative stress, probably because of its lack of pigmentation. Our results contribute to the understanding of the responses to oxidative stress of the studied fungi, which are naturally.