Controle biológico da resinose do coqueiro

Abstract

The stem bleeding is important disease in coconut crop caused by the fungus Thielaviopsis paradoxa, which has been gradually growing and causing hight losses in plantation areas, it becomes very important the study of the disease. Faced with this problem this work aimed to gain insight into the pathossystem of coconut stem bleeding and select microorganisms with potential biocontrol of the disease and the mechanisms used for this. After collecting samples from diseased plants, the isolates obtained of T. paradoxa were selected by the pathogenicity test, the TC.060 isolated that had higher severity values and also showed larger external and internal injury when inoculated by spraying of the previously wound rachis. Bacillus spp. And Trichoderma spp. obtained from rhizosphere samples from symptomatic and asymptomatic plants that growing in vitro were selected area as potential for pathogen control. Among the microorganisms obtained, 7% of the isolates belong to the genus Bacillus spp. and 9% to the genus Trichoderma spp. The potential of these isolates for biological control of the coconut Resinose was confirmed by enzyme production. All isolates of Bacillus sp. assessed had protease production. While the production of chitinase was positive for Bacillus sp. B.01 and B.0. The production of β-1,3-glucanase was observed only at B.57. The Trichoderma sp. showed no enzyme activity. The volatiles profiles analyzed by GC-MS identified 16 potential biocontroler‟s VOCs of diseases on plants, such as carbon dioxide, 2-propanone, ethanol, acetic acid, phenol, benzene, benzaldehyde, 2-ethylhexanol. The isolated B.01, B.02 and B.04 produced more VOCS the other strains. The benzaldehyde compounds, phenol and 2-ethylhexane were all produced by Bacillus sp., While 2-decanone and 2-nonanone were produced exclusively by B.01 B.02 and. This study demonstrated that isolates of Bacillus spp. Assessed produce volatile compounds with antifungal potential and present efficient enzymatic activity to degrade the cell wall of T. paradoxa.