Potencial dos extratos de plantas da caatinga com atividade antifúngica e indutora de resistência

Abstract

Phytopathogens control using product effective and with low persistence is the aim of healthy food. One way to obtain molecules base is to analyze the potential of the substance produced by plants that grow in extreme climatic conditions. In this context, the objective of this study was to evaluate in vitro the capacity of four medicinal plant extracts collected in the caatinga (Anadenanthera colubrina, Mimosa tenuiflora, Lippia origanoides e Myracodruon urundeuva) to inhibiting the growing fungi and the induced resistance in Solanum sculentum (Micro-Tom). The capacity to inhibiting the growing fungi was tested against ten phytopathogens in three different classes (Pythium sp., Phytophthora palmivora, Moniliophthora perniciosa, Sclerotium rolfsii, Colletotrichum gloeosporioides, Colletotrichum musae, Colletotrichum coccodes, Colletotrichum truncatum, Cercosporidium sp e Curvularia sp.). The induced potential resistance was studied only with the best extract and the parts of the extract obtained after filtration. The induced resistance was determined in S. sculetum using the activity increased enzyme from peroxidase (POX), polyphenoloxidase (PPO) and phenylalanine ammonia-lyase (PAL). All enzymes are associated with vegetal defense response. The antimicrobial activity was tested by incorporating the extract into two different dilutions (100 e 1000 μg.mL-1) in PDA media (Potato, Dextrose and Agar, 2%). The L. origanoides ethanolic extract inhibit 100% of all pathogens and was fracted into four parts (Hexane, Chloroform, Methanol e Ethyl acetate). The antimicrobial activity was tested by incorporating each fraction into three different dilutions (40, 400 e 4000 μg.mL-1). The hexane fraction was effective at 400 μg.mL-1 against all the pathogens. However, the Ethyl acetate fraction inhibits growing Oomycetes at 4000 μg.mL-1. The induced potential resistance was verified by pulverizing S. sculetum water solutions with crude extract or fractions at 400 μg.mL-1. All treatments increased the enzyme activity except for the crude extract. All the results demonstrate the Lippia origanoides with one abundant font in the molecules with potential agricultural use and reveal three potential substances for pathogen control: the first with general antimicrobial activity, the second specificly against Oomicytes and third resistance to indutor substance.