Secondary compounds found in medicinal plants play important role in plant-pathogen interactions by having direct antimicrobian effect on them or inducing the defense mechanisms on defense of other plants. To verify the fungi toxic effect of the eucalyptus on the micelial growth of Rhizoctonia solani, Sclerotium rolfsii, Phytophthora sp, Alternaria alternata and Colletotrichum sublineolum, the crude extract (CE) was incorporate to PDA and the essential oil (EO) and distributed in the surface of the middle with Drigalski loop. Germination of spores of C. sublineolum was also evaluated in the presence of different brackets of EO using two methodologies. In order to verify the induction phytoalexins sorghum mesocotyls were asperged with CE to 20% or then dived in suspensions of EO. For the gliceolin induction, 20 µL of CE were put in cotyledons soybean. The presence of fungitoxic compounds in EO and CE through the thin layer chromatography was also evaluated. The results evidenced inhibition of the fungus micelial growth for concentrations of CE above 20%. All of the aliquots of the oil inhibited micelial growth micelial fungi, except for R. solani whose inhibition happened for aliquots above 20µL. There was inhibition of 100% in conidia germination for all of the aliquots of EO tested in the first methodology. However, in the second methodology EO did not promote inhibition of conidia germination. It was observed the presence of one fraction fungitoxic in EO, and CE did not present fungitoxic fractions. There was the phytoalexins production just in sorghum mesocotyls treated with CE.
deoxyanthocyanidin; gliceollin; secondary compounds; medicinal plant
