ABSTRACT
This work aimed to verify the phytoalexin induction and the peroxidase activities in sorghum and soybean treated with extracts of P. sanguineus basidiocarp. To this end, dichloromethane, hexane and ethanol extracts, in concentrations of 100, 250, 500 and 750 mg/L were texted for phytoalexin induction and peroxidase activity in soybean cotyledons and sorghum etiolated mesocotyls. Acybenzolar-Smethyl (ASM) (200 mg/L of commercial product) and distilled water + Tween 20 (0.5%) were used as positive and negative control treatments, respectively. For the phytoalexin assay in sorghum mesocotyls, the hexanic extract in the concentration 750 mg/L provided the highest induction, however without differing significantly from ASM. For the phytoalexin assay in the soybean cotyledons, P. sanguineus extracts did not induce activity significantly different from the positive and negative control treatments, and showed a suppression of glyceollin synthesis for the dichloromethane extract. In relation to peroxidases, the dichloromethane extracts for sorghum and soybean and ethanol extract for soybean inhibited the enzymatic activity. The induction verified for the hexanic extract in sorghum was not different from the ASM control. The specific activity of peroxidase in soybeans was inhibited by the ethanol extract and it was induced by the hexanic, but with no differences in relation to the treatment with ASM. These results indicate the weak potential of these extracts for the induction of resistance in pathosystems involving sorghum and soybeans.
KEY WORDS
Induced resistance; glyceollins; deoxyanthocyanidins