The objective of this work was to evaluate the capacity of soybean plant to respond to spraying of fatty acids, lipoxygenase substract, by lipoxygenase pathway through the biochemical and kinetic characterization of the "pool" of lipoxygenases from leaves. Two cultivars of soybean were used: one normal (cultivar IAC-100) and the other devoid of three lipoxygenases in the seeds (cultivar IAC-100 TN). The plants were treated with arachidonic, linoleic and linolenic acids at the beginning of the development stage V2, up to the stage V3. The trifoliates were collected at 0, 24 and 48 hours after the last spraying of fatty acids. The results of the biochemical and kinetic studies showed a peak of lipoxygenase activity at pH 6.0 and temperature at 25°C. The activity values for both genotypes were higher in the treatment than in the respective control, and the K M app values decreased 48 hours after the last spray with linoleic and linolenic acids, in the treatments towards respective controls. These results suggest that the soybean plant responds to the application of fatty acids in the leaves by increasing lipoxygenase activity, and that removing lipoxygenases from the seed has not changed the response of the plant to the fatty acids treatment, since IAC-100 and IAC-100 TN presented similar biochemical and kinetic behaviors.
Glycine max; enzymic activity; oxidoreductases; isoenzymes; plant response
