PHYSIOLOGICAL FUNCTION OF SOYBEAN LEAVES LIPOXYGENASES SUBMITTED TO ATTACK BY VELVET CATERPILLAR (ANTICARSIA GEMMATALIS HÜBNER.)

ABSTRACT

The objective of this work was to investigate the role of the “Lipoxygenases Pathway” in the mechanisms of response of the soybean plant subjected to attack of velvet caterpillar (Anticarsia gemmatalis Hübner - chewing insect). For this, the biochemical and kinetic characterization of the lipoxygenases pool was undertaken, cultivar IAC-100 (normal soybean cultivar) and the genotype IAC-100 TN (absence of seed lipoxygenase), as well as the determination of the final products of that pathway. The values of K_Mapp decreased up to 48 hours, after the removal of the insect, and the levels of proteases inhibitors, total aldehydes and hexanal, final products of the pathway, increased. Those data suggest alterations of the pool of the lipoxygenases and activation of those isozymes, in response to the attack of velvetbean caterpillar. In addition, it was verified that the genetic removal of lipoxygenases from the seeds has not changed the expression of these isozymes in the leaves which act on the defense mechanism of the soybean plant.

KEY WORDS:
Soybean; “Lipoxygenase Pathway”; inhibitors proteases; defense mechanisms.