Behavior of Lipoxygenase during Establishment, Senescence, and Rejuvenation of Soybean Cotyledons

Abstract

Lipoxygenase protein and activity were examined during establishment, senescence, and rejuvenation of soybean cotyledons. Lipoxygenase protein, as determined on `Western' immunoblots, and lipoxygenase-1 and -2/3 activities decreased during mobilization of seed reserves 3 to 9 days following planting. Lipoxygenase-1 activity decreased more rapidly than lipoxygenase-2/3 and was not detectable by 11 days after planting. Lipoxygenase protein increased after day 11 while lipoxygenase-2/3 activity continued to decline. During the later stages of cotyledon senescence, both lipoxygenase protein and lipoxygenase-2/3 activity decreased. Upon rejuvenation, lipoxygenase-2/3 activity, but not that of lipoxygenase-1, increased. These results demonstrate that elevated lipoxygenase activity does not represent a universal characteristic of senescent plant tissue.