title: Hormonal Regulation, and Intracellular Localization of a 33-kD Cationic Peroxidase in Excised Cucumber Cotyledons.
abstract: Ethylene enhanced chlorosis and levels of 33-kilodalton cationic peroxidase (33-CPO) in excised cucumber (Cucumis sativus L. cv ;Poinsett 76') cotyledons. Compared to other hormones, such as kinetin, indoleacetic acid, gibberellic acid, and abscisic acid, ethylene was the only effective promoter of 33-CPO synthesis. The hypothesis that peroxidase plays a role in chlorophyll degradation was tested by comparing levels of 33-CPO in cotyledons treated with compounds thought to either retard (kinetin, indoleacetic acid and gibberellic acid), or promote (abscisic acid and methyl jasmonate [MJ]) senescence. It was concluded that 33-CPO did not play a role in senescence since no direct correlation between chlorophyll content and 33-CPO was observed. MJ was as effective as ethylene in inducing senescence. However, ethylene did not appear to be involved in the action of MJ. Using immunocytochemistry, 33-CPO was found to be located primarily around starch grains and near the plasmalemma. High levels of 33-CPO were also found in cells destined to be vascular tissue.
authors: U.S. Department of Agriculture, Agricultural Research Service, Appalachian Fruit Research Station, Rt. 2, Box 45, Kearneysville, West Virginia 25430.
authors: F B
authors: FB
authors: Abeles
authors: W L
authors: WL
authors: Hershberger
authors: L J
authors: LJ
authors: Dunn