Invasion of Coffea arabica (Linn.) by Cuscuta jalapensis (Schlecht): in situ activity of peroxidase

Abstract

One of the factors leading to a decline in quality and productivity of certain plantations is the presence of parasitic plants. This study was conducted to determine the role played by peroxidase in the process of invasion of coffee stems by Cuscuta jalapensis. The ill situ activity of peroxidase during the phases of attachment and host penetration, was determined by histochemical tests. These tests indicate the activity of peroxidase in relation to morphological changes that take place, during the development of the haustorial cushion on the cell walls and vacuoles of the epidermal cells, and during the processes of disorganization of the tissue of Cuscuta stems and formation of the haustorium. The activity of peroxidase was shown to be associated with the processes of invasion and destruction of tissues of the host up until the moment when the haustorium makes contact with the vascular bundle. The activity of peroxidase in the cell walls of Cuscuta jalapensis is intimately associated to the morphogenesis of the adherence structures, as well as to the processes leading to the invasion of the host. We propose that this enzyme be included within the set of compounds elements needed to initiate an invasion of a host by a parasitic angiosperm. The information acquired gives significance to the probable participation of free radicals and their reactivity in relation to the morphogenesis and invasion processes. (c) 2005 Elsevier B.V. All rights reserved.