Lipoxygenase activity and rhizomes ultrastructure of vegetative and generative shoots of Equisetum arvense L.

Abstract

The pattern of changes of lipoxygenaze activity (LOX) and cell ultrustructure of the horsetail rhizome (Equisetum arvense L.) in ontogenesis was studied. LOX activity in the rhizome of spore-bearing and vegetative shoots in ontogenesis was analyzed. Dormancy release was found to occur against the background of 9-LOX activity increase. In vegetative shoot rhizomes there was identified 9-LOX activity while generative shoot rhizomes displayed 9-LOX and 13-LOX activity. It is shown that changes in the activity of lipoxygenase consistent with the dynamics of lipid metabolizing rhizome E. arvense throughout ontogeny. In contrast to a ground stem, a differentiated rhizome of E. аrvense has no internal valecular channels and hollows. The whole space between integumentary tissue and conducting bundles is filled with large cells of the main parenchyma, which functions as storing tissue. Parenchyma cells are vacuolated and contain numerous aminoplasts filled with starch grains. Specific changes were found in the horsetail rhizome cell ultrustructure during dormancy release, viz: reduction of starch grains in aminoplasts and increase in the number of lipid drops that form typical accumulations close to the plasmolemma. In epidermis (rhyzodermis) cells and parenchyma cell surface layers located closer to the rhyzodermis numerous osmiumphylic pigment granules were identified. The are characterized by a considerable electro­nic density which determine the rhizome colour.

Keywords

• Equisetum arvense L.
• lipoxygenase
• jasmonic acid
• ultrastructure