Etude des composés terpéniques au cours de la croissance des aiguilles du Pin maritime : comparaison de données biochimiques et ultrastructurales

Abstract

In maritime pine needles, comparisons of infrastructural and biochemical results show that a preferential site of synthesis for the monoterpene hydrocarbons (C10) is located in the epithelial cells of the resin ducts, the basal part of the needles having a higher content of monoterpenes than the upper parts. The incorporation of 14C in the monoterpenes at the base is respectively 16 and 66 times more important than at the medium and upper parts. An electron microscopic study of the evolution of the epithelial cells of the resin ducts shows a temporary activity of these cells and this activity is very intense only at the base of the needles.In contrast, the sesquiterpenes (C15) are synthesized in the whole needle according to a permanent process. The three parts of the needles present a progressive and continuous accumulation, and a significant incorporation of 14CO2 in sesquiterpenes. The electron microscopy reveals an irreversible degenerating process of the epithelial cells of the ducts in the upper parts. Therefore, the sesquiterpene synthesis is not only related to the activity of the ducts but is also present in the secretory structures presenting a permanent activity and located in cells devoid of specialized secretory functions.