OZONE INDUCTION OF EXTENSIN MESSENGER-RNA IN SCOTS PINE, NORWAY SPRUCE AND EUROPEAN BEECH

Fumigation of tree seedlings and saplings with ozone increased the mRNA level of extensin, a hydroxyproline-rich cell wall glycoprotein. European beech (Fagus sylvatica L.), Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) seedlings and saplings of various ages were treated with ozone concentrations from 20 nl l(-1) up to 200 nl l(-1) for 1 h up to several weeks. A strong increase of extensin transcript levels was detected within a few hours of fumigation. The induction occurred in needles and hypocotyls of Scots pine, needles of Norway spruce and leaves of European beech. Hypocotyls and roots with high levels of constitutive lignification were not induced. The degree of lignification in hypocotyls of equally old pine and spruce seedlings correlated with the degree of ozone-induced transcription of extensin genes.