Plant cell death and cellular alterations induced by ozone: Key studies in Mediterranean conditions

An account of the studies executed in Italy on the effect of ozone on crop and forest species both at histo-cytological and ultrastructural level is given, with emphasis on their contribution in understanding the mechanisms of induced cell death. Significant results were obtained by investigating the relationships between ROS levels in tissues and the type of cell death (necrosis or PCD), and the role of hormones. A DAB-Evans blue staining was proposed to validate ozone symptoms at microscopical level and for an early diagnosis of ozone injury. In Italian forest vegetation, anatomical and ultrastructural alterations were very similar to those reported on the same species in Northern Europe, despite much higher ozone levels. This would confirm the environmental limitation to O3 uptake and inherent characteristics of Mediterranean vegetation as responsible for the containment of tissue damages.