Structural and ultrastructural injuries in leaves of Baccharis conferta and Buddleja cordata broad-leaved species of a forest impacted with ozone

Abstract

The present study showed evidence of ozone damage to the structure of leaves of Baccharis conferta HBK and Buddleja cordata HBK broad-leaved species of the southwest of the Valley of Mexico using light, transmission, and scanning electron microscopy. These species are growing in the forests of Mexico City Metropolitan Area, one of the most polluted regions in the world for ozone. Ozone in the plants causes damage to the leaves and intensifies the decline of the forest at high altitudes such as the mountains where Desierto de los Leones, a National Park (DLNP), as treatment, compared with the forest of Miguel Hidalgo National Park (NINR), as control, exposed to low levels of air pollution. The most notorious damages were in the mesophyll, vascular bundle, and epidermis of the species studied in DLNP. Also the ultrastructure showed gradual injuries at the cellular level, initially higher in the vacuoles and chloroplasts and smaller in cytoplasm and mitochondria. NINR studies showed no evidence of damage in either of the two selected species or in the different microscopic techniques, which are related to measurements of low levels of air pollution.