Oxidative Damage and Content of Photosynthetic Pigments in Morus Alba Leaves in the Urban Area of Mendoza, Argentina

Abstract

The activity of plants in an urban environment is under stress due to multiple environmental factors that have an adverse effect on their growth, productivity and reproductive capacity. Our hypothesis considers that any process of environmental stress can be detected early through the chlorophyll and ROS production analysis. The objective was to evaluate the lipid oxidative damage and the photosynthetic pigment content in leaves of Morus alba in two urbanistically contrasting sites in the urban area of Mendoza (Argentina). Ten trees were randomly sampled per site (micro-town and park). In each sample, 10 leaves were randomly collected, including the entire canopy. Each determination included 10 repetitions per site. Considering that M. alba is a deciduous species, leaf collection was made at the beginning of summer, when an important exposition period of leaves to many environmental factors has passed. The chlorophyll content analysis results effective in evaluating the answer to environmental stress under urban conditions. The relationship chlorophyll a and b showed significant differences among sites, minor in the micro-town, implying a decrease of chlorophyll a in relation to chlorophyll b, a possible indicator of damage by photo-oxidation. The results suggest the generation of oxidative stress due to accumulation of H2O2 in leaves, affecting cell structures, as evidenced by the major malonaldehyde content.