Estudo anatômico foliar do clone híbrido 4430 de Tradescantia: alterações decorrentes da poluição aérea urbana

Abstract

(Anatomic studies on Tradescantia hibrid clone 4430 leaves: changes caused by urban air pollution). The relationship between the urban air pollution and respiratory diseases of human populations have been confirmed through several epidemiological studies. Continuous monitoring of air pollutant concentrations is perfomed by CETESB (The State Agency of Air Quality Control) in the city of São Paulo. However, biomonitoring programs using plants are other complementary and important ways to measure and prevent the effects of air pollutants on the biological systems and to a certain extent human health. The clone 4430 of Tradescantia has been used in biossays (Trad-MCN, Trad-SH) to monitor the genotoxic potential of several substances. However, the possibility of using the changes in some features of plants from these clones, which are indicators of air pollution effects, has never been explored. Thus, after establishing the structural pattern of these plants, the present study intended to select, among their anatomical characteristics, the most adequate as bioindicators of air quality. Plants of clone 4430 from EMBRAPA-Jaguaríuna (out of the influence of air pollution of São Paulo city - control) were cultivated in parts under standardised conditions and exposed for three months to the environment of three polluted sites of São Paulo: Instituto de Botânica, Cerqueira César and Congonhas. The structural analysis of the leaves revealed the presence of an unstratified epidermis with glandular and non-glandular trichomes in both surfaces, diacytic stomata, mesophyll with only spongy parenchyma, angular collenchyma near to colateral vascular bundles, and water storing cells near the central bundle. No qualitative changes were observed among the leaves from the four studied sites, but significant reductions in the stomata size, metaxylem diameter, and leaf thickness were detected in plants from the polluted sites. The results showed that some structural aspects of the clone 4430 can be used as bioindicators of the effects of the air pollution.