The efficiency of tobacco Bel-W3 and native species for ozone biomonitoring in subtropical climate, as revealed by histo-cytochemical techniques

摘要

We aimed to verify whether hydrogen peroxide (H_2O_2) accumulation and cell death are detected early in three bioindicators of ozone (O_3), Nicotiana tabacum 'Bel-W3 Ipomoea nil 'Scarlet O'Hara' and Psidium guajava 'Paluma', and whether environmental factors also affect those microscopic markers. The three species were exposed to chronic levels of O_3 in a subtropical area and a histo-cytochemical technique that combines 3,3'-diaminobenzidine (DAB) with Evans blue staining was used in the assessments. The three species accumulated H_2O_2, but a positive correlation with O_3 concentration was only observed in N. tabacum. A positive correlation between O_3 and cellular death was also observed in N. tabacum. In /. nil and P. guajava, environmental factors were responsible for symptoms at the microscopic level, especially in P. guajava. We conclude that the most appropriate and least appropriate bioindicator plant for O_3 monitoring in the subtropics are N. tabacum 'Bel-W3' and P. guajava 'Paluma', respectively.