Pollen chemosensitivity to ozone and peroxides

The sensitivity of pollen from seven plant species to ozone and the stable products of ozone treatment, such as hydrogen peroxide and tert-butylhydrop eroxide, was tested using pollen autofluorescence and germination as assays . Total ozone doses corresponding to 0.15-5.0 ppm (mul h) were applied. In the carotenoid-enriched pollen of Passiflora coerulea, Philadelphus grandif lorus, and Hemerocallis fulva, the treatment with low ozone doses (0.15 ppm ) resulted in the disappearance of carotenoid Fluorescence maxima in the re gion of 535-560 nm and the appearance of novel peaks, probably related to l ipofuscins, in the region of 460-480 nm. Similar changes occurred one day a fter pollen treatment with peroxides. In the carotenoid-depleted pollen of Hippeastrum hybridum and Plantago major, the ozone treatment shifted a sing le peak at 480-490 nm toward the long- or short-wavelength region, dependin g on the ozone dose, and also changed (increased or decreased) the total fl uorescence intensity. In anthocyanin-rich pollen of Papaver orientale and P etunia hybrida, neither ozone nor peroxides affected the spectrum pattern, though ozone enhanced fluorescence. Ozone and peroxides exerted opposite ef fects on pollen germination: ozone suppressed, whereas peroxide stimulated pollen tube growth. It is proposed that the damaging effect of ozone is not mediated by peroxide formation (which stimulates pollen germination), but rather is related to the direct oxidation of the pollen-wall components by O-3 itself or by the hydroxyl radicals thereby produced.