Effects of low concentrations of ozone on the fine structure of radish leaves

Abstract

Radish (Raphamis sativus L.) plants were fumigated with ()-l or 0-05 //I 1 ' O., for 8 or 24 h a day for 6 to 18 d and the leaf tissues examined by light and electron microscopy. Ultrastructural damage was apparent in the leaves fumigated with as low as 005 //I 1' O^ for 8 h a day for 6 d. Ozone induced an increase in both the number and size of the plastoglobules but a decrease in chloroplast dimensions. These changes in the chloroplasts developed further e\ en after ()., fumigation had been discontinued. The plastoglobules were electron dense in the early stages of exposure to O., but subsequently became electron translucent. Finally large plastoglobules were extruded into the vacuole, a phenomenon which may partly account for the reduction m chloroplast size. Ozone also caused disruption of the tonoplast and this was followed by collapse ot the cells. Low concentrations of (),, appear to accelerate senescence of the chloroplasts.

Lipid Bodies in <italic>Eremosphaera viridis</italic> De Bary (Chlorophyceae)

“…Our hypothesis is in accordance with observations by Lichtenthaler and Peveling (1966), describing lipid globules leaving chloroplasts of Hoya carnosa, and Miyake et al (1989), reporting plastoglobuli containing TAG released from plastids into the vacuole.…”

Tropospheric ozone-induced structural changes in leaf mesophyll cell walls in grapevine plants

“…This is in accordance to the work of Miyake et al (1989), Violini et al (1992), and Mikkelsen & Heide-Jørgensen (1996) who found out that ozone caused an increase in the number and the size of plastoglobules in the chloroplasts of radish, common bean, and beech. They interpreted these changes as signs of premature ageing caused by ozone.…”

Exposure of spring wheat (Triticum aestivum) to ozone in open‐top chambers. Effects on acyl lipid composition and chlorophyll content of flag leaves

“…The aim of the present investigation was to determine if ambient or slightly elevated concentrations of ozone afTect the membrane lipids of flag leaves of spring wheat exposed in open-top chambers. Usually chloroplasts are reported to be the cell structure most sensitive to ozone (Miyake et al, 1989;Sutinen et aL, 1990;Ojanpera et aL, 1992). By analysing chlorophyll and the plastid-specific galactolipids as well as lipids, predominantly (PC) or exclusively (PE), present in non-plastid membranes (Harwood, 1980), an indication would be obtained of whether or not any change occurred to chloroplast membranes before phospholipid-enriched membranes.…”