Abstract
The ozone-sensitive and ozone-tolerant tobacco varieties Bel-W3 and Bel-B have been widely used as bioindicators of ozone. However, the mechanisms for the difference in ozone sensitivity in these two varieties are not fully understood. Here, the cell suspension cultures derived from both varieties were newly prepared from plantlets. Then, both cell lines were genetically transformed with aequorin gene for direct monitoring of the changes in cytosolic Ca2+ concentration ([Ca2+]c). When both cell lines were exposed to ozone, Bel-W3 cells showed much higher sensitivity to ozone leading to cell death compared to Bel-B cells. In general, [Ca2+]c elevation induced by the redox changes (both oxidative and reducing events) was greater in Bel-W3 cells compared to Bel-B cells. Especially, Ca2+ influx induced in response to extracellular thiols were unexpectedly marked in Bel-W3 cells. To a lesser extent, such thiol-induced Ca2+ influx could be observed in tobacco BY-2 cells and rice cells.
