Abstract
The mechanism of freezing injury in wheat (Triticum monococcum L.) cells cultured on medium containing abscisic acid (ABA) was investigated. Cells which had fully developed freezing resistance on ABA-medium showed a higher rate of TTC (triphenyltetrazolium chloride) reduction than that of non-frozen control cells when frozen to lethal freezing temperatures. However, this increase in TTC reduction diminished when frozen-thawed cells were incubated at 25℃ for 48 hr, suggesting that the process of freezing injury further advances during the incubation after thawing. A very similar increment of TTC reduction was observed in ABA-cultured cells even when the cells were treated for a short time with ethanol or detergents such as Triton X-100. In ABA-cultured cells, in contrast to 2,4-D-cultured cells, a relatively higher rate of O_2-consumption of cells was maintained and a rapid influx of TTC into cells was observed after freeze-thawing or after treatment with ethanol or detergents. Therefore, these are considered to be the cause of the incremental response of TTC reduction in ABA-cultured cells after freeze-thawing, and it is suggested that some structural changes in the plasma membrane occur during freeze-thawing at lethal freezing temperatures.
