Relation of several antioxidant enzymes to rapid freezing resistance in suspension cultured cells from alpine Chorispora bungeana.
Chorispora bungeana Fisch. & C.A. Mey (Crucifer) is a rare alpine subnival plant surviving sudden snowstorms. In this paper, we have attempted to explore possible roles of autoxidation rate (AR) and the antioxidant enzymes associated with cryoprotective mechanisms in the plant cells. The results showed that when the suspension cultures growing at 25 degrees C were suddenly exposed to -8 degrees C for 15 days, 2,3,5-triphenyltetrazolium chloride reduction was not affected within 9 days and AR remained at a low level in comparison with controls. This indicated that the cells maintained considerable amounts of soluble protein and the integrity of the cell membranes was intact during the whole freezing test. Furthermore, on average, the activity of antioxidant enzymes such as superoxide dismutase, dehydroascorbate reductase, ascorbate peroxidase and glutathione reductase were prominently enhanced in the freezing-stressed cells. Peroxidase activity significantly increased soon after freezing, possibly to make up for the early decrease of catalase activity in the cells. Statistical analysis showed negative correlations between resistance to rapid freezing and antioxidant enzyme activity in the cultured cells after exposure from 25 to -8 degrees C, indicating that the reduction of cell viability with freezing activates a combination of antioxidant enzymes that results in intact cells. All of these findings suggest a synergy between these antioxidant enzymes, leading to a low autoxidation rate that contributes to the protection of the cell membranes and plays an important role in the resistance of suspension cultured cells of C. bungeana to sudden freezing.
Guo
Feng-Xia
FX
Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, China.
Zhang
Man-Xiao
MX
Chen
Yuan
Y
Zhang
Wei-Hua
WH
Xu
Shi-Jian
SJ
Wang
Jian-Hui
JH
An
Li-Zhe
LZ
D032429:Alpinia / Q000201:enzymology*; D000975:Antioxidants / Q000502:physiology*; D018929:Cell Culture Techniques; D002478:Cells, Cultured; D015925:Cryopreservation; D004789:Enzyme Activation; D005615:Freezing; D015227:Lipid Peroxidation; D011506:Proteins / Q000378:metabolism; D013997:Time Factors
D000975:Antioxidants; D011506:Proteins