Establishment And Antioxidation Ability Of Suspension Cell Lines Of Japonica Rice 95122A And 95122B

Cytoplasmic male sterility (CMS) is the basis of heterosis. Revealing the mechanism of CMS will be helpful for utilizing rice heterosis. Two indica CMS systems, Wild-abortive and Honglian, are widely applied for hybrid rice production in practice. However, applications of japonica CMS system for rice production are limited. In this study, Japonic CMS line 95122A and its maintainer line 95122B were selected as materiels to establish good suspension cell lines. After stress treatment with different concentrations of H2O2, morphological changes of suspension cell nuclei were observed. Then we focused on comparative analysis of antioxidant enzyme activities in 95122A and 95122B suspension cells under control and stress conditions. The results obtained in this study will, lay the foundation for further research on the molecular and genetic mechanisms of Japonica CMS line 95122A, and they will also provide a strong theoretical basis for utilazing Japonica CMS lines in practice. The main results are as follows:1. Mature and plump seeds of 95122A and 95122B were selected for callus induction. Calli, which showed yellow, round and granular after subculture for 3-6 times, would be good for establishment of suspension cell lines. Suspension cells with better states would be obtained after subculture about 3 months, apparently pale yellow, uniform and tiny particulate, and a lot of individual cells or tiny cell groups with abundant inclusions would be observed in these suspension cells under the microscope. Exponential growth of cell suspension was found in 3-6 days during subculture. Suspension cells on day 3 or day 4 after subculture had stonger cell viabilities, which would be suitable for subsequent experiments.2. Suspension cells of 95122A and 95122B were treated with 0,5,10,15,20 and 40 mmol/L of H2O2 for 12 hours. After DAPI staining, nuclei of the above two kinds of suspension cells were gradually found to be agglutinative and pyknotic, followed by apoptotic bodies until the degradation disappeared, dead cells dissolved. However, suspension cells of 95122B showed tolerance to higher H2O2 concentrations when similar apoptotic phenomenon occured3. Activities of four antioxidative enzymes (SOD, CAT, APX and POD) in the above suspension cells of 95122A and 95122B were measured.The results showed that all the enzyme activities increased slightly at low concentrations, and then decreased gradually as the concentrations of H2O2 increased.However, the degree of enzyme activity change (increase or decrease) and its corresponding concentration of H2O2 were different according to defferent antioxidative enzymes. Under the same conditions, all the four antioxidative enzyme activities in the suspension cells of 95122B were higher than those in the suspension cells of 95122A, implying that 95122B should have higher tolerance under H2O2 stress.