EFFECTS OF STORAGE CONDITIONS ON THE ULTRA-STRUCTURE AND ANTIOXIDANT ENZYME ACTIVITY OF RICE GERMPLASM WITH HIGHQUALITY

The present study was to investigate the changes of physico-chemical indexes and antioxidant enzymes and antioxidants in the antioxidant defense system of rice cells stored under the conditions of conventional moisture content (13.5%,14.5%) and temperature (15℃,20℃ and 30℃) using'liangyou series'high-quality rice as raw material.The cell structure of rice embryo was observed to investigate the effect of storage conditions on the aging of rice cells.The results showed that with the increase of ambient temperature and prolongation of storage time,superoxide anion radicals,fatty acid and malondialdehyde showed a gradual increase trend,while soluble protein showed an opposite trend.The accumulation of harmful substances such as fatty acids and superoxide anion radical destroyed the metabolic balance of cells of rice.Meanwhile,the ability of enzyme synthesis was weakened,the amount of antioxidant enzymes,including superoxide dismutase (SOD),catalase (CAT) and peroxidase (POD) was reduced greatly,the antioxidant enzyme system was destroyed,and the aging of cells was accelerated.At the late stage of storage,the rice embryo cells were seriously deformed under high temperature,cell wall appeared to dissolve,cell membrane was collapsed and damaged,protoplast shrank seriously,nuclear membrane was dissolved and damaged,nucleolus was deformed and split,the nucleus hetero-chromatin condensation was deepened,heterochromatin was filled the entire nucleus,and the ultra-structure of rice germ cell was seriously damaged.On the contrary,under the storage condition of lower temperature,the cell wall structure of rice embryo cells had no wrinkles,nuclear membrane was clear,nucleolus had normal morphology,chromatin condensation was slightly deepened,and the structure of embryonic cell was integrated,indicating that the storage conditions of low temperature and low moisture was beneficial to the quality preservation of rice with high quality.