Zizania Pregnant Wild Rice During The Physiological And Biochemical Changes

In the present study, the contents of total sugar, reducing sugar, sucrose, starch, protein, lignin and cellulose, and activities of some enzymes (superoxide dismutase, catalase, peroxidase, polyphenol oxidase, and phenylalanine ammonia-lyase) in stem of water bamboo (Zizania latifolia L), a vegetable only grown in China, were measured during the stem swelling stage. The possible correlation between these biochemical changes and the formation of the swollen stem, which is used as vegetable in Chinese kitchen, were discussed. In addition, the total proteins of "male" stem (non-swollen stem) and swollen stem were compared through SDS-PAGE gel electrophoresis. The results are as follows:The stem weight increased sharply with a slow rise in volume at early swelling phase; while both the weight and volume of the swollen stem showed a rapid increase at later swelling phase. Then the weight and volume of the swollen stem did not vary appreciably when the stem started senescence phase.The contents of sugar and reducing sugar increased during the early stem swelling stage, then decreased with senescence of the swollen stem. The sucrose content also increased during stem swelling stage until the stem became mature, then kept a stable level.An increase in the contents of soluble protein and insoluble protein was observed with the stem swelling, which attained their peak values at day 6 of swelling, then decreased. While the change in starch level showed a contrast trend compared to protein, it rose with the swelling of stem, and a sharp rise was recorded when the protein started to decline, suggesting that a possible competition in synthesis substrate between the protein and starch existed.The contents of lignin and cellulose exhibited the following trend: both of them declined with stem swelling, reached a lowest levels at day 8 of swelling, then they start to rise.The activities of catalase and superoxide dismutase declined continuouslyduring the stem swelling stage, especially the catalase, which showed a rapid decrease compared with superoxide dismutase. However, a different tendency of changes in peroxidase activity was found: it increased slowly at earlier swelling stage, and rapid rise occurred afterwards. It is suggested peroxidase involve the process of catalysing the decomposition of IAA during stem swelling stage.The activity of polyphenol oxidase rose sharply at early swelling stage, remained high afterwards, peaked at late stage with senescence of the swollen stem.The highest activity of phenylalanine ammonia-lyase was observed at earlier swelling stage, followed by a decline until day 8 of swelling, but again increasing at the later swelling stage.By using the method of SDS-PAGE gel electrophoresis, the total proteins in the "male" water bamboo and swollen stem were analyzed. The results showed there was no difference on the bands of protein in swollen stem among different swelling stages. The different part of the "male" stem also have shown the same protein bands. But, differences existed between the protein bands of the "male" stem and the swollen stem, each harboring a differential band.