茭白孕茭期间生理生化变化的研究

【作者】 程龙军；

【导师】 郭得平； 朱祝军；

【作者基本信息】 浙江大学 ， 蔬菜学， 2002， 硕士

【摘要】 本实验研究了茭白变态茎不同膨大阶段的形态指标，糖、淀粉、蛋白质、木质素、纤维素，以及几种生物活性酶(SOD、POD、CAT、PPO和PAL)的变化情况，并且分析了这些生理、生化指标与茭白品质及茭白茎膨大机理的可能关系。另外，还利用SDS-PAGE凝胶电泳，比较了雄茭茎与不同膨大阶段正常茭中蛋白质种类的差异。 茭白变态茎膨大的早期阶段主要表现为茭白重量的快速增加，但体积增加相对较小；后期阶段主要表现为为重量和体积都快速的增长。然后，当茭体进入成熟衰老阶段时，重量和体积的变化不大，维持相对稳定。 总糖和还原糖在茭白膨大的早期阶段迅速上升，之后又有所下降。蔗糖在茭白变态茎形成过程中呈现一个先上升，后稳定的趋势。 在变态茎膨大的早期阶段，可溶性蛋白质和不溶性蛋白质的含量呈上升态势，在膨大的第6天含量最高，然后又开始下降。而淀粉的含量变化与蛋白质不同，其含量在变态茎膨大过程中一直上升，当蛋白质含量下降时，其含量大幅上升。这个结果说明蛋白质和淀粉的合成之间可能存在竞争关系。 木质素和纤维素在变态茎膨大的早期含量较高，随着茎的膨大，其含量持续下降，至膨大的第8天其含量最低，然后，二者的含量又明显上升。 茭白变态茎膨大过程中，与植物的成熟和衰老密切相关的SOD和CAT活性都表现出不断下降的趋势，尤以CAT在孕茭早期下降幅度较大；而POD的活性在整个变态茎膨大过程中持续上升，孕茭早期上升缓慢，茭白迅速膨大期至成熟阶段，上升较快。POD可能与清除茭白组织内的活性氧，以及降解生长素类物质的活性有关。 PPO活性在茭白变态茎膨大过程中也不断上升，孕茭早期其活性快速上升，而后活性表现相对稳定，至茭白成熟时活性达到最高。 PAL在茎膨大早期活性最大，膨大过程中不断下降，至膨大的第8天活性其最低，然后活性又明显上升。 对不同膨大时期变态茎中的总蛋白分析发现，不同时期膨大茎中蛋白质没有明显差异，含量以成熟菱较高，幼荚次之，老菱最少。雄菱不同部位的茎中蛋白种类也没有差异，含量以中部正常茎最多，墓茎次之，基部老茎最少。而雄菱茎和正常变态茎中的蛋白质电泳图谱表明，二者在蛋白质种类上有一定的差异，各有一条明显的特异性谱带。更多还原

【Abstract】 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.更多还原