摘要
Recent evidence indicates that hydrogen peroxide may function as regulator in the development of organism. It is known that excised garlic scape is a kind of whole sink-source unit, a system of cell contents redistribution. All the cell contents of growing clove are transferred from scape, especially from the hasal part of scape, and the latter turns withered. In present experiment, the redistribution of the cell contents is significantly decreased by GA3 treated at the end of scape. The effects of GA3 on the H2O2 metabolism during redistribution of cell contents in excised garlic scape were investigated. The short term treatment (48h) effects of GA3 showed that: (1) The H2O2 level in the clove was signifcantly higher than that in the control while that in the hasal scape was lower than that in the control; (2) The SOD activity in the clove was markedly higher in the earlier period of treatment but lower in the later time than that in control, while in the hasal scape, the SOD activity showed the contrary; (3) GA3 enhanced the POD activity in the clove but inhibited that in the hasal scape; (4) The CAT activity in both the clove and the hasal scape were inhibited significantly by GA3, particularly in the later period of treatment. The long term treatment (20 d) effects of GAs showed that: (1)The H2O2, level in the clove was significantly higher than that in the control while that in the basal scape was shown lower than that in the control and increased slowly; (2) The SOD activities in the clove and the hasal scape were higher than these in the control, especially in the earlier period of treatment; (3) The POD activities in the clove was enhanced significantly by GA3, 3.9-4.3 fold (10-15 d) the control while that in the hasal scape was shown lower than that in the control; (4) The CAT activity in the clove was significantly higher than that in the control while that in the hasal scape was shown on the contrary and decreased quickly till 5 d treatment and then was kept at a very low level. GA3 enhanced the H2O2 level and the activities of SOD, POD and CAT in the clove but inhibited the H2O2 level and the in the activities of POD and CAT in the hasal scape, the activity of SOD in the hasal scape was enhanced by GA3.
离体蒜苔构成一个完整的细胞内含物再分配系统。25℃条件下，于黑暗中贮存时，苔茎基部细胞内含物转移到顶端珠蒜中，最后苔茎下部枯萎，顶端形成鲜嫩多汁的珠蒜。适当浓度GA3处理苔茎基部可以有效抑制上0述细胞内含物再分配过程。已有研究表明，H2O2由超氧化物歧化酶（SOD）催化产生，被过氧化物酶（POD）和过氧化氢酶（CAT）催化降解；H2O2对生物个体发育具有重要调节作用。本文主要测定GA3对离体蒜苔H2O2代谢的影响，为进一步探讨H2O2在细胞内含物再分配中的作用提供参考。取珠蒜未明显膨大的离体蒜苔为供试材料，采用50μg/mLGA3溶液处理蒜苔基部，用比色法和氧电极法测定珠蒜和苔茎下部H2O2水平和SOD、POD、CAT活性。结果表明：（1）在处理后48h内，珠蒜和苔茎下部H2O2代谢即产生明显差异（Fig.1-4)；（2）贮存20d后对照珠蒜明显膨大，而GA3不蒜无显著变化（Table1)；（3）GA3处理显著提高了珠蒜H2O2水平和SOD、POD、CAT活性，相反苔茎下部H2O2水平和POD、CAT活性受到显著抑制，而SOD活性提高(Fig.5-8)。GA3处理对珠蒜和苔茎下部H2O2代谢的相反作用可能是其调节细胞内含物再分配的作用机制。
