多胺与激动素对稀脉浮萍离体叶状体衰老的影响

多胺与ＫＴ 都可抑制暗诱导衰老的稀脉浮萍（Ｌｅｍ ｎａ ａｅｑｕｉｎｏｃｔｉａｌｉｓ）离体叶状体的叶绿素损失，且多胺的作用大于ＫＴ。ＫＴ 还显著抑制蛋白质的损失与蛋白酶活性的上升，而多胺对此却无大的影响。０．０５ ｍ ｍ ｏｌ／Ｌ的甲基乙二醛二脒基－腙（ＭＧＢＧ）轻微促进叶绿素和蛋白质的损失。０．０５ ｍ ｍ ｏｌ／Ｌ的ＫＴ 可抑制衰老过程中腐胺（Ｐｕｔ）的上升和亚精胺（Ｓｐｄ）的下降，而对精胺（Ｓｐｍ ）无明显影响。在稀脉浮萍中，精氨酸脱羧酶（ＡＤＣ）活性占优势。ＫＴ 可轻微促进ＡＤＣ 活性，而对鸟氨酸脱羧酶（ＯＤＣ）和Ｓ－腺苷甲硫氨酸脱羧酶（ＳＡＭＤＣ）活性无显著影响。讨论了多胺与细胞分裂素在抑制植物叶片衰老过程中作用途径的可能关系

EFFECTS OF POLYAMINES AND KINETIN ON IN VITRO FROND SENESCENCE IN LEMNA AEQUINOCTIALIS 6746

Both polyamines and kinetin could retard the loss of chlorophyll during dark induced senescence in excised frond of Lemna aequinoctialis 6746.The effect of polyamines on retarding the chlorophyll loss was stronger than that of kinetin.Kinetin remarkably inhibited the loss of soluble proteins and the increase of protease activity, while no similar effects were observed from polyamines.An inhibitor of polyamine biosynthesis, methylglyoxal bis (guanylhydrazone) (MGBG), slightly increased the loss of chlorophyll and soluble proteins.During senescience, both the increase of putrescine (Put) content and the decrease of spermidine (Spd) content were inhibited by kinetin at the concentration of 0 05 mmol/L, but the spermine (Spm) level was not affected by kinetin.The arginine decarboxylase (ADC) activity was dominant in frond of Lemna aequinoctialis 6746.Kinetin slightly increased ADC activity, while it had no marked effect on ornithine decarboxylase (ODC) and s adenosylmethionine decarboxylase (SAMDC).The possible relationship between polyamines and cytokinins in retarding senescence was also discussed.