Saini H S, Consolacion E D, Bassi P K, Spencer M S
Department of Plant Science, University of Alberta, Edmonton, Alberta, Canada T6G 2P5.
Plant Physiol. 1986 Aug;81(4):950-3. doi: 10.1104/pp.81.4.950.
Application of exogenous ethylene in combination with gibberellic acid (GA(3)), kinetin (KIN), and/or CO(2) has been reported to induce germination of lettuce seeds at supraoptimal temperatures. However, it is not clear whether endogenous ethylene also plays a mediatory role when germination under these conditions is induced by treatment regimes that do not include ethylene. Therefore, possible involvement of endogenous ethylene during the relief of thermoinhibition of lettuce (Lactuca sativa L. cv Grand Rapids) seed germination at 32 degrees C was investigated. Combinations of GA(3) (0.5 millimolar), KIN (0.05 millimolar), and CO(2) (10%) were used to induce germination. Little germination occurred in controls or upon treatment with ethylene, KIN, or CO(2). Neither KIN nor CO(2) affected the rate of ethylene production by seeds. Both germination and ethylene production were slightly promoted by GA(3). Treatments with GA(3)+CO(2), GA(3)+KIN, or GA(3)+CO(2)+KIN resulted in approximately 10-to 40-fold increases in ethylene production and 50 to 100% promotion of germination as compared to controls. Initial ethylene evolution from the treated seeds was greater than from the controls and a major surge in ethylene evolution occurred at the time of visible germination. Application of 1 millimolar 2-aminoethoxyvinyl glycine (AVG), an inhibitor of ethylene synthesis, in combination with any of above three treatments inhibited the ethylene production to below control levels. This was accompanied by a marked decline in germination percentage. Germination was also inhibited by 2,5-norbornadiene (0.25-2 milliliters per liter), a competitive inhibitor of ethylene action. Application of exogenous ethylene (1-100 microliters per liter) overcame the inhibitory effects of AVG and 2,5-norbornadiene on germination. The results demonstrate that endogenous ethylene synthesis and action are essential for the alleviation of thermoinhibition of lettuce seeds by combinations of GA(3), KIN, and CO(2). It also appears that these treatment combinations do not act exclusively via promotion of ethylene evolution as the application of exogenous ethylene alone did not promote germination.
据报道，外源乙烯与赤霉素（GA₃）、激动素（KIN）和/或二氧化碳联合使用可诱导生菜种子在超适宜温度下发芽。然而，当在不包括乙烯的处理方案诱导这些条件下的发芽时，内源性乙烯是否也起介导作用尚不清楚。因此，研究了内源性乙烯在32℃缓解生菜（Lactuca sativa L. cv Grand Rapids）种子热抑制萌发过程中的可能作用。使用GA₃（0.5毫摩尔）、KIN（0.05毫摩尔）和二氧化碳（10%）的组合来诱导发芽。对照或用乙烯、KIN或二氧化碳处理时发芽很少。KIN和二氧化碳均不影响种子的乙烯产生速率。GA₃略微促进了发芽和乙烯产生。与对照相比，用GA₃ + 二氧化碳、GA₃ + KIN或GA₃ + 二氧化碳 + KIN处理导致乙烯产生增加约10至40倍，发芽率提高50%至100%。处理过的种子最初的乙烯释放量大于对照，并且在可见发芽时乙烯释放量出现大幅激增。应用1毫摩尔2-氨基乙氧基乙烯基甘氨酸（AVG），一种乙烯合成抑制剂，与上述三种处理中的任何一种联合使用，可将乙烯产生抑制到对照水平以下。这伴随着发芽率的显著下降。发芽也受到2,5-降冰片二烯（0.25 - 2毫升/升）的抑制，2,5-降冰片二烯是一种乙烯作用的竞争性抑制剂。应用外源乙烯（1 - 100微升/升）克服了AVG和2,5-降冰片二烯对发芽的抑制作用。结果表明，内源性乙烯合成和作用对于GA₃、KIN和二氧化碳组合缓解生菜种子的热抑制至关重要。似乎这些处理组合并非仅通过促进乙烯释放起作用，因为单独应用外源乙烯并不能促进发芽。
