【摘要】 在自然光照下玉米叶片内PAL活性呈周期性变化，光一方面可以启动和激活PAL活性，另一方面可以促进PAL-I的合成，使PAL活性达到一定峰值后开始下降，在连续光照下，光对PAL活性也同样具有双重影响，使PAL活性产生24h循环节奏波动、在连续黑暗中PAL活性表现较稳定的低水平。更多还原

【Abstract】 The activity of Phenylalanine ammonia-lyase(PAL) in lamina of maize changed periodically under natural sunlight. The function of light in the process, one is stimulating and starting the activity of PAL; an other is that it can synthetize PAL-I. The result is that the activity begin to decline after it go up to some peak value.Under continuous illumination the effect of light on PAL is the same as above, and the activity fluctuate in certain rhythm with a 24-hour period. In the continuous dark, the activity is a steadier level with a low val ue.更多还原