The phenomenon of pulse alteration of bioelectric potential difference (BEPD) U(Beta ) approximately 10 mV between the top and the base of a plant is observed when a leaf is irradiated locally by a low intensity laser beam ((lambda) equals 632.8 nm, W approximately 40 mW/cm2). This effect is absent completely if an infrared laser ((lambda) equals 828.3 nm, W approximately 40 mW/cm2) is used for irradiation. There exists a threshold value of the background illumination below which U(Beta ) equals 0. The speed of U(Beta ) propagation from the irradiated zone along the axes plant organs is around 8 mm/sec. We observed the effect of U(Beta ) transmission from the irradiated two weeks plant cucumber to a nonirradiated one, if the plant roots are contacting in the soil. We observed also the complex periodic BEPD response to the periodic local laser irradiation.