Kelly M O, Leopold A C
Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, New York 14853.
Plant Physiol. 1992;98(3):835-9. doi: 10.1104/pp.98.3.835.
Roots of Merit variety corn (Zea mays L.) require red light for orthogravitropic curvature. Experiments were undertaken to identify the step in the pathway from gravity perception to asymmetric growth on which light may act. Red light was effective in inducing gravitropism whether it was supplied concomitant with or as long as 30 minutes after the gravity stimulus (GS). The presentation time was the same whether the GS was supplied in red light or in darkness. Red light given before the GS slightly enhanced the rate of curvature but had little effect on the lag time or on the final curvature. This enhancement was expanded by a delay between the red light pulse and the GS. These results indicate that gravity perception and at least the initial transduction steps proceed in the dark. Light may regulate the final growth (motor) phase of gravitropism. The time required for full expression of the light enhancement of curvature is consistent with its involvement in some light-stimulated biosynthetic event.
优良品种玉米（Zea mays L.）的根进行正向重力弯曲需要红光。开展了实验以确定从重力感知到不对称生长这一途径中光可能作用的步骤。无论红光与重力刺激（GS）同时提供还是在重力刺激后长达30分钟提供，红光都能有效诱导向重力性。无论GS是在红光下还是在黑暗中提供，呈现时间都是相同的。在GS之前给予红光略微提高了弯曲速率，但对延迟时间或最终弯曲影响不大。红光脉冲与GS之间的延迟扩大了这种增强效果。这些结果表明重力感知以及至少最初的转导步骤在黑暗中进行。光可能调节向重力性的最终生长（运动）阶段。曲率光增强的充分表达所需时间与其参与某些光刺激的生物合成事件一致。
