Carnegie Institution of Washington, Department of Plant Biology, Stanford, California 94305-1297.
Plant Physiol. 1984 Jun;75(2):359-63. doi: 10.1104/pp.75.2.359.
Light-induced modification of gravitropism in etiolated roots of Zea mays cv Bear x W38 is a low fluence response mediated by phytochrome. This cultivar has a threshold of 10(-6) mol m(-2) and becomes saturated with 10(-2) mol m(-2) of red light. The maximum light-mediated response of 32 degrees downward from horizontal occurs in roots 10 to 30 millimeters in length, 120 to 165 minutes after irradiation. Reciprocity is valid from 2 to at least 9,000 seconds and the response can be about 90% reversed by far red light. Photoreversibility is lost (;escape' occurs) about 20 minutes after red irradiation but appears to be regained 60 to 80 minutes later. A red light-induced (or synchronized) nutation in the apparent curvature rather than unusual escape characteristics may explain these results.
光诱导玉米黄化根向光性的改变是由光敏色素介导的低光通量反应。该品种的阈值为 10(-6) mol m(-2),用 10(-2) mol m(-2)的红光即可达到饱和。红光照射 120 至 165 分钟后,水平方向向下 32 度的最大光介导响应发生在长度为 10 至 30 毫米的根中。从 2 到至少 9000 秒的时间内具有互易性,远红光可以将响应逆转约 90%。红光照射约 20 分钟后,光可逆性丧失(出现“逃逸”),但约 60 至 80 分钟后似乎又恢复。红光诱导(或同步)的明显曲率的章动而不是不寻常的逃逸特征可能解释了这些结果。