Search for chemical substances controlling gravitropism in plant movement

从黄化萝卜下胚轴和玉米胚囊中分离到重力诱导生长抑制剂。经理化分析，萝卜源和玉米源抑制剂分别为3,6′-二氨基酰基蔗糖（DSS）和2,4-二羟基-7-甲氧基-1,4-苯并恶嗪-3-one （DIMBOA）。当黄化萝卜和玉米幼苗水平放置时，DSS和DIMBOA的含量分别在萝卜下胚轴和玉米胚囊的上半部迅速增加。单施DSS于萝卜下胚轴，单施DIMBOA于玉米胚轴，均可使其向施药部位弯曲。这一发现表明，向地刺激通过增加上半部分DSS和DIMBOA的含量，从而抑制黄化萝卜下胚轴和玉米胚皮上侧的生长速度，造成向地弯曲。

Gravity-induced growth inhibitors were isolated from etiolated radish hypocotyls and maize coleoptiles. The radish-derived and maize-derived inhibitors were determined to be 3,6'-disinapoylsucrose (DSS) and 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) by physicochemical analyses, respectively. When etiolated radish and maize seedlings were placed horizontally, the contents of DSS and DIMBOA rapidly increased in the upper halves of the radish hypocotyls and the maize coleoptiles, respectively. Unilateral application of DSS to the radish hypocotyls and DIMBOA to the maize coleoptiles caused both of them to bend toward the sites of application. This finding suggests that gravitropic stimulation suppresses the growth rates at the upper sides of etiolated radish hypocotyls and maize coleoptiles by increasing the contents of DSS and DIMBOA in the upper halves, causing gravitropic curvature.