表油菜素内酯对黄瓜下胚轴伸长、内源GA~3,ABA及淀粉含量的影响

1 ppm表油菜素内酯(epiBR)能显著地促进光下生长的黄瓜下胚轴伸长。其促进伸长的效应需约5h滞后期,明显超过IAA而与GA_3的滞后期接近。GA_3对epiBR促进黄瓜下胚轴的伸长具有增效作用。epiBR能提高内源GA_3,ABA的水平,处理24h后,GA_3/ABA值约为对照的两倍。经epiBR处理后的黄瓜下胚轴内淀粉含量较低,并维持在同一水平,这与GA_3的作用颇为一致。

Epibrassinolide-Induced Changes in the Elongation, Endogenous GA_3, ABA and Starch Content of Cucumber Hypocotyls

The effects of epibrassinolide (epi BR), a synthetic brassinosteroid on the endogenous GA_3, ABA and the starch content of lightgrown cucumber hypocotyls were studied. The stimulating effect of epiBR on elongation growth of hypocotyls was greater than that of IAA and GA_3 However, the lag period (5 h) of epi BR effect was longer thanthat of IAA, but was similar to that of GA_3. Endogenous GA_3 and ABA increased in cucumber hypocotyls treated with epiBR. After 24 h of treatment the ratio of GA_3/ABA in epiBR-treated hypocotyls was twice as much as that in control. EpiBR treatment reduced the starch content of hypocotyls irrespective of whether glucose was present. The total amount of starch, however, was markedly increased in the presence of glucose. Electron microscopic examination of elongatio region of hypocotyl segments indicated that epiBR and GA_3 reduced the content of starch in chloroplast. It was also shown that the effects of epiBR and GA_3 were additive enhancing hypocotyl elongation and starch hydrolysis. These results suggested that the action of epiBR was similar to that of GA_3.