| Abstract: | In order to assess the potential role of endogenous cytokininsin the germination of Zea mays L. caryopses, cytokinin activitywas determined in mature kernels and in kernels 1, 2, and 3d after imbibition. Cytokinin activity was also recorded inthe endosperm and embryo tissue of mature kernels and of kernels3 d after imbibition to establish the localization and changesin the levels of endogenous cytokinins during imbibition andearly germination. Using chromatographic, chemical, and enzymic techniques, compoundswith chromatographic properties resembling those of zeatin,zeatin riboside, zeatin glucoside, zeatin riboside glucoside,and their respective dihydro derivatives were detected in extractsfrom mature maize kernels. From analyses of the endosperm andembryo tissue at the two stages, it appears that the cytokininglucosides present in the endosperm are transported to the embryonicaxis for utilization in growth and development of the seedling.This concept is supported by the fact that the levels of ß-glucosidaseactivity detected were highest in the embryos, particularlyin the radicles, 3 d after imbibition. |
