Zeatin

About: Zeatin is a research topic. Over the lifetime, 2467 publications have been published within this topic receiving 64092 citations. The topic is also known as: Zeatin & (E/Z)-zeatin.

Hydroxylation of N6-(Δ2-Isopentenyl)adenine to Zeatin Relative Activities of Organ Systems from Actinidia arguta

Abstract: By incubating explants from Actinidia arguta seedlings on a nutrient medium supplemented with 20 to 30 micromolar N(6)-(Delta(2)-isopentenyl)adenine (i(6)Ade) and then measuring zeatin (io(6)Ade) accumulation in tissues, the distribution of i(6)Ade hydroxylase activities in whole plants could be determined. Based on analyses with three entire plants, it is estimated that, as an organ system, roots contain approximately 68% of the plant's hydroxylase, while stems and leaves account for about 26% and 6%, respectively, of the total activity. Depending on the part of the root examined, hydroxylase activities ranged from 20 to 148 nanomoles io(6)Ade accumulated per gram fresh weight per 24 hours of incubation. Stem activities ranged from 17 to 165 nanomoles per gram fresh weight per 24 hours with the lowest activities being found at the tip. Leaf activities were substantially lower (1-10 nanomoles per leaf depending on position) than either root or stem.

Evaluation of H+ Secretion Relative to Zeatin-Induced Growth of Detached Cucumber Cotyledons

Abstract: Cytokinins promote expansion of cotyledons detached from seedlings of more than a dozen species. The zeatin-enhanced expansion of cucumber (Cucumis sativus L. cv Marketer) cotyledons was investigated. In addition, whether acid secretion is involved in wall loosening accompanying such accelerated growth was evaluated. For cotyledons abraded with carborundum or cut into either eight or 18 pieces, we detected no zeatin-enhanced acidification of the growth medium during growth periods of 3 days. Measurements of pH values on each surface of zeatin-treated, abraded cotyledons after 3 days of growth also showed no detectable acidification caused by the hormone. Furthermore, with several buffers at pH values ranging from 5 to 8, growth of nonabraded, abraded, or cut cotyledons with or without zeatin was independent of external pH. However, experiments restricted to about 12 hours indicated that certain acidic buffers enhanced growth of cotyledons cut into 18 pieces. Lastly, concentrations of fusicoccin that caused growth promotion equal to that of zeatin initiated substantial acidification of the medium. Collectively, these data suggest that zeatin-induced expansion of detached cucumber cotyledons is independent of H+ secretion.