Brock T G, Kaufman P B
Department of Biology, University of Michigan, Ann Arbor 48109, USA.
Plant Physiol. 1988;87(1):130-3. doi: 10.1104/pp.87.1.130.
Pulvini of excised segments from oats (Avena sativa L. cv Victory) were treated unilaterally with indoleacetic acid (IAA) or gibberellic acid (GA3) with or without gravistimulation to assess the effect of gravistimulation on hormone action. Optimum pulvinus elongation growth (millimeters) and segment curvature (degrees) over 24 hours were produced by 100 micromolar IAA in vertical segments. The curvature response to IAA at levels greater than 100 micromolar, applied to the lower sides of gravistimulated (90 degrees) pulvini, was significantly less than the response to identical levels in vertical segments. Furthermore, the bending response of pulvini to 100 micromolar IAA did not vary significantly over a range of presentation angles between 0 and 90 degrees. In contrast, the response to IAA at levels less than 10 micromolar, with gravistimulation, was approximately the sum of the responses to gravistimulation alone and to IAA without gravistimulation. This was observed over a range of presentation angles. Also, GA3 (0.3-30 micromolar) applied to the lower sides of horizontal segments significantly enhanced pulvinus growth and segment curvature, although exogenous GA3 over a range of concentrations had no effect on pulvinus elongation growth or segment curvature in vertical segments. The response to GA3 (10 micromolar) plus IAA (1.0 or 100 micromolar) was additive for either vertical or horizontal segments. These results indicate that gravistimulation produces changes in pulvinus responsiveness to both IAA and GA3 and that the changes are unique for each growth regulator. It is suggested that the changes in responsiveness may result from processes at the cellular level other than changes in hormonal sensitivity.
用吲哚乙酸(IAA)或赤霉素(GA3)对燕麦(燕麦属栽培品种胜利)离体节段的叶枕进行单侧处理,处理时施加或不施加重力刺激,以评估重力刺激对激素作用的影响。垂直节段中,100微摩尔IAA在24小时内可使叶枕达到最佳伸长生长(毫米)和节段弯曲(度)。在重力刺激(90度)的叶枕下侧施加高于100微摩尔的IAA时,其弯曲反应明显小于垂直节段中对相同浓度IAA的反应。此外,叶枕对100微摩尔IAA的弯曲反应在0至90度的一系列呈现角度范围内没有显著变化。相比之下,在重力刺激下,低于10微摩尔的IAA的反应大约是单独重力刺激的反应与无重力刺激时IAA的反应之和。这在一系列呈现角度中都有观察到。同样,将GA3(0.3 - 30微摩尔)施加到水平节段的下侧可显著增强叶枕生长和节段弯曲,尽管在一系列浓度范围内,外源GA3对垂直节段的叶枕伸长生长或节段弯曲没有影响。对于垂直或水平节段,对GA3(10微摩尔)加IAA(1.0或100微摩尔)的反应是相加的。这些结果表明,重力刺激会使叶枕对IAA和GA3的反应性发生变化,并且每种生长调节剂的变化都是独特的。有人提出,反应性的变化可能是由细胞水平上的过程引起的,而不是激素敏感性的变化。