Arteca Richard N, Arteca Jeannette M
Department of Horticulture, The Pennsylvania State University, University Park, PA 16802, USA.
J Exp Bot. 2008;59(11):3019-26. doi: 10.1093/jxb/ern159. Epub 2008 Jun 25.
Inflorescence stalks produced the highest amount of ethylene in response to IAA as compared with other plant parts tested. Leaf age had an effect on IAA-induced ethylene with the youngest leaves showing the greatest stimulation. The highest amount of IAA-induced ethylene was produced in the root or inflorescence tip with regions below this producing less. Inflorescence stalks treated with IAA, 2,4-D, or NAA over a range of concentrations exhibited an increase in ethylene production starting at 1 microM with increasingly greater responses up to 100 microM, followed by a plateau at 500 microM and a significant decline at 1000 microM. Both 2,4-D and NAA elicited a greater response than IAA at all concentrations tested in inflorescence stalks. Inflorescence leaves treated with IAA, 2,4-D, or NAA exhibited the same trend as inflorescence stalks. However, they produced significantly less ethylene. Inflorescence stalks and leaves treated with 100 microM IAA exhibited a dramatic increase in ethylene production 2 h following treatment initiation. Inflorescence stalks showed a further increase 4 h following treatment initiation and no further increase at 6 h. However, there was a slight decline between 6 h and 24 h. Inflorescence leaves exhibited similar rates of IAA-induced ethylene between 2 h and 24 h. Light and high temperature caused a decrease in IAA-induced ethylene in both inflorescence stalks and leaves. Three auxin-insensitive mutants were evaluated for their inflorescence's responsiveness to IAA. aux2 did not produce ethylene in response to 100 microM IAA, while axr1-3 and axr1-12 showed reduced levels of IAA-induced ethylene as compared with Columbia wild type. Inflorescences treated with brassinolide alone had no effect on ethylene production. However, when brassinolide was used in combination with IAA there was a dramatic increase in ethylene production above the induction promoted by IAA alone.
与测试的其他植物部位相比,花序梗对吲哚乙酸(IAA)的响应产生的乙烯量最高。叶龄对IAA诱导的乙烯有影响,最幼嫩的叶片显示出最大的刺激作用。IAA诱导产生乙烯量最高的部位是根或花序顶端,其下方区域产生的乙烯较少。用一系列浓度的IAA、2,4-二氯苯氧乙酸(2,4-D)或萘乙酸(NAA)处理花序梗,乙烯产量从1微摩尔/升开始增加,在100微摩尔/升时反应越来越大,随后在500微摩尔/升时达到平稳,在1000微摩尔/升时显著下降。在花序梗中测试的所有浓度下,2,4-D和NAA引发的反应均比IAA更大。用IAA、2,4-D或NAA处理的花序叶表现出与花序梗相同的趋势。然而,它们产生的乙烯显著较少。用100微摩尔/升IAA处理的花序梗和叶在处理开始后2小时乙烯产量急剧增加。花序梗在处理开始后4小时进一步增加,6小时时不再增加。然而,在6小时至24小时之间略有下降。花序叶在2小时至24小时之间表现出相似的IAA诱导乙烯生成速率。光照和高温导致花序梗和叶中IAA诱导的乙烯减少。评估了三个生长素不敏感突变体的花序对IAA的反应。aux2对100微摩尔/升IAA不产生乙烯,而与哥伦比亚野生型相比,axr1-3和axr1-12显示出IAA诱导的乙烯水平降低。单独用油菜素内酯处理花序对乙烯产量没有影响。然而,当油菜素内酯与IAA联合使用时,乙烯产量比单独由IAA促进的诱导量有显著增加。