Hormone levels and response during de-etiolation in pea
Hormone levels and response during de-etiolation in pea
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DOI：
10.1007/s00425-002-0860-z
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发表时间：
2002
期刊：
影响因子：
4.3
通讯作者：
G. M. Symons;J. B. Reid
中科院分区：
文献类型：
--
作者：
G. M. Symons;J. B. Reid
本研究的目的是增加我们的了解激素调节的黄化豌豆（豌豆sativumL.）幼苗在暴露于连续白色光之后。最近的报道表明，豌豆的脱黄化可能是由于油菜素类固醇（BR）生物合成途径中的一种酶的下调。随后的审查强调了直接测量BR水平以支持这一假设的必要性。我们已经表明，内源性Castasterone和6-deoxocasterone水平在暴露于光后不会大大降低;事实上，6-deoxocasterone水平实际上增加了。同样，在连续光照下生长的植物，或已转入光照的黑暗生长的植物中，对外源芸苔素的伸长反应比在连续黑暗中生长的植物中更大。这些结果提供了进一步的证据，表明BR不负调节豌豆中的去黄化。然而，其他几种激素水平的变化也与光调节发育有关。我们同时定量吲哚-3-乙酸（IAA），赤霉素（GA），脱落酸水平在整个幼苗，暴露于光后，这些物质的水平变化揭示了一个复杂的模式。这些变化中的第一个也是最引人注目的是GA 1水平的显著降低，在暴露于光后8小时达到最低水平。虽然GA 1水平迅速下降，IAA水平在短期内保持不变，在曝光后，这表明GA 1水平可能是主要的因素调节在去黄化过程中的伸长生长减少。在长期光照后，IAA水平经历了一个短暂的上升过程，在48 h达到峰值，到96 h有所下降。然而，脱落酸水平在暴露于光后的第一个1小时内保持不变，然后随着时间的推移稳步下降。这些变化在介导光诱导的植物形态变化的相对重要性进行了讨论。
The objective of this study was to increase our understanding of the hormonal regulation of de-etiolation by investigating endogenous hormone levels and response in etiolated pea (Pisum sativumL.) seedlings after exposure to continuous white light. Recent reports suggest that de-etiolation may result from the down-regulation of an enzyme in the brassinosteroid (BR) biosynthesis pathway in pea. A subsequent review highlighted the need for direct measurements of BR levels to support this hypothesis. We have shown that endogenous castasterone and 6-deoxocastasterone levels are not greatly reduced after exposure to light; indeed, 6-deoxocastasterone levels were actually increased. Similarly, the elongation response to exogenous brassinolide was greater in plants grown in continuous light, or in dark-grown plants that had been transferred into the light, than in plants that were grown in continuous darkness. These results provide further evidence to suggest that BRs do not negatively regulate de-etiolation in pea. However, changes in the levels of several other hormones have also been implicated in light-regulated development. We have simultaneously quantified indole-3-acetic acid (IAA), gibberellin (GA), and abscisic acid levels in whole seedlings, which revealed a complex pattern of changes in the levels of these substances after exposure to light. The first and most dramatic of these changes was a significant reduction in GA1levels, which reached a minimum 8 h after exposure to light. Whilst GA1levels rapidly decreased, IAA levels remained unchanged in the short term after exposure to light, suggesting that GA1levels may be the primary factor regulating the reduction in elongation growth during de-etiolation. In the long term after exposure to light, IAA levels underwent a transitory increase, which peaked at 48 h, and had abated by 96 h. However, abscisic acid levels remained unchanged in the first 1 h after exposure to light before undergoing a steady decline over time. The relative importance of these changes in mediating light-induced changes in plant morphology is discussed.