Lanteri María Luciana, Laxalt Ana María, Lamattina Lorenzo
Instituto de Investigaciones Biológicas, Universidad Nacional de Mar del Plata, 7600 Mar del Plata, Argentina.
Plant Physiol. 2008 May;147(1):188-98. doi: 10.1104/pp.107.111815. Epub 2008 Mar 28.
Auxin and nitric oxide (NO) play fundamental roles throughout plant life. NO is a second messenger in auxin signal transduction leading to root developmental processes. The mechanisms triggered by auxin and NO that direct adventitious root (AR) formation are beginning to be unraveled. The goal of this work was to study phospholipid (PL) signaling during the auxin- and NO-induced AR formation in cucumber (Cucumis sativus) explants. Explants were labeled with 32P-inorganic phosphate and treated with the auxins indole-3-acetic acid or 1-naphthylacetic acid, or the NO donor S-nitroso N-acetyl penicillamine, in the presence or absence of the specific NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide. PLs were separated by thin-layer chromatography and quantified. We report that the signaling PLs phosphatidic acid (PA), phosphatidylinositol phosphate, and phosphatidylinositol bisphosphate accumulated within 1 min after auxin or NO treatment. Both auxin and NO evoked similar and transient time course responses, since signaling PLs returned to control levels after 20 or 30 min of treatment. The results indicate that auxin relies on NO in inducing PA, phosphatidylinositol phosphate, and phosphatidylinositol bisphosphate accumulation. Furthermore, we demonstrate that auxin and NO trigger PA formation via phospholipase D (PLD) activity. Explants treated for 10 min with auxin or NO displayed a 200% increase in AR number compared with control explants. In addition, PLD activity was required for the auxin- and NO-induced AR formation. Finally, exogenously applied PA increased up to 300% the number of ARs. Altogether, our data support the idea that PLD-derived PA is an early signaling event during AR formation induced by auxin and NO in cucumber explants.
生长素和一氧化氮（NO）在植物的整个生命过程中发挥着重要作用。NO是生长素信号转导中的第二信使，参与根系发育过程。生长素和NO诱导不定根（AR）形成的机制正逐渐被揭示。本研究的目的是探讨黄瓜（Cucumis sativus）外植体在生长素和NO诱导AR形成过程中的磷脂（PL）信号转导。外植体用32P-无机磷酸盐标记，在有或无特异性NO清除剂2-(4-羧基苯基)-4,4,5,5-四甲基咪唑啉-1-氧基-3-氧化物的情况下，用生长素吲哚-3-乙酸或1-萘乙酸，或NO供体S-亚硝基-N-乙酰青霉胺处理。PL通过薄层层析分离并定量。我们发现，在生长素或NO处理后1分钟内，信号磷脂磷脂酸（PA）、磷脂酰肌醇磷酸和磷脂酰肌醇二磷酸积累。生长素和NO引发了相似的瞬时时间进程反应，因为在处理20或30分钟后，信号磷脂恢复到对照水平。结果表明，生长素在诱导PA、磷脂酰肌醇磷酸和磷脂酰肌醇二磷酸积累方面依赖于NO。此外，我们证明生长素和NO通过磷脂酶D（PLD）活性触发PA形成。用生长素或NO处理10分钟的外植体与对照外植体相比，AR数量增加了200%。此外，生长素和NO诱导的AR形成需要PLD活性。最后，外源施加的PA使AR数量增加了300%。总之，我们的数据支持这样的观点，即PLD衍生的PA是黄瓜外植体中生长素和NO诱导AR形成过程中的早期信号事件。
