Nitric Oxide Triggers Phosphatidic Acid Accumulation via Phospholipase D during Auxin-Induced Adventitious Root Formation in Cucumber    

Abstract

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 32 P-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.

The Heme Oxygenase/Carbon Monoxide System Is Involved in the Auxin-Induced Cucumber Adventitious Rooting Process

“…The concentrations of the above chemicals used for our experiments were supported by other published results (Pagnussat et al, 2002(Pagnussat et al, , 2003(Pagnussat et al, , 2004Cao et al, 2007b;Xuan et al, 2007). Excised cucumber hypocotyls (5-mm-long segments of the hypocotyl base, where adventitious roots develops; Lanteri et al, 2008) were used for the following determination.…”

“…Treatment of phytohormones, including indole acetic acid (IAA), 6-benzyladenine, abscisic acid, and GA, enhanced the accumulation of CSCPK5 transcript in etiolated cucumber cotyledons (Kumar et al, 2004). Recently, it was suggested that, together with nitric oxide (NO), which also increases the activity of CDPK and phospholipase D, IAA plays a role in a signaling pathway that regulates CDPK and phospholipase D activity, leading to cucumber adventitious root formation (Lanteri et al, 2006(Lanteri et al, , 2008.…”

N-3-Oxo-Decanoyl-l-Homoserine-Lactone Activates Auxin-Induced Adventitious Root Formation via Hydrogen Peroxide- and Nitric Oxide-Dependent Cyclic GMP Signaling in Mung Bean

“…In fact, our own data and other reports suggest that ethylene and jasmonic acid signals may be involved in plant responses to AHLs or plant growthpromoting rhizobacteria stimulation (MorquechoContreras et al, 2010;Shi et al, 2010). The roles of these, as well as other messengers, such as phosphatidic acid and carbon monoxide, have been reported to regulate adventitious root formation in cucumber (Lanteri et al, 2008;Xuan et al, 2008); however, their roles in AHL-induced plant adventitious root formation remain to be investigated in further experiments.…”

Phospholipase Dα1 and Phosphatidic Acid Regulate NADPH Oxidase Activity and Production of Reactive Oxygen Species in ABA-Mediated Stomatal Closure inArabidopsis

“…ROS produced by PA-Rboh interaction may inhibit ABI1 activity, which is likely another mechanism by which PA regulates stomatal closure. On the other hand, recent evidence shows that NO triggers PA accumulation during auxin-induced adventitious root formation (Lanteri et al, 2008) and elicitor response (Laxalt et al, 2007). Whether such a feedback regulation loop exists in ABAmediated stomatal closure needs to be tested.…”