Delayed leaf senescence by exogenous lyso phosphatidylethanolamine: towards a mechanism of action

Hong, J.H. and Chung, G. and Cowan, A.K. (2009) Delayed leaf senescence by exogenous lyso phosphatidylethanolamine: towards a mechanism of action. Plant Physiology and Biochemistry, 47 (6). pp. 526-534. ISSN 0981-9428

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Official URL: http://dx.doi.org/10.1016/j.plaphy.2008.12.014

Abstract

Exogenous application of the lysophospholipid, lyso-phosphatidylethanolamine (LPE) is purported to delay leaf senescence in plants. However, lyso-phospholipids are well known to possess detergent-like activity and application of LPE to plant tissues might be expected to rather elicit a wound-like response and enhance senescence progression. Since phosphatidic acid (PA) accumulation and leaf cell death are a consequence of wounding, PA- and hormone-induced senescence was studied in leaf discs from Philodendron cordatum (Vell.) Kunth plants in the presence or absence of egg-derived 18:0-LPE and senescence progression quantified by monitoring both lipid peroxidation (as the change in malondialdehyde concentration), and by measuring retention of total chlorophyll (Chla+b) and carotenoids (Cc+x). Only abscisic acid (ABA) stimulated lipid peroxidation whereas ABA, 1-aminocyclopropane-1-carboxylic acid (ACC), the immediate precursor to ethylene (ETH), and 16:0-18:2-PA stimulated loss of chloroplast pigments. Results using primary alcohols as attenuators of the endogenous PA signal confirmed a role for PA as an intermediate in both ABA- and ETH-mediated senescence progression. Exogenous 18:0-LPE did not appear to influence senescence progression and was unable to reverse hormone-induced senescence progression. However, when supplied together with 16:0-18:2-PA at 1:1 (mol:mol), activity of phosphatidylglycerol (PG) hydrolase, chlorophyllase (E.C. 3.1.1.14), and progression of leaf senescence were negated. This apparent anti-senescence activity of exogenous 18:0-LPE was associated with induction of the pathogenesis-related protein, extracellular acid invertase (Ac INV, E.C. 3.2.1.26) suggesting that 18:0-LPE like 16:0-18:2-PA functions as an elicitor.

Item Type:Article
Additional Information:Professor AK Cowan is the director of the Institute for Environmental Biotechnology (EBRU) at Rhodes University, Grahamstown, South Africa
Uncontrolled Keywords:Acid invertase; Lyso-phosphatidylethanolamine; Phosphatidic acid; Phospholipids; Senescence; Philodendron; Philodendron cordatum
Subjects:Y Unknown > Subjects to be assigned
Divisions:Research Institutes and Units > Environmental Biotechnology Research Unit (EBRU)
ID Code:1410
Deposited By: Mrs Eileen Shepherd
Deposited On:01 Jul 2009
Last Modified:06 Jan 2012 16:20
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