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J Chem Ecol

Title:		Phloem sugar flux and jasmonic acid-responsive cell wall invertase control extrafloral nectar secretion in Ricinus communis
Author(s):		Millan-Canongo C; Orona-Tamayo D; Heil M;
Address:		"Departamento de Ingenieria Genetica, CINVESTAV-Irapuato, Km. 9.6 Libramiento Norte, 36821, Irapuato, Guanajuato, Mexico"
Journal Title:		J Chem Ecol
Year:		2014
Volume:		20140715
Issue:		7
Page Number:		760 - 769
DOI:		10.1007/s10886-014-0476-3
ISSN/ISBN:		1573-1561 (Electronic) 0098-0331 (Linking)
Abstract:		"Plants secrete extrafloral nectar (EFN) that attracts predators. The efficiency of the resulting anti-herbivore defense depends on the quantity and spatial distribution of EFN. Thus, according to the optimal defense hypothesis (ODH), plants should secrete EFN on the most valuable organs and when herbivore pressure is high. Ricinus communis plants secreted most EFN on the youngest (i.e., most valuable) leaves and after the simulation of herbivory via the application of jasmonic acid (JA). Here, we investigated the physiological mechanisms that might produce these seemingly adaptive spatiotemporal patterns. Cell wall invertase (CWIN; EC 3.2.1.26) was most active in the hours before peak EFN secretion, its decrease preceded the decrease in EFN secretion, and CWIN activity was inducible by JA. Thus, CWIN appears to be a central player in EFN secretion: its activation by JA is likely to cause the induction of EFN secretion after herbivory. Shading individual leaves decreased EFN secretion locally on these leaves with no effect on CWIN activity in the nectaries, which is likely to be because it decreased the content of sucrose, the substrate of CWIN, in the phloem. Our results demonstrate how the interplay of two physiological processes can cause ecologically relevant spatiotemporal patterns in a plant defense trait"
Keywords:		Carbohydrate Metabolism/physiology Cell Wall/*drug effects/metabolism/radiation effects Cyclopentanes/metabolism/*pharmacology Light Oxylipins/metabolism/*pharmacology Phloem/*metabolism Plant Leaves/chemistry/metabolism/radiation effects Plant Nectar/*me;
Notes:		"MedlineMillan-Canongo, Cynthia Orona-Tamayo, Domancar Heil, Martin eng Research Support, Non-U.S. Gov't 2014/07/16 J Chem Ecol. 2014 Jul; 40(7):760-9. doi: 10.1007/s10886-014-0476-3. Epub 2014 Jul 15"