Effects of feeding Spodoptera littoralis on lima bean leaves. I. Membrane potentials, intracellular calcium variations, oral secretions, and regurgitate components.

Abstract

Membrane potentials (V(m)) and intracellular calcium variations were studied in Lima bean (Phaseolus lunatus) leaves when the Mediterranean climbing cutworm (Spodoptera littoralis) was attacking the plants. In addition to the effect of the feeding insect the impact of several N-acyl Glns (volicitin, N-palmitoyl-Gln, N-linolenoyl-Gln) from the larval oral secretion was studied. The results showed that the early events upon herbivore attack were: a) a strong V(m) depolarization at the bite zone and an isotropic wave of V(m) depolarization spreading throughout the entire attacked leaf; b) a V(m) depolarization observed for the regurgitant but not with volicitin [N-(17-hydroxy-linolenoyl)-Gln] alone; c) an enhanced influx of Ca(2+) at the very edge of the bite, which is halved, if the Ca(2+) channel blocker Verapamil is used. Furthermore, the dose-dependence effects of N-acyl Gln conjugates-triggered influx of Ca(2+) studied in transgenic aequorin-expressing soybean (Glycine max) cells, showed: a) a concentration-dependent influx of Ca(2+); b) a configuration-independent effect concerning the stereochemistry of the amino acid moiety; c) a slightly reduced influx of Ca(2+) after modification of the fatty acid backbone by functionalization with oxygen and; d) a comparable effect with the detergent SDS. Finally, the herbivore wounding causes a response in the plant cells that cannot be mimicked by mechanical wounding. The involvement of Ca(2+) in signaling after herbivore wounding is discussed.

• Authors: Massimo Maffei, Simone Bossi, Dieter Spiteller, Axel Mithöfer, Wilhelm Boland
• Journal: Plant physiology (Plant Physiol) Vol. 134 Issue 4 Pg. 1752-62 (Apr 2004) ISSN: 0032-0889 [Print] United States
• PMID: 15051862 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Calcium Channel Blockers
• Palmitic Acids
• volicitin
• alpha-Linolenic Acid
• Glutamine
• N-palmitoylglycine
• Verapamil
• Calcium
• Glycine

Topics

• Animals
• Bodily Secretions (physiology)
• Calcium (metabolism, pharmacology)
• Calcium Channel Blockers (pharmacology)
• Fabaceae (drug effects, metabolism, parasitology)
• Feeding Behavior (physiology)
• Glutamine (analogs & derivatives, metabolism, pharmacology)
• Glycine (analogs & derivatives, metabolism, pharmacology)
• Immunity, Innate
• Insect Bites and Stings (metabolism)
• Larva (growth & development, metabolism)
• Palmitic Acids (metabolism, pharmacology)
• Plant Diseases (parasitology)
• Plant Leaves (drug effects, metabolism, parasitology)
• Signal Transduction (drug effects)
• Soybeans (drug effects, metabolism)
• Spodoptera (growth & development, metabolism)
• Stress, Mechanical
• Verapamil (pharmacology)
• alpha-Linolenic Acid (analogs & derivatives, metabolism, pharmacology)