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First published online August 7, 2003; 10.1104/pp.103.024174 Plant Physiology 133:295-306 (2003) © 2003 American Society of Plant Biologists Nitrogen Deficiency Increases Volicitin-Induced Volatile Emission, Jasmonic Acid Accumulation, and Ethylene Sensitivity in Maize1Center of Medical, Agricultural, and Veterinary Entomology, U.S. Department of Agriculture, Agricultural Research Service, Gainesville, Florida 32608 (E.A.S., J.E., J.H.T.); and Department of Entomology and Nematology, University of Florida, Gainesville, Florida 32611-0620 (H.T.A.)
Insect herbivore-induced plant volatile emission and the subsequent attraction of natural enemies is facilitated by fatty acid-amino acid conjugate (FAC) elicitors, such as volicitin [N-(17-hydroxylinolenoyl)-L-glutamine], present in caterpillar oral secretions. Insect-induced jasmonic acid (JA) and ethylene (E) are believed to mediate the magnitude of this variable response. In maize (Zea mays) seedlings, we examined the interaction of volicitin, JA, and E on the induction of volatile emission at different levels of nitrogen (N) availability that are known to influence E sensitivity. N availability and volicitin-induced sesquiterpene emission are inversely related as maximal responses were elicited in N-deficient plants. Plants with low N availability demonstrated similar volatile responses to volicitin (1 nmol plant-1) and JA (100 nmol plant-1). In contrast, plants with medium N availability released much lower amounts of volicitin-induced sesquiterpenes compared with JA, suggesting an alteration in volicitin-induced JA levels. As predicted, low N plants exhibited greater sustained increases in wound- and volicitin-induced JA levels compared with medium N plants. N availability also altered volicitin-E interactions. In low N plants, E synergized volicitin-induced sesquiterpene and indole emission 4- to 12-fold, with significant interactions first detected at 10 nL L-1 E. Medium N plants demonstrated greatly reduced volicitin-E interactions. Volicitin-induced sesquiterpene emission was increased by E and was decreased by pretreatment the E perception inhibitor 1-methylcyclopropene without alteration in volicitin-induced JA levels. N availability influences plant responses to insect-derived elicitors through changes in E sensitivity and E-independent JA kinetics.
1 This work was supported by the U.S. Department of Agriculture-Agricultural Research Service and by the Defense Advanced Research Project Agency. * Corresponding author; e-mail eschmelz{at}gainesville.usda.ufl.edu; fax 352-374-5707. Received March 25, 2003; returned for revision April 24, 2003; accepted June 2, 2003. This article has been cited by other articles:
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