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Differential Effectiveness of Microbially Induced Resistance Against Herbivorous Insects in Arabidopsis

July 2008 , Volume 21 , Number  7
Pages  919 - 930

Vivian R. Van Oosten,1,2 Natacha Bodenhausen,3 Philippe Reymond,3 Johan A. Van Pelt,1 L. C. Van Loon,1 Marcel Dicke,2 and Corné M. J. Pieterse1

1Graduate School Experimental Plant Sciences, Section Plant-Microbe Interactions, Institute of Environmental Biology, Faculty of Science, Utrecht University, P.O. Box 800.56, 3508 TB Utrecht, The Netherlands; 2Graduate School Experimental Plant Sciences, Laboratory of Entomology, Wageningen University, P.O. Box 8031, 6700 EH Wageningen, The Netherlands; 3Department of Plant Molecular Biology, University of Lausanne, CH-1015 Lausanne, Switzerland

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Accepted 24 March 2008.

Rhizobacteria--induced systemic resistance (ISR) and pathogen-induced systemic acquired resistance (SAR) have a broad, yet partly distinct, range of effectiveness against pathogenic microorganisms. Here, we investigated the effectiveness of ISR and SAR in Arabidopsis against the tissue-chewing insects Pieris rapae and Spodoptera exigua. Resistance against insects consists of direct defense, such as the production of toxins and feeding deterrents and indirect defense such as the production of plant volatiles that attract carnivorous enemies of the herbivores. Wind-tunnel experiments revealed that ISR and SAR did not affect herbivore-induced attraction of the parasitic wasp Cotesia rubecula (indirect defense). By contrast, ISR and SAR significantly reduced growth and development of the generalist herbivore S. exigua, although not that of the specialist P. rapae. This enhanced direct defense against S. exigua was associated with potentiated expression of the defense-related genes PDF1.2 and HEL. Expression profiling using a dedicated cDNA microarray revealed four additional, differentially primed genes in microbially induced S. exigua-challenged plants, three of which encode a lipid-transfer protein. Together, these results indicate that microbially induced plants are differentially primed for enhanced insect-responsive gene expression that is associated with increased direct defense against the generalist S. exigua but not against the specialist P. rapae.

© 2008 The American Phytopathological Society