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Submitted to: Insect Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/21/2008 Publication Date: 4/1/2008 Citation: Chen, M. 2008. Inducible direct plant defense against insect herbivores - a review. Insect Science. 15:101-114. Interpretive Summary: Research in direct plant defenses against insect pests has been advancing rapidly. Numerous papers have been published in a broad range of journals. This article provides a brief review of recent research advances in direct plant defenses against insect herbivores, including overall defense categories, specific defense chemicals, and future research directions. The article provides valuable information for a broad audience including scientists, graduate students, and pest managers. Technical Abstract: Plants respond to insect herbivory with responses broadly known as direct defenses, indirect defenses, and tolerance. Direct defenses include all plant traits that affect susceptibility of host plants by themselves. Overall categories of direct plant defenses against insect herbivores include limiting food supply, reducing nutrient value, reducing preference, disrupting physical structures, and inhibiting chemical pathways of the attacking insect. Major known defense chemicals include plant secondary metabolites, protein inhibitors of insect digestive enzymes, proteases, lectins, amino acid deaminases and oxidases. Multiple factors with additive or even synergistic impact are usually involved in defense against a specific insect species, and factors of major importance to one insect species may only be of secondary importance or not effective at all against another insect species. Extensive qualitative and quantitative high throughput analyses of temporal and spatial variations in gene expression, protein level and activity, and metabolite concentration will accelerate not only the understanding of the overall mechanisms of direct defense, but also accelerate the identification of specific targets for enhancement of plant resistance for agriculture. |
