caa a22 4500 467893810 CHVBK 20180406152756.0 cr unu---uuuuu 170328e20060301xx s 000 0 eng 10.1007/s11103-005-4923-y doi (NATIONALLICENCE)springer-10.1007/s11103-005-4923-y Caterpillar Herbivory and Salivary Enzymes Decrease Transcript Levels of Medicago truncatula genes Encoding Early Enzymes in Terpenoid Biosynthesis [Elektronische Daten] [Jacqueline Bede, Richard Musser, Gary Felton, Kenneth Korth] In response to caterpillar herbivory, alfalfa and related plant species defend themselves through the induction of saponin and volatile terpenoid biosynthesis. Both these types of defensive compounds are derived from the metabolic intermediate, isopentenyl diphosphate (IPP). In plants, two distinct biosynthetic pathways can generate IPP; the cytosolic mevalonate pathway and the plastid-associated 2C-methyl erythritol 4-phosphate (MEP) pathway. In Medicago truncatula, transcript levels of key regulatory genes active in the early steps of these biosynthetic pathways were measured in response to larval herbivory by the beet armyworm, Spodoptera exigua. Transcripts encoding enzymes at early steps of both terpenoid pathways were lower in caterpillar-damaged leaves. Higher degrees of herbivore damage accentuated the decrease in transcript levels; however, transcript amounts were not affected by insect larval stage. Insect larvae, manipulated to reduce labial gland salivary secretions, were used to examine the role of the salivary elicitors in modulating gene expression. Results suggest that an insect salivary factor, possibly glucose oxidase (GOX), may be involved in reduction of transcript levels following herbivory. Addition of GOX or hydrogen peroxide to mechanically wounded leaves confirm these findings. In comparison, transcript levels of a gene encoding a putative terpene synthase are induced in mechanically- or insect-damaged leaves. These data show that insect salivary factors can act to suppress transcript levels of genes involved in plant defense pathways. Findings also suggest that in response to stress such as insect herbivory, regulation occurs at the early steps of the MEP pathway. Springer, 2006 2C-methyl erythritol 4-phosphate (MEP) pathway nationallicence glucose oxidase nationallicence indole nationallicence mevalonate (MVA) pathway nationallicence DMNT : (3E)-4,8-dimethyl-1,3,7-nonatriene nationallicence dxs1 : d-1-deoxyxylulose 5-phosphate synthase nationallicence dxr1 : d-1-deoxyxylulose 5-phosphate reductoisomerase nationallicence GOX : glucose oxidase nationallicence hmg1 : 3-hydroxy- 3-methylglutaryl CoA reductase nationallicence H2O2 : hydrogen peroxide nationallicence IPP : isopentenyl diphosphate nationallicence MVA : mevalonate nationallicence MEP : 2C-methyl erythritol 4-phosphate nationallicence TMTT : (E,E)-4,8-12-trimethyl-1,3,7-tridecatetraene nationallicence tps1 : terpene synthase nationallicence Bede Jacqueline Department of Plant Pathology, University of Arkansas, Fayetteville, 72701, AR, USA aut Musser Richard Department of Entomology, University of Arkansas, 72701, Fayetteville, AR, USA aut Felton Gary Department of Entomology, Penn State University, University Park, 16802, PA, USA aut Korth Kenneth Department of Plant Pathology, University of Arkansas, Fayetteville, 72701, AR, USA aut Plant Molecular Biology Kluwer Academic Publishers 60/4(2006-03-01), 519-531 0167-4412 60:4<519 2006 60 11103 https://doi.org/10.1007/s11103-005-4923-y text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11103-005-4923-y text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Bede Jacqueline Department of Plant Pathology, University of Arkansas, Fayetteville, 72701, AR, USA aut NATIONALLICENCE 700 1- Musser Richard Department of Entomology, University of Arkansas, 72701, Fayetteville, AR, USA aut NATIONALLICENCE 700 1- Felton Gary Department of Entomology, Penn State University, University Park, 16802, PA, USA aut NATIONALLICENCE 700 1- Korth Kenneth Department of Plant Pathology, University of Arkansas, Fayetteville, 72701, AR, USA aut NATIONALLICENCE 773 0- Plant Molecular Biology Kluwer Academic Publishers 60/4(2006-03-01), 519-531 0167-4412 60:4<519 2006 60 11103 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer