Herbivore-induced defense response in a model legume. Two-spotted spider mites induce emission of (E)-beta-ocimene and transcript accumulation of (E)-beta-ocimene synthase in Lotus japonicus.
Indirect defense of plants against herbivores often involves the induced emission of volatile infochemicals including terpenoids that attract natural enemies of the herbivores. We report the isolation and characterization of a terpene synthase cDNA (LjEbetaOS) from a model legume, Lotus japonicus. Recombinant LjEbetaOS enzyme produced (E)-beta-ocimene (98%) and its Z-isomer (2%). Transcripts of LjEbetaOS were induced in L. japonicus plants infested with two-spotted spider mites (Tetranychus urticae), coinciding with increasing emissions of (E)-beta-ocimene as well as other volatiles, (Z)-3-hexenyl acetate and (E)-4,8-dimethyl-1,3,7-nonatriene, by the infested plants. We suggest that LjEbetaOS is involved in the herbivore-induced indirect defense response of spider mite-infested L. japonicus via de novo formation and emission (E)-beta-ocimene. Mechanical wounding of the leaves or application of alamethicin (ALA), a potent fungal elicitor of plant volatile emission, also induced transiently increased levels of LjEbetaOS transcripts in L. japonicus. However, wounding or ALA did not result in elevated release of (E)-beta-ocimene. Differences in volatile emissions after herbivory, mechanical wounding, or treatment with ALA suggest that neither a single mechanical wounding event nor ALA simulate the effect of herbivore activity and indicate that herbivore-induced emission of (E)-beta-ocimene in L. japonicus involves control mechanisms in addition to up-regulation of LjEbetaOS transcripts.
Arimura
Gen-ichiro
G
Biotechnology Laboratory, Department of Botany, and Department of Forest Sciences, University of British Columbia, Vancouver V6T 1Z3, British Columbia, Canada. garimura@ice.mpg.de
Ozawa
Rika
R
Kugimiya
Soichi
S
Takabayashi
Junji
J
Bohlmann
Jörg
J
D000080462:Acyclic Monoterpenes; D000475:Alkenes / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D017124:Conserved Sequence; D018076:DNA, Complementary / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D000070116:Lotus / Q000201:enzymology / Q000235:genetics* / Q000469:parasitology*; D008925:Mites / Q000502:physiology*; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
D000080462:Acyclic Monoterpenes; D000475:Alkenes; D018076:DNA, Complementary; D011994:Recombinant Proteins; C443996:beta-ocimene