Herbivore-induced volatiles induce the emission of ethylene in neighboring lima bean plants.
Herbivore attacks induce leaves to emit a specific blend of volatiles. Here we show that exposure to Tetranychus urticae-induced volatiles, as well as T. urticae infestation and artificial wounding, activates the transcription of the genes involved in the biosynthesis of ethylene [S-adenosylmethionine (SAM) synthetase and 1-aminocyclopropane-1-carboxylic acid oxidase] and a gene involved in the biosynthesis of polyamines from SAM (SAM decarboxylase) in lima bean leaves. Moreover, exposure of leaves to any one of the seven major chemical components of T. urticae-induced volatiles also induces expression of these genes. Furthermore, we found that, when lima bean plants were exposed to T. urticae-induced volatiles, they emitted ethylene. Lima bean plants infested by T. urticae and artificially wounded plants also emitted ethylene. Endogenous polyamine levels were not increased in the exposed leaves or the infested leaves, suggesting that polyamine production from SAM was only slightly promoted at the metabolic levels present in the leaves. We found that jasmonate (JA) accumulated in leaves exposed to T. urticae-induced volatiles, and that both JA and salicylate (SA) accumulated in leaves infested by T. urticae. These findings, as well as results of pharmacological analyses, suggest that, in leaves exposed to T. urticae-induced volatiles, ethylene biosynthesis might be regulated by pathways involving JA and the ethylene positive feedback loop. They also suggest that ethylene biosynthesis might be regulated by signaling pathways involving JA, SA and ethylene in T. urticae-infested leaves.
Arimura
Gen-ichiro
G
Bio-oriented Technology Research Advancement Institution, Tokyo 105-0001, Japan.
Ozawa
Rika
R
Nishioka
Takaaki
T
Boland
Wilhelm
W
Koch
Thomas
T
Kühnemann
Frank
F
Takabayashi
Junji
J
D012437:Adenosylmethionine Decarboxylase / Q000235:genetics / Q000378:metabolism; D000594:Amino Acid Oxidoreductases / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D003517:Cyclopentanes / Q000378:metabolism / Q000494:pharmacology; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D004798:Enzymes / Q000235:genetics* / Q000378:metabolism; D005030:Ethylenes / Q000096:biosynthesis*; D007887:Fabaceae / Q000235:genetics / Q000378:metabolism* / Q000469:parasitology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D008716:Methionine Adenosyltransferase / Q000235:genetics / Q000378:metabolism; D008925:Mites / Q000254:growth & development; D008969:Molecular Sequence Data; D009943:Organophosphorus Compounds / Q000494:pharmacology; D054883:Oxylipins; D018515:Plant Leaves / Q000378:metabolism / Q000469:parasitology; D011073:Polyamines / Q000378:metabolism*; D020156:Salicylic Acid / Q000378:metabolism / Q000494:pharmacology; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000187:drug effects; D013314:Stress, Mechanical
D003517:Cyclopentanes; D018076:DNA, Complementary; D004798:Enzymes; D005030:Ethylenes; D009943:Organophosphorus Compounds; D054883:Oxylipins; D011073:Polyamines; C011006:jasmonic acid; C036216:ethylene; D000594:Amino Acid Oxidoreductases; C059460:1-aminocyclopropane-1-carboxylic acid oxidase; D008716:Methionine Adenosyltransferase; D012437:Adenosylmethionine Decarboxylase; D020156:Salicylic Acid; C005073:ethephon