Jasmonate is involved in the induction of tyrosine aminotransferase and tocopherol biosynthesis in Arabidopsis thaliana.
Coronatine-inducible tyrosine aminotransferase (TAT), which catalyses the transamination from tyrosine to p-hydroxyphenylpyruvate, is the first enzyme of a pathway leading via homogentisic acid to plastoquinone and tocopherols, the latter of which are known to be radical scavengers in plants. TAT can be also induced by the octadecanoids methyl jasmonate (MeJA) and methyl-12-oxophytodienoic acid (MeOPDA), as well as by wounding, high light, UV light and the herbicide oxyfluorfen. In order to elucidate the role of octadecanoids in the process of TAT induction in Arabidopsis thaliana (L.) Heynh., the jasmonate-deficient mutant delayed dehiscence (dde1) was used, in which the gene for 12-oxophytodienoic acid reductase 3 is disrupted. The amount of immunodetectable TAT was low. The enzyme was still fully induced by coronatine as well as by MeJA although induction by the latter was to a lesser extent and later than in the wild type. Treatment with MeOPDA, wounding and UV light, however, had hardly any effects. Tocopherol levels that showed considerable increases in the wild type after some treatments were much less affected in the mutant. However, starting levels of tocopherol were higher in non-induced dde1 than in the wild type. We conclude that jasmonate plays an important role in the signal transduction pathway regulating TAT activity and the biosynthesis of its product tocopherol.
Sandorf
Iris
I
Ruhr-Universität Bochum, Lehrstuhl für Pflanzenphysiologie, Universitätsstr. 150, 44780 Bochum, Germany.
Holländer-Czytko
Heike
H
D000085:Acetates / Q000494:pharmacology; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D003517:Cyclopentanes / Q000494:pharmacology*; D004790:Enzyme Induction / Q000187:drug effects / Q000528:radiation effects; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D055768:Halogenated Diphenyl Ethers; D006540:Herbicides / Q000494:pharmacology; D008027:Light; D009154:Mutation; D054883:Oxylipins; D010647:Phenyl Ethers / Q000494:pharmacology; D010667:Phenylpyruvic Acids / Q000378:metabolism; D013314:Stress, Mechanical; D024505:Tocopherols / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism; D014444:Tyrosine Transaminase / Q000096:biosynthesis*; D014466:Ultraviolet Rays
D000085:Acetates; D003517:Cyclopentanes; D005231:Fatty Acids, Unsaturated; D055768:Halogenated Diphenyl Ethers; D006540:Herbicides; D054883:Oxylipins; D010647:Phenyl Ethers; D010667:Phenylpyruvic Acids; C010590:4-hydroxyphenylpyruvic acid; D014443:Tyrosine; C016027:oxyfluorofen; C025999:12-oxophytodienoic acid; C011006:jasmonic acid; C072239:methyl jasmonate; D014444:Tyrosine Transaminase; D024505:Tocopherols