Differential induction by methyl jasmonate of genes encoding ornithine decarboxylase and other enzymes involved in nicotine biosynthesis in tobacco cell cultures.
A cDNA of tobacco BY-2 cells corresponding to an mRNA species which was rapidly induced by methyl jasmonate (MeJA) in the presence of cycloheximide (CHX) was found to encode ornithine decarboxylase (ODC). Another cDNA from a MeJA-inducible mRNA encoded S-adenosylmethionine synthase (SAMS). Although these enzymes could be involved in the biosynthesis of polyamines, the level of putrescine, a reaction product of ODC, increased slowly and while the levels of spermidine and spermine did not change following treatment of cells with MeJA. However, N-methylputrescine, which is a precursor of pyrrolidine ring of nicotine, started to increase shortly after MeJA-treatment of cells and the production of nicotine occured thereafter. The levels of mRNA for arginine decarboxylase (ADC), an alternative enzyme for putrescine synthesis, and that for S-adenosylmethionine decarboxylase (SAMDC), required for polyamine synthesis, were not affected by MeJA. In addition to mRNAs for ODC and SAMS, mRNA for putrescine N-methyltransferase (PMT) was also induced by MeJA. Unlike the MeJA-induction of ODC mRNA, MeJA-induction of SAMS and PMT mRNAs were blocked by CHX. The level of ODC mRNA declined after 1 to 4 h following MeJA treatment, while the levels of mRNAs for SAMS and PMT continued to increase. Auxin significantly reduced the MeJA-inducible accumulation of mRNAs for ODC, SAMS and PMT. These results indicate that MeJA sequentially induces expression of a series of genes involved in nicotine biosynthesis by multiple regulatory mechanisms.
Imanishi
S
S
Laboratory of Biochemistry, Graduate School of Bioagricultural Sciences Nagoya University, Chikusa, Japan.
Hashizume
K
K
Nakakita
M
M
Kojima
H
H
Matsubayashi
Y
Y
Hashimoto
T
T
Sakagami
Y
Y
Yamada
Y
Y
Nakamura
K
K
D000085:Acetates / Q000494:pharmacology*; D000595:Amino Acid Sequence; D001483:Base Sequence; D002478:Cells, Cultured; D003517:Cyclopentanes / Q000494:pharmacology*; D017931:DNA Primers; D018076:DNA, Complementary; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000502:physiology*; D008969:Molecular Sequence Data; D009538:Nicotine / Q000096:biosynthesis*; D009955:Ornithine Decarboxylase / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D054883:Oxylipins; D010937:Plant Growth Regulators / Q000494:pharmacology*; D010947:Plants, Toxic; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014026:Nicotiana / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D014158:Transcription, Genetic
D000085:Acetates; D003517:Cyclopentanes; D017931:DNA Primers; D018076:DNA, Complementary; D054883:Oxylipins; D010937:Plant Growth Regulators; D012333:RNA, Messenger; D009538:Nicotine; C072239:methyl jasmonate; D009955:Ornithine Decarboxylase