title: Expression and internal feedback regulation of ACC synthase and ACC oxidase genes in ripening tomato fruit.
abstract: We have examined whether or not a positive feedback regulation of gene expression for 1-aminocyclopropane-1-carboxylate (ACC) synthase and ACC oxidase also operates in ripening tomato (Lycopersicon esculentum) fruit during the burst of ethylene production. Two cDNA fragments for ACC synthase and one for ACC oxidase were cloned with high homology to already known genes involved in ethylene biosynthesis in ripening tomato fruit. Accumulation of mRNAs which hybridize to these cDNA probes were induced in mature green fruit within two days by treatment with propylene. In the fruit ripened from the turning stage, red color development, ethylene production, ACC content, and activities of ACC synthase and ACC oxidase increased as maturity progressed. The abundance of two ACC synthase and one ACC oxidase mRNAs in the fruit increased from the turning to pink stage and were followed by a slight decline towards the red stage. These increases in mRNAs abundance with ripening were prevented to a large extent by treatment with the ethylene action inhibitor, 1-methylcyclopropene (MCP). This was most pronounced in the fruit treated with MCP at the turning stage, in which the accumulation of ACC synthase and ACC oxidase transcripts was almost completely eliminated in the first two d, precisely the same stage at which the control fruit had the greatest level of each mRNA accumulation. The inhibition of transcript accumulation recovered to the control level within two to four d. MCP also decreased ethylene biosynthetic activity, although this decrease did not reflect the reduction in the mRNAs accumulation. These results suggest that a strong positive feedback regulation is involved in ethylene biosynthesis at the gene transcriptional level in tomato fruit, even at the stage with a burst of ethylene production.
authors.affiliation: Laboratory of Postharvest Agriculture, Faculty of Agriculture, Okayama University, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Nakatsuka
authors.forename: S
authors.initials: S
authors.lastname: Shiomi
authors.forename: Y
authors.initials: Y
authors.lastname: Kubo
authors.forename: A
authors.initials: A
authors.lastname: Inaba
mesh_terms: D000475:Alkenes / Q000494:pharmacology; D000594:Amino Acid Oxidoreductases / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D003521:Cyclopropanes / Q000494:pharmacology; D018076:DNA, Complementary; D018744:DNA, Plant; D005030:Ethylenes / Q000096:biosynthesis / Q000494:pharmacology; D005638:Fruit / Q000235:genetics / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D008190:Lyases / Q000235:genetics*; D018551:Solanum lycopersicum / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data
chemical_list: D000475:Alkenes; D003521:Cyclopropanes; D018076:DNA, Complementary; D018744:DNA, Plant; D005030:Ethylenes; C105498:1-methylcyclopropane; C036216:ethylene; C013658:propylene; D000594:Amino Acid Oxidoreductases; C059460:1-aminocyclopropane-1-carboxylic acid oxidase; D008190:Lyases; C021773:1-aminocyclopropanecarboxylate synthase