title: Expression of arginine decarboxylase and ornithine decarboxylase genes in apple cells and stressed shoots.
abstract: Arginine decarboxylase (ADC) and ornithine decarboxylase (ODC) are two important enzymes responsible for putrescine biosynthesis. In this study, a full-length ADC cDNA (MdADC) was isolated from apple [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.]. Meanwhile, a partial ODC (pMdODC) could be amplified only by a second RCR from the RT-PCR products, whereas a full-length ODC could not be obtained by either cDNA library screening or 5'- and 3'-RACEs, suggesting quite low expression. Moreover, D-arginine, an ADC inhibitor, caused a decrease in ADC activity and severely inhibited the growth of apple callus, which could be partially resumed by exogenous addition of putrescine, whereas alpha-difluoromethylornithine (DFMO), an inhibitor for ODC, caused the incomplete repression of callus growth without changing ODC activity. RNA gel blot showed that the expression level of MdADC was high in young tissues/organs with rapid cell division and was positively induced by chilling, salt, and dehydration, implying its involvement in both cell growth and these stress responses. By contrast, the transcript of ODC could not be detected by RNA gel blot analysis. Based on the present study, it is possible to conclude that (i) the ODC pathway is active in apple, although the expression level of the pMdODC gene homologous with its counterparts found in other plant species is quite low; and (ii) MdADC expression correlates with cell growth and stress responses to chilling, salt, and dehydration, suggesting that ADC is a primary biosynthetic pathway for putrescine biosynthesis in apple.
authors.affiliation: Department of Plant, Cell and Environment, National Institute of Fruit Tree Science, Tsukuba, Ibaraki 305-8605, Japan.
authors.forename: Yu-Jin
authors.initials: YJ
authors.lastname: Hao
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Kitashiba
authors.forename: Chikako
authors.initials: C
authors.lastname: Honda
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Nada
authors.forename: Takaya
authors.initials: T
authors.lastname: Moriguchi
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002262:Carboxy-Lyases / Q000235:genetics* / Q000378:metabolism; D017124:Conserved Sequence; D017931:DNA Primers; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D007700:Kinetics; D027845:Malus / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D009955:Ornithine Decarboxylase / Q000235:genetics* / Q000378:metabolism; D018520:Plant Shoots / Q000201:enzymology* / Q000235:genetics; D016133:Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D017931:DNA Primers; D002262:Carboxy-Lyases; D009955:Ornithine Decarboxylase; C019722:arginine decarboxylase