title: Expression and function of cell wall-bound cationic peroxidase in asparagus somatic embryogenesis.
abstract: Cultured asparagus (Asparagus officinalis L. cv Y6) cells induced to regenerate into whole plants through somatic embryogenesis secreted a 38-kD protein into cell walls. The full-length cDNA sequence of this protein (Asparagus officinalis peroxidase 1 [AoPOX1]) determined by reverse transcriptase-polymerase chain reaction showed similarity with plant peroxidases. AoPOX1 transcripts were particularly abundant during early somatic embryogenesis. To evaluate the in vivo function of AoPOX1 protein, purified recombinant AoPOX1 protein was reacted with a series of phenolic substrates. The AoPOX1 protein was effective in the metabolism of feruloyl (o-methoxyphenol)-substituted substrates, including coniferyl alcohol. The reaction product of coniferyl alcohol was fractionated and subjected to gas chromatography-mass spectrometry analysis and (1)H-nuclear magnetic resonance analysis, indicating that the oxidation product of coniferyl alcohol in the presence of AoPOX1 was dehydrodiconiferyl alcohol. The concentration of dehydrodiconiferyl alcohol in the cultured medium of the somatic embryos was in the range of 10(-8) M. Functions of the AoPOX1 protein in the cell differentiation are discussed.
authors.affiliation: Faculty of Integrated Arts and Sciences, Hiroshima University, Kagamiyama, Higashihiroshima, 739-8521, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Takeda
authors.forename: Toshihisa
authors.initials: T
authors.lastname: Kotake
authors.forename: Naoki
authors.initials: N
authors.lastname: Nakagawa
authors.forename: Naoki
authors.initials: N
authors.lastname: Sakurai
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Nevins
mesh_terms: D000595:Amino Acid Sequence; D027761:Asparagus Plant / Q000196:embryology* / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D002412:Cations / Q000378:metabolism; D002473:Cell Wall / Q000201:enzymology*; D002478:Cells, Cultured; D003001:Cloning, Molecular; D003470:Culture Media / Q000737:chemistry; D015870:Gene Expression; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D008031:Lignin / Q000032:analysis; D008969:Molecular Sequence Data; D010544:Peroxidases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D002412:Cations; D003470:Culture Media; D010940:Plant Proteins; D008031:Lignin; D010544:Peroxidases