Open AccessMolecular Cloning and Tissue-Specific Expression of an Anionic Peroxidase in Zucchini1
Author(s) -
Sabine Carpin,
Michèle Crèvecœur,
Hubert Greppin,
Claude Penel
Publication year - 1999
Publication title -
plant physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.554
H-Index - 312
eISSN - 1532-2548
pISSN - 0032-0889
DOI - 10.1104/pp.120.3.799
Subject(s) - hypocotyl , biology , complementary dna , microbiology and biotechnology , peroxidase , gene expression , biochemistry , epidermis (zoology) , cdna library , auxin , gene , cucurbita pepo , enzyme , botany , anatomy
A calcium-pectate-binding anionic isoperoxidase (APRX) from zucchini (Cucurbita pepo) was purified and subjected to N-terminal amino acid microsequencing. The cDNA encoding this enzyme was obtained by reverse transcriptase polymerase chain reaction from a cDNA library. It encoded a mature protein of 309 amino acids exhibiting all of the sequence characteristics of a plant peroxidase. Despite the presence of a C-terminal propeptide, APRX was found in the apoplast. APRX protein and mRNA were found in the root, hypocotyls, and cotyledons. In situ hybridization showed that the APRX-encoding gene was expressed in many different tissues. The strongest expression was observed in root epidermis and in some cells of the stele, in differentiating tracheary elements of hypocotyl, in the lower and upper epidermis, in the palisade parenchyma of cotyledons, and in lateral and adventitious root primordia. In the hypocotyl hook there was an asymmetric expression, with the inner part containing more transcripts than the outer part. Treatment with 2,3,5-triiodobenzoic acid reduced the expression of the APRX-encoding gene in the lower part of the hypocotyl. Our observations suggest that APRX could be involved in lignin formation and that the transcription of its gene was related to auxin level.