Structure of two maize phytase genes and their spatio-temporal expression during seedling development

• Published in: Plant molecular biology 1999-02, Vol.39 (3), p.503-514
• Main Authors: Maugenest, S. (Laboratoire de Biologie des Semences INRA, Versailles (France).), Martinez, I, Godin, B, Perez, P, Lescure, A.M
• Format: Article
• Language: English
• Subjects: 6-Phytase - genetics; Amino Acid Sequence; Base Sequence; Corn; DNA, Plant - chemistry; DNA, Plant - genetics; DNA, Plant - isolation & purification; EXPRESION GENICA; EXPRESSION DES GENES; FITASA; GENE EXPRESSION; Gene Expression Regulation, Developmental; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Genes, Plant - genetics; GERMINACION; GERMINATION; Germination - genetics; Immunohistochemistry; In Situ Hybridization; Isoenzymes - genetics; Molecular Sequence Data; NUCLEOTIDE SEQUENCE; PHYTASE; Plant Development; Plants - enzymology; Plants - genetics; PLANTULAS; PLANTULE; Proteins; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - genetics; RNA, Messenger - metabolism; Roots; SECUENCIA NUCLEOTIDICA; SEEDLINGS; Seeds - enzymology; Seeds - genetics; Seeds - growth & development; Sequence Homology, Amino Acid; Sequence Homology, Nucleic Acid; SEQUENCE NUCLEOTIDIQUE; Tissue Distribution; Transcription, Genetic; ZEA MAYS; Zea mays - chemistry; Zea mays - enzymology; Zea mays - genetics
• ISSN: 0167-4412; 1573-5028
• DOI: 10.1023/A:1006131506193

Up to 80% of Zea mays L. grain phosphorus is stored in the form of phytin in the embryo. Our objective is to determine the control of phytin mobilization during germination and seedling growth. A maize phytase cDNA, phy S11, has been previously characterized (Maugenest et al., Biochem J 322: 511-517, 1997). In the present work, phy S11 was used to screen a maize genomic library and two distinct genes, PHYT I and PHYT II, were isolated and sequenced. The transcribed sequences of these two genes presented a strong homology whereas the untranscribed upstream and downstream sequences appeared very different. Northern blot analysis and in situ hybridization showed a high accumulation of phytase mRNA at the early steps of germination in the coleorhiza, radicle cortex and coleoptile parenchyma. Phytase expression was also detected at a lower extent in the scutellum. In adult plants, northern blot analyses revealed low but significant levels of phytase mRNA in the roots. In situ hybridizations on root cross-sections localized phytase mRNA in rhizodermis, endodermis and pericycle layers. Immunolocalization analysis showed phytase accumulation at the same sites as its mRNA. A RT-PCR approach was used in an attempt to discriminate between the transcripts from each gene in the different situations. These experiments indicate that both genes are expressed during germination, whereas only PHYT I is expressed in adult roots. This suggests that signals responsible for phytase gene expression in roots are different from those responsible for gene expression during germination.