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GrainGenes Reference Report: PLA-219-132

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Reference	PLA-219-132
Title	Formation of wheat (Triticum aestivum L.) embryogenic callus involves peroxide-generating germin-like oxalate oxidase
Journal	Planta
Year	2004
Volume	219
Pages	132-140
Author	Caliskan M Turet M Cuming AC
Abstract	Summary: In wheat (Triticum aestivum L.), embryogenic callus formation comprises suppression of precocious germination by the zygotic embryo and the initiation of dedifferentiated cellular proliferation within it. Embryogenic calli are induced by treating immature embryos with 2,4-dichlorophenoxyacetic acid (2,4-D). Upon withdrawal from 2,4-D, somatic embryos develop from the periphery of the callus. Prior to visible callus formation, there is a striking induction of 'germin-like' oxalate oxidase ('gl-OXO': EC 1.2.3.4) gene expression. Accumulation of gl-OXO mRNA is rapidly stimulated upon auxin treatment, with a consequent development of apoplastic enzyme activity producing H2O2 within the cell wall. Within the dedifferentiated calli, gl-OXO enzyme activity becomes widespread over the surface of embryogenic calli. Differentiation of somatic embryos is initiated in regions of densely cytoplasmic, meristematic cells that are marked by highly localised expression of gl-OXO activity within these embryogenic cell masses. We suggest that this localised generation of H2O2 by gl-OXO promotes peroxidative cross-linking of cell wall components, thereby preventing cellular expansion and maintaining these cell masses in an embryogenically competent condition
Keyword	[ Hide all but 1 of 37 ] 2,4 d accumulation acid bioaccumulation biosynthesis callus cells cross-linking differentiation enzyme enzyme activity expression gene gene expression gene expression regulation gene-expression generation germination glycoproteins hydrogen peroxide immature embryos in vitro regeneration induction messenger rna mrna oxalate oxidase oxalic acid oxidoreductases plant proteins regions somatic embryogenesis somatic embryos suppression triticum triticum aestivum triticum-aestivum wheat

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