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GrainGenes Reference Report: PPS-125-1508

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Reference
PPS-125-1508
Title
Expression of a gibberellin 2-oxidase gene around the shoot apex is related to phase transition in rice
Journal
Plant Physiology
Year
2001
Volume
125
Pages
1508-1516
Author
Sakamoto T
[ Show all 8 ]
Abstract
Summary: A major catabolic pathway for gibberellin (GA) is initiated by 2beta-hydroxylation, a reaction catalyzed by GA 2-oxidase. We have isolated and characterized a cDNA, designated Oryza sativa GA 2-oxidase 1 (OsGA2ox1) from rice (Oryza sativa L. cv Nipponbare) that encodes a GA 2-oxidase. The encoded protein, produced by heterologous expression in Escherichia coli, converted GA1, GA4, GA9, GA20, and GA44 to the corresponding 2beta-hydroxylated products GA8, GA34, GA51, GA29, and GA98, respectively. Ectopic expression of the OsGA2ox1 cDNA in transgenic rice inhibited stem elongation and the development of reproductive organs. These transgenic plants were deficient in endogenous GA1. These results indicate that OsGA2ox1 encodes a GA 2-oxidase, which is functional not only in vitro but also in vivo. OsGA2ox1 was expressed in shoot apex and roots but not in leaves and stems. In situ hybridization analysis revealed that OsGA2ox1 mRNA was localized in a ring at the basal region of leaf primordia and young leaves. This ring-shaped expression around the shoot apex was drastically decreased after the phase transition from vegetative to reproductive growth. It was absent in the floral meristem, but it was still present in the lateral meristem that remained in the vegetative phase. These observations suggest that OsGA2ox1 controls the level of bioactive GAs in the shoot apical meristem; therefore, reduction in its expression may contribute to the early development of the inflorescence meristem
Keyword
[ Hide all but 1 of 53 ]
apex
apical meristem
cdna
deficient
development
developmental stages
early development
ectopic expression
elongation
enzyme activity
escherichia coli
floral meristem
gas
gene
gene expression
genetic regulation
genetic variation
gibberellin
growth
heterologous expression
hybridization
in situ
in situ hybridization
in vitro
in vivo
inflorescence
its
leaf primordia
meristem
mrna
oryza sativa
oxidation
oxidoreductases
phase
plant anatomy
plant morphology
products
reduction
rice
root
sexual reproduction
shoot
shoot apex
shoot apical meristem
situ hybridization
stem
stem elongation
transgenic
transgenic plant
transition
vegetative period
vitro
young leaf

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