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Abstract Detail

Hormone Biology

Lo, Shuen-Fang [1], Yu, Su-May [2], Chen, Liang-Jwu [3].

Functional identification and expression analyses of two T-DNA insertion mutants with activated expression of rice gibberellin 2-oxidase genes OsGA2ox5 and OsGA2ox6 respectively.

Two T-DNA insertion mutants that activate the expression of gibberellin 2-oxidase genes, OsGA2ox5 and OsGA2ox6, were isolated respectively from the Taiwan Rice Insertion Mutant (TRIM) pool and characterized. M0047191, one of the T-DNA insertion mutant lines, encoding OsGA2ox6 showed a dwarf phenotype with dark green, curled leaves and being nearly sterile, a typical bioactive GA deficiency phenotype. While significant amounts of OsGA2ox6 RNAs were detected in leaves and all the tissues tested in this mutant, the expression of OsGA2ox6 was slightly observed in leaves at all stages and barely detectable in the panicles and reproductive organs of the wild-type rice plant. In addition, the expression pattern of OsGA2ox6 was very different from the eight other available OsGA2ox gene families. Genotyping of T-DNA insertion in T1 progenies revealed that the T-DNA insertion and the activation of OsGA2ox6 gene were tightly linked to the dwarf phenotype, and that the dwarf phenotype can be partially rescued by treatment with GA3. Transgenic expression of this OsGA2ox6 gene in wild-type plant revealed all dwarf phenotypes, the same as that of the T-DNA insertion mutant. Another mutant M0027337, with its T-DNA inserted at 23 bp upstream of the stop codon of the OsGA2ox5 gene, resulted in activated expression of a truncated gene and showed a normal phenotype. However, transgenic lines over-expressed the intact OsGA2ox5 gene showed all dwarf phenotypes, indicating the same effect as that of OsGA2ox6. Sequences comparisons revealed that OsGA2ox5 and OsGA2ox6 are homologous to previously reported AtGA2ox7, AtGA2ox8 and SoGA2ox3 genes which were identified to play novel roles in GA metabolism. Whether or not these two newly identified OsGA2ox genes play important roles in regulating GA metabolism in rice requires further investigation.

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1 - National Chung Hsing University, Institute of Molecular Biology
2 - Academia Sinica, Institute of Molecular Biology
3 - National Chung Hsing University, Institute of Molecular Biology, 250 Kuo-Kuang Road, Taichung, Taiwan, 40227, Taiwan

Mutant Screening
Activation Tagging.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P35035
Abstract ID:1359

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