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Effect of Temperature on Gibberellin (GA) Responsiveness and on Endogenous $\text{GA}_{1}$ Content of Tall and Dwarf Wheat Genotypes
Near-isogenic wheat (Triticum aestivum L.) lines differing in height-reducing (Rht) alleles were used to investigate the effects of temperature on endogenous gibberellin (GA) levels and seedling growth response to applied GA3. Sheath and lamina lengths of the first leaf were measured in GA treated a...
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Published in: | Plant physiology (Bethesda) 1989-07, Vol.90 (3), p.854-859 |
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Main Authors: | , , , |
Format: | Article |
Language: | English |
Subjects: | |
Online Access: | Get full text |
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Summary: | Near-isogenic wheat (Triticum aestivum L.) lines differing in height-reducing (Rht) alleles were used to investigate the effects of temperature on endogenous gibberellin (GA) levels and seedling growth response to applied GA3. Sheath and lamina lengths of the first leaf were measured in GA treated and control seedlings, grown at 11, 18, and 25°C, of six Rht genotypes in each of two varietal backgrounds, cv Maris Huntsman and cv April Bearded. Endogenous $\text{GA}_{1}$ levels in the leaf extension zone of untreated seedlings were determined by gas chromatography-mass spectrometry with a deuterated internal standard in the six Maris Huntsman Rht lines grown at 10 and 25°C. Higher temperature increased leaf length considerably in the tall genotype, less so in the Rht1 and Rht2 genotypes, and had no consistent effect on the Rht1+2, Rht3 and Rht2+3 genotypes. In all genotypes, endogenous $\text{GA}_{1}$ was higher at 25°C than at 10°C. At 10°C the endogenous $\text{GA}_{1}$ was at a similar level in all the genotypes (except Rht2+3). At 25°C it increased 1.6-fold in the tall genotype, 3-fold in Rht1 and Rht2, 6-fold in Rht3, and 9-fold in Rht1+2. Likewise, the genotypic differences in leaf length were very conspicuous at 25°C, but were only slight and often unsignificant at 11°C. The response of leaf length to applied GA3 in the Rht1, Rht2, and Rht1+2 genotypes increased significantly with lowering of temperature. These results suggest the possibility that the temperature effect on leaf elongation is mediated through its effect on the level of endogenous $\text{GA}_{1}$ and that leaf elongation response to endogenous or applied GAs is restricted by the upper limits set by the different Rht alleles. |
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ISSN: | 0032-0889 1532-2548 |