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The Brassica rapa elongated internode (EIN) gene encodes phytochrome B
P F Devlin1, D E Somers, P H Quail
1Department of Botany, University of Leicester, UK.
Plant Molecular Biology
|June 1, 1997
Summary
The elongated internode (ein) mutation in Brassica rapa causes a deficiency in phytochrome B due to a DNA deletion. This mutation partially affects plant responses to light, showing a link between phytochrome B levels and plant phenotype.
Area of Science:
- Plant genetics
- Molecular biology
- Photomorphogenesis
Background:
- The elongated internode (ein) mutation in Brassica rapa is associated with reduced phytochrome B levels.
- Phytochrome B plays a crucial role in plant photomorphogenesis and light responses.
Purpose of the Study:
- To investigate the molecular basis of the ein mutation in Brassica rapa.
- To understand the impact of the mutation on phytochrome B levels and light responsiveness.
Main Methods:
- Molecular analysis of the PHYB gene in wild-type and ein mutant Brassica rapa.
- Restriction fragment length polymorphism (RFLP) and inverse PCR to characterize DNA deletion.
- Quantification of immunochemically detectable phytochrome B.
- Assessment of seedling response to red light and red/far-red light ratios.
Main Results:
- A 500 bp deletion was identified in the DNA flanking the 5' region of the PHYB gene in ein mutants.
- Heterozygous EIN/ein seedlings exhibited approximately 50% of wild-type phytochrome B levels.
- Seedling elongation responses to light were intermediate in heterozygotes, indicating partial dominance of the ein mutation.
Conclusions:
- The deletion in the PHYB gene's 5' flanking region likely affects phytochrome B transcription or processing.
- Partial dominance of the ein mutation suggests a direct correlation between phytochrome B levels and plant phenotype.
- This study elucidates the genetic and molecular mechanisms underlying light-mediated growth regulation in Brassica rapa.