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Arabidopsis HY8 locus encodes phytochrome A
K Dehesh1, C Franci, B M Parks
1University of California-Berkeley/U.S. Department of Agriculture, Albany 94710.
The Plant Cell
|September 1, 1993
Summary
Mutants defective in far-red light response lack functional phytochrome A (phyA). A specific mutation in phyA disrupts its regulatory activity, not its light perception, highlighting glycine-727
Area of Science:
- Plant biology
- Molecular genetics
- Photomorphogenesis
Background:
- Arabidopsis mutants hy8 exhibit defects in far-red light response.
- These mutants are deficient in functional phytochrome A (phyA).
Purpose of the Study:
- To identify the molecular basis of the hy8 long hypocotyl mutants.
- To elucidate the role of phytochrome A in light signaling.
Main Methods:
- Sequencing of the phytochrome A gene (phyA) in hy8 mutant lines.
- Analysis of phyA protein expression and activity.
- Quantitative fluence rate response analysis.
Main Results:
- Two classes of hy8 mutants were identified: hy8-1/hy8-2 with premature stop codons in phyA, and hy8-3 with a glycine-to-glutamate missense mutation at residue 727.
- The hy8-3 mutant produced a non-functional phyA protein, indicating glycine-727 is crucial for phyA regulatory activity.
- phyA was confirmed to reside at the HY8 locus.
Conclusions:
- The HY8 locus encodes phytochrome A.
- A missense mutation at glycine-727 in phyA abolishes its regulatory function, essential for far-red light response.
- Glycine-727 is critical for phytochrome A's regulatory activity, not its ability to perceive light.