PLANT PHYSIOLOGY , Vol 115, Issue 1 23-28, Copyright © 1997 by American Society of Plant Biologists
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DEVELOPMENT AND GROWTH REGULATION |
The Dark-Adaptation Response of the De-Etiolated Pea Mutant lip1 Is Modulated by External Signals and Endogenous Programs
S. Frances and W. F. Thompson
Departments of Genetics (S.F.) and Botany (S.F., W.F.T.), North Carolina State University, Raleigh, North Carolina 27695
The lip1 mutant of pea (Pisum sativum L.) exhibits a de-etiolated
phenotype. When grown in darkness, lip1 plants have several characteristics
normally associated only with light-grown plants. Young wild-type (WT)
seedlings accumulate high levels of transcripts from plastid-related genes
(such as those encoding chlorophyll a/b-binding proteins, ferredoxin, and
the small subunit of Rubisco) only in the light. In contrast, regardless of
the light conditions under which the plants are grown, young mutant
seedlings accumulate transcript levels equal to or greater than those seen
in light-grown WT seedlings of the same age. Under some conditions,
light-grown lip1 seedlings failed to respond to dark treatment. The largest
response to darkness observed in the mutant occurred when older seedlings
were first grown under low-light conditions before transfer to darkness.
The mutant's inability to respond to darkness is not due to a gross
disturbance in the circadian clock. We conclude that environmental signals
(light) and endogenous programs (developmental and circadian) regulate gene
expression in both WT and mutant plants. However, mutant seedlings exhibit
a developmentally regulated and exaggerated response to light. In addition,
the effect of the mutation may be greatest during a brief period early in
development.
