PLANT PHYSIOLOGY , Vol 112, Issue 1 61-66, Copyright © 1996 by American Society of Plant Biologists
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DEVELOPMENT AND GROWTH REGULATION |
The Gibberellin Status of lip1, a Mutant of Pea That Exhibits Light-Independent Photomorphogenesis
V. M. Sponsel, J. J. Ross, M. R. Reynolds, G. M. Symons and J. B. Reid
Division of Life Sciences, University of Texas at San Antonio, San Antonio, Texas 78249 (V.M.S.)
Dark-grown seedlings of the lip1 (light independent photomorphogenesis)
mutant of Pisum sativum L. display many features of de-etiolated growth and
are similar in many respects to wild-type (WT) seedlings grown in the
light. The involvement of gibberellins (GAs) with the mutant phenotype was
examined by applying GA1 and GA20 to the mutant and WT, and by quantifying
endogenous GA1, GA8, GA19, GA20, and GA29 levels in the two genotypes.
These experiments were conducted in both the light and the dark. In neither
environment could GA application restore elongation in the mutant to that
in GA-treated WT plants. Quantification of GAs provided further evidence
that the mutant phenotype is not attributable to a deficiency in endogenous
GA1. However, dark-grown lip1 seedlings contained lower levels of GA19 and
higher levels of GA20 than dark-grown WT plants, whereas in the light, the
effect of the mutation on the ratio of GA19 to GA20 was reversed. Thus,
there appears to be a complex interaction between the lip1 mutation, the
light regime, and the step GA19 to GA20.
