PLANT PHYSIOLOGY , Vol 108, Issue 2 517-523, Copyright © 1995 by American Society of Plant Biologists
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DEVELOPMENT AND GROWTH REGULATION |
Effect of the Growth Retardant 3,5-Dioxo-4-butyryl-cyclohexane Carboxylic Acid Ethyl Ester, an Acylcyclohexanedione Compound, on Fruit Growth and Gibberellin Content of Pollinated and Unpollinated Ovaries in Pea
C. M. Santes and J. L. Garcia-Martinez
Instituto de Biologia Molecular y Celular de Plantas, Universidad Politecnica de Valencia-Consejo Superior de Investigaciones Cientificas, Camino de Vera s/n, 46022-Valencia, Spain
Treatment of pollinated pea (Pisum sativum L. cv Alaska, line V1) ovaries
with 3,5-dioxo-4-butyryl-cyclohexane carboxylic acid ethyl ester (LAB), an
acylcyclohexanedione derivative that competitively inhibits
2-oxoglutarate-dependent gibberellin (GA) dioxygenases, caused a reduction
of pod elongation proportional to the amount of inhibitor applied. The
effect of LAB was counteracted by GA1 and GA3, and partially by GA20. The
inhibitor decreased the contents of GA1 and GA3 (the purported active GAs)
and GA8, increased those of GA19 and GA20, and did not affect that of GA29
in both the pod and the developing seeds. These results provide evidence
that GA1 and/or GA3 control pod development in pea and show that GA20 is
not active per se. In contrast to its effect on pollinated ovaries, LAB
promoted parthenocarpic development of unpollinated ovaries, which is
associated with an increase of GA1 and GA8 content. The inhibitor enhanced
the response of unpollinated ovaries to GA1 and GA20, but it did not alter
the response to GA3. LAB is proposed to promote parthenocarpic development
and enhance the response to exogenous GAs by blocking the
2[beta]-hydroxylation of GA1 more efficiently than 3[beta]-hydroxylation of
GA20.
