PLANT PHYSIOLOGY , Vol 101, Issue 3 759-764, Copyright © 1993 by American Society of Plant Biologists
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DEVELOPMENT AND GROWTH REGULATION |
Expression of the le Mutation in Young Ovaries of Pisum sativum and Its Effect on Fruit Development
C. M. Santes, P. Hedden, V. M. Sponsel, J. B. Reid and J. L. Garcia-Martinez
Instituto de Agroquimica y Tecnologia de Alimentos (Consejo Superior de Investigaciones Cientificas), Jaime Roig 11, 46010-Valencia, Spain (C.M.S., J.L.G.-M.)
The effect of the le mutation on the growth and gibberellin (GA) content of
developing fruits was investigated using the near-isogenic lines of Pisum
sativum L. 205+ (LeLe) and 205- (lele). Although stem elongation is known
to be reduced in 205- plants by approximately 65%, the growth of pods and
seeds was unaffected by the le mutation. GA1, GA3, and GA20 stimulated
parthenocarpic development of unpollinated ovaries on both 205+ and 205-
plants. GA20 was less active on 205- ovaries than on 205+, whereas GA1 had
similar, high activity in both lines. The activity of GA3 was even higher
than that of GA1 in both lines. Decapitation of 205+ plants induced
parthenocarpic development of unpollinated ovaries, but this treatment was
much less effective on 205- plants. The contents of GA1 and GA8 in entire
ovaries 6 d after anthesis, as well as in the pod and fertilized ovules,
were substantially lower in 205- than in 205+ plants, whereas the reverse
was true for the levels of GA20 and GA29. These results suggest that
3[beta]-hydroxylation of GA20 to GA1 is reduced in ovaries as well as in
vegetative tissues. Thus, the le mutation appears to be expressed in young
reproductive organs of the 205- line, even though it does not affect the
fruit phenotype. Because the content of GA3 in the ovary was similar in the
two lines, one explanation for the normal fruit size in the 205- line is
that GA3 is the native regulator of pod growth. Alternatively, sufficient
GA1 may still be produced in 205- fruits to maintain normal pod growth.
