PLANT PHYSIOLOGY , Vol 115, Issue 3 1221-1230, Copyright © 1997 by American Society of Plant Biologists
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CELL BIOLOGY AND SIGNAL TRANSDUCTION |
Pollen-Stigma Adhesion in Kale Is Not Dependent on the Self-(In)Compatibility Genotype
D. T. Luu, P. Heizmann and C. Dumas
Reproduction et Developpement des Plantes, Unite Mixte de Recherche, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Ecole Normale Superieure de Lyon, 46 allee d'Italie, F-69364 Lyon cedex 07, France
The adhesion of pollen on the stigmas of flowering plants is a critical
step for the success of reproduction in angiosperms, long considered to
present some specificity in terms of self-incompatibility. We carried out
quantitative measurements of the pollen-stigma adhesion (expressed in
Newtons) in kale (Brassica oleracea), using the flotation force of
Archimedes exerted by dense sucrose solutions (50%, w/v) to release pollen
grains fixed on the surface of stigmas. We demonstrate that pollen adhesion
varies with the genotypes of the plants used as partners, but increases
with time in all cases for about 30 to 60 min after pollination. There is
no correlation with the self- or cross-status of the pollinations, nor with
the self-compatible or -incompatible genotypes of the parents. Only late
events of pollination, after the germination or arrest of the pollen tube,
depend on compatibility type. Biochemical and physiological dissection of
pollen-stigma adhesion points to major components of this interaction:
among male components, the pollen coating, eliminated by delipidation (or
modified by mutation in the case of the cer mutants of the related species
Arabidopsis thaliana), plays a major role in adhesion; the genetic
background of the pollen parent is also of some importance. On the female
side, the developmental stage of the stigma and the protein constituents of
the stigmatic pellicle are critical for pollen capture. The SLG and SLR1
proteins are not involved in the initial stages of pollen adhesion on the
stigma but one or both may be involved in the later stages.
