Distribution of pectins in the pollen apertures of Oenothera hookeri.velans ster/+ster:

I.Noher De Halac,M.I Rodriguez-Garc韆,I.A Cismondi,G.fam� G.Fam�

doi:10.32604/biocell.2003.27.011

Abstract

Cell wall pectins are some of the most complex biopolymers known, and yet their functions remain largely mysterious. The aim of this paper was to deepen the study of the spatial pattern of pectin distribution in the aperture of Oenothera hookeri.velans ster/+ster fertile pollen. We used "in situ" immunocytochemical techniques at electron microscopy, involving monoclonal antibodies JIM5 and JIM7 directed against pectin epitopes in fertile pollen grains of Oenothera hookeri.velans ster/+ster. The same region was also analyzed by classical cytochemistry for polysaccharide detection. Immunogold labelling at the JIM7 epitope showed only in mature pollen labelling mainly located at the intine endo-aperture region. Cytoplasmic structures near the plasma membrane of the vegetative cell showed no labelling gold grains. In the same pollen stge the labelling at the JIM5 epitope was mostly confined to a layer located in the limit between the endexine and the ektexine at the level of the border of the oncus. Some tubuli at the base of the ektexine showed also an accumulation of gold particles. No JIM5 label was demonstrated in the aperture chamber and either in any cytoplasmic structure of the pollen grains. The immunocytochemical technique, when compared with the traditional methods for non-cellulose polysaccharide cytochemistry is fare more sensitive and allows the univocal determination of temporal and spatial location of pectins recognized by the JIM7 and JIM5 MAbs.

Highlights

Cell wall pectins are some of the most complex biopolymers known (Fry, 1986; Jarvis, 1984; Schols et al, 1995; Geitmann et al, 1995; Albersheim et al, 1996; Willats et al, 2001)
In the present work we study the spatial pattern of pectins and other polysaccharides in the aperture of Oenothera hookeri.velans ster/+ster fertile pollen using the “in situ” immunolabelling technique at electron microscopy level, with JIM7 and JIM5 monoclonal antibodies (MAbs) as markers
The morphological structure and the staining characteristics of the sporoderm were: a) Configuration in three layers: the endexine, the ektexine and the intine; b) The endexine was smooth looking with electron microscopy (Figs. 4-8) being composed of sporopollenin and other materials reacting greenish with toluidine blue (Fig. 3) and not changing color with ruthenium red (Fig. 2), nor with alcian blue (Fig. 1); c) The ektexine is a delicate network of branching sporopollenin rods, with ed the same staining properties than the endexine

Summary

Introduction

Cell wall pectins are some of the most complex biopolymers known (Fry, 1986; Jarvis, 1984; Schols et al, 1995; Geitmann et al, 1995; Albersheim et al, 1996; Willats et al, 2001). Pectin is a family of complex polysaccharides present in all plant primary cell walls. Quired to synthesize pectin, suggests that pectins have multiple functions in plant growth and development (Ridley et al, 2001). They play important roles in cell wall hydration, adhesion of adjacent cells, wall plasticity during growth and recognition reactions between plant cells and bacterial and fungal pathogens. The role of pectin esterification and the ability to form gels remain unclear in terms of pectin function within plant cell walls. The methylesterification of the carboxyl groups prevents the formation of calcium bridges

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