sporopollenin


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sporopollenin

(spôr′ə-pŏl′ə-nĭn)
n.
A decay-resistant complex biopolymer that constitutes the outer wall of spores and pollen grains.
References in periodicals archive ?
1998), the patterned sporopollenin polymerisation in the anther mediated by 'white lines' and a glycocalyx, and the possible contribution of in vivo self-assembly of sporopollenin in the development of the sporoderm (Gabarayeva & Hemsley, 2006).
4) Finally, the potential of orbicules as a model system for in vivo research on patterned sporopollenin polymerization (including genetic control by gametophyte/sporophyte and self-assembly processes) is demonstrated.
At the free microspore stage, a material with a similar electron density to sporopollenin fills the whole locule and deposits over the pollen grain wall.
In a study by Nehring (1996), Scrippsiella trochoidea was the dominant cyst species in the water column and very common as living cysts in sediment, but this species was relatively underrepresented as empty cysts in sediment, attributable to the fragility of these cysts compared with cysts of sporopollenin.
A distinctly patterned multilayered spore wall containing sporopollenin develops around each spore/microspore.
Sporopollenin is the most biologically resistant material on earth.
Perforations and small sporopollenin granules may occur on the surface.
The tapetum and the microspores contain homologous, nearly identical genetic information for the production, release, and accumulation of sporopollenin (Hesse, 1986; Pacini et al.
Thus it is uncertain whether it is composed of sporopollenin, like those in the Asclepiadoideae, or of elastoviscin, which Dannenbaum and Schill (1991) found covering the tetrads in Raphionacme (P eriplocoideae).
The secretory tapetum is composed of cells usually with large nuclei [ILLUSTRATION FOR FIGURES 1, 64, 67 OMITTED], and it stains dark due to the cytoplasmic contents of lipids, proteins, and sporopollenin precursors [ILLUSTRATION FOR FIGURES 4, 5, 38, 42, 45, 47-50, 54, 62, 63, 65, 66 OMITTED].
Lipids, proteins, starch, and sporopollenin precursors are produced by the plasmodium [ILLUSTRATION FOR FIGURE 9 OMITTED].
Up to now these minute structures, covering the inner surface of most secretory tapeta, remained enigmatic and therefore highly attractive to botanists concerned with anther structure, pollen development, and sporopollenin synthesis.