Pollen sporopollenin: degradation and structural elucidation

Abstract

We report the isolation of purified sporopollenin from pollen grains of different species and its complete solubilization. Exine from Pinus pinaster, Betula alba, Ambrosia elatior and Capsicum annuum was extracted by treatment with hydrogen fluoride in pyridine. These exines were purified from their aromatic moieties and from fatty acids linked by ester bonds using acidolysis and saponification treatments. The biopolymer obtained retains almost completely the shape of the original pollen grain. Fourier-transform infrared spectroscopy analysis of the isolated sporopollenin showed the absence of polysaccharide and phenolic material and the presence of carboxylic acid groups joined to unsaturations and ether linkages. Sporopollenin samples were successfully degraded by exhaustive 24-h ozonolysis at room temperature. Gentle ozonolysis (3 h at 0°C) did not completely degrade the biopolymer. The compounds obtained after exhaustive ozonolysis were analysed by gas chromatography-mass spectrometry. Dicarboxylic acids with a low number of carbon atoms were identified as major components of sporopollenin from P. pinaster, A. elatior and C. annuum, representing 28.8%, 63.2% and 88.5%, respectively, of the total compounds obtained. Fatty acids and n-alkanes also were identified in P. pinaster, A. elatior and B. alba sporopollenin. From the data obtained, an hypothesis about the chemical nature and structural arrangement of the sporopollenin is proposed.

Novel Phenanthrene Sorption Mechanism by Two Pollens and Their Fractions

“…The H-to-C and O-to-C atomic ratios of NHC (e.g., sporopollenin) are lower in this study than those reported previously. 37 It seems that there are significant correlations among H-to-C and O-to-C atomic ratios and the sorption affinity of Phen by the pollens and their fractions, as observed previously for other biosorbents. 20 Structure of Bulk Pollen and Isolated Fractions.…”

LAP3, a novel plant protein required for pollen development, is essential for proper exine formation

“…lap3-2 leads to a wide variety of metabolic consequences in developing anthers. Given the model of sporopollenin composed of fatty acid and phenolic compounds (Guilford et al 1988;Kawase and Takahashi 1995;Ahlers et al 1999Ahlers et al , 2000Ahlers et al , 2003Dominguez et al 1999;MeuterGerhards et al 1999;Bubert et al 2002), it is of interest to note that some changes were detected in the levels of lipids (such as a-linolenic acid, 1-18:3-lysophophatidylethanolamine, 1-16:0-lysophophatidylethanolamine, a-eleosteric acid, and 10E,12Z-octadecadienoic acid, linoleic acid, nonacosane and palmitic acid) and of at least one phenylpropanoid (naringenin chalcone).…”

“…In addition, a possibility exists that sporopollenin is not a single substance, but instead varies chemically between species and even between different stages of development (Hemsley et al 1993;Meutergerhards et al 1995). Despite these difficulties, tracer experiments, NMR and spectroscopic/spectrometric studies have yielded a model of sporopollenin composed of polyhydroxylated unbranched aliphatics and phenolics covalently coupled with ether and ester linkages (Guilford et al 1988;Kawase and Takahashi 1995;Ahlers et al 1999Ahlers et al , 2000Ahlers et al , 2003Dominguez et al 1999;Meuter-Gerhards et al 1999;Bubert et al 2002).…”

Pollen fillers for reinforcing and strengthening of epoxy composites

“…The exine, composed of a substance called sporopollenin, is highly crosslinked and consists of fatty acid, phenylpropanoid, and phenolic substances. Sporopollenin is an extraordinarily stable natural organic substance [18,19]. The monomers and macromers thought to comprise sporopollenin include aliphatic chains, aromatic cross-linkers (mainly cinnamic acids), ether cross-linkers, Electronic supplementary material The online version of this article (https://doi.org/10.1007/s42247-018-0009-x) contains supplementary material, which is available to authorized users.…”