US EPA

5078781 

Journal Article 

The molecular structure of plant sporopollenin 

Li, FS; Phyo, P; Jacobowitz, J; Hong, M; Weng, JK 

2019 

5 

1 

41-46 

English 

30559416 

10.1038/s41477-018-0330-7 

WOS:000457910100014 

http://www.nature.com/articles/s41477-018-0330-7
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Sporopollenin is a ubiquitous and extremely chemically inert biopolymer that constitutes the outer wall of all land-plant spores and pollen grains1. Sporopollenin protects the vulnerable plant gametes against a wide range of environmental assaults, and is considered a prerequisite for the migration of early plants onto land2. Despite its importance, the chemical structure of plant sporopollenin has remained elusive1. Using a newly developed thioacidolysis degradative method together with state-of-the-art solid-state NMR techniques, we determined the detailed molecular structure of pine sporopollenin. We show that pine sporopollenin is primarily composed of aliphatic-polyketide-derived polyvinyl alcohol units and 7-O-p-coumaroylated C16 aliphatic units, crosslinked through a distinctive dioxane moiety featuring an acetal. Naringenin was also identified as a minor component of pine sporopollenin. This discovery answers the long-standing question about the chemical make-up of plant sporopollenin, laying the foundation for future investigations of sporopollenin biosynthesis and for the design of new biomimetic polymers with desirable inert properties.