Abstract:  Sporopollenin is a biopolymer considered as one of the most stable organic substances on the Earth. As a principal component of the outer walls of terrestrial plant spores and pollen, sporopollenin plays a pivotal role in the evolutionary transition of plants from aquatic to terrestrial environments. Its unique chemical stability enhances the resistance of pollen and sporewalls, thereby assisting plants in adapting to various terrestrial stresses such as high temperature, drought, and ultraviolet radiation. Despite its crucial protective role in plant reproduction, the high stability of sporopollenin has long posed significant challenges for elucidating its chemical composition. However, through a series of structural, chemical, and genetic experiments, researchers have made substantial progress in revealing the molecular structure and biosynthesis mechanisms of this biopolymer. Scientists have utilized gene localization techniques to decipher the pathways involved in sporopollenin biosynthesis, including fatty acid pathways, phenylpropanoid pathways, and flavonoid pathways, which exhibit considerable conservation among terrestrial plants. Recent analyses combining chemical dissolution methods with nuclear magnetic resonance and mass spectrometry have resolved the core structure of sporopollenin. Phenylpropanoid derivatives form polymers through carbon-carbon bond cross-coupling, while hydroxylated fatty acids crosslink these polymers to constitute the core structure of sporopollenin. These new findings not only provide a foundation for understanding the reproductive mechanisms of how plants cope with stress in terrestrial environments but also open up new avenues for utilizing this abundant and highly stable biological material

Key words:  , sporopollenin, pollen wall, spore wall, composition, structure