Sporopollenin, a critical innovation in the evolution of terrestrial plants, is the core building brick for the outer wall of land-plant spores and pollen. Despite its significance, the basic structure of sporopollenin remains elusive due to its extreme chemical inertness. In this study, we used ethanolamine to completely dissolve rape sporopollenin and successfully identified a total of 22 components, including fatty acids, p-coumaric acid, sterols and polymeric phenylpropanoid derivatives. After that, using NaOH treatment and partial dissolution, alongside Arabidopsis mutants analysis and spectroscopic methods, we determined that polymeric phenylpropanoid derivatives crosslinked by hydroxyl fatty acids serve as the core structure of sporopollenin. The free hydroxyl groups and carboxyl groups of the polymeric phenylpropanoid derivatives can be modified by other fatty acids (C16:0, C18:0 and C18:3) as well as alcohols/phenols (for example, naringenin, β-sitosterol), resulting in a structure that protects pollen from terrestrial stresses. This discovery provides a basis for further exploration of sporopollenin’s role in plant reproduction and evolution.

孢粉素是陆生植物进化的关键创新，是陆地植物孢子和花粉外壁的核心构建砖。尽管它很重要，但由于其极端的化学惰性，孢粉素的基本结构仍然难以捉摸。在这项研究中，我们使用乙醇胺完全溶解油菜孢粉素，并成功鉴定了总共 22 种成分，包括脂肪酸、对香豆酸、甾醇和聚合苯丙烷衍生物。之后，使用 NaOH 处理和部分溶解，以及拟南芥突变体分析和光谱方法，我们确定由羟基脂肪酸交联的聚合物苯丙烷衍生物作为孢粉素的核心结构。聚合物苯丙烷衍生物的游离羟基和羧基可被其他脂肪酸（C16：0、C18：0 和 C18：3）以及醇/酚类（例如柚皮素、β-谷甾醇）修饰，从而形成保护花粉免受陆地胁迫的结构。这一发现为进一步探索孢粉素在植物繁殖和进化中的作用提供了基础。