Plant stigmas distinguish the pollen grains and allow compatible ones to fertilize female gametes. To analyze the underlying mechanism, conditional male-sterile mutations with impaired pollen coat and pollen–stigma recognition were isolated. The mutant pollen could germinate in vitro but not in vivo, suggesting that they are viable. The mutant stigma cells that contacted their own pollen-generated callose, a carbohydrate typically produced in response to foreign pollen. The defects of pollen hydration and fertilization in the mutants were rescued by high humidity, indicating that hydration is required for pollen–stigma interaction. Pollination with mixture of wild type and mutant pollens demonstrated that the pollen–stigma recognition of mutant pollen was disrupted. The mutant plants exhibited lack of stem waxes and postgenital fusion between aerial floral organs. In addition, the mutant pollen was deficient in very-long-chain lipids and had excess tryphine. Transmission electron microscopy analysis showed that mutant pollen had almost the same surface structure as the wild type at bicellular pollen stage. However, abnormal plastoglobuli were observed in the plastids of the mutant tapetum, which was an indicative of altered lipid accumulation. CER3 transcripts were found in anther tapetum and microspores at development stage 9. Our data reveal that CER3 is required for biosynthesis of tryphine lipids which function to maintain hydration for pollen–stigma recognition during fertilization.

植物柱头可区分花粉粒，并允许相容的花粉使雌配子受精。为了分析潜在的机制，分离了带有花粉被膜受损和花粉-柱头识别的条件性雄性不育突变。突变的花粉可以在体外发芽，但不能在体内发芽，表明它们是可行的。突变的柱头细胞接触到它们自己的花粉产生的ose，一种通常响应外来花粉而产生的碳水化合物。高湿度可以挽救突变体中花粉水合和受精的缺陷，这表明花粉-柱头相互作用需要水合。野生型和突变型花粉混合物的授粉表明突变型花粉的花粉-柱头识别被破坏。突变植物表现出茎蜡的缺乏和生殖器官之间的生殖器融合。此外，突变体花粉缺乏超长链脂质，并含有过量的胰蛋白酶。透射电镜分析表明，在双细胞花粉阶段，突变体花粉的表面结构几乎与野生型相同。然而，在突变绒毡层的质体中观察到异常的质体球，这表明脂质积累发生了改变。在发育阶段9的花药绒毡层和小孢子中发现了CER3转录本。我们的数据表明，CER3是胰蛋白酶脂质生物合成所必需的，其功能是在受精过程中维持水合作用，以实现花粉-柱头的识别。