We aimed to unravel the underlying mechanisms of pollen wall development in Hydrangea bretschneiderii. For this, we tested our hypothesis that distinct physical processes, phase separation and micellar self-assembly, underpinned exine development by taking the substances, determined by the genome, through several phase transitions. We traced each developmental stage with TEM; then, we obtained in vitro simulations corresponding to those stages. The main steps of exine ontogeny observed in the microspore periplasmic space were initiated with phase separation, resulting in the conversion of homogeneous contents to heterogeneous two-layered state of the material. After each step of phase, separation self-assembly picked up the initiative and took the substances through the sequence of micellar mesophases which were the base for all the exine structures. These mesophases are as follows: spherical micelles, transforming first into columns, and then to cylindrical micelles which turn to columellae after initial sporopollenin accumulation. The tectum appeared along the interface of the phase separated material. After the tetrad disintegration and the next phase separation, laminate mesophase appeared being the base for the endexine lamellae. Then, a new step of phase separation at aperture sites brought the appearance of a granular endexine layer; the latter became intermixed finally with lamellae. This gives, together with experimental simulation, strong evidence that the genome "shifts a part of work" on exine formation onto physical processes, and the latter are an inherent mechanism of evolution.

中文翻译：

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绣球花的花粉壁发育 Dippel。（绣球科）：通过物理输入的高级解释，具有体外实验验证

我们旨在解开绣球花花粉壁发育的潜在机制。为此，我们测试了我们的假设，即不同的物理过程、相分离和胶束自组装，通过将基因组确定的物质通过几个相变来支持外壁发育。我们用 TEM 追踪了每个发展阶段；然后，我们获得了对应于这些阶段的体外模拟。在小孢子周质空间中观察到的外壁个体发育的主要步骤是从相分离开始的，导致材料的同质内容物转化为异质的两层状态。在每个阶段之后，分离自组装占据了主动权，并将物质通过胶束中间相序列，这是所有外壁结构的基础。这些中间相如下：球形胶束，首先转化为柱状，然后转化为圆柱形胶束，在初始孢粉素积累后转变为柱状体。顶盖沿着相分离材料的界面出现。在四分体崩解和下一相分离之后，层状中间相出现，成为endexine 薄片的基础。然后，孔位相分离的新步骤带来了粒状endexine层的出现；后者最终与薄片混合在一起。这与实验模拟一起提供了强有力的证据表明基因组“转移了一部分工作”