Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, China.
Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, China.
J Plant Physiol. 2021 May;260:153388. doi: 10.1016/j.jplph.2021.153388. Epub 2021 Feb 12.
In angiosperms, mature pollen is wrapped by a pollen wall, which is important for maintaining pollen structure and function. Pollen walls provide protection from various environmental stresses and preserve pollen germination and pollen tube growth. The pollen wall structure has been described since pollen ultrastructure investigations began in the 1960s. Pollen walls, which are the most intricate cell walls in plants, are composed of two layers: the exine layer and intine layer. Pollen wall formation is a complex process that occurs via a series of biological events that involve a large number of genes. In recent years, many reports have described the molecular mechanisms of pollen exine development. The formation process includes the development of the callose wall, the wavy morphology of primexine, the biosynthesis and transport of sporopollenin in the tapetum, and the deposition of the pollen coat. The formation mechanism of the intine layer is different from that of the exine layer. However, few studies have focused on the regulatory mechanisms of intine development. The primary component of the intine layer is pectin, which plays an essential role in the polar growth of pollen tubes. Demethylesterified pectin is mainly distributed in the shank region of the pollen tube, which can maintain the hardness of the pollen tube wall. Methylesterified pectin is mainly located in the top region, which is beneficial for improving the plasticity of the pollen tube top. In this review, we summarize the developmental process of the anther, pollen and pollen wall in Arabidopsis; furthermore, we describe the research progress on the pollen wall formation pattern and its molecular mechanisms in detail.
在被子植物中，成熟花粉被花粉壁包裹，花粉壁对于维持花粉结构和功能至关重要。花粉壁提供了对各种环境胁迫的保护，并保持花粉的萌发和花粉管的生长。自 20 世纪 60 年代开始对花粉超微结构进行研究以来，人们就已经对花粉壁结构进行了描述。花粉壁是植物中最复杂的细胞壁，由两层组成：外壁层和内壁层。花粉壁的形成是一个复杂的过程，涉及一系列生物学事件，涉及大量基因。近年来，许多报道描述了花粉外壁发育的分子机制。形成过程包括胼胝质壁的发育、原外壁的波浪形态、绒毡层中角鲨烯的生物合成和运输，以及花粉外壁的沉积。内壁层的形成机制与外壁层不同。然而，很少有研究关注内壁发育的调控机制。内壁层的主要成分是果胶，它在花粉管的极性生长中起着重要作用。去甲酯化果胶主要分布在花粉管的柄部区域，可保持花粉管壁的硬度。甲酯化果胶主要位于顶部区域，有利于提高花粉管顶部的可塑性。在这篇综述中，我们总结了拟南芥花药、花粉和花粉壁的发育过程；此外，还详细描述了花粉壁形成模式及其分子机制的研究进展。
