Vicente O, Moreno R M, Heberle-Bors E
Institute of Microbiology and Genetics, University of Vienna, Austria.
Cell Biol Rev. 1991;25(4):295-306.
In in vitro cultures, isolated microspores and pollen grains can undergo two fundamentally different types of development. In conditions that simulate the tapetum they continue normal gametophytic development to produce functional pollen. Under stress conditions, they are induced to form haploid embryos and plants (sporophytes). In vitro matured pollen is a "minimal" pollen that lacks substances to enhance its reproductive success. In vitro pollen maturation is presented as an experimental system to study pollen development and its interaction with the tapetum. For young binucleate pollen grains, a starvation treatment is sufficient to induce sporophytic development, for microspores a heat shock treatment is required. During the stress treatments, transcription of specific mRNAs is activated. An important aspect of embryogenic induction of binucleate pollen is the derepression of the cell cycle in the G1-arrested vegetative cell.
在体外培养中，分离的小孢子和花粉粒可经历两种根本不同类型的发育。在模拟绒毡层的条件下，它们继续正常的配子体发育以产生有功能的花粉。在胁迫条件下，它们被诱导形成单倍体胚胎和植株（孢子体）。体外成熟的花粉是一种“最小化”的花粉，缺乏增强其繁殖成功率的物质。体外花粉成熟被视为一种研究花粉发育及其与绒毡层相互作用的实验系统。对于年轻的双核花粉粒，饥饿处理足以诱导孢子体发育，而对于小孢子则需要热激处理。在胁迫处理期间，特定mRNA的转录被激活。双核花粉胚胎发生诱导的一个重要方面是在G1期停滞的营养细胞中细胞周期的去抑制。
