Spielman M, Preuss D, Li F L, Browne W E, Scott R J, Dickinson H G
Department of Plant Sciences, University of Oxford, UK.
Development. 1997 Jul;124(13):2645-57. doi: 10.1242/dev.124.13.2645.
In flowering plants, male meiosis occurs in the microsporocyte to produce four microspores, each of which develops into a pollen grain. Here we describe four mutant alleles of TETRASPORE (TES), a gene essential for microsporocyte cytokinesis in Arabidopsis thaliana. Following failure of male meiotic cytokinesis in tes mutants, all four microspore nuclei remain within the same cytoplasm, with some completing their developmental programmes to form functional pollen nuclei. Both of the mitotic divisions seen in normal pollen development take place in tes mutants, including the asymmetric division required for the differentiation of gametes; some tes grains perform multiple asymmetric divisions in the same cytoplasm. tes pollen shows a variety of abnormalities subsequent to the cytokinetic defect, including fusion of nuclei, formation of ectopic internal walls, and disruptions to external wall patterning. In addition, ovules fertilized by tes pollen often abort, possibly because of excess paternal genomes in the endosperm. Thus tes mutants not only reveal a gene specific to male meiosis, but aid investigation of a wide range of processes in pollen development and function.
在开花植物中，雄配子减数分裂发生在小孢子母细胞中，产生四个小孢子，每个小孢子发育成一个花粉粒。我们在此描述了拟南芥中TETRASPORE（TES）基因的四个突变等位基因，该基因对小孢子母细胞胞质分裂至关重要。在tes突变体中，雄配子减数分裂胞质分裂失败后，所有四个小孢子核都保留在同一细胞质中，其中一些完成其发育程序形成功能性花粉核。正常花粉发育中出现的两次有丝分裂在tes突变体中均会发生，包括配子分化所需的不对称分裂；一些tes花粉粒在同一细胞质中进行多次不对称分裂。在胞质分裂缺陷之后，tes花粉表现出多种异常，包括细胞核融合、异位内壁形成以及外壁图案破坏。此外，由tes花粉受精的胚珠通常会败育，可能是因为胚乳中父本基因组过多。因此，tes突变体不仅揭示了一个雄配子减数分裂特有的基因，还有助于研究花粉发育和功能中的广泛过程。
