Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois 60637, USA.
Plant Cell. 2012 Nov;24(11):4452-64. doi: 10.1105/tpc.112.101220. Epub 2012 Nov 6.
Pollen grains protect the sperm cells inside them with the help of the unique cell wall, the exine, which exhibits enormous morphological variation across plant taxa, assembling into intricate and diverse species-specific patterns. How this complex extracellular structure is faithfully deposited at precise sites and acquires precise shape within a species is not understood. Here, we describe the isolation and characterization of the novel Arabidopsis thaliana gene INAPERTURATE POLLEN1 (INP1), which is specifically involved in formation of the pollen surface apertures, which arise by restriction of exine deposition at specific sites. Loss of INP1 leads to the loss of all three apertures in Arabidopsis pollen, and INP1 protein exhibits a unique tripartite localization in developing pollen, indicative of its direct involvement in specification of aperture positions. We also show that aperture length appears to be sensitive to INP1 dosage and INP1 misexpression can affect global exine patterning. Phenotypes of some inp1 mutants indicate that Arabidopsis apertures are initiated at three nonrandom positions around the pollen equator. The identification of INP1 opens up new avenues for studies of how formation of distinct cellular domains results in the production of different extracellular morphologies.
花粉粒借助独特的细胞壁——外壁，来保护内部的精子细胞。外壁在植物类群中表现出巨大的形态变异，组装成复杂多样的物种特异性模式。在一个物种中，这种复杂的细胞外结构如何在精确的部位被准确地沉积并获得精确的形状尚不清楚。在这里，我们描述了拟南芥新型基因 INAPERTURATE POLLEN1（INP1）的分离和鉴定，该基因专门参与花粉表面孔的形成，这些孔是通过在外壁沉积的特定部位限制而产生的。INP1 的缺失导致拟南芥花粉中所有三个孔的缺失，而 INP1 蛋白在发育中的花粉中表现出独特的三分体定位，表明其直接参与了孔位置的指定。我们还表明，孔的长度似乎对外壁蛋白 1 （INP1）的剂量敏感，INP1 的错误表达会影响全局外壁图案。一些 inp1 突变体的表型表明，拟南芥的孔是在花粉赤道周围的三个非随机位置开始形成的。INP1 的鉴定为研究不同细胞域的形成如何导致不同细胞外形态的产生开辟了新的途径。
