Characterization of genes for cell polarity and asymmetric cell division in plants

不对称细胞分裂产生两个不同的子细胞。虽然已知mRNA或蛋白质的不均匀分布对每个子细胞的特化起着关键作用，但植物中的这些分子在很大程度上仍然未知。小壶藓原胞的原生质体和顶端干细胞不对称分裂，产生两个不同的子细胞。我们之前已经报道了59个基因作为不对称细胞分裂的候选基因。对于这些候选植物，我们利用基因靶向技术构建了表达黄嘌呤融合蛋白的转基因植物，在其天然启动子的控制下研究了蛋白质的定位。我们对这些蛋白在不对称细胞分裂过程中进行了延时成像，发现一些蛋白在干细胞中优先积累，而在分化的原体细胞中不积累。我们还发现其中一些细胞在原体细胞去分化后恢复了积累。

Asymmetric cell division produces two different daughter cells. Although unequal distribution of mRNA or proteins has been known to play a pivotal role to specialize each daughter cell, such molecules in plants remain largely unknown. Protoplasts and apical stem cells of protonemata of the moss, Physcomitrella patens divide asymmetrically to generate two different daughter cells. We have previously reported 59 genes as candidates involved in the asymmetric cell division. For those candidates, we made transgenic plants expressing the citrine-fusion protein by using the gene targeting technique to investigate protein localization under a control of their native promoters. We carried out time-lapse imaging of these proteins during asymmetric cell division and found some proteins accumulated preferentially in the stem cells but not in differentiated protonemal cells. We also showed some of them resumed the accumulation upon dedifferentiation of the protonemal, somatic cells.