Exine dehiscing induces rape microspore polarity, which results in different daughter cell fate and fixes the apicalbasal axis of the embryo
Exine dehiscing induces rape microspore polarity, which results in different daughter cell fate and fixes the apicalbasal axis of the embryo
复制标题
DOI：
10.1093/jxb/ers327
复制
发表时间：
2013-01-01
影响因子：
6.9
通讯作者：
Sun, Meng-xiang
中科院分区：
文献类型：
--
作者：
Tang, Xingchun;Liu, Yuan;Sun, Meng-xiang
细胞极性和早期胚胎发育中的第一次不对称分裂在决定顶端基底细胞命运中的作用尚不清楚。在此之前，人们建立了一种新的甘蓝型油菜小孢子胚胎发生系统，利用物理胁迫诱导油菜外壁开裂的小孢子。与传统的小孢子培养不同，外壁开裂的小孢子出现了细胞极化和随后的不对称分裂，最终发育成典型的具胚柄的胚胎。进一步的研究表明，极性是决定顶端基细胞命运和胚柄形成的关键。然而，第一次分裂的模式不仅由细胞的极性决定，而且还受外壁破裂的位置调节。第一个分割可以是相等的，也可以不相等，其方向基本上垂直于极轴。在这两种类型的细胞分裂中，两个子细胞可以有不同的细胞命运，并产生带有胚柄的胚胎，类似于合子顶端基细胞的分化。两个子细胞的排列方向与未来胚胎发育的顶基轴方向一致。结果表明，外壁开裂诱导油菜小孢子极化，这种极化导致不同的细胞命运，并固定了胚胎发生的顶端基轴，但与细胞的不对称分裂无关。本研究揭示了早期胚胎发育过程中细胞极性、细胞不对称分裂和细胞命运决定之间的关系。
The roles of cell polarity and the first asymmetric cell division during early embryogenesis in apicalbasal cell fate determination remain unclear. Previously, a novel Brassica napus microspore embryogenesis system was established, by which rape exine-dehisced microspores were induced by physical stress. Unlike traditional microspore culture, cell polarity and subsequent asymmetric division appeared in the exine-dehisced microspore, which finally developed into a typical embryo with a suspensor. Further studies indicated that polarity is critical for apicalbasal cell fate determination and suspensor formation. However, the pattern of the first division was not only determined by cell polarity but was also regulated by the position of the ruptured exine. The first division could be equal or unequal, with its orientation essentially perpendicular to the polar axis. In both types of cell division, the two daughter cells could have different cell fates and give rise to an embryo with a suspensor, similar to zygotic apicalbasal cell differentiation. The alignment of the two daughter cells is consistent with the orientation of the apicalbasal axis of future embryonic development. Thus, the results revealed that exine dehiscing induces rape microspore polarization, and this polarity results in a different cell fate and fixes the apicalbasal axis of embryogenesis, but is uncoupled from cell asymmetric division. The present study demonstrated the relationships among cell polarity, asymmetric cell division, and cell fate determination in early embryogenesis.