Kono Atsushi, Umeda-Hara Chikage, Adachi Sumiko, Nagata Noriko, Konomi Mami, Nakagawa Tsuyoshi, Uchimiya Hirofumi, Umeda Masaaki
Institute of Molecular and Cellular Biosciences, University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan.
Plant Cell. 2007 Apr;19(4):1265-77. doi: 10.1105/tpc.106.046763. Epub 2007 Apr 20.
Cyclin D (CYCD) plays an important role in cell cycle progression and reentry in response to external signals. Here, we demonstrate that Arabidopsis thaliana CYCD4 is associated with specific cell divisions in the hypocotyl. We observed that cycd4 T-DNA insertion mutants had a reduced number of nonprotruding cells and stomata in the hypocotyl epidermis. Conversely, CYCD4 overexpression enhanced cell division in nonprotruding cell files in the upper region of the hypocotyls, where stomata are usually formed in wild-type plants. The overproliferative cells were of stomatal lineage, which is marked by the expression of the TOO MANY MOUTHS gene, but unlike the meristemoids, most of them were not triangular. Although the phytohormone gibberellin promoted stomatal differentiation in the hypocotyl, inhibition of gibberellin biosynthesis did not prevent CYCD4 from inducing cell division. These results suggested that CYCD4 has a specialized function in the proliferation of stomatal lineage progenitors rather than in stomatal differentiation. We propose that CYCD4 controls cell division in the initial step of stomata formation in the hypocotyl.
细胞周期蛋白D（CYCD）在细胞周期进程以及响应外部信号重新进入细胞周期过程中发挥着重要作用。在此，我们证明拟南芥CYCD4与下胚轴中的特定细胞分裂相关。我们观察到，CYCD4 T-DNA插入突变体在下胚轴表皮中不突出细胞和气孔的数量减少。相反，CYCD4过表达增强了下胚轴上部非突出细胞列中的细胞分裂，在野生型植物中气孔通常在此处形成。过度增殖的细胞属于气孔谱系，以过多气孔基因的表达为标记，但与分生细胞不同，它们大多数不是三角形的。尽管植物激素赤霉素促进下胚轴中的气孔分化，但抑制赤霉素生物合成并不能阻止CYCD4诱导细胞分裂。这些结果表明，CYCD4在气孔谱系祖细胞的增殖中具有特殊功能，而非在气孔分化中。我们提出，CYCD4在下胚轴气孔形成的初始步骤中控制细胞分裂。
