Pierdonati Emanuela, Unterholzner Simon Josef, Salvi Elena, Svolacchia Noemi, Bertolotti Gaia, Dello Ioio Raffaele, Sabatini Sabrina, Di Mambro Riccardo
Dipartimento di Biologia e Biotecnologie, Laboratory of Functional Genomics and Proteomics of Model Systems, Università di Roma, Sapienza-via dei Sardi, 70⁻00185 Rome, Italy.
Department of Biology, University of Pisa-via L. Ghini, 13⁻56126 Pisa, Italy.
Plants (Basel). 2019 Apr 8;8(4):94. doi: 10.3390/plants8040094.
The root is a dynamic system where the interaction between different plant hormones controls root meristem activity and, thus, organ growth. In the root, a characteristic graded distribution of the hormone auxin provides positional information, coordinating the proliferating and differentiating cell status. The hormone cytokinin shapes this gradient by positioning an auxin minimum in the last meristematic cells. This auxin minimum triggers a cell developmental switch necessary to start the differentiation program, thus, regulating the root meristem size. To position the auxin minimum, cytokinin promotes the expression of the gene , which conjugates auxin with amino acids, in the most external layer of the root, the lateral root cap tissue. Since additional genes are expressed in the root, we questioned whether cytokinin to position the auxin minimum also operates via different genes. Here, we show that cytokinin regulates meristem size by activating the expression of and genes, in addition to . Thus, cytokinin activity provides a robust control of auxin activity in the entire organ necessary to regulate root growth.
根是一个动态系统，不同植物激素之间的相互作用控制着根分生组织的活性，进而控制器官的生长。在根中，激素生长素的特征性梯度分布提供位置信息，协调细胞的增殖和分化状态。激素细胞分裂素通过在最后一个分生组织细胞中形成生长素最小值来塑造这种梯度。这种生长素最小值触发细胞发育转换，这是启动分化程序所必需的，从而调节根分生组织的大小。为了定位生长素最小值，细胞分裂素促进根最外层即侧根冠组织中与氨基酸结合生长素的基因的表达。由于根中还表达其他基因，我们质疑细胞分裂素定位生长素最小值是否也通过不同的基因起作用。在这里，我们表明，除了基因外，细胞分裂素还通过激活基因和的表达来调节分生组织大小。因此，细胞分裂素活性对调节根生长所需的整个器官中的生长素活性提供了强有力的控制。
