Department of Biotechnology, Indian Institute of Technology, Roorkee, Roorkee, Uttarakhand, 247667, India.
Plant Cell Rep. 2021 Aug;40(8):1367-1375. doi: 10.1007/s00299-020-02618-9. Epub 2020 Oct 12.
We reveal the onset and dynamic tissue-specific cytokinin signaling domains and functional importance of auxin in the auxin-cytokinin interaction domains in shaping root architecture in the economically important rice plant. Plant hormones such as auxin and cytokinin are central regulators of root organogenesis. Typical in the grass species, the root system in rice is primarily composed of post-embryonic adventitious/crown roots (ARs/CRs). Antagonistic auxin-cytokinin activities mutually balance each other to ensure proper root development. Cytokinin has been shown to inhibit crown root initiation in rice; albeit, the responsive domains remain elusive during the initiation and outgrowth of crown root primordia (CRP). Here, we show the cytokinin response domains during various stages of CRP development. RNA-RNA in situ hybridization and protein immunohistochemistry studies of the reporter gene expressed under the cytokinin responsive synthetic promoter revealed detailed spatio-temporal cytokinin signaling domains in the developing CRP. Furthermore, rice lines genetically depleted for endogenous auxin in the cytokinin responsive domains provided insight into the functional importance of auxin signaling during crown root development. Thus, our study demonstrates the onset and dynamic tissue-specific cytokinin response and functional significance of auxin-cytokinin interaction during root architecture formation in rice, a model grass species.
我们揭示了在经济上重要的水稻植物中，生长素-细胞分裂素相互作用域中生长素和细胞分裂素在塑造根构型中的作用以及它们在组织特异性细胞分裂素信号转导域中的起始和动态。植物激素如生长素和细胞分裂素是根器官发生的主要调节剂。在禾本科植物中，典型的根系统主要由胚后不定根/冠根（AR/CR）组成。拮抗的生长素-细胞分裂素活性相互平衡，以确保适当的根发育。细胞分裂素已被证明抑制水稻中冠根的起始；尽管如此，在冠根原基（CRP）的起始和生长过程中，应答域仍然难以捉摸。在这里，我们展示了 CRP 发育过程中不同阶段的细胞分裂素应答域。在响应细胞分裂素的合成启动子下表达的报告基因的 RNA-RNA 原位杂交和蛋白质免疫组织化学研究揭示了发育中的 CRP 中详细的时空细胞分裂素信号转导域。此外，在细胞分裂素应答域中遗传耗尽内源生长素的水稻品系提供了生长素信号在冠根发育过程中的功能重要性的深入了解。因此，我们的研究表明，在模式禾本科植物水稻中，根构型形成过程中细胞分裂素的起始和动态组织特异性应答以及生长素-细胞分裂素相互作用的功能意义。
