Molecular and Environmental Plant Sciences, Vegetable and Fruit Improvement Center, Department of Horticultural Sciences, Texas A&M University, College Station, TX, 77843, USA.
Molecular and Environmental Plant Sciences, Department of Soil and Crop Sciences, Texas A&M University, College Station, TX, 77843, USA.
Plant J. 2018 Jun;94(5):799-812. doi: 10.1111/tpj.13895. Epub 2018 Apr 17.
De novo shoot organogenesis (DNSO) is a post-embryonic development programme that has been widely exploited by plant biotechnology. DNSO is a hormonally regulated process in which auxin and cytokinin (CK) coordinate suites of genes encoding transcription factors, general transcription factors, and RNA metabolism machinery. Here we report that silencing Arabidopsis thaliana carboxyl-terminal domain (CTD) phosphatase-like 4 (CPL4 ) resulted in increased phosphorylation levels of RNA polymerase II (pol II) CTD and altered lateral root development and DNSO efficiency of the host plants. Under standard growth conditions, CPL4 lines produced no or few lateral roots. When induced by high concentrations of auxin, CPL4 lines failed to produce focused auxin maxima at the meristem of lateral root primordia, and produced fasciated lateral roots. In contrast, root explants of CPL4 lines were highly competent for DNSO. Efficient DNSO of CPL4 lines was observed even under 10 times less the CK required for the wild-type explants. Transcriptome analysis showed that CPL4 , but not wild-type explants, expressed high levels of shoot meristem-related genes even during priming on medium with a high auxin/CK ratio, and during subsequent shoot induction with a lower auxin/CK ratio. Conversely, CPL4 enhanced the inhibitory phenotype of the shoot redifferentiation defective2-1 mutation, which affected snRNA biogenesis and formation of the auxin gradient. These results indicated that CPL4 functions in multiple regulatory pathways that positively and negatively affect DNSO.
从头发生器官发生 (DNSO) 是一种广泛应用于植物生物技术的胚胎后发育程序。DNSO 是一个受激素调节的过程，其中生长素和细胞分裂素 (CK) 协调转录因子、一般转录因子和 RNA 代谢机制的基因表达。在这里，我们报告拟南芥羧基末端结构域 (CTD) 磷酸酶样 4 (CPL4) 的沉默导致 RNA 聚合酶 II (pol II) CTD 的磷酸化水平升高，并改变了宿主植物的侧根发育和 DNSO 效率。在标准生长条件下，CPL4 系几乎不产生侧根。当受到高浓度生长素的诱导时，CPL4 系未能在侧根原基的分生组织处产生集中的生长素最大值，而是产生了束状侧根。相比之下，CPL4 系的根外植体非常适合 DNSO。即使在 CK 浓度比野生型外植体低 10 倍的情况下，CPL4 系也能有效地进行 DNSO。转录组分析表明，CPL4 系，而不是野生型外植体，即使在高生长素/CK 比的培养基上进行诱导时，也表达高水平的茎分生组织相关基因，并且在随后用较低生长素/CK 比进行茎诱导时也是如此。相反，CPL4 增强了 shoot redifferentiation defective2-1 突变体的抑制表型，该突变体影响 snRNA 生物发生和生长素梯度的形成。这些结果表明，CPL4 在线粒体中多个调节途径中发挥作用，这些途径对 DNSO 具有正、负调节作用。
