Tao Jinyuan, Sun Huwei, Gu Pengyuan, Liang Zhihao, Chen Xinni, Lou Jiajing, Xu Guohua, Zhang Yali
State Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Ministry of Agriculture, Nanjing Agricultural University, Weigang1, Xuanwu District, Nanjing, 210095 China.
Plant Methods. 2017 Oct 27;13:89. doi: 10.1186/s13007-017-0232-0. eCollection 2017.
Cytokinins play many essential roles in plant growth and development, mainly through signal transduction pathways. Although the cytokinin signaling pathway in rice has been clarified, no synthetic reporter for cytokinin signaling output has been reported for rice. The sensitive synthetic reporter two-component signaling sensor () is used in the model plant Arabidopsis; however, whether the reporter reflects the cytokinin signaling output pattern in rice remains unclear.
Early-cytokinin-responsive type-A OsRR-binding element (A/G)GAT(C/T) was more clustered in the 15 type-A OsRRs than in the 13 control genes. Quantitative polymerase chain reaction analysis showed that the relative expression of seven type-A in roots and shoots was significantly induced by exogenous cytokinin application, and that of seven , mainly in roots, was inhibited by exogenous auxin application. We constructed a transgenic rice plant harboring a beta-glucuronidase (GUS) driven by the synthetic promoter . was expressed in the meristem of germinated rice seed and rice seedlings. Furthermore, expression in rice seedlings was induced specifically by exogenous cytokinin application and decreased by exogenous auxin application. Moreover, no obvious reduction in GUS levels was observed after three generations of selfing of transgenic plants, indicating that is not subject to transgene silencing.
We report here a robust and sensitive synthetic sensor for monitoring the transcriptional output of the cytokinin signaling network in rice.
细胞分裂素在植物生长发育中发挥着许多重要作用，主要通过信号转导途径实现。尽管水稻中的细胞分裂素信号通路已被阐明，但尚未有报道称存在用于水稻细胞分裂素信号输出的合成报告基因。敏感的合成报告基因双组分信号传感器（）用于模式植物拟南芥；然而，该报告基因是否反映水稻中的细胞分裂素信号输出模式仍不清楚。
早期细胞分裂素响应型A类水稻反应调节因子（OsRR）结合元件（A/G）GAT（C/T）在15个A类OsRR中比在13个对照基因中更聚集。定量聚合酶链反应分析表明，外源施加细胞分裂素可显著诱导根和茎中7个A类的相对表达，而外源施加生长素则抑制主要在根中的7个的相对表达。我们构建了一个转基因水稻植株，其含有由合成启动子驱动的β-葡萄糖醛酸酶（GUS）。在发芽的水稻种子和水稻幼苗的分生组织中表达。此外，水稻幼苗中的表达在外源施加细胞分裂素时特异性诱导，在外源施加生长素时降低。而且，转基因植物自交三代后未观察到GUS水平明显降低，表明不受转基因沉默影响。
我们在此报告了一种强大且敏感的合成传感器，用于监测水稻中细胞分裂素信号网络的转录输出。
