Royo Joaquín, Muñiz Luís M, Gómez Elisa, Añazco-Guenkova Ana M, Hueros Gregorio
Departamento de Biomedicina y Biotecnología, Campus Universitario, Universidad de Alcalá, Alcalá de Henares, 28805 Madrid, Spain.
Plants (Basel). 2022 Jul 30;11(15):1992. doi: 10.3390/plants11151992.
ZmTCRR1 and 2 are type-A response regulators expressed in the maize endosperm transfer cells (TC). While type-B response regulators transcriptionally control canonical type-A response regulators, as part of the cytokinin signal transduction mechanism, the ZmTCRRs are regulated by ZmMRP1, a master regulator of TC identity. In addition, the corresponding proteins are not detected in the TC, accumulating in the inner endosperm cells instead. These features suggest these molecules are not involved in classical, cell-autonomous, cytokinin signalling pathways. Using transgenic Arabidopsis plants ectopically expressing these genes, we have shown that ZmTCRR1 and 2 can modulate auxin and cytokinin signalling, respectively. In Arabidopsis, the ectopic expression of ZmTCRR2 blocked, almost completely, cytokinin perception. Given the conservation of these signalling pathways at the molecular level, our results suggest that the ZmTCRRs modulate cytokinin and auxin perception in the inner endosperm cells.
ZmTCRR1和ZmTCRR2是在玉米胚乳转运细胞（TC）中表达的A型响应调节因子。虽然B型响应调节因子作为细胞分裂素信号转导机制的一部分，在转录水平上控制典型的A型响应调节因子，但ZmTCRRs受TC身份的主要调节因子ZmMRP1调控。此外，在转运细胞中未检测到相应的蛋白质，而是在内胚乳细胞中积累。这些特征表明这些分子不参与经典的、细胞自主的细胞分裂素信号通路。通过在异位表达这些基因的转基因拟南芥植物中进行研究，我们发现ZmTCRR1和ZmTCRR2分别可以调节生长素和细胞分裂素信号。在拟南芥中，ZmTCRR2的异位表达几乎完全阻断了细胞分裂素的感知。鉴于这些信号通路在分子水平上的保守性，我们的结果表明ZmTCRRs在内胚乳细胞中调节细胞分裂素和生长素的感知。
