Department of Molecular Biology, Max Planck Institute for Developmental Biology, Spemannstraße 35, Tübingen, 72076, Germany.
Department of Metabolic Networks, Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, Potsdam, 14476, Germany.
Plant J. 2020 Nov;104(3):768-780. doi: 10.1111/tpj.14965. Epub 2020 Sep 5.
The vegetative phase change marks the beginning of the adult phase in the life cycle of plants and is associated with a gradual decline in the microRNA miR156, in response to sucrose status. Trehalose 6-phosphate (T6P) is a sugar molecule with signaling function reporting the current sucrose state. To elucidate the role of T6P signaling in vegetative phase change, molecular, genetic, and metabolic analyses were performed using Arabidopsis thaliana loss-of-function lines in TREHALOSE PHOSPHATE SYNTHASE1 (TPS1), a gene coding for an enzyme that catalyzes the production of T6P. These lines show a significant delay in vegetative phase change, under both short and long day conditions. Induced expression of TPS1 complements this delay in the TPS1 knockout mutant (tps1-2 GVG::TPS1). Further analyses indicate that the T6P pathway promotes vegetative phase transition by suppressing miR156 expression and thereby modulating the levels of its target transcripts, the SQUAMOSA PROMOTER BINDING PROTEIN-LIKE genes. TPS1 knockdown plants, with a delayed vegetative phase change phenotype, accumulate significantly more sucrose than wild-type plants as a result of a feedback mechanism. In summary, we conclude that the T6P pathway forms an integral part of an endogenous mechanism that influences phase transitions dependent on the metabolic state.
植物生命周期中的成年阶段以营养生长向生殖生长的转变为标志，该转变与 microRNA miR156 的逐渐下降有关，miR156 的下降是植物对蔗糖状态的响应。海藻糖-6-磷酸（T6P）是一种具有信号功能的糖分子，它可以报告当前的蔗糖状态。为了阐明 T6P 信号在营养生长向生殖生长转变中的作用，使用拟南芥中 TREHALOSE PHOSPHATE SYNTHASE1（TPS1）基因的功能丧失系进行了分子、遗传和代谢分析，TPS1 基因编码的酶可以催化 T6P 的生成。在短日和长日条件下，这些系在营养生长向生殖生长转变中表现出明显的延迟。TPS1 的诱导表达弥补了 tps1-2 GVG::TPS1 突变体中的这种延迟。进一步的分析表明，T6P 途径通过抑制 miR156 的表达，从而调节其靶标转录物 SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 基因的水平，从而促进营养生长向生殖生长的转变。由于反馈机制，表现出营养生长向生殖生长转变延迟表型的 TPS1 敲低植物比野生型植物积累了显著更多的蔗糖。总之，我们的结论是，T6P 途径是影响依赖于代谢状态的转变的内源性机制的一个组成部分。
