Department of Metabolic Networks, Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Potsdam, Germany.
Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, 78000, Versailles, France.
New Phytol. 2019 Jul;223(2):814-827. doi: 10.1111/nph.15812. Epub 2019 Apr 17.
Optimal timing of flowering, a major determinant for crop productivity, is controlled by environmental and endogenous cues. Nutrients are known to modify flowering time; however, our understanding of how nutrients interact with the known pathways, especially at the shoot apical meristem (SAM), is still incomplete. Given the negative side-effects of nitrogen fertilization, it is essential to understand its mode of action for sustainable crop production. We investigated how a moderate restriction by nitrate is integrated into the flowering network at the SAM, to which plants can adapt without stress symptoms. This condition delays flowering by decreasing expression of SUPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1) at the SAM. Measurements of nitrate and the responses of nitrate-responsive genes suggest that nitrate functions as a signal at the SAM. The transcription factors NIN-LIKE PROTEIN 7 (NLP7) and NLP6, which act as master regulators of nitrate signaling by binding to nitrate-responsive elements (NREs), are expressed at the SAM and flowering is delayed in single and double mutants. Two upstream regulators of SOC1 (SQUAMOSA PROMOTER BINDING PROTEIN-LIKE3 (SPL3) and SPL5) contain functional NREs in their promoters. Our results point at a tissue-specific, nitrate-mediated flowering time control in Arabidopsis thaliana.
开花的最佳时间是作物生产力的主要决定因素，它受环境和内源性信号的控制。已知营养物质可以改变开花时间；然而，我们对营养物质如何与已知途径相互作用的理解，特别是在茎尖分生组织（SAM）中，仍然不完整。鉴于氮施肥的负面影响，了解其作用模式对于可持续的作物生产至关重要。我们研究了硝酸盐的适度限制是如何整合到 SAM 中的开花网络中的，植物可以在没有应激症状的情况下适应这种限制。这种情况下，通过降低 SAM 中 SOC1 的表达来延迟开花。硝酸盐的测量和硝酸盐响应基因的反应表明，硝酸盐在 SAM 中作为一种信号发挥作用。转录因子 NIN-LIKE PROTEIN 7（NLP7）和 NLP6 通过与硝酸盐响应元件（NREs）结合作为硝酸盐信号的主调节剂，在 SAM 中表达，并且在单突变体和双突变体中开花被延迟。SOC1 的两个上游调节剂（SQUAMOSA PROMOTER BINDING PROTEIN-LIKE3（SPL3）和 SPL5）在其启动子中含有功能 NREs。我们的结果表明，拟南芥中存在一种组织特异性的、硝酸盐介导的开花时间控制。
