Physcomitrella patens MAX2 characterization suggests an ancient role for this F‐ox protein in photomorphogenesis rather than strigolactone signalling

First author: Mauricio Lopez‐Obando; Affiliations: Université Paris‐Saclay (巴黎-萨克雷大学): Versailles Cedex, France

Corresponding author: Sandrine Bonhomme

Strigolactones (SLs; 独脚金内酯) are key hormonal regulators of flowering plant development and are widely distributed amongst streptophytes (链型植物). In Arabidopsis, SLs signal via the F‐ox protein MORE AXILLARY GROWTH2 (MAX2), affecting multiple aspects of development including shoot branching, root architecture and drought tolerance. Previous characterization of a Physcomitrella patensmoss mutant with defective SL synthesis supports an ancient role for SLs in land plants, but the origin and evolution of signalling pathway components are unknown. Here we investigate the function of a moss homologue of MAX2, PpMAX2, and characterize its role in SL signalling pathway evolution by genetic analysis. We report that the moss Ppmax2 mutant shows very distinct phenotypes from the moss SL‐deficient mutant. In addition, the Ppmax2 mutant remains sensitive to SLs, showing a clear transcriptional SL response in dark conditions, and the response to red light is also altered. These data suggest divergent evolutionary trajectories for SL signalling pathway evolution in mosses and vascular plants. In P. patens, the primary roles for MAX2 are in photomorphogenesis (光形态建成) and moss early development rather than in SL response, which may require other, as yet unidentified, factors.

独脚金内酯是调控开花植物发育重要激素，广泛分布于链型植物中。在拟南芥中，独脚金内酯信号由F‐ox类蛋白MAX2调控，进而影响包括茎分枝、根结构及干旱抗性等在内的植物发育的许多方面。之前对于独脚金内酯合成缺陷的小立碗藓的研究揭示了独脚金内酯在陆地植物中的古老作用，然而改信号通路组分的起源和演化仍然不清楚。本文，作者研究了小立碗藓中MAX2同源蛋白PpMAX2的功能，并通过遗传学分析鉴定了其在独角金内酯信号通路演化中的作用。本文的研究显示小立碗藓Ppmax2突变体与独脚金内酯缺陷突变体的表型有着明显的差别。另外，Ppmax2突变体仍然对独脚金内酯敏感，在黑暗条件下明显表现出对于独脚金内酯的转录响应，并且对于红光的响应也有所改变。这些数据表明苔藓和维管植物中的独脚金内酯信号转导通路演化有着明显不同的演化轨迹。在小立碗藓中，MAX2的主要作用更多的在于光形态建成和早期发育，而不是独角金内酯响应，在小立碗藓中参与独角金内酯响应的可能是其他的某些为鉴定的因子。

doi: https://doi.org/10.1104/pp.18.00331

Journal: New Phytologist

First Published date: 21 May, 2018

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