Root system architecture (RSA) influences the effectiveness of resources acquisition from soils but the genetic networks that control RSA remain largely unclear. We used rhizoboxes, X-ray computed tomography, grafting, auxin transport measurements and hormone quantification to demonstrate that Arabidopsis and Medicago CEP (C-TERMINALLY ENCODED PEPTIDE)-CEP RECEPTOR signalling controls RSA, the gravitropic set-point angle (GSA) of lateral roots (LRs), auxin levels and auxin transport. We showed that soil-grown Arabidopsis and Medicago CEP receptor mutants have a narrower RSA, which results from a steeper LR GSA. Grafting showed that CEPR1 in the shoot controls GSA. CEP receptor mutants exhibited an increase in rootward auxin transport and elevated shoot auxin levels. Consistently, the application of auxin to wild-type shoots induced a steeper GSA and auxin transport inhibitors counteracted the CEP receptor mutant's steep GSA phenotype. Concordantly, CEP peptides increased GSA and inhibited rootward auxin transport in wild-type but not in CEP receptor mutants. The results indicated that CEP-CEP receptor-dependent signalling outputs in Arabidopsis and Medicago control overall RSA, LR GSA, shoot auxin levels and rootward auxin transport. We propose that manipulating CEP signalling strength or CEP receptor downstream targets may provide means to alter RSA.

中文翻译：

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CEP受体信号传导控制拟南芥和苜蓿的根系结构。

根系统架构（RSA）影响从土壤中获取资源的有效性，但控制RSA的遗传网络仍然不清楚。我们使用了根瘤菌，X射线计算机断层摄影术，嫁接，生长素运输测量和激素定量分析来证明拟南芥和Medicago CEP（C末端编码肽）-CEP RECEPTOR信号控制着RSA，即外侧的重力设定点角（GSA）根（LRs），生长素水平和生长素运输。我们表明，土壤生长的拟南芥和Medicago CEP受体突变体的RSA较窄，这是由较陡峭的LR GSA产生的。嫁接显示，芽中的CEPR1控制了GSA。CEP受体突变体显示出向植物生长素的运输增加，并增加了植物生长素的水平。一致地，生长素在野生型芽上的应用诱导了更陡峭的GSA，而生长素转运抑制剂则抵消了CEP受体突变体的陡峭GSA表型。一致地，在野生型中，CEP肽增加了GSA并抑制了向生长素的运输，但在CEP受体突变体中却没有。结果表明，拟南芥和苜蓿中CEP-CEP受体依赖性信号输出控制总体RSA，LR GSA，芽生长素水平和根向生长素的运输。我们建议，操纵CEP信号强度或CEP受体下游目标可能提供改变RSA的手段。结果表明，拟南芥和苜蓿中CEP-CEP受体依赖性信号输出控制总体RSA，LR GSA，芽生长素水平和根向生长素的运输。我们建议，操纵CEP信号强度或CEP受体下游目标可能提供改变RSA的手段。结果表明，拟南芥和苜蓿中CEP-CEP受体依赖性信号输出控制总体RSA，LR GSA，芽生长素水平和根向生长素的运输。我们建议，操纵CEP信号强度或CEP受体下游目标可能提供改变RSA的手段。