Ravazzolo Laura, Boutet-Mercey Stéphanie, Perreau François, Forestan Cristian, Varotto Serena, Ruperti Benedetto, Quaggiotti Silvia
Department of Agronomy, Food, Natural Resources, Animals and Environment, University of Padova, Viale dell'Università 16, Legnaro 35020, Italy.
Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, Versailles 78000, France.
Plant Cell Physiol. 2021 Sep 24;62(4):610-623. doi: 10.1093/pcp/pcab014.
In maize, nitrate regulates root development thanks to the coordinated action of many players. In this study, the involvement of strigolactones (SLs) and auxin as putative components of the nitrate regulation of lateral root (LR) was investigated. To this aim, the endogenous SL content of maize root in response to nitrate was assessed by liquid chromatography with tandem mass Spectrometry (LC-MS/MS) and measurements of LR density in the presence of analogues or inhibitors of auxin and SLs were performed. Furthermore, an untargeted RNA-sequencing (RNA-seq)-based approach was used to better characterize the participation of auxin and SLs to the transcriptional signature of maize root response to nitrate. Our results suggested that N deprivation induces zealactone and carlactonoic acid biosynthesis in root, to a higher extent if compared to P-deprived roots. Moreover, data on LR density led to hypothesize that the induction of LR development early occurring upon nitrate supply involves the inhibition of SL biosynthesis, but that the downstream target of SL shutdown, besides auxin, also includes additional unknown players. Furthermore, RNA-seq results provided a set of putative markers for the auxin- or SL-dependent action of nitrate, meanwhile also allowing to identify novel components of the molecular regulation of maize root response to nitrate. Globally, the existence of at least four different pathways was hypothesized: one dependent on auxin, a second one mediated by SLs, a third deriving from the SL-auxin interplay, and a last one attributable to nitrate itself through further downstream signals. Further work will be necessary to better assess the reliability of the model proposed.
在玉米中，硝酸盐通过许多参与者的协同作用来调节根系发育。在本研究中，研究了独脚金内酯（SLs）和生长素作为硝酸盐对侧根（LR）调节的假定成分的作用。为此，通过液相色谱-串联质谱法（LC-MS/MS）评估了玉米根对硝酸盐响应时的内源性SL含量，并在存在生长素和SLs类似物或抑制剂的情况下测量了LR密度。此外，采用了一种基于非靶向RNA测序（RNA-seq）的方法，以更好地表征生长素和SLs对玉米根对硝酸盐响应的转录特征的参与情况。我们的结果表明，与缺磷根相比，氮素缺乏更能诱导根中玉米素内酯和独脚金醇酸的生物合成。此外，关于LR密度的数据表明，硝酸盐供应后早期发生的LR发育诱导涉及SL生物合成的抑制，但SL关闭的下游靶点除了生长素外，还包括其他未知因素。此外，RNA-seq结果提供了一组硝酸盐依赖生长素或SL作用的假定标记，同时也有助于识别玉米根对硝酸盐响应的分子调控的新成分。总体而言，推测至少存在四种不同的途径：一种依赖生长素，第二种由SLs介导，第三种源于SL-生长素相互作用，最后一种归因于硝酸盐本身通过进一步的下游信号。需要进一步的工作来更好地评估所提出模型的可靠性。
