The maize root response to nitrogen fluctuations involved a coordinated role for strigolactones and auxin

Nitrogen acts as a signal in regulating plant development in response to the environment. Our previous results suggest that strigolactones (SLs) and auxin might cooperate to regulate the response of maize primary root to nitrate. Furthermore, our recent findings demonstrate that N deficiency triggers zealactone exudation, while nitrate strongly and early prevent this process. The inhibition of SL exudation observed in response to nitrate would seem to take part to the complex signalling pathway leading to lateral root developmental response upon nitrate provision. In the present research, thanks to liquid chromatography tandem-mass spectrometry analyses (LC-MS/MS) SLs were also quantified in maize root tissues of maize seedlings. Results obtained are in accordance with our previous results on exudates, thus confirming the role of zealactone production as a clear response to N-deprivation. Furthermore, lateral root density and root expression of some selected auxin-responsive genes (i.e. Aux/IAA, ARF and LBD) were assessed in N-deprived or nitrate-provided seedlings and in the presence of various SL and auxin analogues or inhibitors. Our preliminary results suggest that SLs and auxin share overlapping and divergent pathways to regulate maize lateral root development in response to nitrate availability.