| Salinity stress highly affects plant growth and productivity.It is well known that sufficient supply of nitrogen(N)fertilizers improves plant salt tolerance and hence alleviates salinity stress in agricultural practice.However,the underlying mechanism of N-dependent salt tolerance is yet to be elucidated.The current study shows that OsMADS27 mediates the nitrate-dependent salt tolerance in rice(Oryza sativa).The OsMADS27 expression is induced specifically by nitrate.NaCl-and ABA-induced expression of OsMADS27 is also dependent on nitrate.Overexpression of OsMADS27 significantly enhanced salt tolerance compared with the wild type,whereas knockout of OsMADS27 substantially decreased salt tolerance.Notably,the expression of OsMADS27 is positively correlated with the concentration of nitrate.Likewise,rice salt tolerance is also positively correlated with nitrate concentration.Therefore,OsMADS27-mediated salt tolerance is nitrate-dependent.The transcriptome analyses showed that OsMADS27 regulates the expression of a number of salt responsive genes,including those involved in anti-oxidation and ion homeostasis.We demonstrated that OsMADS27 activates the expressions of OsSPL7 and OsHKT1.1 by directly binding to their promoters.Taken together,this study reveals a molecular mechanism of nitratedependent salt tolerance in rice.Furthermore,Overexpression of OsMADS27 improved grain yield under salinity stress and sufficient nitrate,indicating that OsMADS27 is a promising candidate gene for the improvement of salt tolerance. |
