In one aspect, there is provided a mutant, non-naturally occurring or transgenic plant cell comprising: (i) a polynucleotide comprising, consisting or consisting essentially of a sequence encoding a member of the CLC family of chloride channels and having at least 60% sequence identity to SEQ ID NO:1 or SEQ ID NO:2 or SEQ ID NO:3 or SEQ ID NO:4 or SEQ ID NO:10 or SEQ ID NO:11； (ii) a polypeptide encoded by the polynucleotide set forth in (i)； (iii) a polypeptide comprising, consisting or consisting essentially of a sequence encoding a member of the CLC family of chloride channels and having at least 60% sequence identity to SEQ ID NO:5 or SEQ ID NO:6 or SEQ ID NO:7 or SEQ ID NO:12 or SEQ ID NO:13 or SEQ ID NO:14； or (iv) a construct, vector or expression vector comprising the isolated polynucleotide set forth in (i)； and wherein the expression or activity of the polynucleotide or the polypeptide is modulated as compared to a control plant and wherein the nitrate levels in the mutant, non-naturally occurring or transgenic plant containing the mutant, non-naturally occurring or transgenic plant cell are modulated as compared to the control plant containing the control plant cell.Dans un aspect, l'invention concerne une cellule végétale mutante, non naturelle ou transgénique comprenant : (i) un polynucléotide comprenant, consistant ou consistant essentiellement en une séquence codant pour un élément de la famille CLC des canaux chlorure et ayant au moins 60 % d'identité de séquence avec SEQ ID NO:1 ou SEQ ID NO:2 ou SEQ ID NO:3 ou SEQ ID NO:4 ou SEQ ID NO:10 ou SEQ ID NO:11； (ii) un polypeptide codé par le polynucléotide présenté dans (i)； (iii) un polypeptide comprenant, consistant ou consistant essentiellement en une séquence codant pour un élément de la famille CLC des canaux chlorure et ayant au moins 60 % d'identité de séquence avec SEQ ID NO:5 ou SEQ ID NO:6 ou SEQ ID NO:7 ou SEQ ID NO:12 ou SEQ ID NO:13 ou SEQ ID NO:14； ou (iv) une construction, un vecteur ou un
