Objective   NnWRKY22 in Nelumbo nucifera was cloned and its expressions in various organs under copper stress analyzed.

  Method   RT-PCR was used to clone the gene from cDNA of lotus leaves, and bioinformatics of the sequence obtained using ProtParam. The gene expressions in roots, stems, leaves, and flowers under an imposed copper stress for varied durations were detected by qRT-PCR.

  Result  The successfully cloned NnWRKY22 had an ORF of 573 bp and encoded 190 amino acid residues. The unstable hydrophilic protein had a sequence containing a conserved WRKY domain and a molecular weight of 21.33 kDa, an isoelectric point of pH 9.03, an instability index of 71.93, and hydrophilicity of −0.692. The phylogenetic analyses revealed a close genetic relationship of the gene with those of Aquilegia coerulea and Macleaya cordata. The qRT-PCR results showed the organ-specific expressions of the gene in the tissues which were highest in the roots and lowest in the flowers. They were significantly upregulated and peaked in 7 d by the copper treatment.

  Conclusion  NnWRKY22 was successfully isolated from lotus and cloned. The gene was most highly expressed in the lotus roots and significantly upregulated by the presence of copper. It presumably played an important role in the response of the lotus plants to copper stress.