Objective  Characteristics and biotic stress response of WRKY transcription factors (TFs) in tomato plants were investigated.

  Method   The latest available bioinformatics and genomics methods were employed to identify the tomato WRKY TFs. RNA-seq of disease-resistant and susceptible tomato inbred lines before and after artificial Ralstonia solanacearum infection were obtained to identify the TFs associated with the pathogenic resistance of the plants.

  Result  Eighty-five tomato WRKY TFs were identified and divided into I, IIa+b, IIc, IId+e, and III categories. The IIe group had the highest number of the TFs. The conserved motif of 9 TFs had one single amino acid variation, and WRKYGKK was the dominant mutant. The TFs, especially those in the IIe group, were mainly found on chromosome 5, at the ends, and in clusters. In them, 45.88% showed collinearity and 58.82% (mainly in I and IIc groups) formed 73 pairs of orthologs with those in Arabidopsis and chili pepper at a Ka/Ks ratio below 1. Sixteen of them, mainly belonging to IIa+b and IIc, responded significantly to the biotic stress with expressions largely in the roots. There were 12 differentially expressed WRKY TFs identified mainly in III and IIb. Of which, the interaction between Solyc03g095770.3 (III) and Solyc09g014990.4 (I) played a significant role in the response of the tomato plant to bacterial wilt.

  Conclusion  The WRKY TFs were identified in tomato plants. Twelve genes responded to the bacterial wilt were isolated.