Abstract: 【Objective】Clone the partial cDNA of the StWRKY8-like gene from a cultivated Solanum tuberosum Zhongshu 3 after inoculation with Ralstonia solanacearum. Analyze the StWRKY8-like gene coding sequence, and study the differential expression pattern of StWRKY8-like between susceptible and resistant S. tuberosum toward R. solanacearum and the tissue-specific expression of StWRKY8-like.【Method】R. solanacearum-resistant ED13 and R. solanacearum-susceptible Zhongshu 3 S. tuberosum were root-inoculated with R. solanacearum strain PO41. RNA were extracted from the leaves and reserve-transcribed into cDNA which was subjected for the construction of subtractive cDNA bank with the PCR Select cDNA Subtraction Kit. 384 positive clones were obtained as SMART cDNA bank and used as a template for 5′-RACE with SMART-RACE cDNA Amplification Kit to PCR amplify the StWRKY8-like gene. The StWRKY8-like gene sequence and DNA sequence similarity were analyzed by BioEdit and BLAST tools. Phylogenetic trees were established by MEGA 5.0. The biochemical feature, tertiary structure, phosphorylation sites and sub-cellular location of the StWRKY8-like protein were predicted by ProtParam/ProtScale, SWISS-MODEL, NetPhos2.0 Server, WOLF PSORT/TargetP1.1 Server, respectively. The RNA were extracted from the leaves of ED13 and Zhongshu 3 S. tuberosum at 6 h, 12 h, 1 d, 2 d, 3 d, 4 d, and 6 d post inoculation of the R. solanacearum strain PO41 for RT-PCR and real-time PCR analysis of the StWRKY8-like gene expression. Digoxin-labeled StWRKY8-like specific probes were in situ hybridized with S. tuberosum stem and leaf sections to determine its expression in different tissues. 【Result】 The partial cDNA of the StWRKY8-like gene (563 bp) was obtained, which contained a 258 bp open reading frame coding a peptide with 85 amino acids. The StWRKY8-like protein has a classical conserved WRKY domain with a zinc finger motif of C₂H₂ and belongs to the subgroup II of WRKY family. The amino acid sequence of StWRKY8-like protein was highly close to the other WRKY members of Solanaceous plants and in 98% similarity with StWRKY8 in R. solanacearum. The StWRKY8-like protein is predicted as a hydrosoluble protein with an isoelectric point of 9.1 and half-life period of 5.5 h. It is a non-spherical protein, contains 3 phosphorylation sites and locates in the cytoplasm. The StWRKY8-like gene was upregulated after the R.solanacearum infection, and differentially expressed in susceptible and resistant S. tubosum. The expression of StWRKY8-like in resistant S. tubosum was significantly higher than in susceptible S. tubosum at 6 h post infection. It was mainly expressed in the vascular system of the stem and leaves. 【Conclusion】 StWRKY8-like was a putative transcription factor gene, upregulated at R. solanacearum infection and differentially expressed in susceptible and resistant S. tubosum. It may be involved in the S. tubosum defense against R. solanacearum.

Key words: Solanum tuberosum, Ralstonia solanacearum, transcription factor, StWRKY8-like, gene expression, tissue-specific expression