Transcriptome analysis of tomato plants following salicylic acid-induced immunity against ssp. .

Salicylic acid (SA) is known to be involved in the immunity against ssp. () that causes bacterial canker in tomato. To identify the candidate genes associated with SA-inducible resistance, transcriptome analysis was conducted via RNA sequencing in tomato plants treated with SA. SA treatment upregulated various defense-associated genes, such as PR and GST genes, in tomato cotyledons. A comparison of SA- and -responsive genes revealed that both SA treatment and infection commonly upregulated a large number of genes. Gene Ontology (GO) analysis indicated that the GO terms associated with plant immunity were over-represented in both SA- and -induced genes. The genes commonly downregulated by both SA treatment and infection were associated with the cell cycle and may be involved in growth and immunity trade-off through cell division. After SA treatment, several proteins that were predicted to play a role in immune signaling, such as resistance gene analogs, Ca sensors, and WRKY transcription factors, were transcriptionally upregulated. The W-box element, which was targeted by WRKYs, was over-represented in the promoter regions of genes upregulated by both SA treatment and infection, supporting the speculation that WRKYs are important for the SA-mediated immunity against . Prediction of protein-protein interactions suggested that genes encoding receptor-like kinases and EF-hand proteins play an important role in immune signaling. Thus, various candidate genes involved in SA-inducible resistance were identified.