Comparative transcriptome analysis of resistant and cultivated tomato lines in response to Clavibacter michiganensis subsp. michiganensis.

Clavibacter michiganensis subsp. michiganensis (Cmm) is a gram-positive bacterium causing destructive bacterial wilt and canker disease in tomato. Herein, a comparative transcriptome analysis was performed on Cmm-resistant and -susceptible tomato lines. Tomato seedlings were inoculated with Cmm and harvested for transcriptome analysis after 4 and 8 day time-points. Twenty-four transcriptome libraries were profiled by RNA sequencing approach. Total of 545 million clean reads was generated. 1642 and 2715 differentially expressed genes (DEG) were identified in susceptible lines within 4 and 8 days after inoculation (DAI), respectively. In resistant lines, 1731 and 1281 DEGs were found following 4 and 8 DAI, respectively. Gene Ontology analysis resulted in a higher number of genes involved in biological processes and molecular functions in susceptible lines. On the other hand, such biological processes, "defense response", and "response to stress" were distinctly indicated in resistant lines which were not found in susceptible ones upon inoculation, according to the gene set enrichment analyses. Upon Cmm-inoculation, several defense responsive genes were found to be differentially expressed. Of which 26 genes were in the resistant line and three were in the susceptible line. This study helps to understand the transcriptome response of Cmm-resistant and -susceptible tomato lines. The results provide comprehensive data for molecular breeding studies, for the purpose to control of the pathogen in tomato.