Transcriptomic Analysis Revealed Key Defense Genes and Signaling Pathways Mediated by the Gene in Response to Infection with pv. Tomato DC3000.

Nucleocytoplasmic transport receptors play key roles in the nuclear translocation of disease resistance proteins, but the associated mechanisms remain unclear. The gene encodes an importin β-like protein. A transgenic Arabidopsis line overexpressing (OESAD2/Col-0) showed obvious resistance to pv. tomato DC3000 ( DC3000) compared to the wild type (Col-0), but the knockout mutant was susceptible. Transcriptomic analysis was then performed on Col-0, OESAD2/Col-0, and leaves at 0, 1, 2, and 3 days post-inoculation with DC3000. A total of 1825 differentially expressed genes (DEGs) were identified as putative biotic stress defense genes regulated by SAD2, 45 of which overlapped between the knockout and overexpression datasets. Gene Ontology (GO) analysis indicated that the DEGs were broadly involved in single-organism cellular metabolic processes and in response to stimulatory stress. Kyoto Encyclopedia of Genes and Genomes (KEGG) biochemical pathway analysis revealed that many of the DEGs were associated with the biosynthesis of flavonoids and other specialized metabolites. Transcription factor analysis showed that a large number of ERF/AP2, MYB, and bHLH transcription factors were involved in SAD2-mediated plant disease resistance. These results provide a basis for future exploration of the molecular mechanisms associated with SAD2-mediated disease resistance and establish a set of key candidate disease resistance genes.