Abstract
We have identified spm-responsive genes in Arabidopsis thaliana. Most of the spm-responsive genes also responded during cucumber mosaic virus (CMV)-elicited hypersensitive response. Spm activated the expression of 6 transcription factor genes including AtbZIP60. Since AtbZIP60 plays a master role in the unfolded protein response in Arabidopsis, it may function to control the expression of genes participating in protein folding and secretion. Spm induction and CMV-triggered up-regulation of the genes described mainly coincided and their induction was suppressed by inhibitors of Spm oxidation. Treatment with those inhibitors prior to CMV inoculation allowed higher viral multiplication in Arabidopsis plants. These results support the existence of a Spm-signaling pathway in Arabidopsis and its significant role in defense against CMV.
