Clade III cytokinin response factors share common roles in response to oxidative stress responses linked to cytokinin synthesis.

Cytokinin response factors (CRFs) are transcription factors that are involved in cytokinin (CK) response, as well as being linked to abiotic stress tolerance. In particular, oxidative stress responses are activated by Clade III CRF members, such as AtCRF6. Here we explored the relationships between Clade III CRFs and oxidative stress. Transcriptomic responses to oxidative stress were determined in two Clade III transcription factors, Arabidopsis AtCRF5 and tomato SlCRF5. AtCRF5 was required for regulated expression of >240 genes that are involved in oxidative stress response. Similarly, SlCRF5 was involved in the regulated expression of nearly 420 oxidative stress response genes. Similarities in gene regulation by these Clade III members in response to oxidative stress were observed between Arabidopsis and tomato, as indicated by Gene Ontology term enrichment. CK levels were also changed in response to oxidative stress in both species. These changes were regulated by Clade III CRFs. Taken together, these findings suggest that Clade III CRFs play a role in oxidative stress response as well as having roles in CK signaling.