A transcriptional recognition site within SOS1 coding region controls salt tolerance in Arabidopsis.

Salt stress impacts plant growth and development, threatening agricultural production. The Na/H antiporter SALT OVERLY SENSITIVE 1 (SOS1) functions in cellular ion homeostasis through facilitating Na excretion and is therefore essential for plant salt tolerance. Here, we report that the transcription factors AUXIN RESPONSE FACTOR 7 (ARF7) and ARF19 are required for salt-induced SOS1 expression and salt tolerance in Arabidopsis thaliana. ARF7 and ARF19 activate SOS1 transcription by binding to SOS1 coding region rather than its promoter. Additionally, an E3 ubiquitin ligase, CHY ZINC-FINGER AND RING PROTEIN 1 (CHYR1), interacts with and degrades ARF7 and ARF19, dampening SOS1 expression. Upon high salinity, CHYR1 expression is inhibited in plants, stabilizing ARF7 and ARF19 proteins and increasing SOS1 expression. Collectively, our study identifies a transcriptional cis-element within SOS1 coding region recognized by ARF7 and ARF19 and elucidates a molecular mechanism governing ARF7 and ARF19 protein stability and SOS1 expression during plant salt stress response.