Identification and characterization of novel functional DOG1 residues regulating the DOG1-dependent ABA response in Arabidopsis
Abscisic acid (ABA) is an important phytohormone regulating seed dormancy and germination. DELAY OF GERMINATION 1 (DOG1) is a pivotal regulator of seed dormancy and regulates the ABA response by binding with ABA HYPERSENSITIVE GERMINATION 1 (AHG1) and heme; however to date the molecular function and regulatory mechanisms of DOG1 remain unclear. Here, we investigate the mechanism of the DOG1-dependent ABA response using RNA-sequencing, genetics, and biochemistry experiments. Our data suggest that DOG1 and AHG1 are regulate the expression of many common genes, including those involved in seed maturation and ABA response. Moreover, DOG1 acts upstream of ABSCISIC ACID INSENSITIVE 5 (ABI5) and regulates ABI5 target genes including LATE EMBRYOGENESIS ABUNDANT 1 (EM1) and EM6. Overall, our data strongly suggest that the DOG1-AHG1 complex regulates ABA response via ABI5, and that the association between heme and AHG1 are critical for the function of DOG1 during regulation of seed germination.