APETALA2 is involved in ABA signaling during seed germination

APETALA2 (AP2) is well known for regulating the development of floral organs, ovules, seed coats, and the mass of seeds, but the role of AP2 in seed germination remains unclear. Here, we report that AP2 interacts with ABI5 in nuclear speckles and functions in controlling seed germination. Genetic study showed that the abi5 mutation could restore the ABA-sensitive phenotype of ap2 mutants, supporting that AP2 antagonizes ABI5 in ABA signaling and ABA-mediated inhibition of seed germination. In addition, we observed the interactions of AP2 with SnRK2.2, SnRK2.3, and SnRK2.6 in nuclear speckles, suggesting that AP2 plays a multifaceted role in the ABA signaling pathway. Our findings revealed that the interactions of AP2 with SnRK2s and ABI5 are critical for ABA signaling in control of seed germination.