MYB70 modulates seed germination and root system development in Arabidopsis

Crosstalk among ABA, auxin, and ROS plays critical roles in modulating seed germination, root growth, and suberization. However, the underlying molecular mechanisms remain largely elusive. Here, MYB70, a R2R3-MYB transcription factor was shown to be a key component of these processes in <i>Arabidopsis thaliana</i>. <i>myb70</i> seeds displayed decreased sensitivity, while MYB70-overexpressing <i>OX70</i> seeds showed increased sensitivity in germination in response to exogenous ABA through MYB70 physical interaction with ABI5 protein, leading to enhanced stabilization of ABI5. Furthermore, MYB70 modulates root system development (RSA) which is associated with increased conjugated IAA content and H₂O₂/O₂ ^⋅- ratio but reduced root suberin deposition, consequently affecting nutrient uptake. In support of these data, MYB70 positively regulates the expression of auxin conjugation-related <i>GH3</i>, while negatively peroxidase-encoding and suberin biosynthesis-related genes. Our findings collectively revealed a previously uncharacterized component that modulates ABA and auxin signaling pathways, H₂O₂/O₂ ^⋅- balance, and suberization, consequently regulating RSA and seed germination.