The transcription factor MYB30 promotes iron homeostasis by maintaining the stability of the FIT transcription factor

Abstract Iron (Fe) is a vital nutrient for the growth and development of plants. In Arabidopsis (Arabidopsis thaliana), the bHLH transcription factor FER-LIKE IRON DEFICIENCY INDUCED TRANSCRIPTION FACTOR (FIT) plays a pivotal role in regulating the response to Fe deficiency. Our study reveals that the R2R3-MYB transcription factor MYB30 is a positive regulator of the Fe-deficiency response by regulating FIT stability. Plants with loss-of-function mutations in MYB30 exhibit pronounced Fe-deficiency symptoms and diminished Fe uptake, while overexpression of MYB30 leads to the opposite effects. We have discovered that MYB30 interacts with BRUTUS LIKE1 (BTSL1) and BTSL2, two partially redundant E3 ubiquitin ligases that negatively regulate the Fe-deficiency response. MYB30 binds to the C-terminal region of BTSL1 through its MYB DNA-binding domain, thereby safeguarding FIT from BTSL1-mediated ubiquitination and degradation, resulting in FIT accumulation for Fe deficiency response. In summary, our research uncovers the role of the transcription factor MYB30 as a regulator of FIT stability, which in turn modulates Fe homeostasis in plants in response to Fe deficiency.