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

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, 2 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.