MYB28 and MYB29 transcription factors regulate iron homeostasis and coumarin synthesis in Arabidopsis

Here, we identify the glucosinolate-associated transcription factors MYB28 and MYB29 as previously unrecognized regulators of Arabidopsis adaptation to Fe deficiency. Across hydroponic, alkaline soil and in vitro growth systems, loss of MYB28 increased sensitivity to Fe deficiency, whereas the myb28myb29 double mutant displayed the strongest chlorosis, reduced root growth and impaired biomass accumulation, indicating cooperative but unequal functions of these transcription factors.

Despite their enhanced Fe-deficiency phenotype, double mutant plants accumulated higher Fe levels in roots and exhibited stronger induction of canonical Fe-deficiency responses, suggesting impaired Fe utilization or distribution rather than defective Fe uptake. RNA-seq revealed extensive transcriptional reprogramming under Fe deficiency, with pronounced deregulation of genes involved in Fe homeostasis, redox processes and growth, particularly in the double mutant.