The transcription factor WRKY12 negatively regulates iron entry into seeds in Arabidopsis

Yellow Stripe 1-Like 1 (YSL1) and Yellow Stripe 1-Like 3 (YSL3) transport metal-nicotianamine (NA) complexes to leaves, pollen, and developing seeds and play an important role in regulating iron (Fe) accumulation during the seed development and maturation stages; however, how their gene transcript levels are regulated remains unknown. In this study, we used yeast one-hybrid screening to identify a transcription factor, WRKY12, in Arabidopsis that directly regulates the transcription levels of YSL1 and YSL3 genes. WRKY12 has opposite expression patterns to YSL1 and YSL3. wrky12 mutants are tolerant to Fe deficiency, whereas WRKY12 overexpression lines are sensitive to Fe deficiency. During the development and maturation of seeds, WRKY12 can directly bind to the promoters of YSL1 and YSL3 and inhibit their expression. Genetic analysis showed that WRKY12 functions upstream of YSL1 and YSL3 in Fe intake during the seed development and maturation stages. Together, our results suggest that WRKY12 negatively regulates the iron intake in plant seeds by inhibiting the expression of YSL1 and YSL3. WRKY12 is a novel transcription factor involved in regulating iron entry into plant seeds by regulating transcription of the genes for the transporters of metal-nicotianamine complexes.