Iron (Fe) and copper (Cu) are indispensable for the growth and development of plants. Although Fe and Cu are crucial for plants, excessive Fe or Cu can be toxic to plants. Therefore, plants must maintain the homeostasis of Fe and Cu.
Despite that the crosstalk between Fe and Cu homeostasis signaling networks exists in plants, the underlined molecular mechanism remains unclear.
In a study published in Plant, Cell & Environment, researchers from the Xishuangbanna Tropical Botanical Garden (XTBG) explored the crosstalk between Cu and Fe signaling pathways in Arabidopsis. They revealed that FER-LIKE IRON DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (FIT) and basic helix-loop-helix (bHLH) Ib are involved in the Cu uptake under Fe deficiency conditions.
Fe deficiency induced the expression of Cu uptake genes (e.g. copper transporter 2 (COPT2), ferric reductase oxidase 4 (FRO4) and FRO5) in an FIT and bHLH Ib dependent manner.
Further investigation revealed that FIT and bHLH Ib activate the expression of COPT2, FRO4, and FRO5. Moreover, Cu application improved the growth of the fit-2 and bhlh4x mutants under –Fe conditions.
Furthermore, they revealed that SQUAMOSA promoter-binding protein-like 7 is not required for the induction of Cu uptake genes by Fe deficiency. FIT and bHLH Ib TFs mediate the crosstalk between Fe and Cu homeostasis by targeting COPT2, FRO4, and FRO5.
“Our finding represents a new aspect of Fe and Cu interaction, and also provides a new node linking signals from the Cu pathway into the Fe deficiency regulation network,” said Dr. LIANG Gang, principal investigator of the study.
“Through the link between bHLH Ib/FIT and COPT2/FRO4/FRO5 under Fe deficiency conditions, this work establishes a new relationship between Cu and Fe homeostasis,” said LIANG.
Reference: Cai, Y., Li, Y. and Liang, G. (2021), FIT and bHLH Ib transcription factors modulate iron and copper crosstalk in Arabidopsis. Plant Cell Environ. Accepted Author Manuscript. https://doi.org/10.1111/pce.14000
Provided by Chinese Academy of Sciences