Iron (Fe) and copper (Cu) are indispensible 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.
Although the crosstalk between iron (Fe) and copper (Cu) homeostasis signaling networks exists in plants, the underlined molecular mechanism remains unclear.
In a study published in Plant, Cell & Environment, researchers from 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 (SPL7) 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.
“This work through the link between bHLH Ib/FIT and COPT2/FRO4/FRO5 under Fe deficiency conditions establishes a new relationship between Cu and Fe homeostasis,” added LIANG.
LIANG Gang Ph.D Principal Investigator
Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun 666303, Yunnan, China