Current biology : CBJul 7, 2026

Coumarins connect low iron levels to growth regulation in plants

Longevity & Aging Weekly Brief ↗PubMed ↗DOI ↗

Updated Jul 8, 2026

Abstract

Plants use coumarins to modulate target of rapamycin (TOR) activity.

Iron deficiency in Arabidopsis thaliana leads to increased levels of coumarins.
Coumarin accumulation is associated with the repression of TOR-S6K signaling.
Root growth is restricted when TOR signaling is inhibited by coumarins.
Structural modeling suggests that the coumarin esculetin competes with ATP for binding to the TOR catalytic site.
These findings highlight the role of specialized metabolites in linking nutrient availability to growth regulation.

Simplified

The target of rapamycin (TOR) is a conserved master regulator of growth¹^,² that integrates nutrient availability with developmental programs. While TOR inhibition under nutrient limitation is generally attributed to upstream signaling pathways, endogenous small-molecule regulators of TOR have not been defined in eukaryotes. Here, we show that plants use coumarins to modulate TOR activity. In Arabidopsis thaliana, we discovered that iron deficiency-induced coumarin accumulation represses TOR-S6K signaling and restricts root growth. Structural modeling and kinase activity analyses support a mechanism consistent with competition between the coumarin esculetin and ATP for binding to the catalytic pocket. Together, these findings identify specialized metabolites as modulators of TOR signaling, linking nutrient-responsive metabolism to growth control.

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Competing interests

Declaration of interests The authors declare no competing interests.

PubMed

Coumarins connect low iron levels to growth regulation in plants

Abstract

Full Text

Funding

Competing interests

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