An Auxin Signaling Repressor IAA12 Enhances Phosphate Deficiency-Induced Inhibition of Primary Root Growth Through Blue Light Signaling in Arabidopsis

초록

In low-phosphate (Pi) environments, plants remodel their root system architecture primarily through the inhibition of primary root growth to promote phosphate uptake at top soil. However, the molecular mechanism by which primary root growth is inhibited in response to phosphate deficiency remains unclear. Here, we show that the auxin signaling repressor IAA12 acts as a positive regulator of the Pi deficiency-induced inhibition of primary root growth. As a molecular mechanism, we found that IAA12 restricts primary root elongation by increasing reactive oxygen species (ROS) accumulation, which subsequently suppresses cell division in the root apical meristem. This developmental role of IAA12 depends on blue light signaling. Notably, ectopic expression of IAA12 completely rescues the insensitive primary root phenotypes of cry1cry2 and hy5 mutants in response to phosphate deficiency, indicating that IAA12 functions genetically downstream of the blue light signaling machinery. Taken together, our study provides a signaling framework in which IAA12 mediates blue light-dependent inhibition of primary root elongation in response to phosphate deficiency.

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