OsPHR2-OsDIR55 Module Enhances Root Barrier Integrity and Rice Tolerance to Phosphate Deficiency

2026-06-17

PRE

Wen Duan

Xuemei Li

Baoping Xue

Zhuo Chen

Lida Wang

Shuai Shi

Chengcai Chu

Yun-Kuan Liang *

DOI：10.1111/pce.70686

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Low bioavailability of inorganic phosphate (Pi) in soil severely constrains plant growth and crop productivity. Here, we demonstrate that Pi deficiency induced localised lignification in rice roots. Overexpression of OsDIR55, a beneficial gene we previously implicated in salt tolerance, significantly enhances plant performance under low Pi conditions, characterised by increased root-to-shoot ratio and biomass accumulation, whereas loss-of-function dir55 mutants exhibit contrast phenotypes. Importantly, the transcription factor OsPHR2 physically binds to the P1BS cis-elements in the OsDIR55 promoter, and Pi deprivation upregulates OsDIR55 expression in an OsPHR2-dependent manner. We further showed that OsDIR55 maintains cellular Pi homoeostasis under Pi starvation by reinforcing root apoplastic barrier functionality. Disruption of OsDIR55 leads to excessive Pi accumulation and aberrant physiological responses under Pi-sufficient conditions with leaf tip necrosis, indicative of Pi toxicity. Our work uncovers an essential role of the OsPHR2-OsDIR55 module in mediating root anatomical adaptations to Pi scarcity, refines Pi stress signalling pathways and highlights the significance of lignification in plant responses to environmental stresses.

Keywords:

nutrient homoeostasis

OsDIR55

phosphate deficiency

plant adaptation

root apoplastic barriers

OsPHR2-OsDIR55 Module Enhances Root Barrier Integrity and Rice Tolerance to Phosphate Deficiency

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