Local regulation of auxin transport in root‐apex transition zone mediates aluminium‐induced Arabidopsis root‐growth inhibition

• Published in: The Plant journal : for cell and molecular biology Vol. 108; no. 1; pp. 55 - 66
• Main Authors: Li, Cuiling, Liu, Guangchao, Geng, Xiaoyu, He, Chunmei, Quan, Taiyong, Hayashi, Ken‐Ichiro, De Smet, Ive, Robert, Hélène S., Ding, Zhaojun, Yang, Zhong‐Bao
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.10.2021
• Subjects: Accumulation; Acidic soils; aluminium; Aluminum; Aluminum - toxicity; Apexes; Arabidopsis - drug effects; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - physiology; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; auxin transport; Auxins; Biological Transport; Biosynthesis; Calmodulin-Binding Proteins - genetics; Calmodulin-Binding Proteins - metabolism; Crop production; Ethylene; Ethylenes - metabolism; Gene Expression Regulation, Plant; Indoleacetic Acids - metabolism; Membrane Transport Proteins - genetics; Membrane Transport Proteins - metabolism; PIN1; Pin1 protein; Plant Growth Regulators - metabolism; Plant Roots - drug effects; Plant Roots - genetics; Plant Roots - growth & development; Plant Roots - metabolism; Proteins; root growth; root‐apex transition zone; Stress; Stress, Physiological; Toxicity; Transition zone; Up-Regulation; aluminium; root-apex transition zone; PIN1; auxin transport; root growth
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/tpj.15424

SUMMARY Aluminium (Al) stress is a major limiting factor for worldwide crop production in acid soils. In Arabidopsis thaliana, the TAA1‐dependent local auxin biosynthesis in the root‐apex transition zone (TZ), the major perception site for Al toxicity, is crucial for the Al‐induced root‐growth inhibition, while the mechanism underlying Al‐regulated auxin accumulation in the TZ is not fully understood. In the present study, the role of auxin transport in Al‐induced local auxin accumulation in the TZ and root‐growth inhibition was investigated. Our results showed that PIN‐FORMED (PIN) proteins such as PIN1, PIN3, PIN4 and PIN7 and AUX1/LAX proteins such as AUX1, LAX1 and LAX2 were all ectopically up‐regulated in the root‐apex TZ in response to Al stress and coordinately regulated local auxin accumulation in the TZ and root‐growth inhibition. The ectopic up‐regulation of PIN1 in the TZ under Al stress was regulated by both ethylene and auxin, with auxin signalling acting downstream of ethylene. Al‐induced PIN1 up‐regulation and auxin accumulation in the root‐apex TZ was also regulated by the calossin‐like protein BIG. Together, our results provide insight into how Al stress induces local auxin accumulation in the TZ and root‐growth inhibition through the local regulation of auxin transport. Significance Statement Local auxin biosynthesis in the root‐apex transition zone (TZ) is crucial for aluminium (Al)‐induced root‐growth inhibition, while the mechanism underlying Al‐regulated auxin accumulation in the TZ is not fully understood. In this study we show that the PIN1‐, PIN2‐, PIN3‐, PIN4‐, AUX1‐, LAX1‐ and LAX2‐dependent local auxin transport in TZ is critical for the Al‐induced root‐growth inhibition, providing new insights into how Al stress induces local auxin accumulation and root‐growth inhibition through the local regulation of auxin transport in the root‐apex TZ.