Root hairs (RHs) are mixed tip- and non-tip-growing protrusions derived from root epidermal cells that play essential roles in nutrient and water uptake, root anchorage, and interactions with soil microorganisms. Nutrient availability and temperature are critical and interconnected factors for sustained plant growth, but the molecular mechanisms that underlie their perception and downstream signaling pathways remain unclear. Here, we show that moderately low temperature (10°C) induces a strong RH elongation response mediated by several molecular components of the auxin pathway. Specifically, auxin biosynthesis mediated by TAA1/YUCCAs, auxin transport via PIN2, PIN4, and AUX1, and auxin signaling regulated by TIR1/AFB2 in conjunction with specific ARFs (ARF6/ARF8 and ARF7, but not ARF19) contribute to the RH response under moderately low temperature. These findings establish the auxin biosynthesis and signaling pathway as a central regulatory process driving RH growth under moderate low-temperature conditions in roots. Our work underscores the importance of moderately low temperature as a stimulus that interacts with complex nutritional signaling originating from the growth medium and the plant nutritional status; this process has the potential to be fine-tuned for future biotechnological applications to enhance nutrient uptake.

ANID Millennium Science Initiative Program Millennium Institute for Integrative Biology Santiago Chile; Centro de Biotecnología Vegetal Facultad de Ciencias de la Vida Universidad Andres Bello Santiago Chile

College of Resources and Environmental Sciences National Academy of Agriculture Green Development China Agricultural University Beijing 100193 China

CONICET Universidad de Buenos Aires Instituto de Ecología Genética y Evolución de Buenos Aires Buenos Aires Argentina

Departamento de Fruticultura y Enología Facultad de Agronomía y Sistema Naturales Pontificia Universidad Católica de Chile Santiago Chile; Facultad de Ciencias Biológicas Pontificia Universidad Católica de Chile Santiago Chile; ANID Millennium Science Initiative Program Millennium Institute Center for Genome Regulation Santiago Chile

Escuela de Agronomía Facultad de Ciencias Agronómicas y de los Alimentos Pontificia Universidad Católica de Valparaíso Calle San Francisco s n La Palma Quillota 2260000 Chile

Fundación Instituto Leloir and IIBBA CONICET Av Patricias Argentinas 435 Buenos Aires C1405BWE Argentina

Fundación Instituto Leloir and IIBBA CONICET Av Patricias Argentinas 435 Buenos Aires C1405BWE Argentina; ANID Millennium Science Initiative Program Millennium Institute for Integrative Biology Santiago Chile; Centro de Biotecnología Vegetal Facultad de Ciencias de la Vida Universidad Andres Bello Santiago Chile

Laboratory of Growth Regulators Faculty of Science of Palacký University and Institute of Experimental Botany of the Czech Academy of Sciences Šlechtitelů 27 779 00 Olomouc Czech Republic

Microscopy and BioImaging Facility Fundación Instituto Leloir CONICET Buenos Aires Argentina

Microscopy and BioImaging Facility Fundación Instituto Leloir CONICET Buenos Aires Argentina; Imaging Platform Broad Institute of Harvard and MIT Cambridge MA USA

Molecular Plant Nutrition Department of Physiology and Cell Biology Leibniz Institute of Plant Genetics and Crop Plant Research Corrensstr 3 06466 Gatersleben Germany

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