Polarization of PIN3‐dependent auxin transport for hypocotyl gravitropic response in Arabidopsis thaliana

• Published in: The Plant journal : for cell and molecular biology 2011-09, Vol.67 (5), p.817-826
• Main Authors: Rakusová, Hana, Gallego‐Bartolomé, Javier, Vanstraelen, Marleen, Robert, Hélène S., Alabadí, David, Blázquez, Miguel A., Benková, Eva, Friml, Jiří
• Format: Article
• Language: English
• Subjects: Arabidopsis - cytology; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - physiology; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; auxin transport; Biological and medical sciences; Biological Transport; Cell physiology; Cell Polarity; Cell transformation and carcinogenesis. Action of oncogenes and antioncogenes; Fundamental and applied biological sciences. Psychology; GNOM ARF GEF; Gravitation; Gravitropism - genetics; Gravitropism - physiology; Gravity Sensing; Guanine Nucleotide Exchange Factors - genetics; Guanine Nucleotide Exchange Factors - metabolism; Hypocotyl - genetics; Hypocotyl - growth & development; Hypocotyl - metabolism; hypocotyl gravitropism; Indoleacetic Acids - metabolism; Kinases; Molecular and cellular biology; Mutation; Phytochemicals; PIN polarity; PINOID kinase; Plant biology; Plant growth; Plant Growth Regulators - genetics; Plant Growth Regulators - metabolism; Plant physiology and development; Plants, Genetically Modified - cytology; Plants, Genetically Modified - genetics; Plants, Genetically Modified - growth & development; Plants, Genetically Modified - physiology; Protein-Serine-Threonine Kinases - genetics; Protein-Serine-Threonine Kinases - metabolism; Seedlings - cytology; Seedlings - genetics; Seedlings - growth & development; Seedlings - physiology
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/j.1365-313X.2011.04636.x

Summary Gravitropism aligns plant growth with gravity. It involves gravity perception and the asymmetric distribution of the phytohormone auxin. Here we provide insights into the mechanism for hypocotyl gravitropic growth. We show that the Arabidopsis thaliana PIN3 auxin transporter is required for the asymmetric auxin distribution for the gravitropic response. Gravistimulation polarizes PIN3 to the bottom side of hypocotyl endodermal cells, which correlates with an increased auxin response at the lower hypocotyl side. Both PIN3 polarization and hypocotyl bending require the activity of the trafficking regulator GNOM and the protein kinase PINOID. Our data suggest that gravity‐induced PIN3 polarization diverts the auxin flow to mediate the asymmetric distribution of auxin for gravitropic shoot bending.