Shoot Circumnutation and Winding Movements Require Gravisensing Cells

• Published in: Proceedings of the National Academy of Sciences - PNAS 2005-12, Vol.102 (51), p.18742-18747
• Main Authors: Daisuke Kitazawa, Yasuko Hatakeda, Motoshi Kamada Nobuharu Fujii, Yutaka Miyazawa, Atsushi Hoshino, Shigeru Lida, Fukaki, Hidehiro, Morita, Miyo Terao, Tasaka, Masao, Hiroshi Suge, Takahashi, Hideyuki, Coen, Enrico
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Arabidopsis - genetics; Base Sequence; Biological Sciences; Botany; Endodermis; Genetic Complementation Test; Genetic mutation; Gravitropism; Gravity perception; Gravity Sensing - physiology; Inflorescences; Ipomoea nil - cytology; Ipomoea nil - genetics; Ipomoea nil - growth & development; Ipomoea nil - physiology; Molecular Sequence Data; Mutation; Mutation - genetics; Nutation; Phenotype; Phenotypes; Physical growth; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Shoots - cytology; Plant Shoots - genetics; Plant Shoots - growth & development; Plant Shoots - physiology; Plants; Plants, Genetically Modified; Proteins; Stems
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0504617102

Circumnutation and winding in plants are universal growth movements that allow plants to survive despite their sessile nature. However, the detailed molecular mechanisms controlling these phenomena remain unclear. We previously found that a gravitropic mutant of Japanese morning glory (Pharbitis nil or Ipomoea nil), Shidare-asagao (weeping), is defective not only in circumnutation but also in the winding response. This phenotype is similar to that of the Arabidopsis SCARECROW (SCR) mutant. We therefore investigated whether morning glory SCR (PnSCR) is involved in the weeping phenotype. We found that one amino acid was inserted into the highly conserved VHIID motif in weeping-type PnSCR; this mutation caused abnormal endodermal differentiation. We introduced either the mutant or WT PnSCR into Arabidopsis scr mutants for complementation tests. PnSCR of the WT, but not of weeping, rescued the shoot gravitropism and circumnutation of scr. These results show that both the abnormal gravitropism and the circumnutation defect in weeping are attributable to a loss of PnSCR function. Thus, our data show that gravisensing endodermal cells are indispensable for shoot circumnutation and the winding response and that PnSCR is responsible for the abnormal phenotypes of weeping.