Arabidopsis reduces growth under osmotic stress by decreasing SPEECHLESS protein.
Plants, which are sessile unlike most animals, have evolved a system to reduce growth under stress; however, the molecular mechanisms of this stress response are not well known. During programmed development, a fraction of the leaf epidermal precursor cells become meristemoid mother cells (MMCs), which are stem cells that produce both stomatal guard cells and epidermal pavement cells. Here we report that Arabidopsis plants, in response to osmotic stress, post-transcriptionally decrease the protein level of SPEECHLESS, the transcription factor promoting MMC identity, through the action of a mitogen-activated protein kinase (MAPK) cascade. The growth reduction under osmotic stress was lessened by inhibition of the MAPK cascade or by a mutation that disrupted the MAPK target amino acids in SPEECHLESS, indicating that Arabidopsis reduces growth under stress by integrating the osmotic stress signal into the MAPK-SPEECHLESS core developmental pathway.
Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043 Japan.
Archana
A
Kumari
Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043 Japan Present address: Molecular Genetics, Leobener Str. 2, NW2, B 1030D, 28359 Bremen, Germany.
Pawan K
PK
Jewaria
Howard Hughes Medical Institute and Department of Biology, Stanford University, Stanford, CA 94305-5020, USA.
Dominique C
DC
Bergmann
Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043 Japan Kakimoto@bio.sci.osaka-u.ac.jp.
Tatsuo
T
Kakimoto
D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D049109:Cell Proliferation; D055864:Droughts; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D020935:MAP Kinase Signaling System; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D009997:Osmotic Pressure; D019441:Plant Epidermis / Q000201:enzymology / Q000235:genetics / Q000502:physiology; D054046:Plant Stomata / Q000201:enzymology / Q000235:genetics / Q000502:physiology
D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D020928:Mitogen-Activated Protein Kinases; C517480:SPEECHLESS protein, Arabidopsis
Arabidopsis thaliana; Mitogen-activated protein kinase; Osmotic stress; SPEECHLESS; Signal integration; Stomata