Light-regulated root gravitropism: a role for, and characterization of, a calcium/calmodulin-dependent protein kinase homolog.
Roots of many species grow downward (orthogravitropism) only when illuminated. Previous work suggests that this is a calcium-regulated response and that both calmodulin and calcium/calmodulin-dependent kinases participate in transducing gravity and light stimuli. A genomic sequence has been obtained for a calcium/calmodulin-dependent kinase homolog (MCK1) expressed in root caps, the site of perception for both light and gravity. This homolog consists of 7265 base pairs and contains 11 exons and 10 introns. Since MCK1 is expressed constitutively in both light and dark, it is unlikely that the light directly affects MCK1 expression, though the activity of the protein may be affected by light. In cultivars showing light-regulated gravitropism, we hypothesize that MCK1, or a homolog, functions in establishing the auxin asymmetry necessary for orthogravitropism.
Lu
Y T
YT
Department of Plant Biology, University of California, Berkeley 94720-3102, USA.
Feldman
L J
LJ
D001483:Base Sequence; D005091:Exons; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D038362:Glycogen Synthase Kinase 3; D006112:Gravitation; D007438:Introns; D008027:Light; D008969:Molecular Sequence Data; D018517:Plant Roots / Q000502:physiology; D011505:Protein-Tyrosine Kinases / Q000096:biosynthesis* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D003313:Zea mays / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects
D029701:Saccharomyces cerevisiae Proteins; D011505:Protein-Tyrosine Kinases; D038362:Glycogen Synthase Kinase 3; C068124:MCK1 protein, S cerevisiae