title: SIS8, a putative mitogen-activated protein kinase kinase kinase, regulates sugar-resistant seedling development in Arabidopsis.
abstract: Sugar signaling pathways have been evolutionarily conserved among eukaryotes and are postulated to help regulate plant growth, development and responses to environmental cues. Forward genetic screens have identified sugar signaling or response mutants. Here we report the identification and characterization of Arabidopsis thaliana sugar insensitive8 (sis8) mutants, which display a sugar-resistant seedling development phenotype. Unlike many other sugar insensitive mutants, sis8 mutants exhibit wild-type responses to the inhibitory effects of abscisic acid and paclobutrazol (an inhibitor of gibberellin biosynthesis) on seed germination. Positional cloning of the SIS8 gene revealed that it encodes a putative mitogen-activated protein kinase kinase kinase (MAPKKK; At1g73660). SIS8mRNA is expressed ubiquitously among Arabidopsis organs. A UDP-glucosyltransferase, UGT72E1 (At3g50740), was identified as an interacting partner of SIS8 based on a yeast two-hybrid screen and in planta bimolecular fluorescence complementation. Both SIS8-yellow fluorescent protein (YFP) and UGT72E1-YFP fusion proteins localize to the nucleus when transiently expressed in tobacco leaf cells. T-DNA insertions in At3g50740 cause a sugar-insensitive phenotype. These results indicate that SIS8, a putative MAPKKK, is a regulator of sugar response in Arabidopsis and interacts with a UDP-glucosyltransferase in the nucleus.
authors: Department of Plant Biology, University of Minnesota, St Paul, MN, 55108, USA.
authors: Yadong
authors: Y
authors: Huang
authors: Chun Yao
authors: CY
authors: Li
authors: Yiping
authors: Y
authors: Qi
authors: Sungjin
authors: S
authors: Park
authors: Susan I
authors: SI
authors: Gibson
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002874:Chromosome Mapping; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D018525:Germination; D005947:Glucose / Q000378:metabolism; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism; D020930:MAP Kinase Kinase Kinases / Q000235:genetics* / Q000378:metabolism; D016254:Mutagenesis, Insertional; D010937:Plant Growth Regulators / Q000494:pharmacology; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D030821:Plants, Genetically Modified; D011993:Recombinant Fusion Proteins; D036226:Seedlings / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D012639:Seeds / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D015398:Signal Transduction; D013395:Sucrose / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism; D014230:Triazoles / Q000494:pharmacology
chemical_list: D029681:Arabidopsis Proteins; D010937:Plant Growth Regulators; D011993:Recombinant Fusion Proteins; D014230:Triazoles; D013395:Sucrose; C053370:paclobutrazol; D000040:Abscisic Acid; D005964:Glucosyltransferases; C000592771:UGT72E1 protein, Arabidopsis; C531403:At1g73660 protein, Arabidopsis; D020930:MAP Kinase Kinase Kinases; D005947:Glucose
keywords: Arabidopsis thaliana; MAP3K; SIS8; UGT72E1; glucose response; glucosyltransferase; sucrose response; sugar response; sugar signaling