title: ACTIVATOR of Spomin::LUC1/WRINKLED1 of Arabidopsis thaliana transactivates sugar-inducible promoters.
abstract: We isolated an enhancer activation-tagged mutant of Arabidopsis thaliana line sGsL carrying the luciferase (LUC) gene under control of a short sugar-inducible promoter derived from a sweet potato sporamin gene (Spomin) that showed high level expression of LUC under non-inducing conditions. The activator of Spomin::LUC1 (ASML1) gene located downstream of the enhancer encoded an APETALA2 (AP2)-type AP2 domain protein, and this gene was shown recently to be responsible for the wrinkled1 mutation which causes defective accumulation of seed storage oil. Overexpression of ASML1 cDNA in sGsL plants resulted in enhanced expression of not only the LUC reporter but also endogenous sugar-inducible genes including Atbeta-Amy encoding beta-amylase. Transient co-expression of 35S::ASML1 with Spomin::LUC or Atbeta-Amy::LUC reporters in protoplasts resulted in an approximately 10-fold transactivation of LUC expression. This transactivation was lost when the C-terminal acidic region of ASML1 was deleted. Expression of ASML1 was high in reproductive organs, and ASML1 mRNA showed transient accumulation in leaves after treatment with 6% sucrose, whereas it did not respond to abscisic acid. These results suggest that ASML1/WRI1 is a transcriptional activator involved in the activation of a subset of sugar-responsive genes and the control of carbon flow from sucrose import to oil accumulation in developing seeds.
authors.affiliation: Laboratory of Biochemistry, Graduate School of Bioagricultural Science, Nagoya University, Chikusa, Nagoya, 464-8601 Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Masaki
authors.forename: Naoko
authors.initials: N
authors.lastname: Mitsui
authors.forename: Hironaka
authors.initials: H
authors.lastname: Tsukagoshi
authors.forename: Terumi
authors.initials: T
authors.lastname: Nishii
authors.forename: Atsushi
authors.initials: A
authors.lastname: Morikami
authors.forename: Kenzo
authors.initials: K
authors.lastname: Nakamura
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D050260:Carbohydrate Metabolism; D002244:Carbon / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter / Q000235:genetics; D018398:Homeodomain Proteins / Q000235:genetics; D008156:Luciferases / Q000235:genetics*; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics; D018515:Plant Leaves / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012639:Seeds / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D015533:Transcriptional Activation / Q000502:physiology
chemical_list: C499534:APETALA2 protein, Arabidopsis; D029681:Arabidopsis Proteins; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; D010940:Plant Proteins; D014157:Transcription Factors; C495665:WRINKLED1 protein, Arabidopsis; C053374:sporamin A protein, Ipomoea batatas; D002244:Carbon; D008156:Luciferases