title: Loss of Arabidopsis thaliana Seed Dormancy is Associated with Increased Accumulation of the GID1 GA Hormone Receptors.
abstract: Dormancy prevents seeds from germinating under favorable conditions until they have experienced dormancy-breaking conditions, such as after-ripening through a period of dry storage or cold imbibition. Abscisic acid (ABA) hormone signaling establishes and maintains seed dormancy, whereas gibberellin (GA) signaling stimulates germination. ABA levels decrease and GA levels increase with after-ripening and cold stratification. However, increasing GA sensitivity may also be critical to dormancy loss since increasing seed GA levels are detectable only with long periods of after-ripening and imbibition. After-ripening and cold stratification act additively to enhance GA hormone sensitivity in ga1-3 seeds that cannot synthesize GA. Since the overexpression of the GA receptor GID1 (GIBBERELLIN-INSENSITIVE DWARF1) enhanced this dormancy loss, and because gid1a gid1b gid1c triple mutants show decreased germination, the effects of dormancy-breaking treatments on GID1 mRNA and protein accumulation were examined. Partial after-ripening resulted in increased GID1b, but not GID1a or GID1c mRNA levels. Cold imbibition stimulated the accumulation of all three GID1 transcripts, but resulted in no increase in GA sensitivity during ga1-3 seed germination unless seeds were also partially after-ripened. This is probably because after-ripening was needed to enhance GID1 protein accumulation, independently of transcript abundance. The rise in GID1b transcript with after-ripening was not associated with decreased ABA levels, suggesting there is ABA-independent GID1b regulation by after-ripening and the 26S proteasome. GA and the DELLA RGL2 repressor of GA responses differentially regulated the three GID1 transcripts. Moreover, DELLA RGL2 appeared to switch between positive and negative regulation of GID1 expression in response to dormancy-breaking treatments.
authors.affiliation: Department of Crop and Soil Science, Washington State University, Pullman, WA 99164-6420, USA.
authors.forename: Amber L
authors.initials: AL
authors.lastname: Hauvermale
authors.affiliation: Molecular Plant Sciences Program, Washington State University, Pullman, WA 99164-6420, USA.
authors.forename: Keiko M
authors.initials: KM
authors.lastname: Tuttle
authors.affiliation: RIKEN, Center for Sustainable Resource Sciences, Yokohama, Kanagawa, Japan.
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Takebayashi
authors.affiliation: RIKEN, Center for Sustainable Resource Sciences, Yokohama, Kanagawa, Japan.
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Seo
authors.affiliation: Department of Crop and Soil Science, Washington State University, Pullman, WA 99164-6420, USA Molecular Plant Sciences Program, Washington State University, Pullman, WA 99164-6420, USA USDA-ARS, Wheat Genetics, Quality, Physiology, and Disease Research Unit, Pullman, WA, USA csteber@wsu.edu.
authors.forename: Camille M
authors.initials: CM
authors.lastname: Steber
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D003080:Cold Temperature; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000528:radiation effects; D005875:Gibberellins / Q000096:biosynthesis / Q000378:metabolism*; D007976:Leupeptins / Q000494:pharmacology; D008027:Light; D009154:Mutation / Q000235:genetics; D057445:Plant Dormancy / Q000187:drug effects / Q000235:genetics; D010937:Plant Growth Regulators / Q000494:pharmacology; D030821:Plants, Genetically Modified; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D061988:Proteasome Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D012639:Seeds / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects
chemical_list: D029681:Arabidopsis Proteins; C512225:GID1a protein, Arabidopsis; D005875:Gibberellins; D007976:Leupeptins; D010937:Plant Growth Regulators; D061988:Proteasome Inhibitors; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde
keywords: After-ripening; DELLA; Dormancy; GID1; Gibberellin; Seed