title: Inhibition of FUSCA3 degradation at high temperature is dependent on ABA signaling and is regulated by the ABA/GA ratio.
abstract: During seed imbibition at supra-optimal temperature, an increase in the abscisic acid (ABA)/gibberellin (GA) ratio imposes secondary dormancy to prevent germination (thermoinhibition). FUSCA3 (FUS3), a positive regulator of seed dormancy, accumulates in seeds imbibed at high temperature and increases ABA levels to inhibit germination. Recently, we showed that ABA inhibits FUS3 degradation at high temperature, and that ABA and high temperature also inhibit the ubiquitin-proteasome system, by dampening both proteasome activity and protein polyubiquitination. Here, we investigated the role of ABA signaling components and the ABA antagonizing hormone, GA, in the regulation of FUS3 levels. We show that the ABA receptor mutant, pyl1-1, is less sensitive to ABA and thermoinhibition. In this mutant background, FUS3 degradation in vitro is faster. Similarly, GA alleviates thermoinhibition and also increases FUS3 degradation. These results indicate that inhibition of FUS3 degradation at high temperature is dependent on a high ABA/GA ratio and a functional ABA signaling pathway. Thus, FUS3 constitutes an important node in ABA-GA crosstalk during germination at supra-optimal temperature.
authors: a Department of Biological Sciences , University of Toronto Scarborough , Toronto , ON , Canada.|b Department of Cell and Systems Biology , University of Toronto , Toronto , ON , Canada.
authors: Rex Shun
authors: RS
authors: Chiu
authors: a Department of Biological Sciences , University of Toronto Scarborough , Toronto , ON , Canada.
authors: Yazan
authors: Y
authors: Saleh
authors: a Department of Biological Sciences , University of Toronto Scarborough , Toronto , ON , Canada.|b Department of Cell and Systems Biology , University of Toronto , Toronto , ON , Canada.
authors: Sonia
authors: S
authors: Gazzarrini
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D017360:Arabidopsis / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D018525:Germination / Q000502:physiology; D005875:Gibberellins / Q000378:metabolism*; D057445:Plant Dormancy / Q000502:physiology; D010937:Plant Growth Regulators / Q000378:metabolism; D012639:Seeds / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D013696:Temperature; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C502726:FUSCA3 protein, Arabidopsis; D005875:Gibberellins; D010937:Plant Growth Regulators; D014157:Transcription Factors; D000040:Abscisic Acid
keywords: ABA; FUSCA3; GA; UPS; dormancy; germination; high temperature; proteasome; protein degradation; thermoinhibition; ubiquitin proteasome system