title: Spatiotemporal modulation of abscisic acid and gibberellin metabolism and signalling mediates the effects of suboptimal and supraoptimal temperatures on seed germination in wheat (Triticum aestivum L.).
abstract: Seed germination is a complex process regulated by intrinsic hormonal cues such as abscisic acid (ABA) and gibberellin (GA), and environmental signals including temperature. Using pharmacological, molecular and metabolomics approaches, we show that supraoptimal temperature delays wheat seed germination through maintaining elevated embryonic ABA level via increased expression of ABA biosynthetic genes (TaNCED1 and TaNCED2), increasing embryo ABA sensitivity through upregulation of genes regulating ABA signalling positively (TaPYL5, TaSnRK2, ABI3 and ABI5) and decreasing embryo GA sensitivity via induction of TaRHT1 that regulates GA signalling negatively. Endospermic ABA and GA appeared to have minimal roles in regulating germination at supraoptimal temperature. Germination inhibition by suboptimal temperature is associated with elevated ABA level in the embryo and endosperm tissues, mediated by induction of TaNCEDs and decreased expression of endospermic ABA catabolic genes (TaCYP707As), and increased ABA sensitivity in both tissues via upregulation of TaPYL5, TaSnRK2, ABI3 and ABI5 in the embryo and TaSnRK2 and ABI5 in the endosperm. Furthermore, suboptimal temperature suppresses GA synthesis in both tissues and GA sensitivity in the embryo via repressing GA biosynthetic genes (TaGA20ox and TaGA3ox2) and inducing TaRHT1, respectively. These results highlight that spatiotemporal modulation of ABA and GA metabolism and signalling in wheat seeds underlies germination response to temperature.
authors.affiliation: Department of Plant Science, University of Manitoba, 222 Agriculture Building, Winnipeg, Manitoba, R3T 2N2, Canada.
authors.forename: Conrad
authors.initials: C
authors.lastname: Izydorczyk
authors.affiliation: Department of Plant Science, University of Manitoba, 222 Agriculture Building, Winnipeg, Manitoba, R3T 2N2, Canada.
authors.forename: Tran-Nguyen
authors.initials: TN
authors.lastname: Nguyen
authors.affiliation: Department of Plant Science, University of Manitoba, 222 Agriculture Building, Winnipeg, Manitoba, R3T 2N2, Canada.
authors.forename: SeoHyun
authors.initials: S
authors.lastname: Jo
authors.affiliation: Department of Plant Science, University of Manitoba, 222 Agriculture Building, Winnipeg, Manitoba, R3T 2N2, Canada.
authors.forename: SeungHyun
authors.initials: S
authors.lastname: Son
authors.affiliation: Department of Plant Science, University of Manitoba, 222 Agriculture Building, Winnipeg, Manitoba, R3T 2N2, Canada.
authors.forename: Pham Anh
authors.initials: PA
authors.lastname: Tuan
authors.affiliation: Department of Plant Science, University of Manitoba, 222 Agriculture Building, Winnipeg, Manitoba, R3T 2N2, Canada.
authors.forename: Belay T
authors.identifier: 0000-0001-9550-2799
authors.initials: BT
authors.lastname: Ayele
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D056625:Endosperm / Q000235:genetics / Q000502:physiology; D018525:Germination; D005875:Gibberellins / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000235:genetics / Q000502:physiology; D015398:Signal Transduction; D062211:Spatio-Temporal Analysis; D013696:Temperature; D014908:Triticum / Q000235:genetics / Q000502:physiology*
chemical_list: D005875:Gibberellins; D010937:Plant Growth Regulators; D010940:Plant Proteins; D000040:Abscisic Acid
keywords: embryo; endosperm; gene expression; imbibition; plant hormones