title: Diversification of phytochrome contributions to germination as a function of seed-maturation environment.
abstract: Environmental conditions during seed maturation influence germination, but the genetic basis of maternal environmental effects on germination is virtually unknown. Using single and multiple mutants of phytochromes, it is shown here that different phytochromes contributed to germination differently, depending on seed-maturation conditions. Arabidopsis thaliana wild-type seeds that were matured under cool temperatures were intensely dormant compared with seeds matured at warmer temperature, and this dormancy was broken only after warm seed-stratification followed by cold seed-stratification. The warm-cold stratification broke dormancy in fresh seeds but not in dry after-ripened seeds. Functional PHYB and PHYD were necessary to break cool-induced dormancy, which indicates a previously unknown and ecologically important function for PHYD. Disruption of PHYA in combination with PHYD (but not PHYB) restored germination to near wild-type levels, indicating that PHYA contributes to the maintenance of cool-induced dormancy on a phyD background. Effects of seed-maturation temperature were much stronger than effects of seed-maturation photoperiod. PHYB contributed to germination somewhat more strongly in seeds matured under short days, whereas PHYD contributed to germination somewhat more strongly in seeds matured under long days. The variable contributions of different phytochromes to germination as a function of seed-maturation conditions reveal further functional diversification of the phytochromes during the process of germination. This study identifies among the first genes to be associated with maternal environmental effects on germination.
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, 22 Divinity Ave., Cambridge, MA 02138, USA.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Donohue
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, 22 Divinity Ave., Cambridge, MA 02138, USA.
authors.forename: M Shane
authors.initials: MS
authors.lastname: Heschel
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, 22 Divinity Ave., Cambridge, MA 02138, USA.
authors.forename: Colleen M
authors.initials: CM
authors.lastname: Butler
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, 22 Divinity Ave., Cambridge, MA 02138, USA.
authors.forename: Deepak
authors.initials: D
authors.lastname: Barua
authors.affiliation: Department of Plant Sciences and Plant Pathology, Montana State University, PO Box 173150, Bozeman, MT 59717-3150, USA.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Sharrock
authors.affiliation: Institute of Genetics, Adrian Building, University of Leicester, University Road, Leicester LE1 7RH, UK.
authors.forename: Garry C
authors.initials: GC
authors.lastname: Whitelam
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, 22 Divinity Ave., Cambridge, MA 02138, USA.
authors.forename: George C K
authors.initials: GCK
authors.lastname: Chiang
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development*; D018506:Gene Expression Regulation, Plant; D014644:Genetic Variation; D018525:Germination; D009154:Mutation; D017440:Photoperiod; D010834:Phytochrome / Q000235:genetics*; D012639:Seeds / Q000254:growth & development*; D013696:Temperature; D013997:Time Factors
chemical_list: D010834:Phytochrome