Nambara E

References (2)

Title : Thermoinhibition uncovers a role for strigolactones in Arabidopsis seed germination - Toh_2012_Plant.Cell.Physiol_53_107
Author(s) : Toh S , Kamiya Y , Kawakami N , Nambara E , McCourt P , Tsuchiya Y
Ref : Plant Cell Physiol , 53 :107 , 2012
Abstract : Strigolactones are host factors that stimulate seed germination of parasitic plant species such as Striga and Orobanche. This hormone is also important in shoot branching architecture and photomorphogenic development. Strigolactone biosynthetic and signaling mutants in model systems, unlike parasitic plants, only show seed germination phenotypes under limited growth condition. To understand the roles of strigolactones in seed germination, it is necessary to develop a tractable experimental system using model plants such as Arabidopsis. Here, we report that thermoinhibition, which involves exposing seeds to high temperatures, uncovers a clear role for strigolactones in promoting Arabidopsis seed germination. Both strigolactone biosynthetic and signaling mutants showed increased sensitivity to seed thermoinhibition. The synthetic strigolactone GR24 rescued germination of thermoinbibited biosynthetic mutant seeds but not a signaling mutant. Hormone analysis revealed that strigolactones alleviate thermoinhibition by modulating levels of the two plant hormones, GA and ABA. We also showed that GR24 was able to counteract secondary dormancy in Arabidopsis ecotype Columbia (Col) and Cape Verde island (Cvi). Systematic hormone analysis of germinating Striga helmonthica seeds suggested a common mechanism between the parasitic and non-parasitic seeds with respect to how hormones regulate germination. Thus, our simple assay system using Arabidopsis thermoinhibition allows comparisons to determine similarities and differences between parasitic plants and model experimental systems for the use of strigolactones.
ESTHER : Toh_2012_Plant.Cell.Physiol_53_107
PubMedSearch : Toh_2012_Plant.Cell.Physiol_53_107
PubMedID: 22173099

Title : A small-molecule screen identifies new functions for the plant hormone strigolactone - Tsuchiya_2010_Nat.Chem.Biol_6_741
Author(s) : Tsuchiya Y , Vidaurre D , Toh S , Hanada A , Nambara E , Kamiya Y , Yamaguchi S , McCourt P
Ref : Nat Chemical Biology , 6 :741 , 2010
Abstract : Parasitic weeds of the genera Striga and Orobanche are considered the most damaging agricultural agents in the developing world. An essential step in parasitic seed germination is sensing a group of structurally related compounds called strigolactones that are released by host plants. Although this makes strigolactone synthesis and action a major target of biotechnology, little fundamental information is known about this hormone. Chemical genetic screening using Arabidopsis thaliana as a platform identified a collection of related small molecules, cotylimides, which perturb strigolactone accumulation. Suppressor screens against select cotylimides identified light-signaling genes as positive regulators of strigolactone levels. Molecular analysis showed strigolactones regulate the nuclear localization of the COP1 ubiquitin ligase, which in part determines the levels of light regulators such as HY5. This information not only uncovers new functions for strigolactones but was also used to identify rice cultivars with reduced capacity to germinate parasitic seed.
ESTHER : Tsuchiya_2010_Nat.Chem.Biol_6_741
PubMedSearch : Tsuchiya_2010_Nat.Chem.Biol_6_741
PubMedID: 20818397