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Karrikins discovered in smoke trigger Arabidopsis seed germination by a mechanism requiring gibberellic acid synthesis and light
Citation
Nelson, DC and Riseborough, J-A and Flematti, GR and Stevens, J and Ghisalberti, EL and Dixon, KW and Smith, SM, Karrikins discovered in smoke trigger Arabidopsis seed germination by a mechanism requiring gibberellic acid synthesis and light, Plant Physiology, 149, (2) pp. 863-873. ISSN 0032-0889 (2009) [Refereed Article]
Copyright Statement
© 2009 American Society of Plant Biologists. All rights reserved.
DOI: doi:10.1104/pp.108.131516
Abstract
Discovery of the primary seed germination stimulant in smoke, 3-methyl-2H-furo[2,3-c]pyran-2-one (KAR1), has resulted in
identification of a family of structurally related plant growth regulators, karrikins. KAR1 acts as a key germination trigger for
many species from fire-prone, Mediterranean climates, but a molecular mechanism for this response remains unknown. We
demonstrate that Arabidopsis (Arabidopsis thaliana), an ephemeral of the temperate northern hemisphere that has never, to our
knowledge, been reported to be responsive to fire or smoke, rapidly and sensitively perceives karrikins. Thus, these signaling
molecules may have greater significance among angiosperms than previously realized. Karrikins can trigger germination of
primary dormant Arabidopsis seeds far more effectively than known phytohormones or the structurally related strigolactone
GR-24. Natural variation and depth of seed dormancy affect the degree of KAR1 stimulation. Analysis of phytohormone
mutant germination reveals suppression of KAR1 responses by abscisic acid and a requirement for gibberellin (GA) synthesis.
The reduced germination of sleepy1 mutants is partially recovered by KAR1, which suggests that germination enhancement by
karrikin is only partly DELLA dependent. While KAR1 has little effect on sensitivity to exogenous GA, it enhances expression
of the GA biosynthetic genes GA3ox1 and GA3ox2 during seed imbibition. Neither abscisic acid nor GA levels in seed are
appreciably affected by KAR1 treatment prior to radicle emergence, despite marked differences in germination outcome. KAR1
stimulation of Arabidopsis germination is light-dependent and reversible by far-red exposure, although limited induction of
GA3ox1 still occurs in the dark. The observed requirements for light and GA biosynthesis provide the first insights into the
karrikin mode of action.
Item Details
| Item Type: | Refereed Article |
|---|---|
| Keywords: | karrikins, smoke, arabidopsis thaliana, seed germination, gibberelic acid synthesis, light |
| Research Division: | Biological Sciences |
| Research Group: | Plant Biology |
| Research Field: | Plant Physiology |
| Objective Division: | Expanding Knowledge |
| Objective Group: | Expanding Knowledge |
| Objective Field: | Expanding Knowledge in the Biological Sciences |
| Author: | Smith, SM (Professor Steven Smith) |
| ID Code: | 101478 |
| Year Published: | 2009 |
| Web of Science® Times Cited: | 119 |
| Deposited By: | Plant Science |
| Deposited On: | 2015-06-24 |
| Last Modified: | 2015-09-22 |
| Downloads: | 0 |
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