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Abscisic acid induced a negative geotropic response in dark-incubated Chlamydomonas reinhardtii

Al-Hijab, Layla; Gregg, Adam; Davies, Rhiannon; Macdonald, Heather; Ladomery, Michael; Wilson, Ian


Layla Al-Hijab

Adam Gregg

Rhiannon Davies


© 2019, The Author(s). The phytohormone abscisic acid (ABA) plays a role in stresses that alter plant water status and may also regulate root gravitropism and hydrotropism. ABA also exists in the aquatic algal progenitors of land plants, but other than its involvement in stress responses, its physiological role in these microorganisms remains elusive. We show that exogenous ABA significantly altered the HCO3− uptake of Chamydomonas reinhardtii in a light-intensity-dependent manner. In high light ABA enhanced HCO3− uptake, while under low light uptake was diminished. In the dark, ABA induced a negative geotropic movement of the algae to an extent dependent on the time of sampling during the light/dark cycle. The algae also showed a differential, light-dependent directional taxis response to a fixed ABA source, moving horizontally towards the source in the light and away in the dark. We conclude that light and ABA signal competitively in order for algae to position themselves in the water column to minimise photo-oxidative stress and optimise photosynthetic efficiency. We suggest that the development of this response mechanism in motile algae may have been an important step in the evolution of terrestrial plants and that its retention therein strongly implicates ABA in the regulation of their relevant tropisms.


Al-Hijab, L., Gregg, A., Davies, R., Macdonald, H., Ladomery, M., & Wilson, I. (2019). Abscisic acid induced a negative geotropic response in dark-incubated Chlamydomonas reinhardtii. Scientific Reports, 9(1),

Journal Article Type Article
Acceptance Date Aug 6, 2019
Online Publication Date Aug 19, 2019
Publication Date Aug 19, 2019
Deposit Date Sep 2, 2019
Publicly Available Date Sep 3, 2019
Journal Scientific Reports
Electronic ISSN 2045-2322
Publisher Nature Research (part of Springer Nature)
Peer Reviewed Peer Reviewed
Volume 9
Issue 1
Article Number 12063
Keywords Abscisic acid, algae, chlamydomonas reinhardtii
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