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COMPARISON OF RESISTANCE TO LIGHT STRESS IN TOXIC AND NON-TOXIC STRAINS OF MICROCYSTIS AERUGINOSA (CYANOPHYTA)1
Version of Record online: 25 JUN 2012
© 2012 Phycological Society of America
Journal of Phycology
Volume 48, Issue 4, pages 1002–1011, August 2012
How to Cite
Deblois, C. P. and Juneau, P. (2012), COMPARISON OF RESISTANCE TO LIGHT STRESS IN TOXIC AND NON-TOXIC STRAINS OF MICROCYSTIS AERUGINOSA (CYANOPHYTA). Journal of Phycology, 48: 1002–1011. doi: 10.1111/j.1529-8817.2012.01191.x
Received 16 September 2011. Accepted 26 April 2012.
- Issue online: 1 AUG 2012
- Version of Record online: 25 JUN 2012
- Accepted manuscript online: 11 MAY 2012 01:15AM EST
- chlorophyll a fluorescence;
- Microcystis aeruginosa;
- non-toxic strain;
- PSII quantum yields;
- toxic strain
Blooms of Microcystis aeruginosa (Kützing) Kützing occur frequently in many freshwater ecosystems around the world, but the role of environmental factors in promoting the growth and determining the proportion of toxic and non-toxic strains still requires more investigation. In this study, four strains (toxic CPCC299 & FACHB905 and non-toxic CPCC632 & FACHB315) were exposed to high light (HL) condition, similar to light intensity found at the surface of a bloom, to evaluate their sensitivity to photoinhibition. We also estimated their capacity to recover from this HL stress. For all strains, our results showed an increased inhibition of the photosynthetic activity with HL treatment time. When comparing the extent of photoinhibition between strains, both toxic strains were more resistant to the treatment and recovered completely their photosynthetic capacity after 3 h, while non-toxic strains needed more time to recover. For toxic strains, the rETR under HL was higher compared to the rETR under low light (LL) control condition despite 50% photoinhibition. This suggests that the detrimental effect of high light (HL; up to 2 h) is outweighed by their higher photosynthetic potential. This conclusion did not stand for non-toxic strains, and indicates their preference for LL environment. We also demonstrated that a LL/HL cycle induced a 259% increase in cell yield for a toxic strain and a decrease by 22% for a non-toxic strain. This also indicates that toxic strains have higher tolerance to HL in a fluctuating light environment. Our data demonstrated that difference of sensitivity to HL between strains can modify the competitive outcome between toxic and non-toxic strains and may affect bloom toxicity.