Highly-efficient NPQ protects both Photosystems in the alga Nannochloropsis gaditana

Volha Chukhutsinaa, Rikard Fristedta, Tomas Morosinottob, Roberta Crocea
aBiophysics of Photosynthesis, VU University Amsterdam, The Netherlands; bDipartimento di Biologia, Università di Padova, Italy

Nannochloropsis gaditana is a member of the Eustigmatophyceae, which are unicellular yellow-green- algae within the phylum Heterokontophyta. They are more closely related to brown algae and diatoms than to green algae[1]. Their antennas, violaxanthin-chlorophyll a proteins (VCP), are characterized by the presence of violaxanthin and vaucheriaxanthin as main carotenoids, and contain exclusively chlorophyll (Chl) a. These antennae lack the accessory chlorophyll Chl c that is present in brown algae and diatoms2. Recently, the Nannochloropsis genus has attracted attention since some of its species can potentially be used for biotechnological applications, because of their high growth rate and lipid accumulation capacity[3,4].

However, little information is available on the photosynthetic apparatus of N. gaditana and on its response to light changes.

Similar to diatoms, N. gaditana can reach extremely high non-photochemical quenching (NPQ) levels 4 under light stress. NPQ build-up and relaxation, however, is much slower in N. gaditana than in diatoms or other algae, suggesting a (partly) different NPQ mechanism. By “locking” the cells at 77K in six different states and performing time-resolved fluorescence measurements, we studied the build-up of NPQ and its recovery in time after light stress. Based on the spectroscopic measurements as well as biochemical and bioinformatics analysis we propose a multistep model of NPQ induction and recovery in N. gaditana.

References

[1] C. Büchel, J Plant Physiol 2015, 172, 62-75.
[2] L. Lubian,. R. Establier, Investigacion Pesquera (Spain) 1983.
[3] J. C. Kromkamp et al Aquatic Microbial Ecology 2009.
[4] D. Simionato et al, Bioresour Technol 2011, 102, 6026-6032.