Photoprotection and xanthophyll‐cycle activity in three marine diatoms¹

Abstract

Light is one of the most important factors affecting marine phytoplankton growth, and its variability in time and space strongly influences algal performance and success. The hypothesis tested in this work is that the activity of the xanthophyll cycle and the development of nonphotochemical quenching could be considered a functional trait of algal diversity. If this hypothesis is true, a relationship must exist between fast-activated pigment variations linked to photoprotective behavior and the ecology of the species. This assumption was tested on three diatoms: Skeletonema marinoi Sarno et Zingone, Thalassiosira rotula Meunier, and Chaetoceros socialis Lauder. These three diatoms occupy different ecological niches. Strains of these diatoms were subjected to five changes in irradiance. Xanthophyllcycle activity, quantum yield of fluorescence, and electron transport rate were the main parameters determined. There were marked interspecific differences in xanthophyll-cycle activity, and these differences were dependent on the light history of the cells. Chaetoceros socialis responded efficiently to changing irradiance, which might relate to its dominance during the spring bloom in some coastal areas. In contrast, T. rotula responded with a slower photoprotection activation, which seems to reflect its more offshore ecological distribution. The photoresponse of S. marinoi (a late-winter coastal species blooming in the Adriatic Sea) was light-history dependent, becoming photoinhibited under high light when acclimated to low light, but capable of reaching a high photoprotection level when acclimated to moderate light. Our hypothesis on the photoprotection capacity as a functional trait in microalgae seems to be validated given the results of this study.

Metabolic fingerprinting reveals differences between northern and southern strains of the cryptic diatomChaetoceros socialis

“…However, reported growth rates from field and experimental data for C. socialis in northern (Eilertsen & Taasen, 1984;Booth et al, 2002;Leu et al, 2007) and southern (Shevchenko et al, 2008) areas are more or less in accordance with our calculated growth rates, which indicates that the environmental conditions were sufficient to support good growth. This is also supported by the maximum quantum yield data, since our results are comparable to or higher than the values reported from experimental work on C. socialis from the NE Atlantic (Leu et al, 2007) and from the Tyrrhenian Sea (Dimier et al, 2007).…”

Metabolic fingerprinting reveals differences between northern and southern strains of the cryptic diatomChaetoceros socialis

“…However, reported growth rates from field and experimental data for C. socialis in northern (Eilertsen & Taasen, 1984;Booth et al, 2002;Leu et al, 2007) and southern (Shevchenko et al, 2008) areas are more or less in accordance with our calculated growth rates, which indicates that the environmental conditions were sufficient to support good growth. This is also supported by the maximum quantum yield data, since our results are comparable to or higher than the values reported from experimental work on C. socialis from the NE Atlantic (Leu et al, 2007) and from the Tyrrhenian Sea (Dimier et al, 2007).…”

PHOTOPROTECTION OF SEA‐ICE MICROALGAL COMMUNITIES FROM THE EAST ANTARCTIC PACK ICE1

“…LIGHT STRESS IN SEA-ICE MICROALGAE were well within reported ranges for chl c:chl a, fuco:chl a, and Dd+Dt:chl a (Sakshaug and Slagstad 1991, Olaizola and Yamamoto 1994, Robinson et al 1997). However, b, b-car:chl a was below previously reported values, and the VAZ pool:chl a was close to values found in temperate diatoms (Dimier et al 2007).…”

“…1997). However, β, β‐car:chl a was below previously reported values, and the VAZ pool:chl a was close to values found in temperate diatoms (Dimier et al. 2007).…”

Growth and photophysiological responses of two picoplanktonicMinutocellusspecies, strains RCC967 and RCC703 (Bacillariophyceae)

“…Whereas Dd and Dt increased together with increasing light intensities in Minutocellus RCC703, their trends become opposite under HL regimes in Minutocellus RCC967, revealing that for a certain PFD and/or Dt content threshold, Dt still increases without any replenishment of Dd. A similar strategy with a very high Dt synthesis has been observed also in the low-light acclimated Skeletonema marinoi when subjected to PFD increase (Dimier et al, 2007b). Such a strong increase, together with the probable low accessibility to the Dt-epoxidase and low level of NPQ, would be related to a photoprotective function of Dt at the level of the thylakoid membrane lipids, against peroxidative stress during excess light energy exposure, as also demonstrated for Zx in higher plants (Havaux & Niyogi, 1999).…”

Metabolic fingerprinting reveals differences between northern and southern strains of the cryptic diatomChaetoceros socialis

“…However, reported growth rates from field and experimental data for C. socialis in northern (Eilertsen & Taasen, 1984;Booth et al, 2002;Leu et al, 2007) and southern (Shevchenko et al, 2008) areas are more or less in accordance with our calculated growth rates, which indicates that the environmental conditions were sufficient to support good growth. This is also supported by the maximum quantum yield data, since our results are comparable to or higher than the values reported from experimental work on C. socialis from the NE Atlantic (Leu et al, 2007) and from the Tyrrhenian Sea (Dimier et al, 2007).…”

PHOTOPROTECTION OF SEA‐ICE MICROALGAL COMMUNITIES FROM THE EAST ANTARCTIC PACK ICE1

“…LIGHT STRESS IN SEA-ICE MICROALGAE were well within reported ranges for chl c:chl a, fuco:chl a, and Dd+Dt:chl a (Sakshaug and Slagstad 1991, Olaizola and Yamamoto 1994, Robinson et al 1997). However, b, b-car:chl a was below previously reported values, and the VAZ pool:chl a was close to values found in temperate diatoms (Dimier et al 2007).…”

“…1997). However, β, β‐car:chl a was below previously reported values, and the VAZ pool:chl a was close to values found in temperate diatoms (Dimier et al. 2007).…”

Growth and photophysiological responses of two picoplanktonicMinutocellusspecies, strains RCC967 and RCC703 (Bacillariophyceae)

“…Whereas Dd and Dt increased together with increasing light intensities in Minutocellus RCC703, their trends become opposite under HL regimes in Minutocellus RCC967, revealing that for a certain PFD and/or Dt content threshold, Dt still increases without any replenishment of Dd. A similar strategy with a very high Dt synthesis has been observed also in the low-light acclimated Skeletonema marinoi when subjected to PFD increase (Dimier et al, 2007b). Such a strong increase, together with the probable low accessibility to the Dt-epoxidase and low level of NPQ, would be related to a photoprotective function of Dt at the level of the thylakoid membrane lipids, against peroxidative stress during excess light energy exposure, as also demonstrated for Zx in higher plants (Havaux & Niyogi, 1999).…”

Metabolic fingerprinting reveals differences between northern and southern strains of the cryptic diatomChaetoceros socialis

“…However, reported growth rates from field and experimental data for C. socialis in northern (Eilertsen & Taasen, 1984;Booth et al, 2002;Leu et al, 2007) and southern (Shevchenko et al, 2008) areas are more or less in accordance with our calculated growth rates, which indicates that the environmental conditions were sufficient to support good growth. This is also supported by the maximum quantum yield data, since our results are comparable to or higher than the values reported from experimental work on C. socialis from the NE Atlantic (Leu et al, 2007) and from the Tyrrhenian Sea (Dimier et al, 2007).…”

PHOTOPROTECTION OF SEA‐ICE MICROALGAL COMMUNITIES FROM THE EAST ANTARCTIC PACK ICE1

“…LIGHT STRESS IN SEA-ICE MICROALGAE were well within reported ranges for chl c:chl a, fuco:chl a, and Dd+Dt:chl a (Sakshaug and Slagstad 1991, Olaizola and Yamamoto 1994, Robinson et al 1997). However, b, b-car:chl a was below previously reported values, and the VAZ pool:chl a was close to values found in temperate diatoms (Dimier et al 2007).…”

“…1997). However, β, β‐car:chl a was below previously reported values, and the VAZ pool:chl a was close to values found in temperate diatoms (Dimier et al. 2007).…”

Growth and photophysiological responses of two picoplanktonicMinutocellusspecies, strains RCC967 and RCC703 (Bacillariophyceae)

“…Whereas Dd and Dt increased together with increasing light intensities in Minutocellus RCC703, their trends become opposite under HL regimes in Minutocellus RCC967, revealing that for a certain PFD and/or Dt content threshold, Dt still increases without any replenishment of Dd. A similar strategy with a very high Dt synthesis has been observed also in the low-light acclimated Skeletonema marinoi when subjected to PFD increase (Dimier et al, 2007b). Such a strong increase, together with the probable low accessibility to the Dt-epoxidase and low level of NPQ, would be related to a photoprotective function of Dt at the level of the thylakoid membrane lipids, against peroxidative stress during excess light energy exposure, as also demonstrated for Zx in higher plants (Havaux & Niyogi, 1999).…”