Photoinhibition and Photoprotective Responses of a Brown Marine Macroalga Acclimated to Different Light and Nutrient Regimes

• Main Authors: Hikaru Endo (Author), Hikari Moriyama (Author), Yutaka Okumura (Author)
• Format: Book
• Published: MDPI AG, 2023-02-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.

Summary

Plants and brown algae avoid photoinhibition (decline in photosystem II efficiency, <i>Fv</i>/<i>Fm</i>) caused by excess light energy and oxidative stress through several photoprotective mechanisms, such as antioxidant xanthophyll production and heat dissipation. The heat dissipation can be measured as non-photochemical quenching (NPQ) and is strongly driven by de-epoxidation of xanthophyll cycle pigments (XCP). Although NPQ is known to increase under high light acclimation and nutrient-deficient conditions, a few studies have investigated the combined effects of the conditions on both NPQ and associated xanthophyll-to-chlorophyll (Chl) a ratio. The present study investigated the photosynthetic parameters of the brown alga <i>Sargassum fusiforme</i> acclimated to three irradiance levels combined with three nutrient levels. Elevated irradiance decreased <i>Fv</i>/<i>Fm</i> but increased NPQ, XCP/Chl <i>a</i> ratio, and fucoxanthin/Chl <i>a</i> ratio, suggesting the photoprotective role of antioxidant fucoxanthin in brown algae. Reduced nutrient availability increased NPQ but had no effect on the other variables, including XCP/Chl <i>a</i> ratio and its de-epoxidation state. The results indicate that NPQ can be used as a sensitive stress marker for nutrient deficiency, but cannot be used to estimate XCP pool size and state.

Item Description

10.3390/antiox12020357
2076-3921