Evidence that UV-B tolerance of the photosynthetic apparatus in microalgae is related to the D1-turnover mediated repair cycle in vivo

Author: Xiong F.

Source: Journal of Plant Physiology, Volume 158, Number 3, March 2001 , pp. 285-294(10)

Publisher: Urban & Fischer

Abstract:

The present study was conceived to elucidate the potential importance of the D1 turnover-mediated repair mechanism in UV-B tolerance of the photosynthetic apparatus in microalgae. To this end, the lab-identified UV-B sensitive and tolerant species of Chlorophyte and Chromophyte algae was used to examine photosynthetic response to UV-B exposure in the presence vs. the absence of streptomycin, an inhibitor of chloroplast protein synthesis. Measurements of photosynthetic O₂ evolution capacity and chlorophyll fluorescence parameters (F_v/F_m, _PSII) illustrated species-specific UV-B sensitivity of the photosynthetic apparatus. Addition of the inhibitor streptomycin caused significant enhancements of UV-B-caused depression of photosynthesis in UV-B tolerant species, while little effect was observed in the sensitive species. In the tolerant species, recovery from UV-B induced 20 % decline in F_v/F_m reached completion within 2 hours, much faster than that in the sensitive species. Immunoblotting revealed that exposure to UV-B radiation caused substantial degradation of the D1 protein in the sensitive Heterococcus brevicellularis, which was little enhanced by addition of the inhibitor. The same UV-B exposure lead to less D1 degradation in the tolerant Scenedesmus sp., which was significantly enhanced by addition of the inhibitor. This study shows that UV-B tolerance of the photosynthetic apparatus in microalgae was associated with a strong capacity for recovery from the UV-B-induced damage and this capacity related to the D1 turnover-mediated repair cycle, and largely determined UV-B tolerance of the photosynthetic apparatus in these organisms.

Keywords: chlorophyll fluorescence; microalgae; photosynthetic oxygen evolution; repair cycle; the D1 turnover; ultraviolet-B radiation

Language: English

Document Type: Miscellaneous

DOI: http://dx.doi.org/10.1078/0176-1617-00306

Affiliations: 1: National Research Center for Photosynthesis and Global Climate Change, Institute of Microbiology, AVCR, Opatovický mlýn, 37981 Trbon, Czech Republicbon, Czech Republic">

Publication date: 2001-03-01

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• In this Subject: Botany
• By this author: Xiong F.

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