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FIRST INDUCED PLASTID GENOME MUTATIONS IN AN ALGA WITH SECONDARY PLASTIDS: psb A MUTATIONS IN THE DIATOM PHAEODACTYLUM TRICORNUTUM (BACILLARIOPHYCEAE) REVEAL CONSEQUENCES ON THE REGULATION OF PHOTOSYNTHESIS 1
Author(s) -
Materna Arne C.,
Sturm Sabine,
Kroth Peter G.,
Lavaud Johann
Publication year - 2009
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.1529-8817.2009.00711.x
Subject(s) - phaeodactylum tricornutum , biology , photosynthesis , plastid , mutant , diatom , photosystem ii , chloroplast , botany , cyanobacteria , mutation , gene , biochemistry , genetics , bacteria
Diatoms play a crucial role in the biochemistry and ecology of most aquatic ecosystems, especially because of their high photosynthetic productivity. They often have to cope with a fluctuating light climate and a punctuated exposure to excess light, which can be harmful for photosynthesis. To gain insight into the regulation of photosynthesis in diatoms, we generated and studied mutants of the diatom Phaeodactylum tricornutum Bohlin carrying functionally altered versions of the plastidic psb A gene encoding the D1 protein of the PSII reaction center (PSII RC). All analyzed mutants feature an amino acid substitution in the vicinity of the Q B ‐binding pocket of D1. We characterized the photosynthetic capacity of the mutants in comparison to wildtype cells, focusing on the way they regulate their photochemistry as a function of light intensity. The results show that the mutations resulted in constitutive changes of PSII electron transport rates. The extent of the impairment varies between mutants depending on the proximity of the mutation to the Q B ‐binding pocket and/or to the nonheme iron within the PSII RC. The effects of the mutations described here for P. tricornutum are similar to effects in cyanobacteria and green microalgae, emphasizing the conservation of the D1 protein structure among photosynthetic organisms of different evolutionary origins.