Unique peripheral antennas in the photosystems of the streptophyte alga Mesostigma viride.

Land plants evolved from a single group of streptophyte algae. One of the key factors needed for adaptation to a land environment is the modification of the peripheral antenna systems of photosystems. Here, the photosystems of Mesostigma viride, an earliest-branched streptophyte alga, were analyzed to gain insight into their evolution. Iso-seq and phylogenetic analyses of Light-Harvesting Complexes (LHCs) revealed that M. viride possesses three algae-specific LHCs, including algae-type LHCA2, LHCA9, and LHCP; while the streptophyte-specific LHCB6 was not identified. These data suggest that the acquisition of LHCB6 and the loss of algae-type LHCs occurred after the M. viride lineage branched off from other streptophytes. Clear-native (CN)-PAGE resolved the photosynthetic complexes, including the PSI-PSII megacomplex, PSII-LHCII, two PSI-LHCI-LHCIIs, PSI-LHCI, and the LHCII trimer. Results indicated that the higher-molecular weight PSI-LHCI-LHCII likely had more LHCII than the lower-molecular weight one, a unique feature of M. viride photosystems. CN-PAGE coupled with mass spectrometry strongly suggested that the LHCP was bound to PSII-LHCII, while the algae-type LHCA2 and LHCA9 were bound to PSI-LHCI, both of which are different from those in land plants. Results of the present study strongly suggest that M. viride photosystems possess unique features that were inherited from a common ancestor of streptophyte and chlorophyte algae. © The Author(s) 2021. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Citation

Michiki Aso, Renon Matsumae, Ayumi Tanaka, Ryouichi Tanaka, Atsushi Takabayashi. Unique peripheral antennas in the photosystems of the streptophyte alga Mesostigma viride. Plant & cell physiology. 2021 Jan 08

PMID: 33416834

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