The unique photosynthetic apparatus of Pinaceae - Analysis of photosynthetic complexes in Norway spruce (Piceaabies)
J Exp Bot. 2019 Apr 2 Epub ahead of print]
Grebe S, Trotta A, Bajwa AA, Suorsa M, Gollan PJ, Jansson S, Tikkanen M, Aro EM

Pinaceae are predominant photosynthetic species in boreal forests, but so far no detailed description of the protein components of the photosynthetic apparatus of these gymnosperms has been available. In this study we report a detailed characterization of the thylakoid photosynthetic machinery of Norway spruce (Piceaabies (L.) Karst). We first customized a spruce thylakoid protein database from translated transcript sequences combined with existing protein sequences derived from gene models, which enabled reliable MS/MS identification of Piceaabies thylakoid proteins from two-dimensional lpBN/SDS-PAGE. This allowed a direct comparison of the 2D protein map of thylakoid protein complexes from Picea abies with the model angiosperm Arabidopsis thaliana. Although the subunit composition of Piceaabies core PSI and PSII complexes is largely similar to Arabidopsis thaliana, high abundance of a smaller PSI-subcomplex, closely resembling the assembly intermediate PSI* complex was detected. In addition, the evolutionary distribution of LHC family members of Pinaceae was compared in-silico with other land plants revealing that Piceaabies and other Pinaceae (also Gnetaceae and Welwitschiaceae) have lost LHCB4, but retained LHCB8 (formerly called LHCB4.3). The findings reported here show the composition of the photosynthetic apparatus of Piceaabies and other Pinaceae members to be unique among land plants.

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