Changes in the Photosynthetic Pigment Contents and Transcription Levels of Phycoerythrin-Related Genes in Three Gracilariopsis lemaneiformis Strains Under Different Light Intensities

Three Gracilariopsis lemaneiformis strains, including wild type and high-temperature-resistant cultivars 981 and 2007, were studied with the changes in their photosynthetic pigment contents and related gene transcription levels under different light intensities (10, 60, 100, and 200 µmol m−2 s−1). The three G. lemaneiformis strains had the following photosynthetic pigments with high-to-low contents: phycoerythrin (PE), phycocyanin (PC), allophycocyanin (APC), and chlorophyll a (Chl a). Among the three strains, cultivar 981 had the highest PE content, followed by cultivar 2007. The PC and APC contents were similar among the three strains, but they were higher in cultivars 981 and 2007 than in the wild type. The Chl a contents in the three G. lemaneiformis strains were equal. A low light intensity (10 µmol m−2 s−1) promoted photosynthetic pigment accumulation in G. lemaneiformis and improved the relative PE gene transcription (peA and peB) in a short period (≤ 6 d). A high light intensity decreased the PE content. PebA and PebB, which catalyzed phycoerythrobilin synthesis, showed no compensatory upregulation at a low light intensity among the strains except for the wild type. At a high light intensity, transcription levels of pebA and pebB in the three strains were upregulated. This study provided an experimental basis for elucidating the photosynthesis of G. lemaneiformis. As key genes of algal growth, photosynthesis-related genes served as useful gene markers for screening elite varieties with good traits in breeding. Cultivar 2007 was superior to cultivar 981 in terms of maintaining high pigment levels in a wide range of light intensities, which is the most suitable for aquaculture.