The gene construct utilizing a codon-modified hygromycin resistance gene (Pyaph7) as a selection marker was introduced into the Neopyropia yezoensis cells by the gene gun method. After that, the Neopyropia yezoensis cells were selected with hygromycin. As a result, the target genes (PyGUS gene and AmCFP gene) were stably expressed.
*Blue-stained algae are those in which PyGUS and AmCFP are expressed.