Color inheritance, pigment characterization, and growth of a rare light green strain of Gracilaria birdiae (Gracilariales, Rhodophyta)

Gracilaria birdiae Plastino et E.C. Oliveira is an economically important marine red alga exploited for the production of agar in Brazil. A rare light green strain of G. birdiae was found in a natural population, which raised new questions regarding intraspecific variation. Crosses were performed in unialgal cultures to determine the mode of color inheritance of this light green strain. We determined the growth rate and pigment composition of the light green strain and compared it to the wild‐type, red strain. The light green color is stable and showed a recessive nuclear transmission. The light green strain had lower contents of chlorophyll‐a and phycobiliproteins (phycoerythrin, phycocyanin, and allophycocyanin), and grew more slowly than the red strain. This low performance is probably the reason why this mutant, although being stable, is so rare in nature. Nevertheless, it can be useful as a genetic visual marker and to investigate the structure and functioning of the photosynthetic apparatus.