Identification and expression analysis of a calmodulin gene in Phycocalida chauhanii (Rhodophyceae, Bangiales)

Calmodulin (CaM) plays an important regulatory role in plant growth and development. In this study, on the basis of previous transcriptomic annotation a homolog of CaM gene (Pc-CaM7) was identified from the red alga Phycocalida chauhanii (previously known as Porphyra chauhanii). It encoded a 151 amino acids protein with 4 EF-hand regions, which was the typical structure of calmodulin family proteins. Evolutionary analysis showed that Pc-CaM7 shared conserved orthologous relationships with CaMs from Neoporphyra haitanensis (formerly Pyropia haitanensis), Porphyra umbilicalis, and Gracilariopsis chorda. During the developmental period of P. chauhanii gametophytic germlings from 25- to 50-day-old, the asexual archeospores were continuedly released from the marginal region of blades, followed by the emergence of spermatangia from 40-day-old germlings. Based on quantitative real-time PCR analysis, it showed that expression trend of Pc-CaM7 was correlated with the rule of archeospores’ formation and release, whereas in N. haitanensis without archeospore characteristic, the expression pattern of the orthologous gene (Pha_00404) was different, which increased and reached a plateau during the same developmental period. These findings suggested that Pc-CaM7 may be involved in the process of archeospores formation and release, which may provide a foundation for understanding the molecular mechanisms of asexual reproduction in Bangiales.