XVI International Botanical Congess

Two cDNA clones representing actin transcripts were isolated from a cDNA library prepared from gametophytic blades of Porphyra purpurea (Rhodophyta). Both cDNAs encode polypeptides of 373 amino acids that share 86% identity. The most similar sequence is an actin sequence from Chondrus crispus (Rhodophyta) which has 84-87% identity. Actin multigene families have rarely been observed in algae. Gene-specific PCR primers and uni-algal cultures were used to confirm that cloning artifacts had not resulted from epiphytic contamination. Other Porphyra species are being analyzed to examine the evolutionary origin of this apparent gene duplication. Based on actin protein sequence, the origin of the Rhodophyta predates the divergence of the eukaryotic lineage into green plants, animals and fungi.