Identification of genomic differences between the sexes and sex-specific molecular markers in Monostroma angicava (Ulvophyceae).

There is little information available regarding genomic differences between sexes in ulvophycean green algae. The detection of these differences will enable the development of sex-discriminating molecular markers, which are useful for algae showing little apparent difference between sexes. In this study, we identified male- and female-specific DNA sequences in the ulvophycean marine green alga Monostroma angicava, which has a dioicous heteromorphic haplo-diplontic life cycle, via next-generation sequencing. Fluorescence in situ hybridization (FISH) showed that signals for the sex-specific sequences exist only in the nuclei of the corresponding sex, confirming the specificity of the sequences. Sex-specific molecular markers that targeted these sequences successfully distinguished the sex of gametophytes even in geographically distant populations, indicating that the sex-specific sequences are universal. These results consistently suggest that male and female gametophytes of M. angicava are genetically different, implying that sex may be determined genetically in this alga.