Genetic Diversity and Relationships among Eighteen Algal Accessions Revealed by RAPD and ISSR Markers

<b>Background and Objective:</b> Microalgae represent an important biological resource with significant potential for applications in aquaculture, biotechnology and sustainable bioresource development. However, information regarding the genetic diversity of indigenous Vietnamese microalgal accessions remains limited. This study aimed to assess the genetic diversity and genetic relationships among 18 indigenous microalgal accessions using 15 RAPD and 15 ISSR molecular markers. <b>Materials and Methods:</b> Amplified loci were scored as binary data and analyzed using Jaccard similarity coefficients. We inferred genetic relationships through UPGMA clustering and principal coordinate analysis (PCoA). The consistency among marker systems was evaluated using Mantel tests and cophenetic correlation coefficients (CCC). <b>Results:</b> RAPD and ISSR markers generated 140 and 188 loci, respectively, with high polymorphism levels of 87.86 and 91.49%. The combined RAPD-ISSR dataset revealed substantial genetic variation among the analyzed accessions, with Jaccard similarity coefficients ranging from 0.263 to 0.938. The UPGMA analysis separated the 18 accessions into three genetic groups, while PCoA produced a congruent distribution pattern. The LC11 and G6 exhibited pronounced genetic divergence from the remaining accessions. Mantel tests revealed strong correlations among RAPD, ISSR and combined datasets (r = 0.865-0.971, p = 0.001). High CCC values (0.963-0.978) further confirmed the reliability of the inferred genetic relationships. <b>Conclusion:</b> The studied microalgal collection possesses substantial genetic diversity and includes highly differentiated genetic lineages. The combined RAPD-ISSR approach provides a reliable framework for genetic characterization and offers valuable information for germplasm conservation, accession selection and future biotechnological exploitation of indigenous microalgae.