Development of a high-resolution molecular marker for tracking Rhizosolenia setigera genetic diversity

Rhizosolenia setigera is cosmopolitan diatom with broad distribution in many ocean regions with diverse environmental features, suggesting that R. setigera may have rich genetic diversity. Because genetic diversity of many phytoplankton species is high, we hypothesize that R. setigera genetic diversity is also high and genetic diversity plays a role in its adaptation and bloom development although no evidence has been documented so far to suggest that R. setigera HAB events are a strain-specific phenomenon. Because common molecular markers including 18S rDNA, 16S rDNA, ITS, and rbcL can not resolve R. setigera genetic diversity due to limited resolution, high-resolution molecular markers are needed for resolving and tracking R. setigera genetic diversity and biogeographic distribution. Here, we designed a new molecular marker R. setigera mitochondrial 1 (rsmt1) with high-resolution and high-specificity by comparative analysis of mitochondrial genomes (mtDNAs) of R. setigera strains isolated from various coastal regions of China. We ascertained R. setigera genetic diversity in coastal regions of China using this newly developed molecular marker and identified distribution patterns of R. setigera strains, demonstrating that rsmt1 could be generally applied to probe R. setigera genetic diversity.