The decoding of the genome of Prymnesium parvum, as it occurred in the Oder in the summer of 2022, forms a basis for further findings, including on the toxicity of this algae strain. © David Ausserhofer/IGB
The toxin-producing alga Prymnesium parvum is not a single species, but a species complex comprising at least 40 genetically distinct strains. It is not yet known how the species or strains of this enormously adaptable alga differ in terms of their toxin production. Under what conditions do they become toxic and which toxins do they produce? And: Is the production of algal toxins a genetic characteristic of certain Prymnesium species or a reaction to environmental conditions? The investigation of the genomic forms of Prymnesium parvum plays an important role in answering these questions and thus contributing to an explanation of how the occurrence of Prymnesium parvum in the Oder in the summer of 2022 could lead to a mass die-off of fish and other organisms. At the same time, the findings will help to distinguish toxic from non-toxic algal blooms in the future.
Subproject 5 "Genomic Prymnesium monitoring – creation of an early warning system using universally applicable Prymnesium reference genomes for the detection of cryptic diversity" is responsible for the genomic identification of Prymnesium. The decoding of the Oder Prymnesium genome and thus its genomic differentiation from other forms of Prymnesium is the first decisive step. Based on the reference genome of the Oder Prymnesium, further studies on the toxin production of the alga (subproject 6), on the effects of the toxin on different groups of organisms in the Oder River and on the quantitative determination by means of qPCR (subproject 7) or sequencing of eDNA (subproject 9) can be carried out.
In subproject 5, the next step will be to determine and compare reference genomes of other types of Prymnesium. The focus here is on the differences relevant to toxin production. As a final goal, the scientists want to develop an early warning method that makes it possible to detect genomic forms and future changes in the algae in a cost- and time-saving manner.
