Closeup of zebra mussels on rock.

MN Impact: Mapping the zebra mussel genome

May 29, 2020

Issue

The zebra mussel (Dreissena polymorpha) is a freshwater invasive species that has spread throughout waterways in Europe and North America. Economically, they are responsible for billions of dollars of damage to the power-generation industry and to recreation and tourism. The invasive mussels also crowd out native species, destroy those species’ food sources, and cause dramatic changes to the food web. Although many researchers have been studying D. polymorpha, there has been little genetic work done to date. 

What has been done

Researchers at the Minnesota Aquatic Invasive Species Research Center partnered with the University of Minnesota Genomics Center and the Minnesota Supercomputing Institute to analyze data and ultimately assemble and annotate the zebra mussel genome. And, in doing so, fill in a large gap in the tree of life as zebra mussels are more than 400 million years diverged from the nearest sequenced relative—roughly the same amount of evolutionary divergence as that between humans and manta rays.

Results

The researchers used long-read sequencing and scaffolding technologies to generate a chromosome-scale assembly of the zebra mussel genome. This represents the highest quality molluscan genome assembly to date. The genome provides insights into important processes for the invasive success of zebra mussels, including shell formation, synthesis of byssal thread attachment fibers (which facilitate their attachment to surfaces and spread between water bodies), and responses to thermal stress.

This chromosome-level assembly is a powerful new tool for basic and applied research on zebra mussels and related invasive bivalves. The researchers identified several genes with roles in shell growth and hardening, byssal thread secretion and attachment, and tolerance of thermal and other stressors. These and others are now targets for development of control technologies.