# Cross-species dissection of saline-related genes by genetically deciphering a euryhaline microalga Chlorella sp

## TL;DR

This study identifies genes in a salt-tolerant alga that help organisms adapt to changes in water salinity, offering insights into evolutionary genetic adaptations.

## Contribution

The study provides a novel genome assembly of a euryhaline alga and identifies key genes involved in salinity adaptation across species.

## Key findings

- The genome of Chlorella sp. MEM25 reveals ancestral and lineage-specific genes related to salinity adaptation.
- Loss-of-function mutants of salt-sensitive genes show increased salt resistance in algae and plants.
- The gene RMI1 is shown to play a role in salinity tolerance across multiple species.

## Abstract

Deciphering adaptation to habitat shifts across the salinity boundary necessitates investigation of “lost” and “acquired” saline genes. By assembling a telomere-to-telomere genome, we propose that the euryhaline Chlorophyta Chlorella sp. MEM25 represents an early-diverging saltwater species that has evolved numerous genes essential for saltwater-freshwater transitions. By comparison with Viridiplantae genomes, we identify ancestral genes and lineage-specific genes related to salinity adaptation. Loss-of-function mutants of the proposed salt-sensitive genes in algae and plants exhibit increased salt resistance, highlighting the potential of the MEM25 genome as a breeding resource. Notably, the gene RMI1 plays an important role in salinity tolerance across species, from microalgae to higher plants.

Life’s transition between saltwater and freshwater environments requires major genetic innovations. This study reveals the key genes for salinity adaptation in Chlorella sp. MEM25, an early saltwater alga.