# Exploration on cold adaptation of Antarctic lichen via detection of positive selection genes

## TL;DR

This study explores how the Antarctic lichen Usnea aurantiacoatra adapts to cold by identifying genes under positive selection and testing their role in cold resistance.

## Contribution

The paper identifies specific genes and protein networks in Antarctic lichen that are under positive selection and functionally linked to cold adaptation.

## Key findings

- Positively selected genes in Antarctic lichen are enriched in transmembrane transporter activity and vacuole components.
- Two protein interaction networks related to RNA helicase and G-protein signaling were identified.
- Disruption of UaRgs1 increased cold sensitivity, suggesting its role in cold resistance.

## Abstract

Lichen as mutualistic symbiosis is the dominant organism in various extreme terrestrial environment on Earth, however, the mechanisms of their adaptation to extreme habitats have not been fully elucidated. In this study, we chose the Antarctic dominant lichen species Usnea aurantiacoatra to generate a high-quality genome, carried out phylogenetic analysis using maximum likelihood and identify genes under positive selection. We performed functional enrichment analysis on the positively selected genes (PSGs) and found that most of the PSGs focused on transmembrane transporter activity and vacuole components. This suggest that the genes related to energy storage and transport in Antarctic U. aurantiacoatra were affected by environmental pressure. Inside of the 86 PSGs screened, two protein interaction networks were identified, which were RNA helicase related proteins and regulator of G-protein signaling related proteins. The regulator of the G-protein signaling gene (UaRGS1) was chosen to perform further verification by the lichen genetic manipulation system Umbilicaria muhlenbergii. Given that the absence of UmRgs1 resulted in elevated lethality to cold shock, the role for UaRgs1 in Antarctic U. aurantiacoatra resistance to cold can be inferred. The investigation of lichen adaptation to extreme environments at the molecular level will be opened up.

The online version contains supplementary material available at 10.1186/s43008-024-00160-x.