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Thermotolerance and post-fire growth in Rhizina undulata is associated with the expansion of heat stress-related protein families

Summary

Rhizina undulata is a fungus that infects conifer trees and uniquely relies on the heat from forest fires to wake up and start growing. Scientists sequenced the fungus’s DNA and discovered it has extra copies of genes that help it survive extreme heat, deal with harmful molecules created by heat stress, and digest burned plant material. These genetic adaptations explain how this fungus has evolved to take advantage of fire events for its survival and spread.

Background

Rhizina undulata is a pyrophilous fungal pathogen of conifers that depends on heat shock from fire events to activate its ascospores for germination and infection. The genetic mechanisms underlying its thermotolerance and post-fire colonization have not been previously investigated.

Objective

This study aimed to identify genetic factors contributing to thermotolerance in R. undulata by sequencing its genome for the first time and conducting comparative genomics with other Pezizomycetes species, both with and without known fire associations.

Results

Three protein families were significantly expanded in R. undulata: heat shock protein 20 (HSP20) uniquely, and glutathione-S transferases (GST) and aromatic compound dioxygenases (ACD) which were also expanded in other fire-associated species. The R. undulata genome was 77.5 Mb in size with 11,213 predicted proteins.

Conclusion

The expansions of HSP20, GST, and ACD protein families in R. undulata likely enable thermotolerance during fire-induced heat stress, detoxification of reactive oxygen species, and metabolism of post-fire organic matter, collectively facilitating ascospore germination and host colonization.
  • Published in:BMC Genomics,
  • Study Type:Comparative Genomic Analysis,
  • Source: 10.1186/s12864-025-11902-5
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