ORIGINAL RESEARCH article
Front. Genet.
Sec. Genomics of Plants and the Phytoecosystem
Volume 16 - 2025 | doi: 10.3389/fgene.2025.1602048
This article is part of the Research TopicSurvival Strategies and Biotechnological Applications of Plants in Extreme EnvironmentsView all 3 articles
The Chloroplast Genome of the Peltigera elisabethae Photobiont Chloroidium sp. W5 and Its Phylogenetic Implications
Provisionally accepted
- Xinjiang University, Urumqi, China
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Lichens are globally distributed symbiotic organisms comprising fungi (mycobionts) and photosynthetic partners (photobionts), with exceptional adaptability to extreme environments.Despite growing interest in lichen symbiosis, chloroplast genome data for photobionts remain scarce, hindering insights into symbiotic coevolution and genomic architecture. Here, we characterize the chloroplast genome of Chloroidium sp. W5, a photobiont of the lichen Peltigera elisabethae, using next-generation sequencing. The circular genome (190,579 bp) lacks the canonical quadripartite structure (LSC/IR/SSC) and exhibits a strong AT bias (56.1%). Annotation identified 110 functional genes, including 79 protein-coding genes, 28 tRNAs, and 3 rRNAs. Repetitive sequence analysis revealed 5,000 dispersed repeats (2.62% of the genome), predominantly forward and palindromic types, with SSR loci showing a significant A/T preference. Codon usage analysis demonstrated a pronounced bias toward A/U-ending codons (RSCU > 1), suggesting translational adaptation to symbiotic nutrient constraints. Phylogenetic reconstruction robustly placed Chloroidium sp. W5 within the Watanabeales clade (ML = 100), while synteny analysis revealed extensive genomic rearrangements compared to close relatives. These findings enrich the chloroplast genome database for lichen photobionts, shedding light on symbiosis-driven genomic plasticity and providing a foundation for studying host-photobiont coevolution and lichen ecological adaptation.
Keywords: lichen symbiosis1, chloroplast genome2, repeat sequences3, genomics4, phylogeny5
Received: 28 Mar 2025; Accepted: 24 Jun 2025.
Copyright: © 2025 Mamut, Adil, Liu and Bao. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Reyim Mamut, Xinjiang University, Urumqi, China
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