Complete Plastome Sequence of Grimmia tergestina Provides a Genomic Resource for Grimmiaceae

Background/Objectives: Grimmia tergestina is a lithophytic moss of Grimmiaceae, but its complete plastome has not previously been reported. This Brief Report presents the complete chloroplast genome of G. tergestina as a genomic resource for future work on species identification, phylogeny, and plastome evolution in Grimmiaceae. Methods: Illumina NovaSeq PE150 reads were quality filtered and assembled into a circular plastome. Genome annotation was verified using current organellar annotation tools and manual curation, and a preliminary phylogenetic analysis was performed using shared chloroplast protein-coding genes from representative moss plastomes. Results: The complete plastome of G. tergestina was 124,153 bp in length and exhibited the typical quadripartite structure of moss plastomes. It encoded 126 genes, including 82 protein-coding genes, 36 tRNA genes, and 8 rRNA genes, with an overall GC content of 28.49%. Fourteen genes contained introns, and nine genes were duplicated in the inverted repeat regions. Codon-usage analyses showed a preference for A/U-ending codons, consistent with the AT-rich composition of the plastome, and supplementary ENC and PR2 analyses supported a conservative interpretation of codon-usage bias. A total of 569 chloroplast simple sequence repeats and 222 dispersed repeats were identified. The preliminary maximum-likelihood phylogeny placed G. tergestina within Grimmiaceae and resolved it close to Niphotrichum japonicum in the sampled plastome dataset. Conclusions: The newly characterized plastome of G. tergestina enriches genomic resources for Grimmia and provides a foundation for future comparative and phylogenetic studies of Grimmiaceae.