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

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.

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.

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.

The newly characterized plastome of G. tergestina enriches genomic resources for Grimmia and provides a foundation for future comparative and phylogenetic studies of Grimmiaceae.