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ABSTRACT The genus Aster represents an important group of flowering plants with complex evolutionary relationships, yet genomic resources for some species remain limited. In this study, we first sequenced and characterized the complete chloroplast genome of Aster lautureanus and conducted comprehensive analyses of genome structure, codon usage, repeat sequences, phylogeny, and divergence time. The chloroplast genome of A. lautureanus was 152,545 bp in length and exhibited a typical quadripartite structure consisting of a large single‐copy (LSC) region, a small single‐copy (SSC) region, and two inverted repeats (IRs). A total of 127 genes were annotated, including 84 protein‐coding genes, 35 tRNA genes, and eight rRNA genes. Codon usage analysis revealed a strong preference for A/U‐ending codons. Neutrality, ENC, and PR2 analyses consistently indicated that natural selection plays a dominant role in shaping codon bias. A total of 85 simple sequence repeats (SSRs) and 42 long repeats were identified, suggesting potential molecular markers for future population genetic studies. Comparative analysis showed that IR regions were conserved, with minor variations at SC/IR boundaries. Phylogenetic analysis supported the placement of A. lautureanus within section Orthomeris . Divergence time estimation indicated that diversification within Aster mainly occurred during the Neogene and Quaternary periods, likely influenced by climatic fluctuations during the Pleistocene. This study provides valuable genomic resources and new insights into plastome evolution, phylogenetic relationships, and evolutionary history within the genus Aster .
Zhang et al. (Wed,) studied this question.