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Chimonanthus of Calycanthaceae is a small endemic genus in China, with unusual winter-blooming sweet flowers widely cultivated for ornamentals and medicinal uses. The evolution of Chimonanthus plastomes and its phylogenetic relationships remain unresolved due to limited availability of genetic resources. Here, we report fully assembled and annotated chloroplast genomes of five Chimonanthus species. The chloroplast genomes of the genus (size range 153,010 – 153,299 bp) reveal high similarities in gene content, gene order, GC content, codon usage, amino acid frequency, simple sequence repeats, oligonucleotide repeats, synonymous and non-synonymous substitutions, and transition and transversion substitutions. Signatures of positive selection are detected in atpF and rpoB genes in C. campanulatus. The correlations among substitutions, InDels, and oligonucleotide repeats reveal weak to strong correlations in distantly related species at the intergeneric levels, and very weak to weak correlations among closely related Chimonanthus species. Chloroplast genomes are used to reconstruct a well-resolved phylogenetic tree, which supports the monophyly of Chimonanthus. Within Chimonanthus , C. praecox and C. campanulatus form one clade, while C. grammatus , C. salicifolius , C. zhejiangensis , and C. nitens constitute another clade. Chimonanthus nitens appears paraphyletic and is closely related to C. salicifolius and C. zhejiangensis , suggesting the need to reevaluate the species delimitation of C. nitens. Chimonanthus and Calycanthus diverged in mid-Oligocene; the radiation of extant Chimonanthus species was dated to the mid-Miocene, while C. grammatus diverged from other Chimonanthus species in the late Miocene. C. salicifolius , C. nitens (a) , and C. zhejiangensis are inferred to have diverged in the Pleistocene of the Quaternary period, suggesting recent speciation of a relict lineage in the subtropical forest regions in eastern China. This study provides important insights into the chloroplast genome features and evolutionary history of Chimonanthus and family Calycanthaceae. [ABSTRACT FROM AUTHOR]

Abstract: Wintersweet [Chimonanthus praecox (L.) Link] (n =11), a dichogamous species, is a famous traditional fragrant flower plant in China. We used AFLPs and ISSR to construct a genetic linkage map on a pseudo-F2 population of wintersweet derived from a cross between the individuals H4 and H29. A total of 370 polymorphism markers was generated from 12 AFLP primer combinations and 9 ISSR primers. Two separate female and male maps were constructed using 84 female-specific and 51 male-specific testcross markers, respectively. The maternal H4 map included 80 markers ordered in 12 linkage groups; while the paternal H29 map had 47 markers in 8 linkage groups. At a minimum logarithm of the odds (LOD) score of 3.0 and maximum map distance of 50cM, the female map covered 2417.8cM, with an average distance of 25.61cM and maximum map distance of 48.2cM between two loci. In contrast, the male map covered 1184.2cM, with an average distance of 25.7cM and maximum map distance of 49.0cM between two loci. These genetic maps will serve as a framework for mapping QTLs and provide basic information for future molecular breeding studies. [Copyright &y& Elsevier]