Chrysanthemum (Chrysanthemum morifolium Ramat) is an important floricultural crop and medicinal herb. Modern chrysanthemum cultivars have complex genetic backgrounds because of multiple cycles of hybridization, polyploidization, and prolonged cultivation. Understanding the genetic background and hybrid origin of modern chrysanthemum cultivars can provide pivotal information for chrysanthemum genetic improvement and breeding. By now, the origin of cultivated chrysanthemums remains unclear. In this study, 36 common chrysanthemum cultivars from across the world and multiple wild relatives were studied to identify the maternal donor of modern chrysanthemum. Chloroplast (cp) genomes of chrysanthemum cultivars were assembled and compared with those of the wild relatives. The structure of cp genomes was highly conserved among cultivars and wild relatives. Phylogenetic analyses based on the assembled cp genomes showed that all chrysanthemum cultivars grouped together and shared 64 substitutions that were distinct from those of their wild relatives. These results indicated that a diverged lineage of the genus Chrysanthemum, which was most likely an extinct or un-sampled species/population, provided a maternal source for modern cultivars. These findings provide important insights into the origin of chrysanthemum cultivars, and a source of valuable genetic markers for chrysanthemum breeding programs.

The complete plastid genome of Chrysanthemum morifolium ‘Anhuishiliuye’, a Chinese traditional cultivar, was determined and analyzed in this work. It had a circular-mapping molecular with the length of 151,059 bp.The LSC and SSC of 82,857 bp and 18,294 bp were separated by two IRs of 24,954 bp. The chloroplast genome of C. morifolium ‘Anhuishiliuye’ contains 125 genes, including 83 protein-coding genes, 34 ribosomal RNA genes and 8 transfer RNA genes. Phylogenetic analysis showed that C. morifolium ‘Anhuishiliuye’ clustered together with other Chrysanthemum species. The data provided would be useful for elucidation of phylogenetics and evolution in Chrysanthemum cultivars.

Begonia versicolor (Code: MK434325) is a perennial plant with unique and precious ornamental value, exhibiting gorgeous leaf morphology and graceful flowers, therefore, it is popular with many horticulturalists and plant hobbyist. The complete chloroplast genome of B. versicolor were reported in this article. It had a typical quarter structure as a circular of 169,506 bp, composed by a large single-copy region (LSC, 75,868 bp), a small single-copy region (SSC, 18,290 bp), and two inverted repeats (IRs, 75,258 bp each). Genome annotations showed that it contained total 185 genes, including 133 protein coding genes (PCGs), 44 transfer RNA (tRNAs), and 8 ribosome RNA (rRNAs). The percentage of total GC content was 35.57%. Phylogenetic analysis suggested that Begoniaceae was closely related to Cucurbitaceae family.