### Phylogenetic study of Amaranthaceae s.l. based on multiple plastid DNA fragments

Gang Yao2

• Received:2019-11-23 Revised:2020-03-01 Online:2020-05-21 Published:2020-07-01
• Contact: Gang Yao E-mail:yaogang1029@163.com

Abstract: Amaranthaceae s.l., including Amaranthaceae s.s. and Chenopodiaceae, is the second largest family in Caryophyllales. However, the family status of Chenopodiaceae is disputable and phylogenetic relationships among all of the subfamilies circumscribed within Amaranthaceae s.l. have not been well resolved to date. In the present study, phylogeny of Amaranthaceae s.l. was reconstructed based on a comprehensive taxonomic sampling of all subfamilies circumscribed using eight plastid DNA fragments, and a molecular dating analysis of the family was also conducted. Results revealed that, the monophyly of Amaranthaceae both in broad and narrow sense was strongly supported, but the monophyly of Chenopodiaceae was rejected. Thus the concept of Amaranthaceae s.l. is accepted here. Phylogenetic positions of all subfamilies were all resolved with strong support values, except that the position of the subfamily Polycnemoideae was weakly supported. Additionally, the crown age of Amaranthaceae s.l. was estimated at ca. 69.9 million years ago (Ma) in the late Cretaceous, with a period of rapid divergence may have occurred near the Cretaceous-Paleogene (K-Pg) boundary (ca. 66.0 Ma).