fpls-12-631884 June 25, 2021 Time: 19:19 # 1 ORIGINAL RESEARCH published: 01 July 2021 doi: 10.3389/fpls.2021.631884 The Conservation of Chloroplast Genome Structure and Improved Resolution of Infrafamilial Relationships of Crassulaceae Hong Chang1†, Lei Zhang1†, Huanhuan Xie1, Jianquan Liu1,2, Zhenxiang Xi1* and Xiaoting Xu1* 1 Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China, 2 State Key Laboratory of Grassland Agro-Ecosystems, College of Life Sciences, Lanzhou University, Lanzhou, China Edited by: Michael R. McKain, Crassulaceae are the largest family in the angiosperm order Saxifragales. Species of University of Alabama, United States this family are characterized by succulent leaves and a unique photosynthetic pathway Reviewed by: known as Crassulacean acid metabolism (CAM). Although the inter- and intrageneric Olwen M. Grace, relationships have been extensively studied over the last few decades, the infrafamilial Royal Botanic Gardens, Kew, United Kingdom relationships of Crassulaceae remain partially obscured. Here, we report nine newly Andrey Gontcharov, sequenced chloroplast genomes, which comprise several key lineages of Crassulaceae. Federal Scientific Center of the East Asia Terrestrial Biodiversity, Far Our comparative analyses and positive selection analyses of Crassulaceae species Eastern Branch of the Russian indicate that the overall gene organization and function of the chloroplast genome Academy of Sciences, Russia are highly conserved across the family. No positively selected gene was statistically *Correspondence: supported in Crassulaceae lineage using likelihood ratio test (LRT) based on branch- Zhenxiang Xi
[email protected] site models. Among the three subfamilies of Crassulaceae, our phylogenetic analyses of Xiaoting Xu chloroplast protein-coding genes support Crassuloideae as sister to Kalanchoideae plus
[email protected] Sempervivoideae.