The Complete Plastid Genomes of Seven Sargassaceae Species and Their Phylogenetic Analysis

Ruoran Li; Xuli Jia; Jing Zhang; Shangang Jia; Tao Liu; Jiangyong Qu; Xumin Wang

doi:10.3389/fpls.2021.747036

The Complete Plastid Genomes of Seven Sargassaceae Species and Their Phylogenetic Analysis

Front Plant Sci. 2021 Nov 5:12:747036. doi: 10.3389/fpls.2021.747036. eCollection 2021.

Authors

Ruoran Li¹, Xuli Jia², Jing Zhang³, Shangang Jia⁴, Tao Liu^{1

5}, Jiangyong Qu¹, Xumin Wang¹

Affiliations

¹ College of Life Sciences, Yantai University, Yantai, China.
² College of Marine Life Sciences, Ocean University of China, Qingdao, China.
³ School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, China.
⁴ College of Grassland Science and Technology, China Agricultural University, Beijing, China.
⁵ State Key Laboratory of Marine Environmental Science and College of Ocean and Earth Sciences, Xiamen University, Xiamen, China.

Abstract

Sargassum is one of the most important genera of the family Sargassaceae in brown algae and is used to produce carrageenan, mannitol, iodine, and other economic substances. Here, seven complete plastid genomes of Sargassum ilicifolium var. conduplicatum, S. graminifolium, S. phyllocystum, S. muticum, S. feldmannii, S. mcclurei, and S. henslowianum were assembled using next-generation sequencing. The sizes of the seven circular genomes ranged from 124,258 to 124,563 bp, with two inverted regions and the same set of plastid genes, including 139 protein-coding genes (PCGs), 28 transfer (t)RNAs, and 6 ribosomal (r)RNAs. Compared with the other five available plastid genomes of Fucales, 136 PCGs were conserved, with two common ones shared with Coccophora langsdorfii, and one with S. fusiforme and S. horneri. The co-linear analysis identified two inversions of trnC(gca) and trnN(gtt) in ten Sargassum species, against S. horneri and C. langsdorfii. The phylogenetic analysis based on the plastid genomes of 55 brown algae (Phaeophyceae) showed four clades, whose ancient ancestor lived around 201.42 million years ago (Mya), and the internal evolutionary branches in Fucales started to be formed 92.52 Mya, while Sargassum species were divided into two subclades 14.33 Mya. Our novel plastid genomes provided evidence for the speciation of brown algae and plastid genomic evolution events.

Keywords: Sargassaceae; brown algae; co-linear analysis; comparative analysis; phylogenetic analysis; plastid genome.