The Complete Chloroplast Genome of the Green Algae Desmodesmus spinosus (Chodat) E.Hegewald: Genome Structure, Phylogeny, and Comparative Analysis

Desmodesmus spinosus (Chodat) E.Hegewald is a common freshwater green microalgae widely distributed in various aquatic environments. Owing to its pollution tolerance and rapid growth characteristics, it is often used in bioremediation and biofuel studies. Here, we report the draft chloroplast (cp) genome of this species here for the first time to facilitate its genomic features and phylogenetic position in Scenedesmaceae. The whole chloroplast genome was 167, 203 base pairs in length, with 104 annotated genes, including 69 protein-coding genes, 29 tRNAs, and 6 rRNAs. The introns identified among them were: rbcL, psaA, and petD, each containing 1 intron; atpB with 2 introns; and psbA with 3 introns. A total of 106 SSRs with 16 motif classes, 50 dispersed repeats, and 17 long tandem repeats were identified in this genome. A total of 221 RNA-editing sites were distributed across 46 protein-coding genes in this genome. In IR boundaries, the position of genes was found to be remarkable in differentiating species, such as trnH and ycf1 at JLB and JSA, cemA, psbC, and rpl22 at JS, and cemA, psbC and rrs at JSB. Notably, psbA-rps11, psbH-psbK, and trnR-ACG-psbM were highly variable regions. Phylogenetic analysis revealed a sister relationship between D. spinosus and D. abundans. Chloroplast genomic data and findings from phylogenetic studies of D. spinosus could provide useful information and shed light on in-depth studies on the evolution pattern of the understudied species, as well as that of Scenedesmaceae.