Characterization of the Plastid Genome of the Vulnerable Endemic Indosasa lipoensis and Phylogenetic Analysis

Abstract

Indosasa lipoensis, an ornamental garden plant, belongs to the Indosasa genus of the subfamily Bambooaceae within Poaceae. Indosasa lipoensis is endangered and requires protection owing to its relatively narrow distribution area. Chloroplast (cp) genome offers a novel awareness of the evolutionary and genetic variation of higher plants. Herein, we assembled and elucidated the complete cp genome of I. lipoensis, and compared it with four previously published cp genomes from this genus. The I. lipoensis cp genome was 139,655 bp in size, with a typical quadripartite structure, encompassing a large single-copy region (LSC, 83,256 bp), a small single-copy region (SSC, 12,809 bp), and a pair of inverted repeat regions (IR, 21,795 bp). The cp genome consisted of 130 genes with 84 protein-coding genes (CDS), 38 tRNA genes, and 8 rRNA genes. The plastomes were highly conservative, compared to other bamboo species, and exhibited similar patterns of codon usage, number of repeat sequences, and expansion and contraction of the IR boundary. Five hypervariable hotspots were identified as potential DNA barcodes, namely rbcL, petA, petB, trnL-UAG, and ndhE-ndhI, respectively. Phylogenetic analysis based on the complete cp genomes revealed, with high resolution, that I. lipoensis and I. gigantea were most closely related. Overall, these results provided valuable characterization for the future conservation, genetic evaluation, and the breeding of I. lipoensis.