Complete sequence of mitochondrial DNA of Gracilaria tenuistipitata var. liui (Rhodophyta)

Abstract

Here, the complete Gracilaria tenuistipitata var. liui mitogenome was determined and analyzed. The complete G. tenuistipitata var. liui mitogenome length was 25,879 bp and contained 50 genes including 24 protein-coding, 2 rRNA, and 23 tRNA genes and one unidentified open reading frame (ORF). Of the 24 protein-coding genes, 23 (95.83%) terminated with the stop codon TAA, and one (4.17%) with TAG (rps3 gene). All protein-coding genes in G. tenuistipitata var. liui started with ATG codon. Mitogenome phylogenetic analysis revealed that G. tenuistipitata var. liui firstly clustered together with Gracilaria tenuistipitata. The complete mitogenome sequence would help in understanding Gracilaria evolution.

Keywords:

• Gracilaria tenuistipitata var. liui
• mitogenome
• phylogenetic analysis

Gracilaria tenuistipitata var. liui Zhang and Xia (Gracilariaceae, Rhodophyta) is found locally in South-East Asia and China (Phang 2006) and extensively cultivated in southern China (Chiang 1980). Being the sources for the phycocolloids and food, the marine red alga Gracilaria tenuistipitata var. liui Zhang and Xia is economically important (Oliveira et al. 2000). To date, many studies have been performed on the growth of G. tenuistipitata var. liui (Israel et al. 1999; Li-hong et al. 2002; Xu et al. 2009). However, information on its genetics and systematics is limited. Herein, we determined the complete mitogenome of G. tenuistipitata var. liui to provide new molecular data for genetics study.

Gracilaria tenuistipitata var. liui individual (specimen number: 2016110001) was collected from Shantou, Guangdong Province in the eastern China (23°24′19′′N, 117°3′15′′E). The high-throughput sequencing method and data processing followed Liu et al. (2017). Gracilaria salicornia (GenBank accession number: NC_023784) was used as the seed sequence.

The complete G. tenuistipitata var. liui (MG592728) mitogenome comprised a circular DNA molecule with the length of 25,879 bp. The overall A + T content of the complete mitogenome was 72.9%. The mitogenome contained 50 genes, including 24 protein-coding, two rRNA, 23 tRNA genes, and one unidentified open reading frame (ORF). Of the 24 protein-coding genes, 23 (95.83%) terminated with the TAA stop codon, and one (4.17%) with TAG (rps3 gene)). All protein-coding genes in G. tenuistipitata var. liui were found to have the start codon ATG. The lengths of two rRNA genes were 2,619 bp (rnl) and 1,394 bp (rns) respectively.

Bayesian analysis based on the complete mitogenomes of the twelve Gracilariaceae species was conducted using MrBayes v. 3. 1.2 (Huelsenbeck and Ronquist 2001). Rhodymenia pseudopalmata (KC875852) and Sebdenia flabellata (KJ398164) served as the out-group. All algae were divided into two clades: Gracilaria and Gracilariopsis (Figure 1). Phylogenetic analyses showed that Gracilaria tenuistipitata var. liui firstly clustered with Gracilaria tenuistipitata. The complete mitogenome data provided in this work would help us to understand Gracilaria evolution.

Figure 1. Phylogenetic tree (Bayesian inference) based on complete mitogenomes of Gracilariaceae. Support values for each node were calculated from Bayesian posterior probability (BPP). Asterisks following species names indicate newly determined mitogenomes.

Disclosure statement

There are no conflicts of interest for all the authors including the implementation of research experiments and writing this article.

Additional information

Funding

This study was funded by Public Science and Technology Research Funds Projects of Ocean [Grant No. 201405020]; China-ASEAN Maritime Cooperation Fund; Major Science and Technology Programme of Hainan Province [ZDKJ2017002]; Agricultural Environmental Pollution Control Programme of Hainan Province [ZWZL2017002]; Supported by China Agriculture Research System-50.