Abstract
The genus Zygophyllum comprises over 150 species within the plant family Zygophyllaceae. These species predominantly grow in arid and semiarid areas, and about 20 occur in northwestern China. In this study, we sampled 24 individuals of Zygophyllum representing 15 species and sequenced their complete chloroplast (cp) genomes. For comparison, we also sequenced cp genomes of two species of Peganum from China representing the closely allied family, Nitrariaceae. The 24 cp genomes of Zygophyllum were smaller and ranged in size from 104,221 to 106,286 bp, each containing a large single-copy (LSC) region (79,245–80,439 bp), a small single-copy (SSC) region (16,285–17,146 bp), and a pair of inverted repeat (IR) regions (3,792–4,466 bp). These cp genomes contained 111–112 genes each, including 74–75 protein-coding genes (PCGs), four ribosomal RNA genes, and 33 transfer RNA genes, and all cp genomes showed similar gene order, content, and structure. The cp genomes of Zygophyllum appeared to lose some genes such as ndh genes and rRNA genes, of which four rRNA genes were in the SSC region, not in the IR regions. However, the SC and IR regions had greater similarity within Zygophyllum than between the genus and Peganum. We detected nine highly variable intergenic spacers: matK-trnQ, psaC-rps15, psbZ-trnG, rps7-trnL, rps15-trnN, trnE-trnT, trnL-rpl32, trnQ-psbK, and trnS-trnG. Additionally, we identified 156 simple sequence repeat (cpSSR) markers shared among the genomes of the 24 Zygophyllum samples and seven cpSSRs that were unique to the species of Zygophyllum. These markers may be useful in future studies on genetic diversity and relationships of Zygophyllum and closely related taxa. Using the sequenced cp genomes, we reconstructed a phylogeny that strongly supported the division of Chinese Zygophyllum into herbaceous and shrubby clades. We utilized our phylogenetic results along with prior morphological studies to address several remaining taxonomic questions within Zygophyllum. Specifically, we found that Zygophyllum kaschgaricum is included within Zygophyllum xanthoxylon supporting the present treatment of the former genus Sarcozygium as a subgenus within Zygophyllum. Our results provide a foundation for future research on the genetic resources of Zygophyllum.
Highlights
Zygophyllum was originally described by Linnaeus (1753) and is one of the 25 genera comprising the plant family Zygophyllaceae according to the Angiosperm Phylogeny Group (APG) IV (2016)
We reported the complete cp genome sequences for 24 individuals of Zygophyllum (Zygophyllaceae), representing 15 species distributed in China, and for 2 closely related species, P. harmala and P. nigellastrum (Nitrariaceae)
Through the comparisons of these newly sequenced cp genomes to additional sequences from species of Zygophyllaceae in public databases, we found that the genomes of Zygophyllum were much smaller, highly conserved in gene content and order, but differed markedly from other genera within the family and from Peganum
Summary
Zygophyllum was originally described by Linnaeus (1753) and is one of the 25 genera comprising the plant family Zygophyllaceae according to the Angiosperm Phylogeny Group (APG) IV (2016). This genus consists of approximately 150 species (Beier et al, 2003), which are widely distributed in northern and southern Africa, the Mediterranean region, and central Asia and Australia (White, 1983; Zyl and Marias, 1999; Retief, 2000). A comprehensive phylogenetic analysis of trnL and morphological data for 43 species of Zygophylloideae showed that the genera, Augea (monotypic, southern Africa), Tetraena (monotypic, China), and Fagonia Molecular phylogenies were used for divergence time dating and biogeographic analyses revealing that Asian Zygophyllum colonized the Asian interior from Africa in the early Oligocene, began diversification in the early Miocene, and underwent rapid radiation in the late Miocene (Wu et al, 2015, 2018)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
