No abstract

Background: Although there has been a long history of cultivation and research on Nymphaea, the taxonomic relationships and evolutionary relationships among Nymphaea species remain controversial. The chloroplast (cp) genome can provide a new method to determine species origin, evolution, and phylogenetic relationships of Nymphaea. However, there are few studies on the cp genomes of Nymphaea, and the data of their genomes are very scarce. The complete cp genomes of seven Nymphaea species were sequenced by high-throughput sequencing technology, and the structural characteristics and phylogenetic relationships of cp genomes were analyzed.

Broccoli (Brassica oleracea var. italica) is an important B. oleracea cultivar, with high economic and agronomic value. However, comparative genome analyses are still needed to clarify variation among cultivars and phylogenetic relationships within the family Brassicaceae. Herein, the complete chloroplast (cp) genome of broccoli was generated by Illumina sequencing platform to provide basic information for genetic studies and to establish phylogenetic relationships within Brassicaceae. The whole genome was 153,364 bp, including two inverted repeat (IR) regions of 26,197 bp each, separated by a small single copy (SSC) region of 17,834 bp and a large single copy (LSC) region of 83,136 bp. The total GC content of the entire chloroplast genome accounts for 36%, while the GC content in each region of SSC,LSC, and IR accounts for 29.1%, 34.15% and 42.35%, respectively. The genome harbored 133 genes, including 88 protein-coding genes, 37 tRNAs, and 8 rRNAs, with 17 duplicates in IRs. The most abundant amino acid was leucine and the least abundant was cysteine. Codon usage analyses revealed a bias for A/T-ending codons. A total of 35 repeat sequences and 92 simple sequence repeats were detected, and the SC-IR boundary regions were variable between the seven cp genomes. A phylogenetic analysis suggested that broccoli is closely related to Brassica oleracea var. italica MH388764.1, Brassica oleracea var. italica MH388765.1, and Brassica oleracea NC_0441167.1. Our results are expected to be useful for further species identification, population genetics analyses, and biological research on broccoli.

No abstract