Complete Chloroplast Genome of Gladiolus gandavensis (Gladiolus) and Genetic Evolutionary Analysis

Abstract

Gladiolus is an important ornamental plant that is one of the world’s four most-grown cut flowers. Gladiolus gandavensis has only been found in the Cangnan County (Zhejiang Province) of China, which is recorded in the “Botanical”. To explore the origin of G. gandavensis, chloroplast genome sequencing was conducted. The results indicated that a total of 151,654 bp of circular DNA was obtained. The chloroplast genome of G. gandavensis has a quadripartite structure (contains a large single-copy (LSC) region (81,547 bp), a small single-copy region (SSC) (17,895 bp), and two inverted repeats (IRs) (IRa and IRb, 52,212 bp)), similar to that of other species. In addition, a total of 84 protein-coding genes, 8 rRNA-encoding genes, and 38 tRNA-encoding genes were present in the chloroplast genome. To further study the structural characteristics of the chloroplast genome in G. gandavensis, a comparative analysis of eight species of the Iridaceae family was conducted, and the results revealed higher similarity in the IR regions than in the LSC and SSC regions. In addition, 265 simple sequence repeats (SSRs) were detected in this study. The results of the phylogenetic analysis indicated that the chloroplast genome of G. gandavensis has high homology with the Crocus cartwrightianus and Crocus sativus chloroplast genomes. Genetic analysis based on the rbcl sequence among 49 Gladiolus species showed that samples 42, 49, 50, and 54 had high homology with the three samples from China (64, 65, and 66), which might be caused by chance similarity in genotypes. These results suggest that G. gandavensis may have originated from South Africa.