Characterizing the chloroplast genome of Mammillaria elongata DC. 1828 in the Cactaceae family and unveiling its phylogenetic affinities within the genus Mammillaria

Abstract

With its nearly 200 species, the Mammillaria genus is the most species-rich within the Cactaceae family, yet surprisingly, few of its chloroplast genomes have been studied. We focused on the species Mammillaria elongata DC. 1828, a petite cactus native to Mexico and favored by horticulturists, yet whose phylogenetic relationships remain uncertain due to a lack of genomic data. We extracted the DNA from a sample obtained in China, sequenced it using the NovaSeq 6000 platform, and assembled the chloroplast genome using GetOrganelle software. Our assembly resulted in a chloroplast genome of 110,981 base pairs with an overall GC content of 36.28%, which included 100 genes (95 unique). Notably, several protein-coding genes were absent. Phylogenetic analysis using 59 shared genes across nine Mammillaria species and one Obregonia species revealed that M. elongata and M. gracilis are closely related, suggesting a recent common ancestor and possible shared evolutionary pressures or ecological niches. This study provides crucial genomic data for M. elongata and hints at intriguing phylogenetic relationships within the Mammillaria genus.

Keywords

• chloroplast genome
• gene loss
• genome size variation
• mammillaria elongata
• phylogenetic analysis