Chromosomes and DNA organization in Armatocereus from the Peruvian Andes

A 2026 paper characterized the chromosomes of Armatocereus matucanensis from the Cosma population in the Peruvian region of Áncash, identified in the publication as Armatocereus mataranus subsp. ancashensis. The researchers combined microscopic chromosome imaging with fluorescent labelling of DNA regions encoding ribosomal RNA. Most of the metaphase spreads examined contained 22 chromosomes, corresponding to two sets of 11. The 5S rDNA regions occurred on two chromosome pairs, while 45S rDNA occurred on a different pair. Flow cytometry of five young plants estimated the diploid nuclear DNA content, designated 2C, at 2.73 pg. Stem tissue also contained nuclei with multiples of this DNA content, indicating endopolyploidy.