Abstract
This study investigates the phylogenetic relationships, genome size variation, and ploidy levels in the genus Arthrophytum Schrenk (Amaranthaceae s.l.), which is endemic to the desert flora of Central Asia. The genus comprises eight species (Arthrophytum iliense Iljin, A. betpakdalense Korovin & Mironov, A. subulifolium Schrenk, A. lehmannianum Bunge, A. korovinii Botsch., A. longibracteatum Korovin, A. pulvinatum Litv., and Haloxylon balchaschense (Iljin) Osmonali, Veselova & Kudab. (A. balchaschense (Iljin) Botsch.), all of which are found in the flora of Kazakhstan and are distributed throughout the Turanian deserts. To explore inter- and intraspecific relationships, we analyzed 16 populations using flow cytometry to determine genome size and ploidy levels. Genome size was measured by flow cytometry using PI-stained nuclei from silica-dried leaves, with Pisum sativum and Petroselinum crispum as internal standards. Additionally, the nuclear ribosomal ITS region and two chloroplast DNA regions were sequenced, and these data, along with sequences retrieved from NCBI, were used to construct a phylogenetic tree. The results enabled the reconstruction of a robust phylogeny for the genus and revealed taxonomically significant genetic patterns. Based on molecular evidence, we propose the following taxonomic changes: A. betpakdalense is transferred from section Euarthrophytum Iljin to section Globosum Ussen S & Osmonali; A. iliense and A. longibracteatum are merged under the name A. iliense Iljin. This integrative approach provides new insights into the taxonomy and evolutionary history of Arthrophytum and contributes to a better understanding of biodiversity in Central Asian desert ecosystems.