Nuclear DNA Amount in a Diverse Collection of Linum usitatissimum Accessions

Flax (Linum usitatissimum) is an important member of the genus Linum. L. usitatissimum has been commonly cultivated as a fiber or oil source. Despite its economic significance, comprehensive genome analyses encompassing a wide range of genotypes remain limited. Nuclear DNA content is defined as the amount of DNA within the nuclei of a eukaryotic organism. The elucidation of the nuclear DNA content may provide valuable insights for genetic studies, biodiversity studies, conservation efforts, and breeding programs, thereby reinforcing the significance of its estimation. Nuclear DNA content variation may arise under different environmental conditions, and its potential adaptive role has attracted considerable interest. In the present study, isolated intact nuclei were stained with propidium iodide as a DNA stain and flow cytometry analyses were performed to estimate the nuclear DNA content of two varieties and 40 accessions from geographically distant locations. FCM analyses revealed that the nuclear DNA content varied from 1.19 pg/2C to 1.37 pg/2C. This corresponds to a 15.13% difference in nuclear DNA content among the genotypes, with PI 182226 having the smallest genome and PI 194998 the largest genome. A minor variation was detected among the genotypes; however, accession PI 194998 showed statistically significant differences compared with some of the analyzed genotypes. The small intraspecific variation observed among the analyzed genotypes may indicate detectable genomic diversity, which could potentially be attributed to differences in the abundance of repetitive elements among these genotypes. The chromosome number of the selected genotypes was determined to rule out ploidy-level variation as a potential explanation of differences in nuclear DNA content, and all shared the expected same ploidy level. Geographical location (longitude and latitude) showed no statistically significant correlation with nuclear DNA content. The potential causes of the intraspecific variation are discussed in the text. The results obtained in this study may constitute a valuable genetic resource for subsequent molecular and breeding research aimed at improving this economically important crop.