Development of a meiotic atlas and chromosomal mapping of abundant genome elements in the orphan crop golden thistle (Scolymus hispanicus L.)

Orphan crops have great potential for sustainable agricultural production. Meiosis in sexually reproducing organisms is a crucial process for maintaining the chromosome complement and ensuring genetic diversity by meiotic crossover and segregation of homologous chromosomes. Repetitive DNA elements differ in quantity, sequence, and distribution pattern among species. These elements are useful for taxonomic, phylogenetic, and evolutionary studies, as well as for establishing species-specific karyotypes. The golden thistle (Scolymus hispanicus L.), an orphan crop, is a diploid plant species (2n = 2x = 20) of the Asteraceae family and is common in the Mediterranean region. Despite some research on its phytochemical properties, there are few studies on its molecular biology, genetics, and cytogenetics. Therefore, we aimed to construct an atlas of the meiosis of golden thistle and to discover repetitive genome elements. A novel 180-bp repetitive DNA element, Sh180, of the golden thistle was identified by bioinformatic, molecular and cytogenetic methods. Chromosomal domains containing Sh180, the telomeric repeat TTTAGGGn, 5S and 35S rDNA were mapped on mitotic metaphase chromosomes by fluorescence in situ hybridization (FISH). The Sh180 signals were mapped in the subtelomeric regions of all mitotic metaphase chromosomes. Our findings provide the first information for future genetics and breeding studies such as meiotic, karyotype and phylogenetic analyses of this underutilized crop.