Metaphase I image set underlying chiasma and configuration analysis in diploid and tetraploid barley

Source Data file containing all metaphase I images used for cytological scoring and chiasma quantification in diploid (2X; n = 124 meiocytes) and autotetraploid (4X; n = 216 meiocytes) barley cv. ‘Morex’. Each image corresponds to a single meiocyte analysed in the study. Images were acquired using high-resolution confocal microscopy and are provided in 16-bit TIFF (.tif) format. Chromosomes were counterstained with DAPI (blue). Fluorescence in situ hybridisation (FISH) was performed using a 5S rDNA probe (yellow) and a barley centromeric G+C repeat probe (magenta) to identify homologous associations and centromere positions. Subtelomeric swellings corresponding to closely spaced terminal–subterminal crossover doublets are indicated by arrows. Non-homologous connections are marked by asterisks. Chromosome associations scored during configuration analysis are outlined with lines to guide interpretation. Images are organised by ploidy and plant identifier. Brightness and contrast adjustments were applied uniformly for clarity; no selective image manipulation was performed. Scale bar = 5 mm.