Genomic Organization of Ribosomal DNA and Karyotypic Diversity in Vicia sativa and Vicia villosa

INTRODUCTION: Common vetch (Vicia sativa) and hairy vetch (Vicia. villosa) are characterized by rapid growth and high biomass yield, making them suitable as high-quality forage and silage. They are also widely used as green manure crops to improve soil fertility and restore ecosystems, playing a significant role in sustainable agriculture. Both species are known to exhibit karyotypic diversity, including variation in basic chromosome number and polyploidy. Moreover, our previous studies have revealed that both materials exhibit excellent germination rates under saline conditions and superior reproductive traits in the growth chamber. METHODS: In this study, we focused on hairy vetch NTU0012 (2n = 14) and the high-yielding common vetch NTU0014 (2n = 12). Cytological analysis was performed using fluorescence in situ hybridization (FISH) following an evaluation of their salt tolerance during germination. RESULTS: We confirmed their chromosome numbers and observed that secondary constrictions can occasionally lead to counting errors. The karyotype of common vetch NTU0014 was classified as 1A (2n =2x=12, x = 5m + 1sm), while that of hairy vetch NTU0012 was determined to be 2A (2n =2x=14, x = 6m + 1sm), showing greater asymmetry (As.K% = 62.81). rDNA-FISH revealed notable differences in rDNA distribution between the two species: V. sativa possesses one pair of 5S and two pairs of 45S rDNA sites, whereas V. villosa has two pairs of 5S and one pair of 45S rDNA sites. Fiber-FISH analysis indicated that the average length of 5S rDNA was 374.37 kb in V. sativa and 399.53 kb in V. villosa. The average lengths of 45S rDNA were 339.27 kb and 364.90 kb, respectively. This study improves our understanding of the genomic structure of Vicia species and provides valuable rDNA information for future genetic research.