Chromosomal FISH analysis of Kengyilia grandiglumis and Elymus breviaristatus

Kengyilia grandiglumis and Elymus breviaristatus are two species of perennial grass distributed in the sandy environment of the Qinghai–Tibet Plateau. In this study, we performed sequential fluorescence in situ hybridization (FISH) and genomic in situ hybridization (GISH) to analyze the metaphase chromosomes of K. grandiglumis and E. breviaristatus root tips using the transposable elements (TEs) probe S5 and tandem repeat probe AAG. The results revealed that GISH signals can successfully distinguish the four subgenomes P, H, St, and Y, and that we were able to obtain details of the distribution of the S5 and AAG probes on the 21 pairs of chromosomes in the two grass species. In K. grandiglumis, S5 signals were primarily distributed in the terminal and subtelomeric regions, and were most frequently observed in the P subgenome. In contrast, AAG signals were mainly distributed in the pericentromeric and subtelomeric regions, with the fewest signals being detected in the intercalary regions, and were most frequently observed in the Y subgenome. In E. breviaristatus, S5 signals were found to be distributed in the terminal, subtelomeric, pericentromeric, and intercalary regions, with signals being detected more frequently in the H subgenome than in the St or Y subgenomes. AAG signals were detected in the pericentromeric, intercalary, and subtelomeric regions, with signals being least abundant in the St subgenome. Our determination of the chromosome signaling characteristics of K. grandiglumis and E. breviaristatus at the subgenomic level will provide a basis for further evaluation and utilization of the germplasm resources of these two allohexaploid grasses.