Oligo-FISH Can Identify Chromosomes and Distinguish Hippophaë rhamnoides L. Taxa

Oligo-fluorescence in situ hybridization (FISH) facilitates precise chromosome identification and comparative cytogenetic analysis. Detection of autosomal chromosomes of Hippophaë rhamnoides has not been achieved using oligonucleotide sequences. Here, the chromosomes of five H. rhamnoides taxa in the mitotic metaphase and mitotic metaphase to anaphase were detected using the oligo-FISH probes (AG₃T₃)₃, 5S rDNA, and (TTG)₆. In total, 24 small chromosomes were clearly observed in the mitotic metaphase (0.89-3.03 μm), whereas 24-48 small chromosomes were observed in the mitotic metaphase to anaphase (0.94-3.10 μm). The signal number and intensity of (AG₃T₃)₃, 5S rDNA, and (TTG)₆ in the mitotic metaphase to anaphase chromosomes were nearly consistent with those in the mitotic metaphase chromosomes when the two split chromosomes were integrated as one unit. Of note, 14 chromosomes (there is a high chance that sex chromosomes are included) were exclusively identified by (AG₃T₃)₃, 5S rDNA, and (TTG)₆. The other 10 also showed a terminal signal with (AG₃T₃)₃. Moreover, these oligo-probes were able to distinguish one wild H. rhamnoides taxon from four H. rhamnoides taxa. These chromosome identification and taxa differentiation data will help in elucidating visual and elaborate physical mapping and guide breeders' utilization of wild resources of H. rhamnoides.