Coix lacryma-jobi L. is a cereal crop belonging to the Poaceae family, valued for its nutritional, medicinal, and ornamental uses. Among its varieties, two prominent landraces, C. lacryma-jobi var. kiboa and var. tapol, are cultivated for their distinct grain morphologies and favorable agronomic traits. However, despite its economic importance, detailed cytogenetic and molecular phylogenetic studies remain limited. This study presents a cytogenetic and molecular phylogenetic analysis of C. lacryma-jobi L. var. kiboa and tapol. Partial cytogenomic characterization on the 45S and 5S rDNA loci as well as Arabidopsis- type telomeric repeats using pre-labeled oligomer probes for fluorescence in situ hybridization (PLOP-FISH) technique confirmed a diploid chromosome number of 2n = 20 in both varieties. The 45S and 5S rDNA loci were localized on the nucleolar organizer region (NOR) of the short arm of chromosome 1 and the long arm of chromosome 4, respectively, indicating conserved chromosomal arrangements. Additionally, Arabidopsis-type telomeric repeats were detected at the terminal regions of all chromosomes. Chromosome sizes ranged from 2.98 ± 0.07 to 3.74 ± 0.11 μm in var. kiboa and from 3.42 ± 0.08 to 4.12 ± 0.05 μm in var. tapol. Phylogenetic analyses based on the internal transcribed spacer (ITS1 and ITS4) genes revealed a close genetic relationship between the two varieties, supporting their shared evolutionary lineage. These findings enhanced our understanding of adlay genetic diversity and provide foundational insights for plant breeding improvement, conservation strategies, and future genomic research.

Genome sequencing has been going on major medicinal plants, including Platycodon grandiflorus, which is commonly used as a functional food and medicinal resource in Korea. Molecular cytogenetic studies using fluorescence in situ hybridization (FISH) show the chromosomal organization of specific DNA sequences. We analyzed the FISH karyotypes of P. grandiflorus ‘Jangbaek’ and a colchicine-induced tetraploid cultivar ‘Etteumbaek’ using 5S and 45S rDNA probes. As a result, ‘Jangbaek’ had chromosome length ranging from 2.34 ± 0.13 to 3.99 ± 0.197 μm with its karyotypic formula of 2n = 2x = 18 = 16m + 2sm (two satellites) whereas ‘Etteumbaek’ had chromosome length of 2.37 ± 0.08 to 4.20 ± 0.16 μm and a karyotypic formula of 2n = 4x = 36 = 24m + 12sm (four satellites). A pair of 5S rDNA signals observed interstitially in chromosome 3 and the co-localization of 5S and 45S rDNA signals occupying the nucleolar-organizing region (NOR) of chromosome 6 was observed in the diploid cultivar ‘Jangbaek’. Doubling of both signals co-localized in the NOR of chromosome 6 were observed in the colchicine induced tetraploid cultivar. However, the tetraploid revealed a modified positioning of 5S rDNA signals on chromosome 3 interstitially, with observable vague dispersed signals in one chromosome of chromosomes 1 and 5. This result will be useful for further breeding program and chromosomal backbone for the Platycodon genome analysis.

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Perilla species (Lamiaceae) have been used as a resource for oilseeds and vegetables, and medicinal purposes. Cytogenetic studies based on chromosomal composition are essential to understand the basic genome structure of a species and to provide vital information for crop improvements. However, only a few studies have assessed the cytogenetic aspects of Perilla species. Fluorescence in situ hybridization (FISH) karyotypes using 5S and 45S rDNA probes were analyzed for the wild and cultivated species of Perilla: P. citriodora and P. frutescens. Chromosome complements were diploid in P. citriodora and allotetraploid in P. frutescens. The chromosome length ranged from 3.07 to 4.92 μm and 2.41 to 5.73 μm in the diploid and allotetraploid variants, respectively. The karyotypic formula was 2n = 12m + 8sm (2 satellites) for P. citriodora and 2n = 20m + 20sm (2 satellites) for P. frutescens. A pair of 5S signals was detected in the telomeric region of chromosome pair 7, while a pair of 45S rDNA signals was detected in the telomeric region extending through the satellite region of chromosome 2 of P. citriodora. However, two pairs of 5S signals were detected from the interstitial to the telomeric regions of chromosome 7 and 17, and a pair of 45S rDNA signals was located on the satellite region of chromosome 20 of P. frutescens. This result will provide useful information to develop a breeding program and to construct the chromosomal backbone for the ongoing genome sequence assembly project.

Citations

Citations to this article as recorded by  

• Cytogenomic profiling of Panax ginseng cultivars and in vitro root cultures through multi-color PLOP-FISH and flow cytometry reveals somaclonal variations
  Eliazar A. Peniton Jr., Hong T. Nguyen, Nomar E. Waminal, Tae-Jin Yang, Hyun Hee Kim
  Journal of Ginseng Research.2026; 50(4): 101058.     CrossRef
• Cytogenomic evaluation of regenerated Aralia elata using PLOP-FISH and flow cytometry
  Eliazar Alumbro Peniton, Hong Thi Nguyen, Nomar Espinosa Waminal, Tae-Jin Yang, Hyun Hee Kim
  Scientific Reports.2024;[Epub]     CrossRef
• Comparative triple-color FISH mapping and genome size advances understanding of the cytogenetic diversity in wild Solanum species
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  Horticulture, Environment, and Biotechnology.2023; 64(5): 811.     CrossRef
• Comparative FISH analysis of Senna tora tandem repeats revealed insights into the chromosome dynamics in Senna
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  Genes & Genomics.2021; 43(3): 237.     CrossRef
• Comparative triple-color FISH mapping in eleven Senna species using rDNA and telomeric repeat probes
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  Horticulture, Environment, and Biotechnology.2021; 62(6): 927.     CrossRef
• FISH Karyotype Comparison ofPlatycodon grandiflorus(Jacq.) A. DC. ‘Jangbaek’ and Its Colchicine-Induced Tetraploid ‘Etteumbaek
  Eliazar Alumbro Peniton Jr., Yurry Um, Hyun Hee Kim
  Plant Breeding and Biotechnology.2020; 8(4): 389.     CrossRef