Unfurling an improved method for visualizing mitotic chromosomes in ferns

• Published in: Applications in plant sciences Vol. 12; no. 4; pp. e11588 - n/a
• Main Authors: Ramirez‐Castillo, Rosa, Palma‐Rojas, Claudio, Seguel, Pedro Jara, Grusz, Amanda L., Araya‐Jaime, Cristian
• Format: Journal Article
• Language: English
• Published: United States John Wiley & Sons, Inc 01.07.2024; Wiley
• Subjects: Cell division; Cellulase; Cheilanthes; Cheilanthes hypoleuca; Cheilanthes mollis; Cheilanthoideae; Chromosome number; Chromosomes; Colchicine; Croziers; Cytogenetics; cytology; cytotypes; Enzymes; evolution; Ferns; ferns and fern allies; Genomes; karyotype; mitosis; Nephrolepidaceae; Nephrolepis cordifolia; Permeability; Plant cells; species; sporophytes; whole‐genome duplication; Cheilanthes mollis; cytology; Nephrolepidaceae; karyotype; whole‐genome duplication; Cheilanthes hypoleuca; Cheilanthoideae; Nephrolepis cordifolia
• ISSN: 2168-0450; 2168-0450
• DOI: 10.1002/aps3.11588

Premise Cytotaxonomy employs chromosome visualization to study organismal relationships and evolution. Despite the critical value of cytogenetic data, cytotypes are lacking for many plant groups. Here, we present an improved approach for visualizing mitotic chromosomes in ferns, a key lineage of land plants, using the dividing cells of unfurling croziers (fiddleheads). Methods and Results Our modified mitotic chromosome preparation incorporates a brief pectinase–cellulase pretreatment, as well as colchicine fixation and the Feulgen reaction to improve the staining and separation of mitotic chromosomes. To demonstrate this easy and efficient assessment, we determined the sporophytic (2n) chromosome number for three fern species: Cheilanthes mollis (2n = 60), Cheilanthes hypoleuca (2n = 120), and Nephrolepis cordifolia (2n = 82). Conclusions The new method presented here improves visualizations of mitotic chromosomes from the dividing nuclei of young fern croziers. Fiddleheads are widely accessible in nature and in living collections worldwide, and this modified approach increases their suitability for fern cytotaxonomic studies.