Karyotype and leaf epidermis histology traits of Digitaria abyssinica (Hochst. Ex A. Rich.) (Poaceae)
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ORIGINAL ARTICLE
Karyotype and leaf epidermis histology traits of Digitaria abyssinica (Hochst. Ex A. Rich.) (Poaceae) Ana Luisa Arantes Chaves 1 & Raquel Bezerra Chiavegatto 1 & Marco Tulio Mendes Ferreira 1 & Laiane Corsini Rocha 1 & Ana Luisa Sousa Azevedo 2 & Flávio Rodrigo Gandolfi Benites 2 & Vânia Helena Techio 1 Received: 8 July 2020 / Accepted: 13 October 2020 # Institute of Molecular Biology, Slovak Academy of Sciences 2020
Abstract Digitaria abyssinica (African couchgrass) has economic potential as forage. This species is taxonomically complex, with a high number of synonyms, basic chromosome number x = 9, and diploid and tetraploid cytotypes. Anatomical, histological, and cytotaxonomic studies may contribute to the taxonomic description of this species and reveal its polyploidization and hybridization events. To this end, this study aimed to characterize the karyotype and leaf epidermis histology of two D. abyssinica genotypes. Chromosome characterization was performed based on chromosome banding using chromomycin A (CMA) and 4,6diamidino-2-phenylindole (DAPI) and identification of 35S and 5S rDNA sites by fluorescent in situ hybridization. Nuclear DNA quantification was performed by flow cytometry. Paradermal sections were obtained for the leaf epidermis study by light and electron microscopy. The results confirmed that both genotypes are tetraploid (2n = 36). The number and distribution of 35S and 5S rDNA sites suggest the occurrence of postpolyploidization structural chromosomal changes or hybridization processes. Despite intraspecific variation in the number of 5S rDNA sites and CMA+/DAPI+ bands, no changes were identified in karyotypical symmetry or genome size. Leaf epidermis histology traits and cytogenetic data can support breeding programs and germplasm banks in identifying species or cultivars. Keywords Polyploidy . Heterochromatin . African couchgrass . Cytotaxonomy . Chromosomal polymorphism
Abbreviations AR Arm ratio CMA Chromomycin A CM Chromosomal morphology DAPI 4,6-diamidino-2-phenylindole FISH Fluorescent in situ hybridization GISH Genomic in situ hybridization LA Long arm length SA Short arm length SEM Scanning electron microscopy TL Total chromosome length TLH Total length of the haploid set * Vânia Helena Techio [email protected] 1
Department of Biology (DBI), Plant Cytogenetics Laboratory, Federal University of Lavras (UFLA), P.O. Box 3037, Lavras, Minas Gerais State, Brazil
2
Empresa Brasileira de Pesquisa Agropecuária, Embrapa Gado de Leite, Juiz de Fora, Minas Gerais State, Brazil
Introduction Digitaria Haller (Crabgrass), a genus in the family Poaceae, subfamily Panicoideae, and tribe Paniceae (Boonsuk et al. 2016), contains approximately 300 species, including annual and perennial plants, and has a cosmopolitan distribution (Vega and Rúgolo de Agrasar 2001; Govaerts 2011). In Brazil, 26 native, nine endemic, and 12 exotic species have been described, with greatest richness in the South and Southeast regions, mainly in Cerrado areas, rocky fields, and sites modified by hu
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