Detection of endopolyploid cells in root tips from two geophytic species pretreated with α-bromonaphthalene
Variation of cellular ploidy levels (somatic polyploidy or endopolyploidy) can result from aberrant DNA re-replication during S-phase, but it can also occur as a normal component of animal or plant development, this is common among mollusks, arthropods, amphibians, and fish, but it is rare among mammals. In plants, it has been described in several species including ferns and flowering plants such as maize, sunflower, tomato, Arabidopsis, brassicas, orchids, among others. Endopolyploidy could be achieved by at least four different mechanisms: endoreduplication, endomitosis, acytokinetic mitosis, or cell fusion; the most common of these is endoreduplication. In this work, we report the frequency of endopolyploid cells in root tips from two species of geophytes: Polianthes howardii and two polyploid cytotypes of Sprekelia formosissima (diploid and pentaploid). The root tips were pretreated in 1:1000 aqueous α-bromonaphthalene solution, fixed in methanol:acetic acid (3:1) solution and macerated in an enzyme mixture solution, finally metaphasic chromosome preparations were stained in 1 μg mL‑1 4',6-diamidino-2-phenylindole (DAPI) or 2% acetorcein solutions and observed in a fluorescence microscopy. The results showed a low frequency of endopolyploid cells in all analyzed plants, being smaller for S. formosissima, 1% for pentaploid cytotype and 3% for diploid cytotype, whereas for P. howardii it was 5%. The kind of mechanism for achieved endopolyploidy for each species is discussed.
Rodríguez-Domínguez, J.M. and Camacho-Alvarado, S. (2020). Detection of endopolyploid cells in root tips from two geophytic species pretreated with α-bromonaphthalene. Acta Hortic. 1288, 117-122
endocycle, endoreplication, ornamental species, Polianthes howardii, Sprekelia formosissima