Ploidy level and obligate apogamy in two populations of Argyrochosma nivea var. tenera (Pteridaceae)

Abstract

Argyrochosma nivea var. tenera is a cheilanthoid fern from the American continent. We present herewith the study of meiotic behavior and gametic number as well as number of spores and reproduction mode (with observations from cultured gametophytes). The study material is from Northwestern Argentina. For the study of meiosis, sporangia were fixed in ethanol-acetic acid (3:1) and stained with 2% propionic haematoxylin. Micrographs were taken using light and scanning electron microscopes. Meiotic chromosome number is 2n = 3x = 81 and the presence of lagging chromosomes at telophase II is mentioned for the first time; three sets of chromosome occur at diakinesis. Sporangia have 32 trilete spores. Adult gametophytes are laminar, cordiform, asymetrical, glabrous, without glandular trichomes. In our samples, the adult gametophytes were neuter, without antheridia or archegonia, with obligate apogamous reproduction. Both populations studied might be of hybrid origin.

Distribution of Ploidy Level on Adiantumdiaphanum Blume at Various Altitudes in Probolinggo

“…Some of these researchers, such as Hastuti et al (2011) and Praptosuwiryo & Darnaedi (2005) who reported that some species of ferns were found in triploid conditions. The emergence of triploid ferns possibly due to a cross hybrid between diploid with tetraploid organisms (Hernández et al, 2015). If the presence of triploid organisms in this study were due to this such cross hybrid there is a possibility Adiantumtetraploid lived in that area.…”

“…Huang, Chou, Wang, & Chiou, 2007). Polyploid ferns were also reported on Dryopteris in Batu (Zubaidah, 2006), Diplazium in Java (Praptosuwiryo & Darnaedi, 2005); Botrychium in Switzerland, Sweden and the United States (Dauphin, Grant, & Mraz, 2016); as well as Argyrochosmanivea in Argentina (Hernández et al, 2015). All of those studies have reported the presence of several natural polyploid ferns in the various locations being studied.…”

“…In the second cause, polyploidy occur due to the fusion of two gametes that have not been reduced. Usually, errors in meiotic division during sporogenesis produce diploid spores which cause the emergence of apogamous sporophytes (Y.-S. Fernández, 2018;Hernández, Andrada, De Los, Páez, & Martínez, 2015). As a result, in both phases of life, ferns remain in diploid conditions (Fernández, 2018).…”

Fase gametofítica de las tres variedades de Argyrochosma nivea (Pteridaceae).

“…Las esporas de Argyrochosma nivea, en sus tres variedades, tienen dimensiones semejantes a las descritas por Morbelli et al (2001), y la cantidad de esporas por esporangio es uniforme en la especie, dato correspondiente con el registro de Gabriel y Galán (2011) y Hernández et al (2015). Las dimensiones de las esporas, en las tres variedades, encontradas en este trabajo son menores que las citadas por Morbelli et al (2001) y Hernández et al (2015).…”

“…Las dimensiones de las esporas, en las tres variedades, encontradas en este trabajo son menores que las citadas por Morbelli et al (2001) y Hernández et al (2015). La variedad nivea se destaca por la amplia variación en el tamaño de las esporas, con DE= 38,3-106 (Morbelli et al, 2001), semejante observación se encuentra en la var.…”