Spore germination and gametophyte development of Cyathea atrovirens (Langsd. & Fisch.) Domin (Cyatheaceae) under different pH conditions

Abstract

Cyathea atrovirens (Langsd. & Fisch.) Domin, an intensely exploited tree fern, is found inside forests in several succession stages, as well as in swamps, roadsides and unused fields in the Rio dos Sinos basin, in the state of Rio Grande do Sul, southern Brazil. This study evaluated the in vitro germination and gametophyte development of C. atrovirens under different pH conditions, as well as spore viability after different storage times at 7 ºC. The lowest germination rate of spores was obtained at pH 7.0. At pH 5.0 to 6.5, laminar gametophyte development started at 20 to 30 days of culture. Antheridia and archegonia were first observed at 35 and 128 days, respectively. Storage at 7 o C did not affect germination rates. The capability of germination at different pH levels may explain the occurrence of the species in a wide range of habitats. The present study contributes to the understanding of the full life-cycle of C. atrovirens and to the analysis of the influence of abiotic components, providing information for the cultivation, management and conservation of the species.Keywords: tree ferns, gametophyte, pH, reproduction, conservation. Rechenmacher, C., Schmitt, JL. and Droste, A. through lens cleaning tissue. Part of the spores were stored in tubes at 7 ± 1 °C for later viability analysis. Spores did not undergo asepsis to keep experimental conditions close to those found in nature. Germinação de esporos e desenvolvimento gametofítico deTo evaluate the effect of pH on germination and initial gametophyte development of fresh spores, seven different pH levels were used: 4.0; 4.5; 5.0; 5.5; 6.0; 6.5; and 7.0. In a laminar flow hood, 10-mg samples of spores were distributed in flasks with 50-mL autoclaved Meyer solution (Meyer et al., 1955). Six replicates were used for each pH level, totalising 42 flasks. The cultures were maintained in a growth chamber at 26 ± 1 °C for a 16-hour photoperiod and photon flux density of 100 µmol.m -2.s -1 provided by cool white fluorescent tubes.Germination was scored at three, six, nine and 12 days of in vitro culture. Six slides (one slide per flask) from each treatment were analysed, verifying 100 spores on each slide. To follow up initial gametophyte development at different pH levels, 10 individuals on each slide (one slide per flask) were photographed and classified according to their developmental stage in the following categories at six, nine and 12 days of culture: a) rhizoid and chlorocyte; b) filamentous stage; and c) laminar stage. At 104, 128 and 150 days, the morphology of one individual from each flask was described.To describe the in vitro development of this species, only gametophytes obtained at pH 6.0 were evaluated at up to 128 days of culture. Representative individuals at different development stages were photographed, and the images were digitalised using a Canon EOS 220 camera coupled to an Olympus CX4 microscope.In a second experiment, the germinability rates of fresh and stored spores (90 and 180 days at 7 °C) were compared, using cultures w...

Propagación in vitro de Cyathea atrovirens (Cyatheaceae): almacenamiento de esporas y condiciones de esterilización

“…This delay was not maintained during the experiment, and there were no significant differences between treatments at the end of the experiment. Furthermore, the presence of reproductive structures at 120 and 130 days corroborate with the findings of Rechenmacher et al (2010) for C. atrovirens cultures without using sterilizing agents, suggesting that the antimicrobial action of these agents does not seem to influence negatively the development of gametophytes. The increasing number of reproductive structures observed during the evaluations suggests the continuity of the developmental process after the study period of 130 days.…”

“…C. Chr. and Rechenmacher et al (2010) for C. atrovirens. On the other hand, although surface sterilizing treatments are commonly referred to as drastically reducing germination (Simabukuro et al, 1998), this did not occur in the present work.…”

“…Three slides (one slide per dish) from each treatment were analyzed, and 100 individuals (spores or young gametophytes) were counted on each slide (300 individuals per treatment). Individuals were classified according to their developmental stage (Rechenmacher, Schmitt & Droste, 2010) in the following classes: non-germinated spores (NG), gametophyte with chlorocyte and rhizoid (G1); filamentous gametophyte (G2); laminar gametophyte (G3) and cordiform gametophyte (G4). The criterion for germination was the emergence of the chlorocite or the rhizoid (Ranal, 1999).…”

Tree ferns dominate secondary succession in abandoned pineapple plantations around Manu National Park, Peru

“…As shown in studies of bean (Thomson et al, 1993), corn (Blevins et al 1977), peach (Tagliavini et al, 1995), and natural temperate ecosystems (Van Miegroet and Cole, 1984) nitrogen fertilizers decrease soil pH. Acidic substrates (pH 4-5), in turn, have been shown to favor spore germination and the development of gametophytes in several tree fern species , Medeiros et al, 2017, Rechenmacher et al 2010. It is possible then that soil acidification following the fertilization of pineapple fields in the Manu region allow tree ferns to recruit more competitively than pioneer arborescent angiosperms such as Cecropia and Jacaranda.…”

Domestication of red jungle fowl: A case study of the red jungle fowl chicks procurement by the communities in Central Bengkulu, Indonesia

“…Spore germination was defined as the emergence of a rhizoid through its spore coat (Camloh 1993). Early gametophytes were classified according to the gametophyte development stages described by Rechenmacher et al (2010) The assemblage of prothalli were separated and observed under Nikon binocular microscope (Nikon SMZ-10A). In order to document spore germination and gametophyte development, photographs were taken using the Olympus microscope connected to a computer monitor camera (Olympus CX 31) fitted with objective lenses 4X-40x.…”