Development of a method for protonema proliferation of peat moss (Sphagnum squarrosum) through regeneration analysis

Abstract

The moss Sphagnum (peat moss) is ecologically and economically important. There is a paucity of physiological and developmental studies on Sphagnum because of the lack of an axenic culture system for its whole life cycle. A culture system has been established for the Sphagnum gametophore, but not the protonema (juvenile vegetative stage after spore germination). Therefore, the aim of this study was to develop a protonema culture system for Sphagnum. Sphagnum squarrosum gametophore tissue was disrupted and then cultured in liquid Knop medium. The regeneration of protonemata from the gametophore fragments was analyzed in detail by microscopy. We observed a developmental balance between filamentous and thalloid protonemata, and growth competition between the thalloid protonema and the gametophore. On the basis of these findings, we established a relatively stable peat moss protonema proliferation method. Using this method, all the developmental stages of peat moss vegetative growth could be obtained through differentiation or regeneration. The method can provide abundant homogeneous Sphagnum materials at desired stages for physiological and developmental studies, and will be useful for large-scale Sphagnum vegetative proliferation. The regeneration analysis method will be useful for establishing protonema proliferation systems for other mosses.

Axenic in vitro cultivation of 19 peat moss (Sphagnum L.) species as a resource for basic biology, biotechnology, and paludiculture

“…To our knowledge, no genetic transformation of any Sphagnum species has been reported hitherto. Because protoplasts derived from protonemal cells are the preferred target for genetic transformation in P. patens , the report about protonema‐induction in S. squarrosum (Zhao et al ., 2019) paves the way for such experiments in the future.…”

“…Initial results with this clone indicated that it can grow in a natural habitat without an intermediate hardening step (Decker & Reski, 2020). Another improvement is the establishment of a protonema‐proliferation protocol for Sphagnum squarrosum (Zhao et al ., 2019). Besides these two species, we found only one report of the establishment of S. fallax cultures in a bioreactor (Rudolph et al ., 1988).…”

Vacuoles in Bryophytes: Properties, Biogenesis, and Evolution

“…Bar = 3 mm. (E) Photo of a leaf with green and white cells in S. squarrosum (Li et al, 2019 ). Bar = 100 μm.…”

The Antarctic Moss Pohlia nutans Genome Provides Insights Into the Evolution of Bryophytes and the Adaptation to Extreme Terrestrial Habitats

“…Similar to other mosses in these regions, they appear to reproduce asexually through dispersal of vegetative propagules-small fragments of colonies (Skotnicki et al, 2002). Protonema proliferation plays an essential role in the asexual processes of differentiation and regeneration (Zhao et al, 2019). Since bryophytes commonly possess most key innovations of land plant evolution, the Antarctic psychrophilic mosses represent an emerging model system for studying responses and sensitivities to environmental changes (Convey and Peck, 2019).…”