Methodologies for soil extraction and conservation analysis of ferns and lycophytes with belowground gametophytes

Abstract

Premise Studies of fern and lycophyte gametophyte biology in natural settings can be challenging, but such analyses are critical to understanding the dispersal, ecology, and conservation of these species. It is especially challenging to study species whose gametophytes and early sporophyte stages develop belowground, as is the case for species of the Ophioglossaceae, Psilotaceae, some species of the Schizeaceae ( Actinostachys ), and some species of the Lycopodiaceae. To study these taxa, gametophytes and young sporophytes must be extracted from the soil. Methods In 1989, Mason and Farrar described a methodology for accomplishing the collection of belowground gametophytes and sporophytes using soil centrifugation. Here, we refine this procedure based on subsequent years of experience. Results We found that many more sporophytes exist belowground than are represented by aboveground leaves, and that belowground sporophytes can survive indefinitely without production of aboveground leaves. Belowground gametophytes are common in areas where spore‐releasing sporophyte leaves are present. Gametophytes are bisexual with male and female gametangia intermixed. Some species of Botrychium also reproduce asexually belowground through production of gemmae. Discussion We conclude that in Botrychium , assessments of population health and structure must include analyses of the belowground plants and their habitat. Conservation management strategies must also include potential changes in the belowground habitat.

Techniques for locating and analyzing subterranean Lycopodium and Diphasiastrum gametophytes in the field

“…The resulting mass of soil containing the remaining organic structures was first suspended in water and centrifuged, after which the sample was resuspended in 30% sucrose solution and centrifuged again. The first centrifugation resulted in sediments of Botrychium underground structures, while centrifuging the samples with 30% sucrose allowed the extraction of particles of interest from the upper fraction and the preparation of the material for examination under a microscope (Johnson‐Groh et al, 2002 ; Farrar and Johnson, 2022 ).…”

The ecology and physiology of fern gametophytes: A methodological synthesis

“…Given that plants need a positive carbon balance for growth and reproduction, differences in the optimal environment for photosynthesis between sporophyte and gametophyte generations may directly impact their respective distributions (Figure 1 ). Therefore, understanding the variation in light requirements and photosynthetic responses to environmental variation across ecologically and phylogenetically diverse species is critical to characterizing the adaptive life history and growth strategies (but see Farrar and Johnson [ 2022 ] and Rimgailė‐Voicik and Naujalis [ 2022 ] for discussion of the special case of subterranean gametophyte ecology). Indeed, research in vascular plant sporophytes, including fern sporophytes, has discovered key traits related to photosynthetic capacity (e.g., the quantum yield of photosynthesis [ Φ ] and photosystem II [ Φ PSII], light compensation point [LCP], maximum rate of carboxylation by RuBisCO [V cmax ], and the maximum rate of electron transport of photosynthesis [J max ]) to be key drivers of species growth strategies (Poorter et al, 1990 ; Wright et al, 2002 ) and correlated with aspects of a species’ ecological niche (Choy‐Sin and Suan, 1974 ; Brach et al, 1993 ; Hietz and Briones, 2001 ; Saldaña et al, 2005 ; Ali et al, 2015 ).…”

Morphogenesis of the gametophyte of Physematium montevidensis (Woodsiaceae)

“…Particularly for Physematium montevidensis, there is no information about the gametophyte phase. Gametophyte features as presence/absence of trichomes, gametangia ontogeny, pattern of gametophyte development, among others, have been considered an important source of information to understand the phylogeny and population biology and dynamics in ferns (Atkinson & Stokey 1964;Nayar & Kaur 1971;Farrar et al 2008;Farrar & Johnson 2022).…”