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Gigantic chloroplasts, including bizonoplasts, are common in shade-adapted species of the ancient vascular plant family Selaginellaceae

Liu JW, Li SF, Wu CT, Valdespino IA, Ho JF, Wu YH, et al.

Am J Bot, 2020 04;107(4):562-576.
PMID: 32227348 DOI: 10.1002/ajb2.1455

PREMISE: Unique among vascular plants, some species of Selaginella have single giant chloroplasts in their epidermal or upper mesophyll cells (monoplastidy, M), varying in structure between species. Structural variants include several forms of bizonoplast with unique dimorphic ultrastructure. Better understanding of these structural variants, their prevalence, environmental correlates and phylogenetic association, has the potential to shed new light on chloroplast biology unavailable from any other plant group.
METHODS: The chloroplast ultrastructure of 76 Selaginella species was studied with various microscopic techniques. Environmental data for selected species and subgeneric relationships were compared against chloroplast traits.
RESULTS: We delineated five chloroplast categories: ME (monoplastidy in a dorsal epidermal cell), MM (monoplastidy in a mesophyll cell), OL (oligoplastidy), Mu (multiplastidy, present in the most basal species), and RC (reduced or vestigial chloroplasts). Of 44 ME species, 11 have bizonoplasts, cup-shaped (concave upper zone) or bilobed (basal hinge, a new discovery), with upper zones of parallel thylakoid membranes varying subtly between species. Monoplastidy, found in 49 species, is strongly shade associated. Bizonoplasts are only known in deep-shade species (<2.1% full sunlight) of subgenus Stachygynandrum but in both the Old and New Worlds.
CONCLUSIONS: Multiplastidic chloroplasts are most likely basal, implying that monoplastidy and bizonoplasts are derived traits, with monoplastidy evolving at least twice, potentially as an adaptation to low light. Although there is insufficient information to understand the adaptive significance of the numerous structural variants, they are unmatched in the vascular plants, suggesting unusual evolutionary flexibility in this ancient plant genus.

Matched MeSH terms: Selaginellaceae*
Kepelbagaian dan habitat pteridofit di hutan simpan angsi, Negeri Sembilan

Maideen H, Desa ZC, Damanhuri A, Latiff A, Rusea G

Sains Malaysiana, 2011;40:1341-1344.

Sejumlah 51 takson pteridofit yang tergolong dalam 30 genus dan 18 famili telah direkodkan di Hutan Simpan Angsi, Negeri Sembilan. Ini termasuk lapan spesies lokofit dalam dua genus dan dua famili. Jumlah ini merangkumi lapan peratus daripada 647 spesies yang telah dilaporkan di Semenanjung Malaysia. Famili terbesar yang direkodkan terdiri daripada Selaginellaceae dan Pteridaceae masing-masing dengan tujuh spesies diikuti oleh Polypodiaceae (enam spesies) dan Tectariaceae (empat spesies). Paku-pakis terestrial merupakan yang paling banyak direkodkan iaitu 60% daripada keseluruhan takson yang didapati diikuti dengan paku pakis epifit (24%) dan paku pakis batuan (16%).

Matched MeSH terms: Selaginellaceae
Systematic significance of stipe anatomy of selaginella (selaginellaceae) in peninsular Malaysia

Haja Maideen, Nor Hazwani A, Nurfarahain Z, Damanhuri A, Noraini T, Qistina L, et al.

Sains Malaysiana, 2013;42:693-696.

An anatomical study was carried out on 14 taxa belonging to Selaginellaceae in an attempt to study their stipe anatomical characteristics and to provide anatomical data for the selected taxa in Selaginellaceae. Out of 29 taxa of Selaginellaceae recorded in Peninsular Malaysia, 14 taxa have been selected namely Selaginella alutacia, S. argentea, S. frondosa, S. intermedia var. intermedia, S. intermedia var. dolichocentrus, S. mayeri, S. morganii, S. ornata, S. plana, S. polita, S. roxburghii var. roxburghii, S. stipulata, S. wallichii and S. willdenowii. Method used in this study was sectioning using sliding microtome. Findings in this study have shown that Selaginellaceae species studied can be clustered into two groups based on the stipe stellar systems, which are monostelic and tristelic groups. There are some variations exist in the cross sections of the stipes of the same species due to the presence and absence of the leaf trace. Each species is proved to have distinct stipe anatomical characteristics that can be used to differentiate species in Selaginellaceae.

Matched MeSH terms: Selaginellaceae
Fulltext Cellular Biochemical Changes in Selaginella tamariscina (Beauv.) Spring and Sellaginella plana (Desv. ex Poir.) Heiron. as Induced by Desiccation

Agduma AR, Sese MD

Trop Life Sci Res, 2016 Aug;27(2):37-52.
PMID: 27688850 DOI: 10.21315/tlsr2016.27.2.4

The biochemical changes in two Selaginella species namely, S. tamariscina (Beauv.) Spring and S. plana (Desv. ex Poir.) Heiron., as induced by desiccation and subsequent rehydration were explored. Plants were allowed to dehydrate naturally by withholding irrigation until shoot's relative water content (RWC) reached <10%. After which, dehydrated plants were watered until fully rehydrated states were obtained which was about 90% RWC or more. Desiccation-tolerance characteristics were observed in S. tamariscina while desiccation-sensitivity features were seen in S. plana. Membrane integrity was maintained in S. tamariscina but not in S. plana as evidenced in the relative electrolyte leakage measurements during desiccation phase and the subsequent rehydration stage. Pigment analyses revealed conservation of some chlorophylls and carotenoids during desiccation and reaching control levels following rehydration in S. tamariscina. Very low pigment contents were found in S. plana during desiccation phase and the pigments were not recovered during rehydration attempt. Meanwhile, compatible solute determination showed rise in total sugar and proline contents of desiccated S. tamariscina only, indicating presence of biochemical protection machineries in this species and absence of such in S. plana during dehydrating conditions. These data indicate that one key element for desiccation-tolerance in lower vascular plants is the ability to protect tissues from severe damages caused by intense desiccation.

Matched MeSH terms: Selaginellaceae