學術資源整合系統-相關推薦

 
作者Liu, J.W.;S.F. Li;Y.H. Wu;C.T. Wu;I.A. Valdespino;H.M. Chang;M.F. Kao;C. Chesson;S. Das;H. Oppenheimer;A. Bakutis;P. Saenger;S.A. Noris;J.W.H. Yong;B. Adjie;R. Kiew;N. Nadkarni;M.S.B. Ku;C.L. Huang;P. Chesson;C.R. Sheue
出版日期2019
著作名稱Bizonoplasts, unique giant chloroplasts of the ancient vascular plant Selaginella: occurrence, variation and adaptive significance
會議名稱Botany 2019
會議地點Arizona
主辦單位Botanical Society of America
國際性會議Y
主題植物
關鍵字Plant Structure-Function
摘要A unique giant chloroplast (monoplastid), the bizonoplast (Bp), has been reported recently from the dorsal epidermal cells of the vascular plant genus Selaginella (Selaginellaceae). Bps are uniquely dimorphic in ultrastructure: the upper zone contains a regular lamellar structure of thylakoids while the lower zone is occupied by both grana and stromal thylakoids. This study systematically explored the occurrence, structural variants, environmental correlates and phylogeny of the various chloroplast types in this diverse family with a view to understanding Bp adaptive significance. Chloroplast ultrastructures of 75 Selaginella species collected worldwide (7 subgenera) were observed with transmission electron microscopy. Environmental data of selected species were recorded. Based on the presence of monoplastidy (M) and chloroplast number in dorsal epidermal cells, five chloroplast categories were delineated: ME (M in a dorsal epidermal cell), MM (M in a mesophyll cell), OL (oligoplastidy (2–8/ cell), Mu (multiplastidy, > 10/ cell) and RC (reduced or vestigial chloroplast). In total, 10 shade adapted species with ME chloroplasts were found to have Bps (ME), but none from the species with MM chloroplasts. All 10 species with Bps belong to the subgenus Stachygynandrum but come from both the Old World and the New World. Moreover, two forms of Bps are recognized: cup-shaped (5 species) and bilobed (5 species). A bilobed Bp is first reported here. It is similar in shape to a bivalve shell with two lobes connected narrowly at the base. Each lobe has an upper zone at the apex, which travels down the interior side of the lobe thinning until it disappears. Both forms of Bps have similar ultrastructure, but species differ in the number of layers in the upper zone. Paradermal sections create concentric or spiral patterns resembling fingerprints in the upper zone of Bps, similar to paradermal sections of the lamelloplasts of Begoniaceae. The most basal species of Selaginella have Mu chloroplasts suggesting that M and Bps are derived traits in this ancient family. Bps are only known from deep-shade adapted (c. 0.5–2.4% full sunlight) and dorsiventral Selaginella with ME and anisophylls, in agreement with other evidence that the upper zone with regular lamellar structure is an adaptation to deep shade environments. It is highly likely that the prevalence of Bps in Selaginellaceae is higher than our current understanding. The lamellar upper zone above a giant chloroplast is an interesting photonic and photosynthetic system that requires further multidisciplinary exploration.
系統號NO000005197

Aug 20 2021 11:12:17
nmns/nmnsweb_2nd_target(0)