學術資源整合系統-相關推薦

 
作者Liu, J.W.;S.F. Li;H.M. Chang;M.F. Kao;C.T. Wu;Y.H. Wu;I. Valdespino;C. Chesson;S. Das;H. Oppenheimer;A. Bakutis;P. Saenger;N. Salazar;J.W.H. Yong;B. Adjie;R. Kiew;N. Nadkarni;C.L. Huang;P. Chesson;C.R. Sheue
出版日期2018
著作名稱The bizonoplast, a unique giant chloroplast, is now known from nine Selaginella species from deep-shade habitats
會議名稱7th Asian Symposium of Ferns and Lycophytes
會議地點Taipei
國際性會議Y
關鍵字giant chloroplast; lamellar structure; Stachygynandrum; Selaginellaceae; shade-adapted
摘要Chloroplasts have been studied for more than 150 years revealing highly conserved structure in land plants. Typical chloroplasts of land plants are small disc-like structures, with grana (stacked thylakoid membranes) and unstacked stromal thylakoids. However, a unique giant chloroplast (monoplastid), the bizonoplast, has been reported recently from the dorsal epidermal cells of the ancient vascular plant genus Selaginella (Selaginellaceae, Lycophyta). Bizonoplastsare uniquely dimorphic in ultrastructure with two distinct zones: the upper zone contains a regular lamellar structure of thylakoids while the lower zone is occupied by both granaandstromal thylakoids. The Selaginellaceae, with a monotypic genus Selaginella, are comprised of more than 700 species globally occurring in a variety of environments. This study systematically explored the occurrence of bizonoplasts in this diverse family to further understand bizonoplast structure and adaptive significance. Chloroplast ultrastructures of 72 Selaginella species collected worldwide (7 subgenera) were observed with transmission electron microscopy. In addition to two species previously known to have bizonoplasts (S. erythropus and S. martensii), 7 shade species of Selaginella with giant chloroplasts in the dorsal epidermal cells were found to have bizonoplasts. All 9 species with bizonoplasts belong to the subgenus Stachygynandrum but come from both the Old World (Asia, 6 species) and the New World (Central and South America, 3 species). Moreover, two forms of bizonoplast structure are recognized: cup-shaped (5 species) and bilobed (4 species). A bilobed bizonoplast is similar in shape to a bivalve shell with the two valves (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 bizonoplast have similar ultrastructural features including an upper zone of about 11 parallel groups and each comprised of 3-5 stacked thylakoids. However, two species native to Taiwan (S. aristata and S. devolii) have significantly thicker thylakoid groups and stromal spacings. Bizonoplasts are only known from deep-shade adapted Selaginella in agreement with other evidence that the upper zone with regular lamellar structure is an adaptation to deep shade environments. The lamellar structure of Selaginella bizonoplasts is similar to the structure of lamelloplasts reported in Begonia species of flowering plants. Regular lamellar structures may have unique optical properties, as suggested theoretically and potentially induce foliar iridescence, but empirical evidence is still needed.
系統號NO000004850

Aug 16 2018 10:46:44
nmns/nmnsweb_2nd_target(0)