@article{f02c0167485e45a2bd45190467c742ee,
title = "Gigantic chloroplasts, including bizonoplasts, are common in shade-adapted species of the ancient vascular plant family Selaginellaceae",
abstract = "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.",
keywords = "Selaginellaceae, Stachygynandrum, bilobed chloroplast, chloroplast diversity, cup-shaped chloroplast, monoplastidy, shade-adapted Selaginella, ultrastructure",
author = "Liu, {Jian Wei} and Li, {Shau Fu} and Wu, {Chin Ting} and Valdespino, {Iv{\'a}n A.} and Ho, {Jia Fang} and Wu, {Yeh Hua} and Chang, {Ho Ming} and Guu, {Te Yu} and Kao, {Mei Fang} and Clive Chesson and Sauren Das and Hank Oppenheimer and Ane Bakutis and Peter Saenger and {Salazar Allen}, Noris and Yong, {Jean W.H.} and Bayu Adjie and Ruth Kiew and Nalini Nadkarni and Huang, {Chun Lin} and Peter Chesson and Sheue, {Chiou Rong}",
note = "Funding Information: This article is dedicated to the memories of the late Professor V. Sarafis and the late Dr. C. C. Tsai, both of whom greatly assisted with this study. The authors thank Prof. M. S. B. Ku and two anonymous reviewers for providing help and valuable comments; the University of Bristol Botanic Garden (UK), Cairns Botanic Gardens (Australia), Sun Yat‐sen University (China), South China Botanic Garden (China), The Dr. Cecilia Koo Botanic Conservation Center (KBCC, Taiwan), Smithsonian Tropical Research Institute, and Mr. Z. X. Chang for providing materials or field trip help; and Dr. W. N. Jane (Academia Sinica, Taiwan) and Miss P. C. Chao (Precision Instruments Center, National Chung Hsing University) for assisting with TEM. This study was supported by the Ministry of Science and Technology, Taiwan (awards MOST‐101‐2621‐B‐005‐002‐MY3; MOST 104‐2621‐B‐005‐002‐MY3; MOST 107‐2621‐B‐005‐001). Funding Information: This article is dedicated to the memories of the late Professor V. Sarafis and the late Dr. C. C. Tsai, both of whom greatly assisted with this study. The authors thank Prof. M. S. B. Ku and two anonymous reviewers for providing help and valuable comments; the University of Bristol Botanic Garden (UK), Cairns Botanic Gardens (Australia), Sun Yat-sen University (China),?South China Botanic Garden (China),?The Dr. Cecilia Koo Botanic Conservation Center (KBCC, Taiwan), Smithsonian Tropical Research Institute,?and Mr. Z. X. Chang for providing materials?or field trip help; and Dr. W. N. Jane (Academia Sinica, Taiwan) and Miss P. C. Chao (Precision Instruments Center, National Chung Hsing University) for assisting with TEM. This study was supported by the Ministry of Science and Technology, Taiwan (awards MOST-101-2621-B-005-002-MY3; MOST 104-2621-B-005-002-MY3; MOST 107-2621-B-005-001). Publisher Copyright: {\textcopyright} 2020 Botanical Society of America",
year = "2020",
month = apr,
day = "1",
doi = "10.1002/ajb2.1455",
language = "English (US)",
volume = "107",
pages = "562--576",
journal = "American Journal of Botany",
issn = "0002-9122",
publisher = "Botanical Society of America Inc.",
number = "4",
}