Genome Size 2011 Genome Size 2011 Journal of Botany
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Journal of Botany Genome Size 2011 Genome Size 2011 Journal of Botany Genome Size 2011 Copyright © 2012 Hindawi Publishing Corporation. All rights reserved. This is a focus issue published in “Journal of Botany.” All articles are open access articles distributed under the Creative Commons Attri- bution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Editorial Board Stephen W. Adkins, Australia Muhammad Hamayun, Pakistan Claude Penel, Switzerland Iftikhar Ahmad, Pakistan Takashi Hashimoto, Japan Lorenzo Peruzzi, Italy Mohammad Anis, India Shamsul Hayat, Saudi Arabia Bala Rathinasabapathi, USA Tadao Asami, Japan Simon Hiscock, UK S. G. Razafimandimbison, Sweden Hiroshi Ashihara, Japan Muhammad Iqbal, Pakistan Zed Rengel, Australia Muhammad Y. Ashraf, Pakistan Gaoming Jiang, China Marko Sabovljevic, Serbia Prem L. Bhalla, Australia Bai-Lian Larry Li, USA Bernd Schneider, Germany Hikmet Budak, Turkey Jutta Ludwig-Mueller, Germany Harald Schneider, UK Bhagirath S. Chauhan, Philippines Tariq Mahmood, Pakistan William K. Smith, USA Kang Chong, China Minami Matsui, Japan Kenneth J. Sytsma, USA Curtis C. Daehler, USA Frederick Meins, Switzerland Hiroshi Tobe, Japan Peter J. De Lange, New Zealand Marcelo Menossi, Brazil An Vanden Broeck, Belgium MariaR.Ercolano,Italy Michael Moeller, UK Philip J. White, UK Muhammad Farooq, Pakistan Akira Nagatani, Japan Andrew Wood, USA Urs Feller, Switzerland Karl Joseph Niklas, USA Guang Sheng Zhou, China M. Fernandez-Aparicio, Spain Masashi Ohara, Japan Contents Polyploidy and Speciation in Pteris (Pteridaceae), Yi-Shan Chao, Ho-Yih Liu, Yu-Chung Chiang, and Wen-Liang Chiou Volume 2012, Article ID 817920, 7 pages Exploring Diversification and Genome Size Evolution in Extant Gymnosperms through Phylogenetic Synthesis, J. Gordon Burleigh, W. Brad Barbazuk, John M. Davis, Alison M. Morse, and Pamela S. Soltis Volume 2012, Article ID 292857, 6 pages On the Coevolution of Transposable Elements and Plant Genomes,PeterCiva´n,ˇ Miroslav Svec,ˇ and Pavol Hauptvogel Volume 2011, Article ID 893546, 9 pages The Genomes of All Angiosperms: A Call for a Coordinated Global Census, David W. Galbraith, Jeffrey L. Bennetzen, Elizabeth A. Kellogg, J. Chris Pires, and Pamela S. Soltis Volume 2011, Article ID 646198, 10 pages Does Large Genome Size Limit Speciation in Endemic Island Floras?, Maxim V. Kapralov and Dmitry A. Filatov Volume 2011, Article ID 458684, 6 pages Genome Diversity in Maize, Victor Llaca, Matthew A. Campbell, and Stephane´ Deschamps Volume 2011, Article ID 104172, 10 pages Evolution of Genome Size in Duckweeds (Lemnaceae), Wenqin Wang, Randall A. Kerstetter, and Todd P. Michael Volume 2011, Article ID 570319, 9 pages Hindawi Publishing Corporation Journal of Botany Volume 2012, Article ID 817920, 7 pages doi:10.1155/2012/817920 Review Article Polyploidy and Speciation in Pteris (Pteridaceae) Yi-Shan Chao,1, 2 Ho-Yih Liu,1 Yu-Chung Chiang,1 and Wen-Liang Chiou2 1 Department of Biological Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan 2 Division of Botanical Garden, Taiwan Forestry Research Institute, Taipei 100, Taiwan Correspondence should be addressed to Yu-Chung Chiang, [email protected] and Wen-Liang Chiou, [email protected] Received 6 June 2011; Revised 19 December 2011; Accepted 6 January 2012 Academic Editor: Kang Chong Copyright © 2012 Yi-Shan Chao et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The highest frequency of polyploidy among plants is considered to occur in the Pteridophytes. In this study, we focused on polyploidy displayed by a specific fern taxon, the genus Pteris L. (Pteridaceae), comprising over 250 species. Cytological data from 106 Pteris species were reviewed. The base number of chromosomes in Pteris is 29. Polyploids are frequently found in Pteris, including triploids, tetraploids, pentaploids, hexaploids, and octoploids. In addition, an aneuploid species, P. deltodon Bak., has been recorded. Furthermore, the relationship between polyploidy and reproductive biology is reviewed. Among these 106 Pteris species, 60% exhibit polyploidy: 22% show intraspecific polyploidy and 38% result from polyploid speciation. Apogamous species are common in Pteris. Diploids are the most frequent among Pteris species, and they can be sexual or apogamous. Triploids are apogamous; tetraploids are sexual or apogamous. Most Pteris species have one to two ploidy levels. The diverse ploidy levels suggest that these species have a complex evolutionary history and their taxonomic problems require further clarification. 1. Introduction Pteris L. (Pteridaceae) is a cosmopolitan fern genus with over 250 species. Some Pteris species have several different Polyploidy provides a rapid route for species evolution and ploidy levels and are found in several geographical areas, such adaptation [1, 2]. Taxa arising from polyploidy are usually as P. cretica and P. vittata [11, 17, 18], which likely reflect characterized by divers gene expression [3]. This variation in the ecological differentiation within species. For example, ff gene expression also has e ects on ecological traits, which different niche preferences have been found in P. fauriei play an important role in speciation because a specialised [19]. In addition, polyploidy can also cause morphological niche is a key factor in the formation of new taxa [4–8]. novelty. Species complexes in Pteris have been frequently For example, ecological isolation can allow taxa with genetic reported [20, 21]. Those species complexes are usually variation to become segregated [9]. It is estimated that the composed of a group of taxa with similar morphologies highest frequency of polyploidy is exhibited in ferns. The and involved several polyploids. This paper depicts the frequency of polyploid speciation in ferns is 31%, which is cytotypes, breeding systems, character variations, and their much higher than 15% in angiosperms [10]. relationships in the genus Pteris. In ferns, a special form of asexual reproduction known as apogamy is common [11, 12]. Apogamy provides a bypass to crossover mispairing of chromosomes and stabilises the 2. Cytotypes of Pteris Species reproduction of polyploids [13–15]. During metaphase I of meiosis, these polyploids present multivalents, which The first studies of polyploidy in Pteris focused mainly on may have difficulty separating equally. Apogamous species ploidy differences and apogamy of P. cretica [22]. Walker are clonal hybrid genotypes, and, as a result, apogamy [12] provided the first comprehensive cytological study of creates reproductive barriers that prevent gene flow among the genus Pteris, which included 82 species, and reported closely related taxa, thereby facilitating sympatric speciation that the base number of chromosomes in Pteris is 29. In [16]. Each taxon maintains an independent genetic lineage, the current study, data from previous cytological studies leading eventually to a new species. of 106 Pteris species were integrated (Table 1). The data 2 Journal of Botany Table 1: Ploidy levels and breeding systems of 106 Pteris species. Sexual Apogamous Apogamous Sexual Apogamous ?2X ?4X Others Reference 2X 2X 3X 4X 4X P. acanthoneura Alston V [12] P. actiniopteroides Christ V [12] P. albersii Hieron. V V [12, 25] P. altissima Poir. V [12] P. arguta Aiton V [12] P. arg yraea Moore V V V [12, 24] P. aspericaulis Wall. V V [12, 26] P. atrovirens Willd. V [12] P. bella Tagawa V V V [27, 28] P. berteroana Ag. V [27] P. biaurita L. V V 6X [12, 29, 30] P. bifurcata Ching V [24] P. boninensis H. Ohba V [31] P. buchananii Bak. ap. Sim. V [12] P. burtonii Bak. V [12] P. cadieri Christ V V [32] P. camerooniana Kuhn V [12, 33] P. catoptera Kze. V [12] P. comans Forst. V [12, 24] P. confusa T. G. Walker V [12] P. cretica L. VV V VV [11, 34–39] P. dactylina Hook. V [12, 24, 38] P. ×delchampsii W.H.Wagner & V[40] Nauman P. deltodon Bak. V V Sexual n = 53, 55 [18, 23, 27] P. dentata Forsskal V [12] P. dispar Kze. V V V [12, 23, 24, 27] [12, 18, 23, 27, P. ensiformis Burm. V V V V 5X; 2n = 84, 168 41–44] P. esquirolii Christ V [24] P. excelsa Gaud. V V V V [18, 24, 45] [12, 27, 39, 44, P. fauriei Hieron. V V 46] P. formosana Bak. V [33] P. friesii Hieron. V [12] P. gallinopes Ching V [18] P. gongalensis T. G. Walker V [12] P. grandifolia L. V [12] P. grevilleana Wall. ex Agardh V V [12, 32, 47] P. haenkeana Presl V [12] P. hamulosa Christ V [12] P. henryi Christ V [39] P. hexagona (L.) Proctor V [12] P. holttumii C. Chr. V [12] P. hookeriana Ag. V [33] P. incompleta Cav. V [24] P. insignis Mett. ex Kuhn V [12] P. intricata Wright V[22] P. kidoi Kurata V [23, 48, 49] Journal of Botany 3 Table 1: Continued. Sexual Apogamous Apogamous Sexual Apogamous ?2X ?4X Others Reference 2X 2X 3X 4X 4X P. kingiana Endl. V [24] P. kiuschiuensis Hieron. V V [21, 50, 51] P. laurisilvicola Kurata V V [24] P. ligulata Gaud. V [12] P. linearis Poir. V V V [27, 28] P. lineata Poir. et Lam. V [39] P. longifolia L. V V [12, 24] P. longipes D. Don V [24] P. longipinnula Wall. V [24] P. macilenta A. Rich. V [12] P. marginata Bory V [12] P. multiaurita Ag. V [12] [12, 18, 23, 27, P. multifida Poir. V V 45, 52] P. nakasimae Tagawa V [12, 23] P. ×namegatae Kurata V [23] P. natiensis Tagawa V [51] P. nemoralis Willd. V [24] P. nipponica Shieh V [33, 53] P. orientalis Alderw. [54] P. oshimensis Hieron. V V [18, 50, 55] P. otaria Bedd. V [12, 29] P. pacifica Hieron. V V [12, 24] P. palustris Poir. V [24] P. papuana Ces. V [12] P. pellucida Presl V V V [12, 31] P.