1
|
Remizowa MV, Sokoloff DD. Patterns of Carpel Structure, Development, and Evolution in Monocots. PLANTS (BASEL, SWITZERLAND) 2023; 12:4138. [PMID: 38140465 PMCID: PMC10748379 DOI: 10.3390/plants12244138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 11/20/2023] [Accepted: 11/28/2023] [Indexed: 12/24/2023]
Abstract
The phenomenon of heterochrony, or shifts in the relative timing of ontogenetic events, is important for understanding many aspects of plant evolution, including applied issues such as crop yield. In this paper, we review heterochronic shifts in the evolution of an important floral organ, the carpel. The carpels, being ovule-bearing organs, facilitate fertilisation, seed, and fruit formation. It is the carpel that provides the key character of flowering plants, angiospermy. In many angiosperms, a carpel has two zones: proximal ascidiate and distal plicate. When carpels are free (apocarpous gynoecium), the plicate zone has a ventral slit where carpel margins meet and fuse during ontogeny; the ascidiate zone is sac-like from inception and has no ventral slit. When carpels are united in a syncarpous gynoecium, a synascidiate zone has as many locules as carpels, whereas a symplicate zone is unilocular, at least early in ontogeny. In ontogeny, either the (syn)ascidiate or (sym)plicate zone is first to initiate. The two developmental patterns are called early and late peltation, respectively. In extreme cases, either the (sym)plicate or (syn)ascidiate zone is completely lacking. Here, we discuss the diversity of carpel structure and development in a well-defined clade of angiosperms, the monocotyledons. We conclude that the common ancestor of monocots had carpels with both zones and late peltation. This result was found irrespective of the use of the plastid or nuclear phylogeny. Early peltation generally correlates with ovules belonging to the (syn)ascidiate zone, whereas late peltation is found mostly in monocots with a fertile (sym)plicate zone.
Collapse
|
2
|
Artuso S, Gamisch A, Staedler YM, Schönenberger J, Comes HP. Evidence for an evo-devo-derived hypothesis on three-dimensional flower shape modularity in a tropical orchid clade. Evolution 2022; 76:2587-2604. [PMID: 36128635 PMCID: PMC9828045 DOI: 10.1111/evo.14621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 08/21/2022] [Accepted: 08/26/2022] [Indexed: 01/22/2023]
Abstract
Covarying suites of phenotypic traits, or modules, are increasingly recognized to promote morphological evolution. However, information on how modularity influences flower diversity is rare and lacking for Orchidaceae. Here, we combine high-resolution X-ray computed tomography scanning with three-dimensional geometric morphometrics and phylogenetic comparative methods to test various hypotheses about three-dimensional patterns of flower evolutionary modularity in Malagasy Bulbophyllum orchids and examine rates and modes of module evolution. Based on the four evolutionary modules identified (i.e., sepals, lateral petals, labellum + column-foot, and column-part), our data support the hypothesis that both genetic-developmental and functional adaptive factors shaped evolutionary flower trait covariation in these tropical orchids. In line with "evo-devo" studies, we also find that the labellum evolved independently from the rest of the petal whorl. Finally, we show that modules evolved with different rates, and either in a neutral fashion (only column-part) or under selective constraints, as likely imposed by pollinators. Overall, this study supports current views that modular units can enhance the range and rate of morphological evolution.
Collapse
Affiliation(s)
- Silvia Artuso
- Department of Environment and BiodiversityUniversity of SalzburgSalzburg5020Austria
| | - Alexander Gamisch
- Department of Environment and BiodiversityUniversity of SalzburgSalzburg5020Austria
| | - Yannick M. Staedler
- Department of Botany and Biodiversity ResearchUniversity of ViennaVienna1030Austria
| | - Jürg Schönenberger
- Department of Botany and Biodiversity ResearchUniversity of ViennaVienna1030Austria
| | - Hans Peter Comes
- Department of Environment and BiodiversityUniversity of SalzburgSalzburg5020Austria
| |
Collapse
|
3
|
Ahmad S, Chen J, Chen G, Huang J, Hao Y, Shi X, Liu Y, Tu S, Zhou Y, Zhao K, Lan S, Liu Z, Peng D. Transcriptional Proposition for Uniquely Developed Protocorm Flowering in Three Orchid Species: Resources for Innovative Breeding. FRONTIERS IN PLANT SCIENCE 2022; 13:942591. [PMID: 35837448 PMCID: PMC9275812 DOI: 10.3389/fpls.2022.942591] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 06/01/2022] [Indexed: 05/04/2023]
Abstract
During orchid seed culture, seeds germinate as protocorms, and protocorms normally develop into plant with leaves and roots. Orchids require many years of vegetative development for flowering. However, under a certain combination of growth cultures, we observed that protocorms can directly flower without leaves and roots. Therefore, we performed comparative transcriptome analysis to identify the different transcriptional regulators of two types of protocorms of Cymbidium ensifolium, Cymbidium sinense, and Cymbidium goeringii. Zinc finger, MYB, AP2, and bHLH were the most abundant transcription factor (TF) families in the transcriptome. Weighted gene coexpression network analysis (WGCNA) was performed to identify hub genes related to leaf and flower development. The key hubs included SPL6, SVP, SEP2, KNOX1, AP2, OFP1, COL12, MYB13, MYB36, MYB59, bHLH086, and ARF7. The hub genes were further validated through statistical tools to propose the roles of key TFs. Therefore, this study initiates to answer that why there is no leaf initiation and root development and how can protocorm bypass the vegetative phase to flower? The outcomes can direct future research on short-span flowering in orchids through protocorms.
Collapse
Affiliation(s)
- Sagheer Ahmad
- Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Jinliao Chen
- Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Guizhen Chen
- Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Jie Huang
- Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Yang Hao
- Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Xiaoling Shi
- Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Yuying Liu
- Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Song Tu
- Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Yuzhen Zhou
- Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Kai Zhao
- Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, China
- College of Life Sciences, Fujian Normal University, Fuzhou, China
| | - Siren Lan
- Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Zhongjian Liu
- Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, China
- *Correspondence: Zhongjian Liu,
| | - Donghui Peng
- Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, China
- Donghui Peng,
| |
Collapse
|
4
|
Rudall PJ. Colourful cones: how did flower colour first evolve? JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:759-767. [PMID: 31714579 DOI: 10.1093/jxb/erz479] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 10/14/2019] [Indexed: 05/09/2023]
Abstract
Angiosperms that are biotically pollinated typically produce flowers with bright and contrasting colours that help to attract pollinators and hence contribute to the reproductive success of the species. This colourful array contrasts with the much less multicoloured reproductive structures of the four living gymnosperm lineages, which are mostly wind pollinated, though cycads and Gnetales are predominantly pollinated by insects that feed on surface fluids from the pollination drops. This review examines the possible evolutionary pathways and cryptic clues for flower colour in both living and fossil seed plants. It investigates how the ancestral flowering plants could have overcome the inevitable trade-off that exists between attracting pollinators and minimizing herbivory, and explores the possible evolutionary and biological inferences from the colours that occur in some living gymnosperms. The red colours present in the seed-cone bracts of some living conifers result from accumulation of anthocyanin pigments; their likely primary function is to help protect the growing plant tissues under particular environmental conditions. Thus, the visual cue provided by colour in flower petals could have first evolved as a secondary effect, probably post-dating the evolution of bee colour vision but occurring before the subsequent functional accumulation of a range of different flower pigments.
Collapse
|
5
|
Pérez-Escobar OA, Chomicki G, Condamine FL, de Vos JM, Martins AC, Smidt EC, Klitgård B, Gerlach G, Heinrichs J. Multiple Geographical Origins of Environmental Sex Determination enhanced the diversification of Darwin's Favourite Orchids. Sci Rep 2017; 7:12878. [PMID: 29018291 PMCID: PMC5635016 DOI: 10.1038/s41598-017-12300-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 09/06/2017] [Indexed: 11/17/2022] Open
Abstract
Environmental sex determination (ESD) - a change in sexual function during an individual life span driven by environmental cues - is an exceedingly rare sexual system among angiosperms. Because ESD can directly affect reproduction success, it could influence diversification rate as compared with lineages that have alternative reproductive systems. Here we test this hypothesis using a solid phylogenetic framework of Neotropical Catasetinae, the angiosperm lineage richest in taxa with ESD. We assess whether gains of ESD are associated with higher diversification rates compared to lineages with alternative systems while considering additional traits known to positively affect diversification rates in orchids. We found that ESD has evolved asynchronously three times during the last ~5 Myr. Lineages with ESD have consistently higher diversification rates than related lineages with other sexual systems. Habitat fragmentation due to mega-wetlands extinction, and climate instability are suggested as the driving forces for ESD evolution.
Collapse
Affiliation(s)
| | - Guillaume Chomicki
- Department of Plant Sciences, University of Oxford, South Park Road, OX1 3RB, Oxford, United Kingdom
| | - Fabien L Condamine
- CNRS, UMR 5554 Institut de Sciences de l'Evolution (Université de Montpellier), Place Eugène Bataillon, 34095, Montpellier, France
| | - Jurriaan M de Vos
- Department of Comparative Plant and Fungal Biology, Royal Botanic Gardens Kew, Richmond, TW9 3AB, United Kingdom.
- Department of Environmental Sciences - Botany, University of Basel, Totengässlein 3, 4051, Basel, Switzerland.
| | - Aline C Martins
- Department of Botany, Federal University of Paraná, PB 19031, Curitiba, PR, 81531-980, Brazil
| | - Eric C Smidt
- Department of Botany, Federal University of Paraná, PB 19031, Curitiba, PR, 81531-980, Brazil
| | - Bente Klitgård
- Department of Identification and Naming, Royal Botanic Gardens Kew, Richmond, TW9 3AB, UK
| | - Günter Gerlach
- Botanischer Garten München, Menzinger Straße 67, D-80638, München, Germany
| | - Jochen Heinrichs
- Department für Biologie I, Systematische Botanik und Mykologie, Ludwig-Maximilians-Universität, Menzinger Straße 67, D-80638, München, Germany
| |
Collapse
|
6
|
Dirks-Mulder A, Butôt R, van Schaik P, Wijnands JWPM, van den Berg R, Krol L, Doebar S, van Kooperen K, de Boer H, Kramer EM, Smets EF, Vos RA, Vrijdaghs A, Gravendeel B. Exploring the evolutionary origin of floral organs of Erycina pusilla, an emerging orchid model system. BMC Evol Biol 2017; 17:89. [PMID: 28335712 PMCID: PMC5364718 DOI: 10.1186/s12862-017-0938-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 03/15/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Thousands of flowering plant species attract pollinators without offering rewards, but the evolution of this deceit is poorly understood. Rewardless flowers of the orchid Erycina pusilla have an enlarged median sepal and incised median petal ('lip') to attract oil-collecting bees. These bees also forage on similar looking but rewarding Malpighiaceae flowers that have five unequally sized petals and gland-carrying sepals. The lip of E. pusilla has a 'callus' that, together with winged 'stelidia', mimics these glands. Different hypotheses exist about the evolutionary origin of the median sepal, callus and stelidia of orchid flowers. RESULTS The evolutionary origin of these organs was investigated using a combination of morphological, molecular and phylogenetic techniques to a developmental series of floral buds of E. pusilla. The vascular bundle of the median sepal indicates it is a first whorl organ but its convex epidermal cells reflect convergence of petaloid features. Expression of AGL6 EpMADS4 and APETALA3 EpMADS14 is low in the median sepal, possibly correlating with its petaloid appearance. A vascular bundle indicating second whorl derivation leads to the lip. AGL6 EpMADS5 and APETALA3 EpMADS13 are most highly expressed in lip and callus, consistent with current models for lip identity. Six vascular bundles, indicating a stamen-derived origin, lead to the callus, stelidia and stamen. AGAMOUS is not expressed in the callus, consistent with its sterilization. Out of three copies of AGAMOUS and four copies of SEPALLATA, EpMADS22 and EpMADS6 are most highly expressed in the stamen. Another copy of AGAMOUS, EpMADS20, and the single copy of SEEDSTICK, EpMADS23, are most highly expressed in the stelidia, suggesting EpMADS22 may be required for fertile stamens. CONCLUSIONS The median sepal, callus and stelidia of E. pusilla appear to be derived from a sepal, a stamen that gained petal identity, and stamens, respectively. Duplications, diversifying selection and changes in spatial expression of different MADS-box genes shaped these organs, enabling the rewardless flowers of E. pusilla to mimic an unrelated rewarding flower for pollinator attraction. These genetic changes are not incorporated in current models and urge for a rethinking of the evolution of deceptive flowers.
Collapse
Affiliation(s)
- Anita Dirks-Mulder
- Endless Forms group, Naturalis Biodiversity Center, Vondellaan 55, 2332 AA, Leiden, The Netherlands.,Faculty of Science and Technology, University of Applied Sciences Leiden, Zernikedreef 11, 2333 CK, Leiden, The Netherlands
| | - Roland Butôt
- Endless Forms group, Naturalis Biodiversity Center, Vondellaan 55, 2332 AA, Leiden, The Netherlands
| | - Peter van Schaik
- Faculty of Science and Technology, University of Applied Sciences Leiden, Zernikedreef 11, 2333 CK, Leiden, The Netherlands
| | - Jan Willem P M Wijnands
- Faculty of Science and Technology, University of Applied Sciences Leiden, Zernikedreef 11, 2333 CK, Leiden, The Netherlands
| | - Roel van den Berg
- Faculty of Science and Technology, University of Applied Sciences Leiden, Zernikedreef 11, 2333 CK, Leiden, The Netherlands
| | - Louie Krol
- Faculty of Science and Technology, University of Applied Sciences Leiden, Zernikedreef 11, 2333 CK, Leiden, The Netherlands
| | - Sadhana Doebar
- Faculty of Science and Technology, University of Applied Sciences Leiden, Zernikedreef 11, 2333 CK, Leiden, The Netherlands
| | - Kelly van Kooperen
- Faculty of Science and Technology, University of Applied Sciences Leiden, Zernikedreef 11, 2333 CK, Leiden, The Netherlands
| | - Hugo de Boer
- Endless Forms group, Naturalis Biodiversity Center, Vondellaan 55, 2332 AA, Leiden, The Netherlands.,The Natural History Museum, University of Oslo, P.O. Box 1172, Blindern, 0318, Oslo, Norway.,Department of Organismal Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, Uppsala, SE-75236, Sweden
| | - Elena M Kramer
- Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Ave, Cambridge, MA, 02138, USA
| | - Erik F Smets
- Endless Forms group, Naturalis Biodiversity Center, Vondellaan 55, 2332 AA, Leiden, The Netherlands.,Ecology, Evolution and Biodiversity Conservation cluster, KU Leuven, Kasteelpark Arenberg 31, 3001, Leuven, Belgium
| | - Rutger A Vos
- Endless Forms group, Naturalis Biodiversity Center, Vondellaan 55, 2332 AA, Leiden, The Netherlands.,Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
| | - Alexander Vrijdaghs
- Ecology, Evolution and Biodiversity Conservation cluster, KU Leuven, Kasteelpark Arenberg 31, 3001, Leuven, Belgium
| | - Barbara Gravendeel
- Endless Forms group, Naturalis Biodiversity Center, Vondellaan 55, 2332 AA, Leiden, The Netherlands. .,Faculty of Science and Technology, University of Applied Sciences Leiden, Zernikedreef 11, 2333 CK, Leiden, The Netherlands. .,Institute Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE, Leiden, The Netherlands.
| |
Collapse
|
7
|
Bateman RM, Molnár V A, Sramkó G. In situ morphometric survey elucidates the evolutionary systematics of the Eurasian Himantoglossum clade (Orchidaceae: Orchidinae). PeerJ 2017; 5:e2893. [PMID: 28168103 PMCID: PMC5289109 DOI: 10.7717/peerj.2893] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 12/09/2016] [Indexed: 12/17/2022] Open
Abstract
Background and Aims The charismatic Himantoglossum s.l. clade of Eurasian orchids contains an unusually large proportion of taxa that are of controversial circumscriptions and considerable conservation concern. Whereas our previously published study addressed the molecular phylogenetics and phylogeography of every named taxon within the clade, here we use detailed morphometric data obtained from the same populations to compare genotypes with associated phenotypes, in order to better explore taxonomic circumscription and character evolution within the clade. Methods Between one and 12 plants found in 25 populations that encompassed the entire distribution of the Himantoglossum s.l. clade were measured in situ for 51 morphological characters. Results for 45 of those characters were subjected to detailed multivariate and univariate analyses. Key Results Multivariate analyses readily separate subgenus Barlia and subgenus Comperia from subgenus Himantoglossum, and also the early-divergent H. formosum from the less divergent remainder of subgenus Himantoglossum. The sequence of divergence of these four lineages is confidently resolved. Our experimental approach to morphometric character analysis demonstrates clearly that phenotypic evolution within Himantoglossum is unusually multi-dimensional. Conclusions Degrees of divergence between taxa shown by morphological analyses approximate those previously shown using molecular analyses. Himantoglossum s.l. is readily divisible into three subgenera. The three sections of subgenus Himantoglossum—hircinum, caprinum and formosum—are arrayed from west to east with only limited geographical overlap. At this taxonomic level, their juxtaposition combines with conflict between contrasting datasets to complicate attempts to distinguish between clinal variation and the discontinuities that by definition separate bona fide species. All taxa achieve allogamy via food deceit and have only weak pollinator specificity. Artificial crossing demonstrates that intrinsic sterility barriers are weak. Although we have found evidence of gene flow among and within the three sections of subgenus Himantoglossum, reports of natural hybrids are surprisingly rare, probably because putative parents are sufficiently similar to questionably warrant the status of species. Phenological separation and increased xeromorphy characterise the origin of subgenus Barlia. Several individual morphological characters show evidence of parallel acquisition, and loss of features is especially frequent in floral markings among members of section caprinum. Detailed patterns of gain and loss demonstrate that several different categories of flower markings are inherited independently. Along with the dimensions of labellar lobes, these pigmentation characters have been over-emphasised in previous taxonomic treatments. Increased plant vigour was a crucial element of the origin of the genus, but vegetative characters underwent remarkably little subsequent evolution. Attempts to reconstruct hypothetical ancestors at internal nodes of the phylogeny are weakened by (a) uncertain placement of Steveniella as sister to Himantoglossum s.l. and (b) uncertain relationships among subtly different putative species within section caprinum. Nonetheless, heterochronic/allometric trends, ultimately limited by functional constraints, clearly dictate transitions between contrasting flower sizes and complex labellum shapes.
Collapse
Affiliation(s)
| | - Attila Molnár V
- Department of Botany, University of Debrecen , Debrecen , Hungary
| | - Gábor Sramkó
- Department of Botany, University of Debrecen, Debrecen, Hungary; MTA-DE "Lendület" Evolutionary Phylogenomics Research Group, Debrecen, Hungary
| |
Collapse
|
8
|
Madrigal Y, Alzate JF, Pabón-Mora N. Evolution and Expression Patterns of TCP Genes in Asparagales. FRONTIERS IN PLANT SCIENCE 2017; 8:9. [PMID: 28144250 PMCID: PMC5239819 DOI: 10.3389/fpls.2017.00009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 01/03/2017] [Indexed: 05/09/2023]
Abstract
CYCLOIDEA-like genes are involved in the symmetry gene network, limiting cell proliferation in the dorsal regions of bilateral flowers in core eudicots. CYC-like and closely related TCP genes (acronym for TEOSINTE BRANCHED1, CYCLOIDEA, and PROLIFERATION CELL FACTOR) have been poorly studied in Asparagales, the largest order of monocots that includes both bilateral flowers in Orchidaceae (ca. 25.000 spp) and radially symmetrical flowers in Hypoxidaceae (ca. 200 spp). With the aim of assessing TCP gene evolution in the Asparagales, we isolated TCP-like genes from publicly available databases and our own transcriptomes of Cattleya trianae (Orchidaceae) and Hypoxis decumbens (Hypoxidaceae). Our matrix contains 452 sequences representing the three major clades of TCP genes. Besides the previously identified CYC specific core eudicot duplications, our ML phylogenetic analyses recovered an early CIN-like duplication predating all angiosperms, two CIN-like Asparagales-specific duplications and a duplication prior to the diversification of Orchidoideae and Epidendroideae. In addition, we provide evidence of at least three duplications of PCF-like genes in Asparagales. While CIN-like and PCF-like genes have multiplied in Asparagales, likely enhancing the genetic network for cell proliferation, CYC-like genes remain as single, shorter copies with low expression. Homogeneous expression of CYC-like genes in the labellum as well as the lateral petals suggests little contribution to the bilateral perianth in C. trianae. CIN-like and PCF-like gene expression suggests conserved roles in cell proliferation in leaves, sepals and petals, carpels, ovules and fruits in Asparagales by comparison with previously reported functions in core eudicots and monocots. This is the first large scale analysis of TCP-like genes in Asparagales that will serve as a platform for in-depth functional studies in emerging model monocots.
Collapse
Affiliation(s)
- Yesenia Madrigal
- Facultad de Ciencias Exactas y Naturales, Instituto de Biología, Universidad de AntioquiaMedellín, Colombia
| | - Juan F. Alzate
- Centro Nacional de Secuenciación Genómica, Sede de Investigación Universitaria, Facultad de Medicina, Universidad de AntioquiaMedellín, Colombia
| | - Natalia Pabón-Mora
- Facultad de Ciencias Exactas y Naturales, Instituto de Biología, Universidad de AntioquiaMedellín, Colombia
| |
Collapse
|
9
|
Endress PK. Development and evolution of extreme synorganization in angiosperm flowers and diversity: a comparison of Apocynaceae and Orchidaceae. ANNALS OF BOTANY 2016; 117:749-67. [PMID: 26292994 PMCID: PMC4845794 DOI: 10.1093/aob/mcv119] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 06/22/2015] [Indexed: 05/04/2023]
Abstract
BACKGROUND AND AIMS Apocynaceae and Orchidaceae are two angiosperm families with extreme flower synorganization. They are unrelated, the former in eudicots, the latter in monocots, but they converge in the formation of pollinia and pollinaria, which do not occur in any other angiosperm family, and for which extreme synorganization of floral organs is a precondition. In each family extensive studies on flower development and evolution have been performed; however, newer comparative studies focusing on flower synorganization and involving both families together are lacking. SCOPE For this study an extensive search through the morphological literature has been conducted. Based on this and my own studies on flowers in various Apocynaceae and Orchidaceae and complex flowers in other angiosperms with scanning electron microscopy and with microtome section series, a review on convergent floral traits in flower development and architecture in the two families is presented. KEY FINDINGS There is a tendency of protracted development of synorganized parts in Apocynaceae and Orchidaceae (development of synorganization of two or more organs begins earlier the more accentuated it is at anthesis). Synorganization (or complexity) also paves the way for novel structures. One of the most conspicuous such novel structures in Apocynaceae is the corona, which is not the product of synorganization of existing organs; however, it is probably enhanced by synorganization of other, existing, floral parts. In contrast to synorganized parts, the corona appears developmentally late. CONCLUSIONS Synorganization of floral organs may lead to a large number of convergences in clades that are only very distantly related. The convergences that have been highlighted in this comparative study should be developmentally investigated directly in parallel in future studies.
Collapse
Affiliation(s)
- Peter K Endress
- Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, 8008 Zurich, Switzerland
| |
Collapse
|
10
|
Gamisch A, Fischer GA, Comes HP. Recurrent polymorphic mating type variation in Madagascan Bulbophyllum species (Orchidaceae) exemplifies a high incidence of auto-pollination in tropical orchids. BOTANICAL JOURNAL OF THE LINNEAN SOCIETY. LINNEAN SOCIETY OF LONDON 2014; 175:242-258. [PMID: 25821245 PMCID: PMC4373168 DOI: 10.1111/boj.12168] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 12/11/2013] [Accepted: 03/24/2014] [Indexed: 05/13/2023]
Abstract
The transition from outcrossing to self-fertilization is one of the most common evolutionary changes in angiosperms. The orchid family exemplifies this evolutionary trend but, because of a general lack of large-scale surveys on auto-pollination in orchid taxa, the incidence and modes of auto-pollination among (sub)tropical orchids remain poorly known. In the present study, we assessed the frequency and mode of auto-pollination within and among species of a largely monophyletic group of Madagascan Bulbophyllum. The capacity for autonomous fruit set was investigated by bagging experiments in the greenhouse and the field, complemented with detailed floral micromorphological studies of the gynostemium. Our survey comprises 393 accessions, representing at least 78 species, and thus approximately 37% of the species diversity of the genus in the Madagascan region. Our studies revealed that mating type is directly related to gynostemium structure, most often involving the presence or absence of a physical barrier termed 'rostellum'. As a novel and unexpected finding, we identified eight species of a single lineage of Madagascan Bulbophyllum (termed 'clade C'), in which auto-pollinating morphs (selfers), either lacking a rostellum or (rarely) possessing a stigmatic rostellum, co-exist with their pollinator-dependent conspecifics (outcrossers). We hypothesize that auto-pollination via rostellum abortion has a simple genetic basis, and probably evolved rapidly and recurrently by subtle changes in the timing of rostellum development (heterochrony). Thus, species of clade C may have an intrinsic genetic and developmental lability toward auto-pollination, allowing rapid evolutionary response under environmental, perhaps human-disturbed conditions favouring reproductive assurance. Overall, these findings should stimulate further research on the incidence, evolution, and maintenance of mating type variation in tropical orchids, as well as how they adapt(ed) to changing environmental conditions.
Collapse
Affiliation(s)
- Alexander Gamisch
- Department of Organismic Biology, University of SalzburgA-5020, Salzburg, Austria
- *Corresponding author. E-mail:
| | - Gunter A Fischer
- Kadoorie Farm and Botanic Garden CorporationLam Kam Road, Tai Po, N.T., Hong Kong SAR
| | - Hans Peter Comes
- Department of Organismic Biology, University of SalzburgA-5020, Salzburg, Austria
| |
Collapse
|
11
|
Bateman RM, Rudall PJ, Moura M. Systematic revision of Platanthera in the Azorean archipelago: not one but three species, including arguably Europe's rarest orchid. PeerJ 2013; 1:e218. [PMID: 24392284 PMCID: PMC3869205 DOI: 10.7717/peerj.218] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 11/08/2013] [Indexed: 11/20/2022] Open
Abstract
Background and Aims. The Macaronesian islands represent an excellent crucible for exploring speciation. This dominantly phenotypic study complements a separate genotypic study, together designed to identify and circumscribe Platanthera species (butterfly-orchids) on the Azores, and to determine their geographic origin(s) and underlying speciation mechanism(s). Methods. 216 individuals of Platanthera from 30 Azorean localities spanning all nine Azorean islands were measured for 38 morphological characters, supported by light and scanning electron microscopy of selected flowers. They are compared through detailed multivariate and univariate analyses with four widespread continental European relatives in the P. bifolia-chlorantha aggregate, represented by 154 plants from 25 populations, and with the highly misleading original taxonomic descriptions. Physiographic and ecological data were also recorded for each study population. Key Results. Despite limited genetic divergence, detailed phenotypic survey reveals not one or two but three discrete endemic species of Platanthera that are readily distinguished using several characters, most floral: P. pollostantha (newly named, formerly P. micrantha) occupies the widest range of habitats and altitudes and occurs on all nine islands; P. micrantha (formerly P. azorica) occurs on eight islands but is restricted to small, scattered populations in laurisilva scrub; the true P. azorica appears confined to a single volcanigenic ridge on the central island of São Jorge. Conclusions. Although hybridity seems low, the excess of phenotypic over genotypic divergence suggests comparatively recent speciation. The most probable of several credible scenarios is that Azorean Platantheras represent a single migration to the archipelago of airborne seed from ancestral population(s) located in southwest Europe rather than North America, originating from within the P. bifolia-chlorantha aggregate. We hypothesise that an initial anagenetic speciation event, aided by the founder effect, was followed by the independent origins of at least one of the two rarer endemic species from within the first-formed endemic species, via a cladogenetic speciation process that involved radical shifts in floral development, considerable phenotypic convergence, and increased mycorrhizal specificity. The recent amalgamation by IUCN of Azorean Platantheras into a single putative species on their Red List urgently requires overruling, as (a) P. azorica is arguably Europe's rarest bona fide orchid species and (b) the almost equally rare P. micrantha is one of the best indicators of semi-natural laurisilva habitats remaining on the Azores. Both species are threatened by habitat destruction and invasive alien plants. These orchids constitute a model system that illustrates the general advantages of circumscribing species by prioritising field-based over herbarium-based morphological approaches.
Collapse
Affiliation(s)
| | | | - Mónica Moura
- CIBIO Research Center in Biodiversity and Genetic Resources – Azores, Department of Biology, University of the Azores, Ponta Delgada, Portugal
| |
Collapse
|
12
|
Gamisch A, Staedler YM, Schönenberger J, Fischer GA, Comes HP. Histological and micro-CT evidence of stigmatic rostellum receptivity promoting auto-pollination in the madagascan orchid Bulbophyllum bicoloratum. PLoS One 2013; 8:e72688. [PMID: 23967332 PMCID: PMC3742538 DOI: 10.1371/journal.pone.0072688] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Accepted: 07/11/2013] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND The rostellum, a projecting part of the gynostemium in orchid flowers, separates the anther(s) from the stigma and thus commonly prevents auto-pollination. Nonetheless, as a modified (usually distal) portion of the median stigma lobe, the rostellum has been frequently invoked of having re-gained a stigmatic function in rare cases of orchid auto-pollination. Here it is shown that a newly discovered selfing variant of Madagascan Bulbophyllumbicoloratum has evolved a modified rostellum allowing the penetration of pollen tubes from in situ pollinia. METHODS Gynostemium micro-morphology and anatomy of selfing and outcrossing variants of B. bicoloratum was studied by using light and scanning electron microscopy and histological sections. Pollen tube growth in the selfing variant was further observed via X-ray computed microtomography (micro-CT), providing 3D reconstructions of floral tissues at a micron scale. FINDINGS Selfing variants possess a suberect ('displaced') rostellum rather than the conventional, erect type. Very early in anthesis, the pollinia of selfers are released from the anther and slide down onto the suberect rostellum, where pollen tube growth preferentially occurs through the non-vascularized, i.e. rear (adaxial) and (semi-) lateral parts. This penetrated tissue is comprised of a thin layer of elongate and loosely arranged cells, embedded in stigmatic exudates, as also observed in the stigmatic cavity of both selfing and outcrossing variants. CONCLUSIONS Our results provide the first solid evidence of a stigmatic function for the rostellum in orchid flowers, thereby demonstrating for the first time the feasibility of the micro-CT technique for accurately visualizing pollen tube growth in flowering plants. Rostellum receptivity in B. bicoloratum probably uniquely evolved as an adaptation for reproductive assurance from an outcrossing ancestor possessing an erect (non-receptive) rostellum. These findings open up new avenues in the investigation of an organ that apparently re-gained its 'primordial function' of being penetrated by pollen tubes.
Collapse
Affiliation(s)
- Alexander Gamisch
- Department of Organismic Biology, University of Salzburg, Salzburg, Austria.
| | | | | | | | | |
Collapse
|