The Phoenix of the cerrado: anatomical explanation to the rapid response of Bulbostylis paradoxa to fire
Aline Redondo Martins1, Patrícia Fernanda Rosalem1, Liliane Santos de Camargos1, Vagner Zanzarini2 & Alessandra Fidelis2
1Universidade Estadual Paulista (UNESP), Faculdade de Engenharia, Lab of Morphology and Plant Anatomy Studies, Departamento de Biologia e Zootecnia Rua Monção, 226, 15385-000, Ilha Solteira, Brazil; 2Universidade Estadual Paulista (UNESP), Instituto de Biociências, Lab of Vegetation Ecology, Departamento de Botânica, Av. 24-A 1515, 13506-900, Rio Claro, Brazil.
aline.botanica@gmail.com
Cerrado is the richest tropical savanna in plant species and fire is a natural disturbance, being an important factor in the evolution and ecology of plant species. Thus, the aim of this study was to evaluate the rapid flowering of Bulbostylis paradoxa species after fire, evaluating anatomical and physiological traits in order to understand flowers emerging from bud development, as well as to determine types of reserves and means of mobilization. We used fire experiments established in Central Brazil. We marked 10 individuals in each area (burned and control) and sampled three individuals for anatomical studies, and three for physiological ones. We repeated the sampling after 24 and 48 hs, and 7 and 45 days. We detected the first inflorescences 30 hours after fire. Some individuals in burned plots had up to 20 inflorescences, whilst the ones in control areas did not have any inflorescences. One week after fire, inflorescences were fully developed and 45 days after fire, we could already observe seeds being dispersed. The anatomical analysis of the stem structure showed the presence of sclereids at covering, including leaf bases. The cortical and vascular regions include the outstanding presence of parenchyma containing starch grains, probably related to the reserves for flowering.
Key words: anatomy, cerrado, Cyperaceae, fire, resprouting.
Funded by: FAPESP - 2015/06743-0
Leaf structure in Alismatales with an emphasis on 3D vasculature and squamulae intravaginales
Anna Platonova1, Dmitry Sokoloff1
1Faculty of Biology, Moscow State University. sokoloff-v@yandex.ru
The core group of the basal monocot order Alismatales includes rather diverse aquatic and semi-aquatic plants. Only a few morphological features are constantly present in all core Alismatales (though it is unclear if they can be regarded as synapomorphies). Among them is the occurrence of so-called squamulae intravaginales attached to stem just above the leaf axil. Novel data on the structure and development of squamulae intravaginales confirm the idea of their secretory function and allow evaluation of possible homologies of the squamulae. Half-submerged members of the group possess well developed aerenchyma in all organs, including leaves. Such thick leaves or their petioles often have a three-dimensional vasculature with slender peripheral bundles. As in angiosperm succulents, the three-dimensional venation in thick leaves of Alismatales serves to reduce transport distances between main bundles and chlorenchyma. In both cases, the patterns of orientation of peripheral bundles (with inverted adaxial or abaxial bundles) are unstable in large clades. We believe that these slender bundles cannot be used for the identification of unifacial leaves. Comparative analyses of thick photosynthetic leaves and stems could help in distinguishing functional and morphogenetic factors governing patterns of three-dimensional vasculature.
Key words: Alismatales, anatomy, leaf, morphology, vasculature.
Funded by: The work is supported by RFBR (grant 18-04-00797).
Functional anatomy, biomechanics and development of the branch-stem-attachment of Dracaena marginata revealed using high-resolution MRI
Linnea Hesse1, Tom Masselter2, Jochen Leupold3 & Thomas Speck2
1Plant Biomechanics Group and Botanic Garden, University of Freiburg, Germany; 2Plant
Biomechanics Group and Botanic Garden, University of Freiburg, Germany. & Freiburg Center for Interactive Materials and Bioinspired Technologies (FIT), Germany; 3Department of Radiology, Medical Physics, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg. linnea.hesse@biologie.uni-freiburg.de
Monocotyledons are unique concept generators for developing novel, bio-inspired fibre-composite structures. However, the utilization of nature’s inventiveness requires methods which enable 3D to 4D in vivo insights into living and intact plants. Common imaging techniques are highly invasive and impede repetitive imaging during ontogenetic development or prevent stress-strain analyses.
Novel methodological approaches using magnetic resonance imaging (MRI) are presented which reveal the load-adapted tissue arrangement and development of branch-stem-attachments of Dracaena marginata. MRI allows the comparison and contrast of various plant tissues without damaging the plant prior to or during image acquisition allowing for repetitive imaging of the same intact plant during long term experiments. In vivo insights into tissue deformations were gained by MRI analyses of a branch before, during and after mechanical loading. This enabled the identification of a load-adapted tissue arrangement within the branching of dragon trees. Additional ontogenetic experiments allowed us to follow the development of these tissues and to better understand the complexity of the branch ontogeny by discerning seven distinct ontogenetic stages.
In summary, MRI is a promising tool for visualizing and analyzing growth, biomechanics and functional anatomy of monocots in general.
Key words: biomechanics, biomimetics, Dracaena marginata, MRI, ontogeny.
Funded by: Linnea Hesse thanks the Joachim Herz Stiftung for support.
A comparative study of shoot apical meristem and bud preformation in monocot and dicot species
Renata Schnablova1, Lin Huang2, Jitka Klimesova3 & Tomas Herben4
1Institute of Botany of the Czech Academy of Sciences, Průhonice, Czech Republic, Institute of Experimental Botany of the Czech Academy of Sciences, Prague, Czech Republic; 2Department of Botany, Faculty of Science, Charles University, Prague, Czech Republic; 3Institute of Botany of the Czech Academy of Sciences, Trebon, Czech Republic; 4Institute of Botany of the Czech Academy of Sciences, Průhonice, Czech Republic, Department of Botany, Faculty of Science, Charles University, Prague, Czech Republic. renata.schnablova@ibot.cas.cz
Perennial plants resprout annually from renewal buds that hide shoot apical meristems (SAM). Even though the SAM plays a key role in plant development, we possess almost no information on the correlation between meristem parameters and individual plant organ sizes. We studied the relationship of SAM anatomical parameters with plant organ sizes. We compared late autumn buds of 24 Central European monocot species with 80 dicot herbaceous species. SAM parameters correlated with a number of size-related traits. The meristem size showed strong phylogenetic signal. However, no significant difference was found between studied monocot and dicot species except for overall lower variation in SAM parameters across the monocot species. We also examined preformation of leaves and flower initials in the late-autumn buds before winter rest in a
large set of species. Bud preformation was fairly more common in monocot (34%) than dicot species (25%). This helps them to accelerate their development after winter rest and resprout and flower earlier (about 35 days). Our analyses demonstrate that SAMs provide a functional link between sizes and numbers of plant organs. SAM parameters determine the timing of growth with monocot species being more often able to accelerate their development due to bud preformation.
Key words: bud preformation, genome size, meristem size, phylogenetic analysis, plant organ size.
Funded by: This study was funded by the Czech Science Foundation (project no. 14-36079G, Centre of Excellence PLADIAS)
Evolution of Kranz anatomy in Cyperaceae
Shirley Martins1, Marccus Alves2 & Vera Lúcia Scatena3
1Centro de Ciências Biológicas e da Saúde, Laboratório de Anatomia e Morfologia de Plantas, Universidade Estadual do Oeste do Paraná; 2Centro de Ciências Biológicas, Departamento de Botânica, Laboratório de Morfotaxonomia Vegetal, Universidade Federal de Pernambuco; 3Instituto de Biociências, Departamento de Botânica, Laboratório de Anatomia Vegetal, Universidade
Estadual Paulista. shirley_botany@yahoo.com.br
Cyperaceae has about 1300 species with C4 photosynthesis, which is related to Kranz anatomy. In general, four different types of Kranz anatomy (chlorocyperoid, eleocharoid, fimbristyloid and rhynchosporoid) have been described in the family. These types differ basically in number of vascular bundle sheaths, continuity of the bundle sheath with large chloroplasts and chloroplast localization. Examining available data about leaf or culm anatomy, taxonomy, phylogeny, geographic distribution and habitat from C4 Cyperaceae species, it was possible to infer the putative origin of Kranz anatomy in the family. Kranz anatomy emerged numerous times (possibly 5-6) in unrelated phylogenetic groups of Cyperaceae with convergence of the chlorocyperoid, eleocharoid and fimbristyloid types in certain groups. In addition, the anatomical types are not associated with specific environmental conditions because the Kranz species of Abildgaardieae, Rhynchospora and some Cypereae occur in similar xeric environments and exhibit different Kranz types. Also, there is no general relationship between Kranz anatomy and xeric environment, because many Cypereae Kranz species are mesophytes and Eleocharis Kranz species are hydrophytes. So, the diverse origin of these Kranz species might result from different environmental pressures that promote the reduction of photorespiration.
Key words: anatomy, C4 photosynthesis, ontogeny, phylogeny, ultrastructure.
Funded by: FAPESP (2008/09380-2)