Evolution and development of the spikelet and flower of Rhynchospora (Cyperaceae)

Premise of research. Rhynchospora, one of the biggest genera of sedges, displays several spikelet and flower modifications and is one of a few genera where the pollination strategy changes from wind to insect pollination; however, the mechanisms that have promoted such diversity in the genus are unknown. We have performed a comparative study of spikelet and flower development of Rhynchospora from an evolutionary perspective to get insight into the bases of spikelet and flower evolution. Particularly, we investigate correlations between the change from wind to insect pollination that occur in the genus and the spikelet and flower traits. Methodology. The spikelet and flower development of nine species of Rhynchospora were studied using SEM images. Parsimony, maximum likelihood, and Bayesian reconstruction analyses were conducted to evaluate the evolutionary history of flower and spikelet developmental programs. Pivotal results. We identified seven morphological and developmental traits that vary among Rhynchospora species; ancestral character reconstructions show that the spikelet and flower morphology and their developmental pathways support the diversification of Rhynchospora lineages. Conclusions. Our results suggest that the evolution of spikelet and flower developmental programs in Rhynchospora may be related to the evolution of its pollination type and mating system. The evolution toward a bisexual spikelet and flowers in which the androecium develops faster than the gynoecium may represent important steps for the transition from a wind- to insect-pollination system. In addition, we found new traits of spikelets and flowers that may help to distinguish natural groups within Rhynchospora.Fil: Lucero, Leandro Exequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Agrobiotecnologia del Litoral; Argentina. Universidad Nacional del Litoral; ArgentinaFil: Vegetti, Abelardo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Agrobiotecnologia del Litoral; Argentina. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas; ArgentinaFil: Reinheimer, Renata. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion; Argentin

Evolution and development of the spikelet and flower of Rhynchospora (Cyperaceae)

Premise of research. Rhynchospora, one of the biggest genera of sedges, displays several spikelet and flower modifications and is one of a few genera where the pollination strategy changes from wind to insect pollination; however, the mechanisms that have promoted such diversity in the genus are unknown. We have performed a comparative study of spikelet and flower development of Rhynchospora from an evolutionary perspective to get insight into the bases of spikelet and flower evolution. Particularly, we investigate correlations between the change from wind to insect pollination that occur in the genus and the spikelet and flower traits. Methodology. The spikelet and flower development of nine species of Rhynchospora were studied using SEM images. Parsimony, maximum likelihood, and Bayesian reconstruction analyses were conducted to evaluate the evolutionary history of flower and spikelet developmental programs. Pivotal results. We identified seven morphological and developmental traits that vary among Rhynchospora species; ancestral character reconstructions show that the spikelet and flower morphology and their developmental pathways support the diversification of Rhynchospora lineages. Conclusions. Our results suggest that the evolution of spikelet and flower developmental programs in Rhynchospora may be related to the evolution of its pollination type and mating system. The evolution toward a bisexual spikelet and flowers in which the androecium develops faster than the gynoecium may represent important steps for the transition from a wind- to insect-pollination system. In addition, we found new traits of spikelets and flowers that may help to distinguish natural groups within Rhynchospora.Fil: Lucero, Leandro Exequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Agrobiotecnologia del Litoral; Argentina. Universidad Nacional del Litoral; ArgentinaFil: Vegetti, Abelardo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Agrobiotecnologia del Litoral; Argentina. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas; ArgentinaFil: Reinheimer, Renata. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion; Argentin

Synflorescence analysis in South American species of Andropogon section Leptopogon (Andropogoneae, Poaceae): a tool to identify different ploidy levels

In southern South America, Andropogon sect. Leptopogon is represented by both diploid and hexaploid species. In order to compare the synflorescence structures and floral arrays in relation to ploidy levels in species of Andropogon, the section Leptopogon was used as model. In this study, the synflorescence structure was typologically characterized. The structural analysis was based on the typology system developed by Troll and Weberling, which has proved useful in describing inflorescences. A comparative analysis of the variations observed in the structure of the synflorescence and a morphometric analysis using principal component analysis were carried out. These results revealed that diploid and hexaploid species present differences mainly in the following parameters: synflorescence length, number of internodes of the enrichment zone main axis, number of internodes and length of paracladia of the trophotagma, number of long paracladia per unit of inflorescence, length of hairs on articulated rachis internodes, pedicellate spikelet length, pedicellate spikelet width, pedicel width, length of hairs on pedicel, sessile spikelet length, awn length and floral system arrangements. This study provides a useful tool to distinguish between diploid and hexaploid species of Andropogon sect. Leptopogon. We propose naming the group of diploid species from Central and South America as the Andropogon selloanus complex.Fil: Nagahama, Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); ArgentinaFil: Vegetti, Abelardo Carlos. Universidad Nacional del Litoral. Facultad de Cs.agrarias. Catedra de Morfologia Vegetal; ArgentinaFil: Anton, Ana Maria Ramona. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); ArgentinaFil: Norrmann, Guillermo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Nordeste. Instituto de Botánica del Nordeste (i); Argentin

El rol del banco de yemas en la tolerancia a glifosato de dos especies herbáceas

Introducción y objetivos: Commelina erecta y Eutsachys retusa son malezas perennes tolerantes a glifosato. El propósito de este estudio fue caracterizar el banco de yemas de ambas especies y evaluar su respuesta a la aplicación de glifosato. M&M: Se analizaron yemas de 120 ejes reproductivos de C. erecta y 60 ejes reproductivos de E. retusa, a los 30 y 60 días después de la aplicación del herbicida. Las dosis empleadas en C. erecta fueron 0 (control), 1.200 y 2.400 g a.i. ha-1 y en E. retusa fueron 0 (control), 480 y 1200 g a.i. ha-1. Resultados: Ambas especies presentaron yemas activas en aproximadamente el 50% de los nudos, incluso después de la aplicación del herbicida. Ambas malezas alteraron la dinámica del banco de yemas y su patrón de crecimiento post-aplicación del herbicida. Es decir, la activación de yemas originalmente inhibidas permitió que ambas malezas rebroten y sobrevivan, alterando su arquitectura. Conclusiones: El banco de yemas juega un papel importante en la tolerancia a Glifosato en ambas malezas. En ambas especies, la capacidad de rebrote fue similar en cualquiera de las dosis de glifosato aplicadas; por lo tanto, una estrategia de control que aumente la dosis de herbicida no sería una alternativa exitosa para el manejo de estas malezas. La interrupción del almacenamiento de reservas en el sistema de rizomas y la reducción de la cantidad de yemas, serían factores claves para un manejo efectivo a largo plazo de estas y otras malezas perennes, en un sistema de labranza cero.Background and aims: Commelina erecta and Eutsachys retusa are two perennial weeds, which show high resprouting after glyphosate application. This behavior represents a serious problem for weed management. The purpose of this study was to characterize the bud bank of both species and to assess their response to glyphosate application. M&M: We analyzed 120 reproductive shoots of C. erecta, and 60 reproductive shoots of E. retusa, at 30- and 60-days post- herbicide application. The doses applied to C. erecta were 0 (control), 1.200 and 2.400 g a.i. ha-1, and to E. retusa were 0 (control), 480 and 1200 g a.i. ha-1. Results: We found that both species presented active buds in approximately 50% of their nodes, even after herbicide application. Bud bank dynamics changed in both weeds after herbicide application, and therefore their growth pattern. The activation of originally inhibited buds allowed weeds to regrow and survive after glyphosate application altering their architecture. Conclusions: The bud bank plays an important role in glyphosate tolerance in both weeds. The resprouting capacity in both species was similar for any dose of glyphosate applied. Therefore, an alternative control strategy based on the increase of the dose of herbicide would not be a successful alternative for the management of these weeds. The interruption of the storage of reserves in the rhizome system and the reduction of the number of buds would be key to effective long-term management of these and other perennial weeds in no tillage cropping system.Fil: Panigo, Elisa. Universidad Nacional del Litoral. Facultad de Cs.Agrarias. Departamento de Biologia Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Dellaferrera, Ignacio Miguel. Universidad Nacional del Litoral. Facultad de Cs.Agrarias. Departamento de Biologia Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Alesso, Carlos Agustín. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Vegetti, Abelardo Carlos. Universidad Nacional del Litoral. Facultad de Cs.Agrarias. Departamento de Biologia Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Perreta, Mariel Gladis. Universidad Nacional del Litoral. Facultad de Cs.Agrarias. Departamento de Biologia Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentin

Morphological characteristics of soybean root apexes as indicators of soil compaction

Plant soil compaction poses a serious problem to agriculture because it produces different types of changes in plant characteristics. No method has been implemented to date to use root morphological changes as indicators of soil compaction levels. Therefore, the aim of the present study was to evaluate whether or not the morphological changes in root apexes of soybean (Glycine max (L.) Merrill) can be used as indicators of soil compaction levels. To this end, a silt-loamy soil material (from a Typic Argiudoll, Esperanza series), sieved through a 2 mm mesh was used and the following soil bulk density levels were determined: 1.1, 1.3 and 1.5 g cm³ for which the corresponding mechanical resistances were < 0.1, 0.5 and 3.5 MPa, respectively. The distance from the apex to the first tertiary root and the root diameter at 1.5 cm from the apex were measured on the secondary root apexes. A form factor equal to the quotient between these two variables was subsequently calculated. An inverse relationship between soil mechanical impedance and secondary root length and form factor as well as a direct relationship with the secondary root diameter were observed. Changes in rhizodermis cells were also recorded. The following morphological characteristics were found to evidence the highest sensitivity to soil compaction: i) the form factor, ii) rhizodermis papillose cells, iii) apical malformations in root hairs, and iv) root diameter in expansion areas. Taken together, the morphological characteristics of root apexes could be considered to be indicative of soil compaction.A compactação do solo causa severos problemas devido a que gera diferentes mudanças nas características das plantas. Não existem métodos que possibilitem o uso das mudanças da morfologia das raízes como indicadores de níveis de compactação do solo. Avaliaram-se se alterações morfológicas nos ápices de soja podem ser utilizadas como indicadores de graus de compactação do solo. Solo peneirado a 2 mm, classificado como Typic Argiudol (série Esperanza), foi compactado até atingir os seguintes valores de densidade do solo: 1.1, 1.3 e 1.5 g cm³, para os quais corresponderam os valores de resistência mecânica de < 0.1, 0.5 e 3.5 MPa, respectivamente. A distância desde o ápice até a primeira raiz terciária e o diâmetro a 1.5 cm desde o ápice foram medidos nas raízes secundarias. Um fator de forma foi calculado fazendo o quociente entre as duas variáveis medidas. Houve uma relação inversa entre o cumprimento da raiz secundaria e fator de forma com a resistência mecânica, e uma relação direta entre esta ultima e o diâmetro das raízes secundárias. Alterações nas células da rizoderme foram determinadas. As seguintes características morfológicas se mostraram muito sensíveis a compactação do solo: i) o fator de forma, ii) as células papilosas da rizoderme, iii) malformações apicais nos pelos das raízes, e iv) diâmetro das raízes em áreas de expansão. As características morfológicas dos ápices das raízes podem ser consideradas indicadores de compactação dos solos

Comparative study of the inflorescence, spikelet and flower development in species of Cynodonteae (Chloridoideae, Poaceae)

Inflorescence morphology in Poaceae subtribes Hilariinae, Monanthochloinae, Boutelouinae, Scleropogoninae and Muhlenbergiinae (Cynodonteae, Chloridoideae) has been revisited recently, but inflorescence development remains largely unexplored. The aim of this study is to contribute additional information on the development of inflorescences in Cynodonteae by generating data on Distichlis, Bouteloua, Munroa, Erioneuron and Muhlenbergia and to compare them with results for other grasses. Using scanning electron microscopy images, we identified common developmental patterns among grasses and described developmental novelties for Bouteloua, Distichlis and Muhlenbergia. Novel developmental features are: The amphipetal initiation of second-order branches along the inflorescence of B. curtipendula, the elongation of the internodes of the inflorescence branches before floral development in M. asperifolius and â Type II' unisexual flowers in D. acerosa. Variable traits among studied species are: Inflorescence symmetry, direction of branch and spikelet initiation and differentiation, number of developing stamens, glume developmental patterns and timing of the arrest of gynoecium development during the formation of unisexual flowers. Our results allow us to postulate that a delicate balance of phytohormones may direct early development of grass inflorescence branching system by controlling direction of first-order branch differentiation. The approach used here provides a link between definitive structures and the underlying genetics.Fil: Pilatti, Vanesa. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Muchut, Sebastián Elías. Universidad Nacional del Litoral. Facultad de Cs.Agrarias. Departamento de Biologia Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Uberti Manassero, Nora Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Vegetti, Abelardo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; ArgentinaFil: Reinheimer, Renata. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentin

Influence of the propagules lignification degree of the garden and minigarden clonal on the cuttings and mini cuttings rooting of Prosopis alba Griseb

Prosopis alba posee potencial para la producción forestal y forrajera, destacándose su utilización en zonas áridas y semi-áridas. La especie, considerada de difícil enraizamiento, se propaga comercialmente mediante semillas. Su clonación permitiría cultivar materiales de interés silvícola altamente productivos y en un menor tiempo. El objetivo de este trabajo fue analizar el grado de lignificación de estacas y miniestacas de P. alba y su relación con su capacidad de enraizamiento. Los brotes obtenidos del jardín y minijardín clonal fueron inducidos al enraizamiento con diferentes concentraciones de IBA. Se realizaron cortes anatómicos de los brotes, previo a la inducción del enraizamiento y 40 días posteriores al mismo para observar la lignificación de estos materiales y relacionarlos con estacas y miniestacas enraizadas. Las miniestacas con mayor grado de juvenilidad y de etiolación presentaron menor grado de lignificación y lograron mayores porcentajes de enraizamiento(99,6%) con respecto a las estacas (7,6%). Se observó que la utilización de la técnica deminiestacas asociada a la de etiolación son promisoras para la propagación vegetativa de P. alba y posiblemente de otras especies nativas de difícil enraizamiento.Prosopis alba has high potential as forest material and important forage features for arid and semi-arid areas. Prosopis alba is commercially propagated by seeds, because of its rooting difficulties. Its cloning would allow to cultivate highly productive silvicultural materials in less time. The aim of this work was to analyze the lignification degree of P. alba cuttings and mini-cuttings and its relation with the rooting capacity. The sprouts obtained from the garden and clonal mini-garden were rooted with different concentrations of IBA. Serial transversal sections of the sprouts were carried out before rooting induction and 40 days after this process to observe the lignification of these material and its relationships with rooted cuttings and mini-cuttings. Results show that mini-cuttings with greater juvenility and etiolation degree presented lower lignification degree and reached higher rooting percentages (99.6%) with respect to cuttings (7.6%). Mini-cutting and etiolation techniques are promising for the vegetative propagation of P. alba and other native species with difficult rooting.Fil: Araujo Vieira de Souza, Jonicelia Cristina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bender, Adrian Gabriel. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; ArgentinaFil: Reutemann Arnolfo, Andrea Guadalupe. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; ArgentinaFil: Perreta, Mariel Gladis. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Córdoba, M. S.. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; ArgentinaFil: Tivano, Juan Carlos. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; ArgentinaFil: Guerra Barroso, Deborah. Universidade Estadual Do Norte Fluminense Darcy Ribeiro. Laboratorio de Fitotecnia; BrasilFil: Gariglio, Norberto Francisco. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; ArgentinaFil: Mroginski, Luis Amado. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias; ArgentinaFil: Vegetti, Abelardo Carlos. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Diversity of inflorescences in the Boutelouinae subtribe (Poaceae: Chloridoideae: Cynodonteae)

The Boutelouinae subtribe is comprised of one monophyletic genus, Bouteloua, with 57 species inhabiting the semi-arid regions of the New World. The inflorescences show significant structural variations, which provides an interesting system to examine their morphological evolution and identify characters and processes that may help to understand the group systematics. The structure of inflorescences was studied in 25 species of Bouteloua. All the species covered under this study have truncated polytelic inflorescences. Structural variations in the inflorescence unit among species may be accounted for by: (1) symmetry of the inflorescence unit, (2) total number of long primary branches, (3) total number of spikelets per branch, (4) number of perfect flowers per spikelet, (5) number of rudimentary flowers, and (6) reproductive system. Homogenization and truncation processes account for the diversity of mature inflorescences that exists in Bouteloua. In this work, we discuss the systematic and taxonomic value of the inflorescence in the Boutelouinae subtribe.Fil: Pilatti, Vanesa. Universidad Nacional del Litoral. Facultad de Cs.agrarias. Departamento de Biologia Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Agrobiotecnologia del Litoral; ArgentinaFil: Vegetti, Abelardo Carlos. Universidad Nacional del Litoral. Facultad de Cs.agrarias. Departamento de Biologia Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Agrobiotecnologia del Litoral; Argentin