Difference in Germination Traits between Congeneric Native and Exotic Species May Affect Invasion.

Germination traits are components of invasion potential, and comparing seed traits in sympatric native and invasive species can offer insights into the invasion process. We characterized seed germination traits and how they influenced the success of Eragrostis mexicana, a native species, and Eragrostis tenuifolia, an exotic species (Poaceae) in Mexico, in the context of their potential for biological invasion. Seeds from both species were collected from four sites in a natural protected area in Mexico City, and the germination of seeds of different ages was conducted in experiments at different temperatures. E. tenuifolia exhibited higher germination percentages than the native E. mexicana across all treatments. Seed age had differential effects, with older seeds of the native E. mexicana germinating better, while E. tenuifolia performed better with younger seeds. Temperature positively impacted germination for both species, although E. mexicana was limited at lower temperatures. Exotic E. tenuifolia can germinate over a wider temperature range with earlier germination rates, and generate a seed bank lasting several years, which may contribute to naturalization. The importance of germination traits in the context of invasive species establishment underscores the potential role of seed banks in facilitating biological invasions.

Dos nuevos registros para la flora agrostológica de Perú / Two new records for the agrostological flora of Peru

Resumen Se reporta por primera vez la presencia de Piptochaetium bicolor (Vahl) É. Desv. y Trichachne californica var. villosissima (Henrard) Wipff & Shaw para Perú, basada en colecciones realizadas en el ecosistema de formación de lomas costeras del departamento de Arequipa. Se presentan descripciones, fotografías, ilustraciones y una clave taxonómica para cada taxón.

Abstract The presence of Piptochaetium bicolor (Vahl) É. Desv. and Trichachne californica var. villosissima (Henrard) Wipff & Shaw are recorded for the first time from Peru, based upon collections made in the coastal lomas formations ecosystem of the department of Arequipa. Descriptions, photographs, illustrations and a taxonomic key are presented for each taxon.

Exogenous Nitric Oxide Alleviates Water Deficit and Increases the Seed Production of an Endemic Amazonian Canga Grass.

Open pit mining can cause loss in different ecosystems, including damage to habitats of rare and endemic species. Understanding the biology of these species is fundamental for their conservation, and to assist in decision-making. Sporobolus multiramosus is an annual grass endemic to the Amazon canga ecosystems, which comprise rocky outcrop vegetation covering one of the world's largest iron ore reserves. Here, we evaluated whether nitric oxide aids S. multiramosus in coping with water shortages and examined the physiological processes behind these adaptations. nitric oxide application improved the water status, photosynthetic efficiency, biomass production, and seed production and germination of S. multiramosus under water deficit conditions. These enhancements were accompanied by adjustments in leaf and root anatomy, including changes in stomata density and size and root endodermis thickness and vascular cylinder diameter. Proteomic analysis revealed that nitric oxide promoted the activation of several proteins involved in the response to environmental stress and flower and fruit development. Overall, the results suggest that exogenous nitric oxide has the potential to enhance the growth and productivity of S. multiramosus. Enhancements in seed productivity have significant implications for conservation initiatives and can be applied to seed production areas, particularly for the restoration of native ecosystems.

Rehabilitation of eroded trails and gullies on quartzite rock outcrops with native species in a high-altitude grassland.

The quartzite rock outcrops and the native vegetation of grasslands located at the Serra da Calçada Mountain in Minas Gerais State (Brazil) have been severely degraded by extreme sports activities such as motocross and off-road vehicles, greatly damaging the abundant headwaters. The main consequences thereof were hilly and gully erosion processes with soil loss and the deviation of the water from its original paths. However, currently, there is no report of successful restoration efforts in severely eroded outcrops in Brazilian high-altitude grasslands (campo rupestre). Through the Universal Soil Loss Equation (USLE), we found a high general erosion rate in the study site (669.91 t·ha-1·year-1), and the specific soil loss provoked by off-road vehicles on trails was significantly greater (49 m3 per 100 m2) than that caused by mountain bikes and trekking (5.8 m3 per 100 m2). We performed the physical reconstruction of eroded outcrops and surface water flow paths by allocating locally available quartzite rocks. These rocks were inoculated with different species of bryophytes and planted with native species under two treatments: un-inoculated and inoculated with arbuscular mycorrhizal fungi (AMF) spores of the Rhizophagus irregularis species. After 2 years, the bryophyte communities showed a similar pattern to the preserved site, and the AMF inoculation favoured plant establishment of most species, especially of the Asteraceae, Cyperaceae, Fabaceae, Malpighiaceae, Orchidaceae and Poaceae families. The AMF also improved the soil fertility, highlighting soil P, SOM, CEC, NH4+-N as well as soil water content and water retention capacity. Poaceae family species showed an outstanding occupation, which was considered a functional indicator of rehabilitation success, functioning as a "hydraulic carpet" for water exportation, conduction and drainage across the outcrops. This study provides an eco-technology to restore severely eroded outcrops over headwaters using native species in the Brazilian high-altitude grasslands.

Anther development in Brachiaria brizantha (syn. Urochloa brizantha) and perspective for microspore in vitro culture.

Brachiaria, a genus from the Poaceae family, is largely cultivated as forage in Brazil. Among the most cultivated varieties of Brachiaria spp., B. brizantha cv. Marandu (syn. Urochloa brizantha) is of great agronomical importance due to the large areas cultivated with this species. This cultivar is apomictic and tetraploid. Sexual diploid genotype is available for this species. The difference in levels of ploidy among sexual and apomictic plants contributes to hindering Brachiaria breeding programs. The induction of haploids and double haploids is of great interest for the generation of new genotypes with potential use in intraspecific crosses. A key factor for the success of this technique is identifying adequate microspore developmental stages for efficient embryogenesis induction. Knowledge of the morphological changes during microsporogenesis and microgametogenesis and sporophytic tissues composing the anther is critical for identifying the stages in which microspores present a higher potential for embryogenic callus and somatic embryo through in vitro culture. In this work, morphological markers were associated with anther and pollen grain developmental stages, through histological analysis. Anther development was divided into 11 stages using morphological and cytological characteristics, from anther with archesporial cells to anther dehiscence. The morphological characteristics of each stage are presented. In addition, the response of stage 8 anthers to in vitro culture indicates microspores initiating somatic embryogenic pathway.

Immature Stages and New Host Plant Records for Three Species in the "Taygetis Clade" of Euptychiina in Southeastern Peru (Lepidoptera: Nymphalidae: Satyrinae).

We report here the immature stages and natural host plants for three species in the so-called "Taygetis clade" of the nymphalid butterfly subtribe Euptychiina, Taygetis echo (Cramer, 1775), Taygetis sosis Hopffer, 1874, and Pseudodebis valentina (Cramer, 1779). The study was carried out at Finca Las Piedras in Madre de Dios department, Peru. Taygetis echo was observed utilizing a species of herbaceous bamboo, Olyra latifolia L. (Poaceae: Bambusoideae: Olyreae), T. sosis was found feeding on another species of herbaceous bamboo, Pariana lunata Nees (Poaceae: Bambusoideae: Olyreae), and P. valentina was found utilizing a species of woody bamboo, Guadua weberbaueri Pilg. (Poaceae: Bambusoideae: Bambuseae). We describe and provide photos of the immatures and host plants, as well as illustrations of the head capsules for each of these three species.

Rediscovery of presumably extinct species of Aristida in São Paulo State, Brazil / Redescoberta de espécies presumivelmente extintas de Aristida no estado de São Paulo, Brasil

Abstract Two species of Poaceae (Aristidoideae) Aristida ekmaniana Henrard and A. macrophylla Hack. considered "presumably extinct" in the Brazilian state of São Paulo were rediscovered during fieldwork. We hereby describe the location, ecosystem, and habitat type where the species were found. We suggest these grasses be removed from the list of extinct species and be placed in a category compatible with the current knowledge about their conservation status in the state of São Paulo.

Resumo Duas espécies de Poaceae (Aristidoideae), Aristida ekmaniana Henrard e A. macrophylla Hack., consideradas "presumivelmente extintas" no estado de São Paulo, Brasil, foram redescobertas durante trabalho em campo. Descrição, ilustração e observações ecológicas são apresentadas, incluindo locais de observação, ecossistemas e habitats. Sugerimos a revisão do status de conservação das espécies no estado de São Paulo.

Low fertilization optimizes the water use efficiency of an Amazonian canga grass for mineland rehabilitation / Baixa fertilização otimiza a eficiência do uso da água de uma gramínea nativa da canga amazônica para reabilitação de minas

The peculiar characteristics of mining waste substrates represent a significant challenge for environmental rehabilitation. Here, we evaluated the revegetation potential of Paspalum cinerascens on substrates from mining areas of Serra dos Carajás, a region harboring a large mine complex in the eastern Brazilian Amazon. Paspalum cinerascens is a native grass widely distributed in the canga ecosystem, a vegetation type covering iron ore reserves. Seeds of P. cinerascens harvested in canga were germinated in sterilized quartzite sand and the seedlings grown in controlled conditions for 90 days. The seedlings were then cultivated in canga topsoil (control, without fertilization) and mining waste substrate with half and complete fertilization currently applied at the beginning of mineland rehabilitation in Serra dos Carajás. Regardless of fertilization, plants grown in the mining waste substrate did not differ in carbon assimilation, tillering rate and root biomass, despite higher leaf nutrient content and lower root: shoot ratio when compared to plants in canga topsoil. Compared to the control, complete fertilization led to significantly taller plants, higher shoot biomass and reduced water use efficiency. Half fertilization led to higher phosphorus and water use efficiency and stomatal density. Our results confirmed that P. cinerascens has adaptive traits to grow and thrive in the harsh environmental conditions of post iron ore mining, and can be used in rehabilitation processes. Moreover, half fertilization led to plants with optimized water loss in exchange for carbon without significant costs to plant growth, an interesting trait for rehabilitation in areas experiencing water restrictions.(AU)

As características peculiares dos substratos de remanescentes da mineração (estéril de mina) representam um desafio para a recuperação ambiental. Neste estudo avaliamos o potencial de uso de Paspalum cinerascens para revegetação de estéril de mina na Serra dos Carajás, Pará (Brasil). Paspalum cinerascens é uma gramínea nativa amplamente distribuída nas cangas, vegetação típica dos campos rupestres que cobrem reservas de minério de ferro. As plantas de P. cinerascens foram cultivadas em topsoil de canga (controle) e em estéril de mina com meio e completo regime de fertilização atualmente empregado para revegetação das áreas mineradas na Serra dos Carajás. Foram utilizadas sementes coletadas nas cangas e as plantas foram cultivadas em condições controladas por 90 dias. Independentemente da fertilização, plantas cultivadas em estéril de mina não apresentaram diferenças significativas na assimilação de carbono, perfilhamento ou biomassa radicular, apesar de valores mais elevados de nutrientes foliares e menor razão raiz: parte aérea quando comparadas às plantas em topsoil de canga. A fertilização completa resultou em plantas mais altas, maior biomassa aérea e menor eficiência no uso da água. Metade da fertilização aumentou a densidade estomática, a eficiência de uso da água e de fósforo. Esses resultados confirmaram que P. cinerascens possui características adaptativas para crescer e prosperar em condições ambientais adversas remanescentes da mineração, sendo indicada para uso em processos de recuperação de áreas degradadas na Serra dos Carajás. Além disso, o uso de metade do regime de fertilização otimiza o uso da água pelas plantas sem perdas significativas de crescimento, uma característica desejável para recuperação de áreas com restrições hídricas.(AU)

Germination of grass species from dry and wet grasslands in response to osmotic stress under present and future temperatures.

PREMISE: Seed germination is controlled by the soil microclimate, which is expected to change with the temperature increase and rainfall irregularity predicted for the future. Because changes in soil characteristics directly affect species recruitment, vegetation dynamics and resilience, we investigated how caryopses of native grasses from dry and wet grasslands respond to water stress under current and future temperature regimes. METHODS: Caryopses were collected from 10 grass species in dry and wet grasslands, subjected or not to a fire event, and tested for germination at increasing osmotic potential (0 to -1.0 MPa) at current (17°/27°C night/day) and future (23°/33°C) simulated temperatures. RESULTS: The viability and germination percentages of caryopses from both dry and wet grassland species were progressively reduced as osmotic stress increased, irrespective of temperature regime. The viability of caryopses from wet grassland species was reduced under the future temperature regime, irrespective of osmotic potential. The slow germination of caryopses of dry grassland species at the present temperature regime was absent when they were incubated in the future temperature regime. CONCLUSIONS: More intense water stress reduced the survival of caryopses for both dry and wet grassland grass species. The predicted future temperature regime reduced the viability of wet grassland species and altered the germination strategy of dry grassland species. These results indicate that increasing water stress and temperature predicted for the future may compromise the recruitment potential of dry and wet grassland species and directly impact the dynamics and resilience of these ecosystems.

Chromosomes of two Olyra l. species from Misiones, Argentina (Poaceae, Bambusoideae, Olyreae) / Cromosomas de dos especies de Olyra l. de Misiones, Argentina (Poaceae, Bambusoideae, Olyreae)

ABSTRACT The subfamily Bambusoideae comprises three monophyletic tribes, Arundinarieae, Bambuseae and Olyreae. Here we report the gametic number and the chromosomal meiotic behavior of two species belonging to the herbaceous tribe Olyreae, Olyra latifolia and Olyrahumilis. Accessions were collected in Misiones, at Northeastern Argentina. We report a new gametic number for O. humilis, n=18, and we confirmed n=11 for O. latifolia. Chromosomal features, like the basic and gametic chromosome number, are important in understanding the evolution of the Poaceae family, especially in delimiting clades and elucidate inter andintra-clades relationships, and therefore it is necessary to continue producing this type of data.

RESUMEN La subfamilia Bambusoideae comprende tres tribus monofiléticas, Arundinarieae, Bambuseae y Olyreae. Aquí reportamos el número gamético y el comportamiento meiótico de los cromosomas de dos especies pertenecientes a la tribu Olyreae de bambúes herbáceos, Olyra latifolia y Olyra humilis. Las introducciones se recolectaron en la provincia de Misiones, en el noreste argentino. Reportamos un nuevo número gamético para O. humilis, n=18, y confirmamos n=11 para O. latifolia. Los números cromosómicos básicos y gaméticos son importantes para comprender la evolución de la familia Poaceae, especialmente para delimitar sus clados y las relaciones existentes entre ellos, por lo que es necesario continuar produciendo este tipo de datos.

Classification of sugarcane genotypes susceptible and resistant to the initial attack of sugarcane borer Diatraea saccharalis using epicuticular wax composition.

Identifying compounds present in the sugarcane epicuticular wax and using these compounds to classify the genotypes susceptible and resistant to the initial attack of sugarcane borer (Diatraea saccharalis) was the aim of this study. A greenhouse experiment was performed in a factorial scheme with and without borer infestation using genotypes previously characterized as resistant or susceptible in field-based experiments. Sugarcane whorls of six-month-old plants were collected before (BI) and after (AI) 72 h of sugarcane borer infestation. The sugarcane epicuticular wax was extracted in both times, i.e., BI and AI and its chemical composition was assessed by gas chromatography coupled to mass spectrometry (GC-MS). Twenty-five compounds were identified for both BI and AI. Classification models were built using partial least squares for discriminant analysis (PLS-DA) and linear discriminant analysis (LDA). Variable selection methods were used to improve the classification models. Ordered predictors selection for discriminant analysis (OPSDA) selected compounds that correctly classified all the test samples before borer infestation (Error = 0.000), and exhibited the most suitable classification parameters for the test set after borer infestation (Error = 0.111). The C30 pentacyclic triterpene friedelin and a high alcohol/aldehyde ratio were associated with the classification of resistant genotypes. Our findings have applicability in developing a screening methodology for breeding programs interested in identifying genotypes resistant to the initial feeding of sugarcane borer.

The acquisitive-conservative axis of leaf trait variation emerges even in homogeneous environments.

BACKGROUND AND AIMS: The acquisitive-conservative axis of plant ecological strategies results in a pattern of leaf trait covariation that captures the balance between leaf construction costs and plant growth potential. Studies evaluating trait covariation within species are scarcer, and have mostly dealt with variation in response to environmental gradients. Little work has been published on intraspecific patterns of leaf trait covariation in the absence of strong environmental variation. METHODS: We analysed covariation of four leaf functional traits [specific leaf area (SLA) leaf dry matter content (LDMC), force to tear (Ft) and leaf nitrogen content (Nm)] in six Poaceae and four Fabaceae species common in the dry Chaco forest of Central Argentina, growing in the field and in a common garden. We compared intraspecific covariation patterns (slopes, correlation and effect size) of leaf functional traits with global interspecific covariation patterns. Additionally, we checked for possible climatic and edaphic factors that could affect the intraspecific covariation pattern. KEY RESULTS: We found negative correlations for the LDMC-SLA, Ft-SLA, LDMC-Nm and Ft-Nm trait pairs. This intraspecific covariation pattern found both in the field and in the common garden and not explained by climatic or edaphic variation in the field follows the expected acquisitive-conservative axis. At the same time, we found quantitative differences in slopes among different species, and between these intraspecific patterns and the interspecific ones. Many of these differences seem to be idiosyncratic, but some appear consistent among species (e.g. all the intraspecific LDMC-SLA and LDMC-Nm slopes tend to be shallower than the global pattern). CONCLUSIONS: Our study indicates that the acquisitive-conservative leaf functional trait covariation pattern occurs at the intraspecific level even in the absence of relevant environmental variation in the field. This suggests a high degree of variation-covariation in leaf functional traits not driven by environmental variables.

Ecophysiology of Fusarium chaquense a Novel Type A Trichothecene Producer Species Isolated from Natural Grasses.

Fusarium chaquense, a recently formally described novel species, has been identified as an T-2 toxin (T-2), HT-2 toxin (HT-2) and other toxins producer in natural grasses (Poaceae) from Argentina. The major objective of this study was to describe the effect of water activity (aW, 0.995, 0.98, 0.95, 0.93 and 0.91), temperature (15, 25 and 30 °C) and incubation time (5, 15 and 25 days) on growth and to evaluate the production of T-2, HT-2 toxins and beauvericin (BEA) by two F. chaquense strains in a grass-based media. The results showed a wide range of conditions for F. chaquense growth and mycotoxin production. Both strains had a maximum growth rate at the highest aW (0.995) and 25 °C. Regarding mycotoxin production, more T-2 than the other analysed mycotoxins were produced by the two strains. T-2 production was favoured at 0.995 aW and 30 °C, while HT-2 production at 0.98-0.95 aW and 15 °C. The maximum levels of BEA were produced at 0.995 aW and 25-30 °C. Two-dimensional profiles of aW by temperature interactions were obtained from these data in order to identify areas where conditions indicate a significant risk of mycotoxins accumulation on grass. For its versatility on growth and mycotoxin production in a wide range of aW and temperatures, F. chaquense would have an adaptive advantage over other Fusarium species, and this would explain its high frequency of isolation in natural grasses grown up in the Chaco wetlands.

Are Grasses Really Useful for the Phytoremediation of Potentially Toxic Trace Elements? A Review.

The pollution of soil, water, and air by potentially toxic trace elements poses risks to environmental and human health. For this reason, many chemical, physical, and biological processes of remediation have been developed to reduce the (available) trace element concentrations in the environment. Among those technologies, phytoremediation is an environmentally friendly in situ and cost-effective approach to remediate sites with low-to-moderate pollution with trace elements. However, not all species have the potential to be used for phytoremediation of trace element-polluted sites due to their morpho-physiological characteristics and low tolerance to toxicity induced by the trace elements. Grasses are prospective candidates due to their high biomass yields, fast growth, adaptations to infertile soils, and successive shoot regrowth after harvest. A large number of studies evaluating the processes related to the uptake, transport, accumulation, and toxicity of trace elements in grasses assessed for phytoremediation have been conducted. The aim of this review is (i) to synthesize the available information on the mechanisms involved in uptake, transport, accumulation, toxicity, and tolerance to trace elements in grasses; (ii) to identify suitable grasses for trace element phytoextraction, phytostabilization, and phytofiltration; (iii) to describe the main strategies used to improve trace element phytoremediation efficiency by grasses; and (iv) to point out the advantages, disadvantages, and perspectives for the use of grasses for phytoremediation of trace element-polluted soils.

Novel Tools for Adjusting Spatial Variability in the Early Sugarcane Breeding Stage.

The detection of spatial variability in field trials has great potential for accelerating plant breeding progress due to the possibility of better controlling non-genetic variation. Therefore, we aimed to evaluate a digital soil mapping approach and a high-density soil sampling procedure for identifying and adjusting spatial dependence in the early sugarcane breeding stage. Two experiments were conducted in regions with different soil classifications. High-density sampling of soil physical and chemical properties was performed in a regular grid to investigate the structure of spatial variability. Soil apparent electrical conductivity (ECa) was measured in both experimental areas with an EM38-MK2® sensor. In addition, principal component analysis (PCA) was employed to reduce the dimensionality of the physical and chemical soil data sets. After conducting the PCA and obtaining different thematic maps, we determined each experimental plot's exact position within the field. Tons of cane per hectare (TCH) data for each experiment were obtained and analyzed using mixed linear models. When environmental covariates were considered, a previous forward model selection step was applied to incorporate the variables. The PCA based on high-density soil sampling data captured part of the total variability in the data for Experimental Area 1 and was suggested to be an efficient index to be incorporated as a covariate in the statistical model, reducing the experimental error (residual variation coefficient, CVe). When incorporated into the different statistical models, the ECa information increased the selection accuracy of the experimental genotypes. Therefore, we demonstrate that the genetic parameter increased when both approaches (spatial analysis and environmental covariates) were employed.

Paper Spray Mass Spectrometry on the Analysis of Phenolic Compounds in Rhynchelytrum repens: A Tropical Grass with Hypoglycemic Activity.

The characterization of plant compounds with pharmacological activity is a field of great relevance in research and development. As such, identification techniques with the goal of developing new drugs or even validating the bioactive properties of extracts must be explored in order to further expand the knowledge of plant extract composition. Most works in this field employ HPLC, when exploring non-structural and cell wall carbohydrates from Rhynchelytrum repens. Phenolic compounds were studied by classical chromatography techniques and UV-vis spectrophotometry, with C-glycosylated flavonoids being detected but with no further details regarding the chemical structure of these compounds. In this work we employ paper spray ionization mass spectrometry (PS-MS) for the evaluation of the chemical profile of R. repens methanol extract. Positive ionization mode identified 15 compounds, belonging to flavonoids, fatty acids, and other classes of compounds; negative mode ionization was able to identify 20 compounds comprising the classes of quinic acids, stilbenes and flavonoids. PS-MS proved effective for the evaluation of R. repens extracts, making it possible to identify a total of thirty-five compounds. The bioactive properties attributed to R. repens were confirmed by the identification and characterization of compounds identified by PS-MS.

Native Amazonian Canga Grasses Show Distinct Nitrogen Growth Responses in Iron Mining Substrates.

Native species may have adaptive traits that are advantageous for overcoming the adverse environmental conditions faced during the early stages of mine land rehabilitation. Here, we examined the nitrogen (N) growth responses of two native perennial grasses (Axonopus longispicus and Paspalum cinerascens) from canga in nutrient-poor iron mining substrates. We carried out vegetative propagation and recovered substantial healthy tillers from field-collected tussocks of both species. These tillers were cultivated in mining substrates at increasing N levels. The tillering rates of both species increased with the N application. Nonetheless, only in P. cinerascens did the N application result in significant biomass increase. Such growth gain was a result of changes in leaf pigment, stomatal morphology, gas exchanges, and nutrients absorption that occurred mainly under the low N additions. Reaching optimum growth at 80 mg N dm-3, these plants showed no differences from those in the field. Our study demonstrates that an input of N as fertilizer can differentially improve the growth of native grasses and that P. cinerascens plants are able to deposit high quantities of carbon and protect soil over the seasons, thus, making them promising candidates for restoring nutrient cycling, accelerating the return of other species and ecosystem services.

LEAF ANATOMY CHARACTERIZATION OF FOUR Apochloa SPECIES: A C3 GENUS RELATED TO EVOLUTION OF C4 PATHWAY IN GRASSES / Caracterización anatómica de hojas de cuatro especies de Apochloa: un género relacionado con la evolución de la vía C4 en gramíneas

ABSTRACT Leaf anatomy characteristics provide important evidences about the transition between C3 and C4 pathways. The C4 photosynthesis pathway allowed to reduce the C3 photorespiratory rate, concentrating CO2 around the Rubisco site and using structures and machinery already presented in C3 plants. In monocots, it is observed a high number of C4 lineages, most of them phylogenetically related to C3 groups. The genus Apochloa (C3), subtribe Arthropogoninae, is related to two C4 genera Coleataenia and Cyphonanthus. The aim of this study was to evaluate four Apochloa species in order to establish anatomical characteristics related to the evolution of C4 pathway in this group. By means of transverse sections fully expanded leaves of A. euprepes, A. lorea, A. molinioides, and A. poliophylla were collected and the characteristics of the mesophyll (M) and bundle sheath (BS) cells were determined. These species showed a rustic Kranz anatomy with enlarged and radial arranged BS cells, which have few organelles organized in a centrifugal position. Although the modifications of BS cells are probably related to the maintenance of plant water status, we also discuss the evolution for the establishment of C4 photosynthesis in the related C4 genera.

RESUMEN Las características de la anatomía de la hoja proporcionan evidencias importantes sobre la transición entre las vías C3 y C4. La fotosíntesis C4 surgió para reducir la tasa de fotorrespiración C3, concentrando el CO2 alrededor del sitio de la Rubisco y utilizando estructuras y maquinaria ya presentes en las plantas C3. En monocotiledóneas, se observa un alto número de linajes C4, la mayoría de ellas filogenéticamente relacionadas con grupos C3. El género C3 Apochloa, que pertenece a la subtribu Arthropogoninae, está relacionado con dos géneros C4 Coleataenia and Cyphonanthus. En este contexto, el objetivo fue evaluar cuatro especies de Apochloa para establecer las características anatómicas relacionadas con la evolución de la via C4 en este grupo. Se colectaron hojas completamente expandidas de A. euprepes, A. lorea, A. molinioides y A. poliophylla y se determinaron las características de las células del mesófilo (M) y del haz de la vaina (HV) a partir de secciones transversales de la hoja. Las especies presentaron una anatomía rústica de Kranz con células HV agrandadas y de distribución radial, con pocas organelas organizadas en posición centrífuga. Aunque las modificaciones de las células HV están probablemente relacionadas con el mantenimiento del estado hídrico de la planta, se puede inferir que facilitan el establecimiento de la fotosíntesis en los géneros C4 relacionados.

Sucrose-phosphate phosphatase from sugarcane reveals an ancestral tandem duplication.

BACKGROUND: Sugarcane is capable to store large amounts of sucrose in the culm at maturity hence it became a major source of sucrose for the food and the renewable energy industries. Sucrose, the main disaccharide produced by photosynthesis, is mainly stored in the vacuole of the cells of non-photosynthetic tissues. Two pathways are known to release free sucrose in plant cells, one is de novo synthesis dependent on sucrose phosphate synthase (SPS) and sucrose phosphate phosphatase (S6PP) while the other is regulatory and dependent on sucrose synthase (SuSy) activity. The molecular understanding of genes that give rise to the expression of the enzyme sucrose phosphate phosphatase, responsible for the release of sucrose in the last synthetic step lag behind the regulatory SuSy gene. RESULTS: Sugarcane genome sequencing effort disclosed the existence of a tandem duplication and the present work further support that both S6PP.1 and S6PP_2D isoforms are actively transcribed in young sugarcane plants but significantly less at maturity. Two commercial hybrids (SP80-3280 and R570) and both Saccharum spontaneum (IN84-58) and S.officinarum (BADILLA) exhibit transcriptional activity at three-month-old plants of the tandem S6PP_2D in leaves, culm, meristem and root system with a cultivar-specific distribution. Moreover, this tandem duplication is shared with other grasses and is ancestral in the group. CONCLUSION: Detection of a new isoform of S6PP resulting from the translation of 14 exon-containing transcript (S6PP_2D) will contribute to the knowledge of sucrose metabolism in plants. In addition, expression varies along plant development and between sugarcane cultivars and parental species.

Antinociceptive constituents from Saccharum officinarum L. juice.

This work aimed to investigate the main components of methanol fractions (MFSC and MFSCf) from Saccharum officinarum L. juice and their in vivo antinociceptive potential. After LC-ESI-MS and ESI-MS/MS analysis, phenolic compounds, such as dicaffeoylquinic acid, schaftoside, vicenin-2, stilbene glycoside and the major compound tricin-7-O-(2″- α-L-rhamnopyranosyl)-α-D-galacturonide (1), were identified. MFSC and MFSCf significantly inhibited nociceptive responses in classical mice pain models. The isolated flavone, 1, inhibited strongly the neurogenic phase in formalin test without interfering with the inflammatory one. The co-administration of the opioid antagonist, naloxone, significantly reversed the antinociceptive effects on the neurogenic phase of both methanol fractions and 1, demonstrating the involvement of the opioid system on the antinociceptive effect. This work describes for the first time the antinociceptive effect of flavonoids present in sugarcane juice, highlighting the isolation and the structural elucidation of tricin-7-O-(2″-α-L-rhamnopyranosyl)-α-D-galacturonide through ESI-MS/MS, 1D- and 2D-NMR.