EFECTO DE LA DENSIDAD Y TAMAÑO FLORAL SOBRE EL EXITO REPRODUCTIVO DE NOTHOSCORDUM GRAMINUM (ALLIACEAE

The size, form and color are signals used by flowers to attract their pollinators. Large and showy color flowers usuallyreceive higher pollinators visitation rates. According to the optimal forage theory, pollinators would tend to visitflower patches where they obtain the maximum reward regarding the energy expenditure in flower search. In highdensity patches, flowers are very close each other, hence, flower discrimination by pollinators would tend to be low.In low density patches, however, where the forage effort is greater, larger flowers are usually associated with higherrewards and would receive higher pollinators visitation achieving greater fitness than co-especifics with smallerflowers. In the present study we assessed the effects of flower density and size on the reproductive success (RS) ofNothoscordum gramineum. Four patches of different densities were delimited and the flowers size of the half ofindividuals at each patch was manually reduced. Results showed that RS was significantly greater in individuals withlarger flowers. Additionally, density has a positive effect on RS, especially in large size flowers. Nevertheless, fruitionsuccess reached maximum values in patches of intermediate density. Individuals with cut flowers did not varied the RSwith the variation of the density, suggesting that flower size is the most important attribute measured as advertisementby pollinators in N. gramineum. Our results do not support the hypothesis that in high density patches, flowerdisplays have low importance.El tamaño, la forma y el color son señales que utilizan las flores para atraer a sus polinizadores. Las flores que presentanun gran tamaño o alta vistosidad reciben una alta tasa de visitas de polinizadores. Según la teoría óptima de forrajeo, lospolinizadores tienden a visitar los parches donde disminuyan el esfuerzo del forrajeo y obtengan una mayor recompensa.En parches de la alta densidad las flores están agrupadas, razón por la cual la discriminación entre las flores tendería aser baja. Sin embargo, en parches de la baja densidad donde el esfuerzo de forrajeo es mayor, flores de mayor tamañorecibirían mayores tasas de visitas de polinizadores y manteniendo un mayor éxito reproductivo que individuos coespecíficos de menor tamaño. En el presente estudio determinamos el efecto de la densidad y del tamaño floral sobre eléxito reproductivo (ER) y el éxito de fructificación (EF) en la especie Nothoscordum gramineum. Cuatro parches dedistintas densidades fueron delimitados y el tamaño de las flores de la mitad de los individuos presentes en cada parchefue reducido manualmente. Los resultados demuestran que tanto la ER como EF son significativamente mayores en losindividuos con flores más grandes. Demostramos además que la densidad tiene un efecto positivo sobre el ER,principalmente en las flores de mayor tamaño. EF alcanzó valores máximos en los parches de densidades intermedias,disminuyendo en los de mayor densidad. Los resultados sugieren que el tamaño floral fue el atributo medido másimportante sobre la adecuación biológica de N. gramineum, debido a que los individuos de flores cortadas no respondieroncon la variación de la densidad. Nuestros resultados no permiten apoyar la hipótesis que en parches de alta densidad,los rasgos florales tendrían menor importancia, puesto que siempre ER y EF fueron mayores en flores enteras sinconsiderar la densidad, y las flores cortadas no demostraron un aumento en ER o EF con el aumento de la densidad

Biological invasions in terrestrial Antarctica: what is the current status and can we respond?

Until recently the Antarctic continent and Peninsula have been little impacted by non-native species, compared to other regions of the Earth. However, reports of species introductions are increasing as awareness of biological invasions as a major conservation threat, within the context of increased human activities and climate change scenarios, has grown within the Antarctic community. Given the recent increase in documented reports, here we provide an up-to-date inventory of known terrestrial non-native species introductions, including those subsequently removed since the 1990s, within the Antarctic Treaty area. This builds on earlier syntheses of records published in the mid-2000s, which focused largely on the sub-Antarctic islands, given the dearth of literature available at that time from the continental and maritime Antarctic regions. Reports of non-native species established in the natural environment (i.e. non-synanthropic) are mainly located within the Antarctic Peninsula region and Scotia Arc, with Deception Island, South Shetland Islands, the most impacted area. Non-native plants have generally been removed from sites of introduction, but no established invertebrates have yet been subject to any eradication attempt, despite a recent increase in reports. Legislation within the Protocol on Environmental Protection to the Antarctic Treaty has not kept pace with environmental best practice, potentially presenting difficulties for the practical aspects of non-native species control and eradication. The success of any eradication attempt may be affected by management practices and the biology of the target species under polar conditions. Practical management action is only likely to succeed with greater co-operation and improved communication and engagement by nations and industries operating in the region

Inducción de trepado en Ipomoea purpurea (L.) Roth.: umbral de la respuesta e inducción por volátiles y por daño por caracoles

Twining in some Convolvulaceae can be induced by leaf damage and jasmonic acid application. This induced response is believed to reduce the likelihood of future leaf damage and it is limited by drought. This response has been detected in the Convolvulaceae family using artifi cial damage. The mechanisms and ecological implications of this response are still unknown. In this study was tested if the induced twining requires a threshold level and if it is induced by volatiles and/or by snail damage. Three separated greenhouse experiments were conducted in order to test the induced twining in Ipomoea purpurea (Convolvulaceae) by applying different levels of artifi cial damage (0, 1, 5, 10 perforations to the leaves), volatiles (ground leaves) and natural damage by snails. Plants receiving the two higher damage levels twined faster than the individuals exposed to the two lower damage levels. Plants exposed to grounded leaves (volatiles) twined faster than control plants. Finally, twining was induced by snail damage more than in undamaged plants. Most growth traits did not change in any treatment. Twining in I. pupurea can be induced by artifi cial or natural damage, and also by volatiles emitted by damaged leaves of neighbor plants, making the induced twining an ecologically relevant response.El trepado en algunas Convolvulaceae puede ser inducido por el daño foliar y por la aplicación de ácido jasmónico. Esta respuesta inducida se cree que reduce la probabilidad de daño futuro a las hojas y está limitada por la sequía. Se ha detectado esta respuesta en la familia Convolvulaceae usando daño artificial. Los mecanismos y las implicancias ecológicas de esta respuesta aún se desconocen. En este trabajo, se evaluó si la inducción de trepado requiere un nivel umbral de daño y si se puede inducir por volátiles y/o por daño por caracoles. Se realizaron tres experimentos independientes donde se registró la inducción de trepado en Ipomoea purpurea (Convolvulaceae) aplicando diferentes niveles de daño (0, 1, 5, 10 perforaciones a las hojas), volátiles (hojas molidas) y daño natural por caracoles. Las plantas expuestas a los dos más altos niveles de daño artifi cial se enroscaron más rápido que las expuestas a los dos niveles menores de daño. Las plantas expuestas a hojas molidas (volátiles) se enroscaron más rápido que las plantas control. Finalmente, el trepado se indujo con el daño por caracoles, siendo más rápido que en las plantas no dañadas. La mayoría de los rasgos de crecimiento no se alteraron en ningún tratamiento. El trepado en I. purpurea puede ser inducido por daño artifi cial o natural, como también por volátiles emitididos por hojas dañadas de plantas vecinas, convirtiendo la inducción de trepado en una respuesta inducida ecológicamente relevante

¿Pueden los rasgos hidráulicos ayudar a explicar los límites de distribución actual en dos especies de Nothofagus en los Andes de Chile?

The Andes of central Chile is a geographical gradient with a marked variation in its climatic conditions. Along its slopes, are distributed the evergreen Nothofagus dombeyi and deciduous Nothofagus pumilio species that show differences in their leaf habits, range extensions, and in their limits of latitudinal distribution. Plant ecology proposes that unfavorable climatic conditions are limiting factors that determine the tree species distributions and that the functional hydraulic traits responses allow understanding the mechanisms underlying the current distribution of them. We hypothesize that both species will have lower mean values of K L and K S in populations near to distribution limits compared with middle populations due that unfavorable climatic conditions are predominant in the latitudinal range limits. We quantify in situ the leaf (K L ) and xylem (K S ) specific hydraulic conductivities in populations of N. dombeyi and N. pumilio near their northern and southern limits of distribution as well as in a middle population along Chilean Andes. Results showed that both species had lower mean values in populations near northern and southern limits compared to populations distributed in middle sites. Also, we found that the hydraulic performance population of N. pumilio distributed in the middle site had higher than N. dombeyi. We concluded that lower hydraulic conductivity associated with distribution limits for both study species implies a lower probability of being affected by embolism, independently of their leaf habits, showing a functional hydraulic convergence to low water availability orLos Andes de Chile es un gradiente geográfico latitudinal con una marcada variación de sus condiciones climáticas. A lo largo de sus laderas se distribuyen la siempreverde Nothofagus dombeyi y la decidua Nothofagus pumilio, las cuales difieren en sus hábitos foliares, extensión de sus rangos y límites de distribución latitudinal. La ecología vegetal propone que las condiciones climáticas desfavorables son factores limitantes en la distribución de las especies arbóreas, y que las respuestas de los rasgos funcionales hidráulicos permiten entender los mecanismos a los que subyace la distribución actual de estas. Hipotetizamos que ambas especies tendrán bajos valores promedio de la conductividad hidráulica específica de hoja (K L ) y del xilema (K S ) en poblaciones cercanas a sus límites de distribución comparado con poblaciones centrales, ya que las primeras tienen predominantemente condiciones climáticas desfavorables. Cuantificamos in situ la K L y K S , en poblaciones cercanas a los límites septentrionales y meridionales como una población central para N. dombeyi y N. pumilio a lo largo de los Andes de Chile. Los resultados muestran que ambas especies el K L y K S tuvieron valores promedios más bajos en sus sitios septentrionales y meridionales comparados con sus sitios centrales. Además, el desempeño hidráulico de los individuos de N. pumilio del sitio central fue mayor que N. dombeyi. Concluimos que una menor conductividad hidráulica asociada a los límites de distribución para ambas especies estudiadas, implica una menor probabilidad de verse afectadas por el embolismo, independiente de su hábito foliar, mostrando una convergencia funcional hidráulica frente a menor disponibilidad de agua o frío

A Systematic Review on the Effects of Epichloë Fungal Endophytes on Drought Tolerance in Cool-Season Grasses

Symptomless fungal endophytes in the genus Epichloë are repeatedly mentioned to increase tolerance of cool-season grasses to a wide range of environmental stress factors, mainly drought. However, the generality of this idea is challenged because (i) most studies have been conducted on two economically important forage grasses {tall fescue [Festuca arundinacea (Schreb.) Dumort] and perennial ryegrass (Lolium perenne L.)}, (ii) endophyte-mediated mechanisms and effects on plant responses to drought have shown to be highly variable across species, and that (iii) symbiosis incidence in plant populations occurring in extremely arid environments is usually low. We question this idea by reviewing the existing information about Epichloë fungal endophyte effects on drought tolerance in cool-season grasses. We combined standard review, vote counting, and calculation of effect sizes to synthesize the literature, identify information gaps, and guide future research. The total number of studies was higher for domesticated than for wild species, a ratio that was balanced when papers with data quality for effect size calculus were considered. After the drought, endophyte-infected plants accumulated more aboveground and belowground biomass than non-infected counterparts, while no effect on tillering was observed. However, these effects remained significant for wild (even on tillering) but not for domesticated species. Interestingly, despite the continuous effort in determining physiological mechanisms behind the endophyte effects, no studies evaluated plant fecundity as a measure of ecological fitness nor vital rates (such as survival) as to escalate individual-level variables to population. Together with the high variability in results, our work shows that generalizing a positive effect of fungal endophytes in plant tolerance to drought may be misleading. Future studies combining field surveys with manipulative experiments would allow us to unravel the role of fungal endophytes in plant adaptation by considering the evolutionary history of species and populations to the different ecological contexts.Fil: Dedcunta, Facundo Alcides. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Perez, Luis Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Malinowski, Dariusz P.. Texas A&M University; Estados UnidosFil: Molina Montenegro, Marco A.. Universidad de Talca; Chile. Universidad Católica del Norte; ChileFil: Gundel, Pedro Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Talca; Chil

Antarctic root endophytes improve physiological performance and yield in crops under salt stress by enhanced energy production and Na+ sequestration

Molina Montenegro, Marco A. Universidad de Talca. Instituto de Ciencias Biológicas. Campus Talca, Chile.Acuña Rodríguez, Ian S. Universidad de Talca. Instituto de Ciencias Biológicas. Campus Talca, Chile.Torres Díaz, Cristian. Universidad del Bío-Bío. Departamento de Ciencias Básicas. Grupo de Biodiversidad y Cambio Global (BCG). Chillán, Chile.Gundel, Pedro Emilio. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA). Buenos Aires, Argentina.Dreyer, Ingo. Universidad de Talca. Facultad de Ingeniería. Centro de Bioinformática y Simulación Molecular (CBSM). Campus Talca, Chile.10Climatic change is pointed as one of the major challenges for global food security. Based on current models of climate change, reduction in precipitations and in turn, increase in the soil salinity will be a sharp constraint for crops productivity worldwide. In this context, root fungi appear as a new strategy to improve plant ecophysiological performance and crop yield under abiotic stress. In this study, we evaluated the impact of the two fungal endophytes Penicillium brevicompactum and P. chrysogenum isolated from Antarctic plants on nutrients and Na+ contents, net photosynthesis, water use efficiency, yield and survival in tomato and lettuce, facing salinity stress conditions. Inoculation of plant roots with fungal endophytes resulted in greater fresh and dry biomass production, and an enhanced survival rate under salt conditions. Inoculation of plants with the fungal endophytes was related with a higher up/down-regulation of ion homeostasis by enhanced expression of the NHX1 gene. The two endophytes diminished the effects of salt stress in tomato and lettuce, provoked a higher efficiency in photosynthetic energy production and an improved sequestration of Na+ in vacuoles is suggested by the upregulating of the expression of vacuolar NHX1 Na+/H+ antiporters. Promoting plant-beneficial interactions with root symbionts appears to be an environmentally friendly strategy to mitigate the impact of climate change variables on crop production

Fungal Endophytes Exert Positive Effects on Colobanthus quitensis Under Water Stress but Neutral Under a Projected Climate Change Scenario in Antarctica

Functional symbiosis is considered one of the successful mechanisms by which plants that inhabit extreme environment improve their ability to tolerate different types of stress. One of the most conspicuous type of symbiosis is the endophyticism. This interaction has been noted to play a role in the adaptation of the native vascular plant Colobanthus quitensis to the stressful environments of Antarctica, characterized by low temperatures and extreme aridity. Projections of climate change for this ecosystem indicate that abiotic conditions will be less limiting due to an increase in temperature and water availability in the soil. Due to this decrease in stress induced by the climate change, it has been suggested that the positive role of fungal endophytes on performance of C. quitensis plants would decrease. In this study, we evaluated the role of endophytic fungi on osmoprotective molecules (sugar production, proline, oxidative stress) and gene expression (CqNCED1, CqABCG25, and CqRD22) as well as physiological traits (stomatal opening, net photosynthesis, and stomatal conductance) in individuals of C. quitensis. Individual plants of C. quitensis with (E+) and without (E−) endophytic fungi were exposed to simulated conditions of increased water availability (W+), having the current limiting water condition (W−) in Antarctica as control. The results reveal an endophyte-mediated lower oxidative stress, higher production of sugars and proline in plants. In addition, E+ plants showed differential expressions in genes related with drought stress response, which was more evident in W− than in W+. These parameters corresponded with increased physiological mechanisms such as higher net photosynthesis, stomatal opening and conductance under presence of endophytes (E+) as well as the projected water condition (W+) for Antarctica. These results suggest that the presence of fungal endophytes plays a positive role in favoring tolerance to drought in C. quitensis. However, this positive role would be diminished if the stress factor is relaxed, suggesting that the role of endophytes could be less important under a future scenario of climate change in Antarctica with higher soil water availability.Fil: Hereme, Rasme. Universidad de Talca; ChileFil: Morales Navarro, Samuel. Universidad de Talca; ChileFil: Ballesteros, Gabriel. Universidad de Talca; ChileFil: Barrera, Andrea. Universidad de Talca; ChileFil: Ramos, Patricio. Universidad de Talca; ChileFil: Gundel, Pedro Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Molina Montenegro, Marco A.. Universidad de Talca; Chil

Fungal Endophytes Enhance the Photoprotective Mechanisms and Photochemical Efficiency in the Antarctic Colobanthus quitensis (Kunth) Bartl. Exposed to UV-B Radiation

Antarctic plants have developed mechanisms to deal with one or more adverse factors which allow them to successfully survive such extreme environment. Certain effective mechanisms to face adverse stress factors can arise from the establishment of functional symbiosis with endophytic fungi. In this work, we explored the role of fungal endophytes on host plant performance under high level of UV-B radiation, a harmful factor known to damage structure and function of cell components. In order to unveil the underlying mechanisms, we characterized the expression of genes associated to UV-B photoreception, accumulation of key flavonoids, and physiological responses of Colobanthus quitensis plants with (E+) and without (E−) fungal endophytes, under contrasting levels of UV-B radiation. The deduced proteins of CqUVR8, CqHY5, and CqFLS share the characteristic domains and display high degrees of similarity with other corresponding proteins in plants. Endophyte symbiotic plants showed lower lipid peroxidation and higher photosynthesis efficiency under high UV-B radiation. In comparison with E−, E+ plants showed lower CqUVR8, CqHY5, and CqFLS transcript levels. The content of quercetin, a ROS-scavenger flavonoid, in leaves of E- plants exposed to high UV-B was almost 8-fold higher than that in E+ plants 48 h after treatment. Our results suggest that endophyte fungi minimize cell damage and boost physiological performance in the Antarctic plants increasing the tolerance to UV-B radiation. Fungal endophytes appear as fundamental biological partners for plants to cope with the highly damaging UV-B radiation of Antarctica.Fil: Barrera, Andrea. Universidad de Talca; ChileFil: Hereme, Rasme. Universidad de Talca; ChileFil: Ruiz Lara, Simon. Universidad de Talca; ChileFil: Larrondo, Luis. Pontificia Universidad Católica de Chile; ChileFil: Gundel, Pedro Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Pollmann, Stephan. Universidad Politécnica de Madrid; EspañaFil: Molina Montenegro, Marco A.. Universidad de Talca; ChileFil: Ramos, Patricio. Universidad de Talca; Chil

Epichloë Fungal Endophytes Influence Seed-Associated Bacterial Communities

Seeds commonly harbour diverse bacterial communities that can enhance the fitness of future plants. The bacterial microbiota associated with mother plant’s foliar tissues is one of the main sources of bacteria for seeds. Therefore, any ecological factor influencing the mother plant’s microbiota may also affect the diversity of the seed’s bacterial community. Grasses form associations with beneficial vertically transmitted fungal endophytes of genus Epichloë. The interaction of plants with Epichloë endophytes and insect herbivores can influence the plant foliar microbiota. However, it is unknown whether these interactions (alone or in concert) can affect the assembly of bacterial communities in the produced seed. We subjected Lolium multiflorum plants with and without its common endophyte Epichloë occultans (E+, E-, respectively) to an herbivory treatment with Rhopalosiphum padi aphids and assessed the diversity and composition of the bacterial communities in the produced seed. The presence of Epichloë endophytes influenced the seed bacterial microbiota by increasing the diversity and affecting the composition of the communities. The relative abundances of the bacterial taxa were more similarly distributed in communities associated with E+ than E- seeds with the latter being dominated by just a few bacterial groups. Contrary to our expectations, seed bacterial communities were not affected by the aphid herbivory experienced by mother plants. We speculate that the enhanced seed/seedling performance documented for Epichloë-host associations may be explained, at least in part, by the Epichloë-mediated increment in the seed-bacterial diversity, and that this phenomenon may be applicable to other plant-endophyte associations.Fil: Bastías, Daniel A.. Grasslands Research Centre; Nueva ZelandaFil: Bubica Bustos, Ludmila Micaela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Jáuregui, Ruy. Grasslands Research Centre; Nueva ZelandaFil: Barrera, Andrea. Universidad de Talca; ChileFil: Acuña Rodríguez, Ian S.. Universidad de Talca; ChileFil: Molina Montenegro, Marco A.. Universidad de Talca; Chile. Universidad Católica del Norte; Chile. Universidad Católica del Maule; ChileFil: Gundel, Pedro Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Talca; Chil

Occurrence of Alkaloids in Grass Seeds Symbiotic With Vertically-Transmitted Epichloë Fungal Endophytes and Its Relationship With Antioxidants

Host organisms can acquire new functional traits through symbiosis. Seed-transmitted Epichloë fungal endophytes are known to protect host plants against herbivores and increase tolerance to abiotic stresses by alkaloids and antioxidants, respectively (currencies of mutualism). Whereas, alkaloids are fungal products with demonstrated effects at plant vegetative stage, few studies have focused on alkaloids in seeds. We assessed the occurrence of fungal alkaloids and determined their concentrations in seeds of two host grasses, Festuca rubra and Lolium multiflorum. Then, we sought for a relationship with the antioxidants tocochromanols and glutathione, which are involved in the control of oxidative stress. Different alkaloids were detected depending on the species and plant genotype. Most notably, loline alkaloids were not detected in F. rubra seeds, whereas ergovaline and peramine were absent in L. multiflorum. In F. rubra, ergovaline concentration was dependent on the maternal line in interaction with the production year, diminishing in seeds after 1 year of storage. The exposure of L. multiflorum plants to ozone had no effect on the seed concentration of lolines. There was a significant positive relationship between the concentrations of ergovaline and tocochromanols in both species, and between ergovaline concentration and EGSSG/2GSH (glutathione half-cell reduction potential) in RAB maternal line of F. rubra. These results suggest that alkaloid and antioxidants have a close association in seeds of host grasses, and that the alkaloid bioactivity could be related with the antioxidant capacity to control stress. This has important implications for the ecology of partner species, thus supporting its consideration for further research