Phenotypic variation in leaf photosynthetic traits, leaf area index, and carbon discrimination of field-grown wheat genotypes and their relationship with yield performance in Mediterranean environments.

MAIN CONCLUSION: Leaf water potential, gas exchange, and chlorophyll fluorescence exhibited significant differences among genotypes, high environmental effects, but low heritability. The highest-yielding and drought-tolerant genotypes presented superior harvest index and grain weight, compared to drought-susceptible ones. Physiological phenotyping can help identify useful traits related to crop performance under water-limited conditions. A set of fourteen bread wheat genotypes with contrasting grain yield (GY) was studied in eight Mediterranean environments in Chile, resulting from the combination of two sites (Cauquenes and Santa Rosa), two water conditions (rainfed-WL and irrigated-WW), and four growing seasons (2015-2018). The objectives were to (i) evaluate the phenotypic variation of leaf photosynthetic traits after heading (anthesis and grain filling) in different environments; (ii) analyze the relationship between GY and leaf photosynthetic traits and carbon isotope discrimination (Δ13C); and (iii) identify those traits that could have a greater impact in the determination of tolerant genotypes under field conditions. Agronomic traits exhibited significant genotypic differences and genotype × environment (GxE) interaction. The average GY under the WW condition at Santa Rosa was 9.2 Mg ha-1 (range 8.2-9.9 Mg ha-1) and under the WL condition at Cauquenes was 6.2 Mg ha-1 (range 3.7-8.3 Mg ha-1). The GY was closely related to the harvest index (HI) in 14 out of 16 environments, a trait exhibiting a relatively high heritability. In general terms, the leaf photosynthetic traits presented low GxE interaction, but high environmental effects and low heritability, except for the chlorophyll content. The relationships between GY and leaf photosynthetic traits were weaker when performed across genotypes in each environment, indicating low genotypic effects, and stronger when performed across environments for each genotype. The leaf area index and Δ13C also presented high environmental effects and low heritability, and their correlations with GY were influenced by environmental effects. The highest-yielding and drought-tolerant genotypes presented superior HI and grain weight, but no clear differences in leaf photosynthetic traits or Δ13C, compared to drought-susceptible ones. It seems that the phenotypic plasticity of agronomic and leaf photosynthetic traits is very important for crop adaptation to Mediterranean environments.

Thermal Imaging Reliability for Estimating Grain Yield and Carbon Isotope Discrimination in Wheat Genotypes: Importance of the Environmental Conditions.

Canopy temperature (Tc) by thermal imaging is a useful tool to study plant water status and estimate other crop traits. This work seeks to estimate grain yield (GY) and carbon discrimination (Δ13C) from stress degree day (SDD = Tc - air temperature, Ta), considering the effect of a number of environmental variables such as the averages of the maximum vapor pressure deficit (VPDmax) and the ambient temperature (Tmax), and the soil water content (SWC). For this, a set of 384 and a subset of 16 genotypes of spring bread wheat were evaluated in two Mediterranean-climate sites under water stress (WS) and full irrigation (FI) conditions, in 2011 and 2012, and 2014 and 2015, respectively. The relationship between the GY of the 384 wheat genotypes and SDD was negative and highly significant in 2011 (r2 = 0.52 to 0.68), but not significant in 2012 (r2 = 0.03 to 0.12). Under WS, the average GY, Δ13C, and SDD of wheat genotypes growing in ten environments were more associated with changes in VPDmax and Tmax than with the SWC. Therefore, the amount of water available to the plant is not enough information to assume that a particular genotype is experiencing a stress condition.

Broad immunogenic spectrum of monovalent and trivalent foot-and-mouth disease virus vaccines containing O1 campos, A24 cruzeiro and A Argentina 2001 strains against circulating viral lineages in cattle and pigs.

FMD remains endemic in many Asian and African countries where multiple variants of serotypes O and A, among others, currently circulate. Due to lack of cross-protection between serotypes and incomplete protection between some strains even within a serotype, an important challenge for the application of effective vaccination programs is to select highly immunogenic and widely cross-reactive vaccine strains. Adaptation of a candidate field virus for use as a vaccine can be quite complex, so that whenever possible, the use of well-established vaccine viruses could have enormous advantages. FMD vaccine strains harmonized for use in South America have shown excellent results in FMD control, not only in the region, where it is still used systematically as a preventive measure, but also more recently in some Asian countries. To gain further insight into the immunogenic spectrum of these strains, VN tests (VNT) were performed with sera from cattle and/or pigs vaccinated with monovalent (type O) or trivalent (types O and A) formulations against 122 type O and 32 type A field viruses isolated from 35 countries in Asia and Africa, belonging to different lineages. Almost all VNT titers obtained were within the expected protective level, indicating the wide immunogenic spectrum of high potency FMD vaccines formulated with O1 Campos, A24 Cruzeiro and A Argentina 2001 South American vaccine strains belonging to EURO-SA topotypes against currently active viruses from other topotypes. These in vitro results are in line with previously reported in vivo challenge tests in pigs against three A/ASIA/Sea-97 isolates and two isolates belonging to type O lineages O/SEA/Mya-98 and O/ME-SA/Ind-2001e.

Exploring plant responses to abiotic stress by contrasting spectral signature changes.

In this study, daily changes over a short period and diurnal progression of spectral reflectance at the leaf level were used to identify spring wheat genotypes (Triticum aestivum L.) susceptible to adverse conditions. Four genotypes were grown in pots experiments under semi-controlled conditions in Chile and Spain. Three treatments were applied: i) control (C), ii) water stress (WS), and iii) combined water and heat shock (WS+T). Spectral reflectance, gas exchange and chlorophyll fluorescence measurements were performed on flag leaves for three consecutive days at anthesis. High canopy temperature ( H CT ) genotypes showed less variability in their mean spectral reflectance signature and chlorophyll fluorescence, which was related to weaker responses to environmental fluctuations. While low canopy temperature ( L CT ) genotypes showed greater variability. The genotypes spectral signature changes, in accordance with environmental fluctuation, were associated with variations in their stomatal conductance under both stress conditions (WS and WS+T); L CT genotypes showed an anisohydric response compared that of H CT , which was isohydric. This approach could be used in breeding programs for screening a large number of genotypes through proximal or remote sensing tools and be a novel but simple way to identify groups of genotypes with contrasting performances.

Genetic Yield Gains and Changes in Morphophysiological-Related Traits of Winter Wheat in Southern Chilean High-Yielding Environments.

Both the temperate-humid zone and the southern part of the Mediterranean climate region of Chile are characterized by high wheat productivity. Study objectives were to analyze the yield potential, yield progress, and genetic progress of the winter bread wheat (Triticum aestivum L.) cultivars and changes in agronomic and morphophysiological traits during the past 60 years. Thus, two field experiments: (a) yield potential and (b) yield genetic progress trials were conducted in high-yielding environments of central-southern Chile during the 2018/2019 and 2019/2020 seasons. In addition, yield progress was analyzed using yield historical data of a high-yielding environment from 1957 to 2017. Potential yield trials showed that, at the most favorable sites, grain yield reached ∼20.46 Mg ha-1. The prolonged growing and grain filling period, mild temperatures in December-January, ample water availability, and favorable soil conditions explain this high-potential yield. Yield progress analysis indicated that average grain yield increased from 2.70 Mg ha-1 in 1959 to 12.90 Mg ha-1 in 2017, with a 128.8 kg ha-1 per-year increase due to favorable soil and climatic conditions. For genetic progress trials, genetic gain in grain yield from 1965 to 2019 was 70.20 kg ha-1 (0.49%) per year, representing around 55% of the yield progress. Results revealed that the genetic gains in grain yield were related to increases in biomass partitioning toward reproductive organs, without significant increases in Shoot DW production. In addition, reducing trends in the NDVI, the fraction of intercepted PAR, the intercepted PAR (form emergence to heading), and the RGB-derived vegetation indices with the year of cultivar release were detected. These decreases could be due to the erectophile leaf habit, which enhanced photosynthetic activity, and thus grain yield increased. Also, senescence of bottom canopy leaves (starting from booting) could be involved by decreasing the ability of spectral and RGB-derived vegetation indices to capture the characteristics of green biomass after the booting stage. Contrary, a positive correlation was detected for intercepted PAR from heading to maturity, which could be due to a stay-green mechanism, supported by the trend of positive correlations of Chlorophyll content with the year of cultivar release.

Genotypic variations in leaf and whole-plant water use efficiencies are closely related in bread wheat genotypes under well-watered and water-limited conditions during grain filling.

Wheat plants growing under Mediterranean rain-fed conditions are exposed to water deficit, particularly during the grain filling period, and this can lead to a strong reduction in grain yield (GY). This study examines the effects of water deficit after during the grain filling period on photosynthetic and water-use efficiencies at the leaf and whole-plant level for 14 bread wheat genotypes grown in pots under glasshouse conditions. Two glasshouse experiments were conducted, one in a conventional glasshouse at the Universidad de Talca, Chile (Experiment 1), and another at the National Plant Phenomics Centre (NPPC), Aberystwyth, UK (Experiment 2), in 2015. Plants were grown under well-watered (WW) and water-limited (WL) conditions during grain filling. The reductions in leaf water potential (Ψ), net CO2 assimilation (An) and stomatal conductance (gs) due to water deficit were 79, 35 and 55%, respectively, during grain filling but no significant differences were found among genotypes. However, chlorophyll fluorescence parameters (as determined on dark-adapted and illuminated leaves) and chlorophyll content (Chl) were significantly different among genotypes, but not between water conditions. Under both water conditions, An presented a positive and linear relationship with the effective photochemical quantum yield of Photosystem II (Y(II)) and the maximum rate of electron transport (ETRmax), and negative with the quantum yield of non-photochemical energy conversion in Photosystem II (Y(NPQ)). The relationship between An and Chl was positive and linear for both water conditions, but under WL conditions An tended to be lower at any Chl value. Both, instantaneous (An/E) and intrinsic (An/gs) water-use efficiencies at the leaf level exhibited a positive and linear relationship with plant water-use efficiency (WUEp = plant dry weight/water use). Carbon discrimination (Δ13C) in kernels presented a negative relationship with WUEp, at both WW and WL conditions, and a positive relationship with GY. Our results indicate that during grain filling wheat plants face limitations to the assimilation process due to natural senesce and water stress. The reduction in An and gs after anthesis in both water conditions was mainly due a decline in the chlorophyll content (non-stomatal limitation), whereas the observed differences between water conditions were mainly due to a stomatal limitation.

Metabolic Effects of Elevated CO2 on Wheat Grain Development and Composition.

The increase in the atmospheric CO2 concentration is predicted to influence wheat production and grain quality and nutritional properties. In the present study, durum wheat (Triticum durum Desf. cv. Sula) was grown under two different CO2 (400 versus 700 µmol mol-1) concentrations to examine effects on the crop yield and grain quality at different phenological stages (from grain filling to maturity). Exposure to elevated CO2 significantly increased aboveground biomass and grain yield components. Growth at elevated CO2 diminished the elemental N content as well as protein and free amino acids, with a typical decrease in glutamine, which is the most represented amino acid in grain proteins. Such a general decrease in nitrogenous compounds was associated with altered kinetics of protein accumulation, N remobilization, and N partitioning. Our results highlight important modifications of grain metabolism that have implications for its nutritional quality.

Exploring Agronomic and Physiological Traits Associated With the Differences in Productivity Between Triticale and Bread Wheat in Mediterranean Environments.

In Mediterranean climates soil water deficit occurs mainly during the spring and summer, having a great impact on cereal productivity. While previous studies have indicated that the grain yield (GY) of triticale is usually higher than bread wheat (Triticum aestivum L.), comparatively little is known about the performance of these crops under water-limited conditions or the physiological traits involved in the different yields of both crops. For this purpose, two sets of experiments were conducted in order to compare a high yielding triticale (cv. Aguacero) and spring wheat (cvs. Pandora and Domo). The first experiment, aiming to analyze the agronomic performance, was carried out in 10 sites located across a wide range of Mediterranean and temperate environments, distributed between 33°34' and 38°41' S. The second experiment, aiming to identify potential physiological traits linked to the different yields of the two crops, was conducted in two Mediterranean sites (Cauquenes and Santa Rosa) in which crops were grown under well-watered (WW) and water-limited (WL) conditions. The relationship between GY and the environmental index revealed that triticale exhibited a higher regression coefficient (Finlay and Wilkinson slope), indicating a more stable response to the environment, accompanied by higher yields than bread wheat. Harvest index was not significantly different between the two cereals, but triticale had higher kernels per spike (35%) and 1000 kernel weight (16%) than wheat, despite a lower number of spikes per square meter. The higher yield of triticale was linked to higher values of chlorophyll content, leaf net photosynthesis (An), the maximum rate of electron transport (ETRmax), the photochemical quantum yield of PSII [Y(II)] and leaf water-use efficiency. GY was positively correlated with Ci at anthesis and Δ13C in both species, as well as with gs at anthesis in triticale, but negatively correlated with non-photochemical fluorescence quenching and quantum yield of non-photochemical energy conversion at grain filling in wheat. These results revealed that triticale presented higher photosynthetic rates that contributed to increase plant growth and yield in the different environments, whereas wheat showed higher photoprotection system in detriment of assimilate production.

Cirugía de hombro en posición silla de playa: estrategias y recomendaciones para la prevención de complicaciones isquémicas / Strategies and recommendations for the prevention of ischemic complications in beach chair position for shoulder surgery

Beach chair position is require for Shoulder surgery frequently for proper resolution. The stroke associated with shoulder surgery is a rare complication and probably underreported. The objective of this article is to review the pathophysiology of the ischemic damage associated with beach chair position, learn about strategies and develop recommendations to minimize risks.

La cirugía de hombro (CH), requiere y requerirá colocar a los pacientes en la posición en silla de playa (PSP), cada vez con mayor frecuencia para su adecuada resolución. El asociado a CH, es una complicación poco frecuente y probablmente subreportada. El objetivo de esta revisión, es repasar la fisiopatología del daño isquémico asociado a PSP, conocer estrategias y elaborar recomedaciones destinadas a minimizar riesgos.

Emergence of antigenic variants of Foot-and-Mouth Disease Virus serotype O in Ecuador and preliminary evaluation of a field strain as a vaccine candidate.

Foot-and-Mouth Disease Virus serotype O has been circulating regularly throughout most provinces of Ecuador, one of the two South American countries that still remain endemic, although satisfactory vaccination coverage was reported. This study concentrates in the characterization of isolates collected during 2008-2011, focusing particularly on the antigenic and immunogenic relationships of the field viruses with the O1/Campos vaccine strain in use in the region and with an experimental vaccine formulated with a representative strain of the 2010 epidemic. The results established that antigenically divergent variants poorly protected by the vaccine in use emerged and co-circulated in a limited period of time. A monovalent vaccine formulated with the representative 2010 strain elicited high antibody titers and protected against challenge with homologous virus. In addition, cross-reactive antibodies to predominant viruses in the region were established. In overall this study indicates the ability of the virus to diversify under field conditions in which a vaccine strain with poor match is applied, and the potential of the selected 2010 field virus as a vaccine candidate for incorporation into strategic antigen banks and/or for addition to current formulations for systematic vaccination, in order to prevent the emergence of even more divergent isolates in the future.

Pronóstico de duración de títulos protectores anti-HBs ag en trabajadores de la salud del Perú luego de 6 años de vacunados / Prognosis of the protection against hepatitis B in peruviana health care workers after six years of vaccination

Siguiendo las recomendaciones de la Organización Mundial de la Salud (OMS) y el Centro para el control de las Enfermedades (CDC) en la protección de los trabajadores de la salud contra la hepatitis viral tipo B (VHB), en 1993 el Instituto Peruano de Seguro Social (Hoy ESSALUD), 1993 orientó la vacunación del personal de riesgo en los 4 hospitales nacionales, utilizando la vacuna cuabna Heberbiovac HB ( 20 mg, esquema 0.1. 2 meses). Nos propusimos evaluar la persistencia de los anticuerpos en los vacunados después de seis años de la inmunización y la posible existencia de marcadores de infección por el virus B. Se estudiaron los sueros de 144 trabajdores de la salud, para una cobertura de 70,24 por ciento con relación a los 203 seroprotegidos en el estudio inicial. Para la detección de los marcadores en el suero se emplearon métodos inmunoenzimáticos comerciales. El antecedente fue el HBsAg y el anti-HBc fueron negativos en todas las muestras serológicas, por lo que afirmamos que en ninguno de los vacunados hubo evidencia de infección por este virus. Luego de 6 años anti-HBs fue positivo estando todos seroconvertidos, con seroprotección e hiperrespuesta de 91,6 y 43,7 por ciento respectivamente. Si bien el tiempo de vida media del antiHB (t 1/2) es de 3 años, pronosticándose que los niveles de anticuerpos serán superiores a 10 Ul/L hasta después de 15 años de finalizado el esquema. Los menores de 40 años tuvieron niveles de seroprotección e hiperrespuesta significativamente mayores; manteniéndose las mujeres en categorías de respuesta superiores. Se recomienda evaluar la memoria post-refuerzo en los casos seroconvertidos, no seroprotegidos, y extender el trabajo de vacunación con EsSaluda otros hospitales del país.

Fujometría Doppler en la enfermedad hipertensiva severa del embarazo con retardo del crecimiento intrauterino / Doppler velocimetry in sever hypertensive disease of pregnancy with intrauterine growth retardation

Objetivo: Evaluar el rol del uso de la ultrasonografía Doppler de las arterias umbilical, uterina y cerebral media en el manejo de la enfermedad hipertensiva con retardo de crecimiento intrauterino y su asociación con resultados perinatales adversos. Material y métodos: En este estudio retrospectivo realizado en el centro de diagnóstico ecográfico Ecomed, se seleccionó 32 pacientes por presentar embarazo de riesgo alto, de un total de 158. A las pacientes se les realizó evaluación del bienestar fetal y Doppler de la arteria uterina, umbilical y cerebral, diagnosticándose RCIU y alteraciones del Doppler materno y fetal, por la presencia de notch en la arteria uterina uni o bilateral y por la disminución de la relación entre los índices de resistencia de la arteria cerebral/arteria umbilical, que normalmente es mayor que 1. Un Doppler de arteria umbilical con ausencia de diástole y un trazo con flujo en reversa fueron considerados signos ominosos para el feto. Se hizo estudios seriados para determinar la conducta obstétrica. Se hizo seguimiento de las pacientes hasta la interrupción del embarazo y posteriormente la evolución de los neonatos en la UCI de recién nacidos, para la determinación de la morbimortalidad neonatal. Conclusiones: La enfermedad hipertensiva del embarazo con retardo de crecimiento intrauterino es causa de morbimortalidad perinatal, cuando se asocia a velocimetría Doppler fetal anormal. La presencia de notch en la arteria uterina podría ser un elemento de diagnóstico para predecir toxemia y retardo de crecimiento intrauterino. La prueba de bienestar fetal modificado podría implementarse para obtener mejores resultados perinatales.

Tabaquismo en 12 ciudades chilenas / Smoking in 12 chilean cities

Se comunican los resultados de las encuestas sobre hábito de fumar practicadas en 1985 en 12 ciudades chilenas en muestras aleatorias de la población de cada ciudad con un total de 2.700 adultos investigados. La prevalencia global de fumadores ajustada al sexo y edad alcanzó al 31% de la población, oscilando entre valores de 41,8% en Viña del Mar y 38,1% en Valparaíso hasta 18,9% en Rancagua y 16,7% en Coronel. En las 12 ciudades estudiadas, la prevalencia masculina tendió a ser aproximadamente el doble de la observada en el sexo femenino. El tabaquismo se inicia en el período de adolescencia, observándose posteriormente las más altas prevalencias entre los 20 y 40 años (50% en varones y 30% en mujeres), con disminución posterior de la proporción de fumadores, paralelo al aumento de edad. El hábito de fumar aparece asociado directamente al ingreso familiar mensual y al nivel de escolaridad; no se observó correlación con el nivel de angustia y preocupaciones de las personas. Junto con discutir el significado de los hallazgos se plantean los elementos prioritarios de un sistema de control del tabaquismo en Chile

El organismo humano: funciones de nutrición, relación y control: libro 2

Contenido: Un sistema complejo y abierto. De la célula al organismo humano. La complejidad del organismo humano. Funciones del organismo humano. Nutrición. Funciones de relación y control...

Biología: el ecosistema y la preservación del ambiente: libro 5

Contenido: Individuo y población. La vida en comunidad. Ecosistemas. El hombre y el ambiente...