An enigma in the genetic responses of plants to salt stresses

Soil salinity is one of the main factors restricting crop production throughout the world. Various salt tolerance traits and the genes controlling these traits are responsible for coping with salinity stress in plants. These coping mechanisms include osmotic tolerance, ion exclusion, and tissue tolerance. Plants exposed to salinity stress sense the stress conditions, convey specific stimuli signals, and initiate responses against stress through the activation of tolerance mechanisms that include multiple genes and pathways. Advances in our understanding of the genetic responses of plants to salinity and their connections with yield improvement are essential for attaining sustainable agriculture. Although a wide range of studies have been conducted that demonstrate genetic variations in response to salinity stress, numerous questions need to be answered to fully understand plant tolerance to salt stress. This chapter provides an overview of previous studies on the genetic control of salinity stress in plants, including signaling, tolerance mechanisms, and the genes, pathways, and epigenetic regulators necessary for plant salinity tolerance

Hepatitis E virus in South America: The current scenario

Hepatitis E virus (HEV) is one of the most frequent causes of acute viral hepatitis of enteric transmission worldwide. In South America the overall epidemiology has been little studied, and the burden of the disease remains largely unknown.A research of all scientific articles about HEV circulation in South America until November 2017 was carried out. Human seroprevalences of HEV varied according to the studied population: blood donors presented prevalence rates ranging from 1.8 to 9.8%, while reports from HIV -infected individuals, transplant recipients and patients on hemodialysis showed higher prevalence rates. Only two cases of chronic hepatitis in solid-organ transplant patients from Argentina and Brazil have been described. Detection of HEV in the swine population is widely prevalent in the region.Anti-HEV antibodies have also been detected in other animal species; among them, antibody detection was recently documented in wild boars from Uruguay. Although scarce, studies focused on environmental and food HEV detection have shown viral presence in these kind of samples, highlighting possible transmission sources ofHEV in the continent . HEV genotype 3 was the most frequently detected in the region, with HEV genotype 1 detected only in Venezuela and Uruguay. HEV is widely distributed throughout South America, producing sporadic cases of acutehepatitis, but as a possible agent of chronic hepatitis. Finding the virus in humans, animals, environmental samples and food, show that it can be transmitted through many sources, alerting local governments and health systems to improve diagnosis and for the implementation of preventive measures.Fil: Pisano, María Belén. Universidad Nacional de Córdoba. Facultad de Medicina. Instituto de Virología Dr. J. M. Vanella; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Martinez Wassaf, Maribel Graciela. Universidad Nacional de Cordoba. Facultad de Medicina. Instituto de Virología; ArgentinaFil: Mirazo Villar, Santiago. Universidad de la República; UruguayFil: Fantilli, Anabella Clara. Universidad Nacional de Córdoba. Facultad de Medicina. Instituto de Virología Dr. J. M. Vanella; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Arbiza Rodonz, Juan Ramón. Universidad de la República; UruguayFil: Debes, José. University of Minnesota; Estados UnidosFil: Ré, Viviana Elizabeth. Universidad Nacional de Córdoba. Facultad de Medicina. Instituto de Virología Dr. J. M. Vanella; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin

PLoS ONE

e014841

First evidence of the Hepatitis E virus in environmental waters in Colombia

RESUMEN: Hepatitis E virus (HEV) is one of the main causes of acute viral hepatitis of enteric transmission. HEV has been detected in environmental samples in several countries from Europe and Asia, constituting a risk factor for waterborne infection. In Colombia, HEV has been identified in samples obtained from patients as well as from swine, but no environmental studies have been carried out. To determine if HEV is present in environmental waters, samples from the main source of drinking water plant and of wastewater system of eight municipalities and two villages of Antioquia state (North West Colombia), were collected between December 2012 and April 2014. The HEV genome was detected by RT-PCR in 23.3% (7/30) of the samples from the main source of drinking water plants and in 16.7% (5/30) from sewage. Viral concentrates obtained from three positive sewage samples were used to inoculate HepG2 cell cultures that were followed for one month; however, the viral genome was not detected in any cell culture. This study demonstrates the circulation of HEV in both source of drinking water plants and wastewater in Antioquia state, Colombia. The presence of HEV in environmental waters could be a risk for waterborne transmission in this population. The findings of the present study, together with the evidence of HEV circulation in human and swine in Colombia, should be consider by public health authorities for the development of surveillance programs and the inclusion of HEV infection diagnosis in the guidelines of viral hepatitis in the country. This is the first report of HEV in environmental samples in Colombia and the second one in Latin America

Nursery fertilization enhances survival and physiological status in Canary Island pine (Pinus canariensis) seedlings planted in a semiarid environment

We tested the hypothesis that fertilized containerized Pinus canariensis seedlings increases survival when planted in semiarid sites through the improvement of their physiological status during the establishment phase by an increment in root growth. Seedlings were cultured under two different regimes: traditional (in non-fertilized natural soil) and alternative (in fertilized peat). Morphological attributes and nitrogen content were measured before planting. Measurements of survival and growth in the plantation were made periodically for 2 years and physiological plant responses (leaf water potential, gas exchange and chlorophyll fluorescence) during the third summer after planting were tested and finally a set of plants were excavated to measure the same parameters as before planting. Seedlings cultivated using fertilized peat achieved the highest values for all of evaluated parameters. During the third dry season, big seedlings exhibited better physiological status. Therefore, enhanced root growth can result in better water uptake during the dry period thereby increasing survival and growth in the next few years after planting. A feed-back physiological model is proposed to explain P. canariensis establishment in a semiarid environment

Seedlings of two Acacia species from contrasting habitats show different photoprotective and antioxidative responses to drought and heatwaves

International audienceAbstractKey messageTwoAcaciaspecies adapted to contrasting habitats showed different response of photoprotective and antioxidative defence systems to imposed drought and heatwave.ContextPredicted increases in drought frequency and intense heatwaves are expected to lead to dieback of sensitive tree species. Stomatal closure restricts CO2 input into the leaf, resulting in imbalances between light energy-driven electron transport rate and electron consumption in the Calvin cycle. Reactive oxygen species formed under these circumstances have to be kept under control by photoprotective and antioxidative defence systems.AimsWe hypothesised that these defence systems behave differently in tree species from contrasting habitats.MethodsAcacia aneura (adapted to arid habitats) and Acacia melanoxylon (adapted to humid habitats) were exposed to two water treatments for 50 days including two short heatwave periods. Responses were assessed by gas exchange, chlorophyll fluorescence and concentrations of antioxidants (phyllodes, roots).ResultsPhotosynthesis and quantum yield of photochemistry decreased significantly in both Acacia species, especially after water was withheld in combination with the second heatwave episode. In phyllodes, the concentration of antioxidants remained unchanged until exposure to severe drought and heatwave conditions (except for A. melanoxylon where changes in glutathione concentration were observed prior to exposure to severe stress), but after water was withheld and the second heatwave occurred, oxidised forms of glutathione increased. After exposure to the second heatwave, well-watered seedlings of A. melanoxylon but not A. aneura increased ascorbic acid concentration in phyllodes. Under well-watered conditions, Acacia species also showed increased concentration of antioxidants in roots following heatwaves.ConclusionsBoth Acacia species showed photodamage to photosystem II (PSII) after water was withheld and the second heatwave imposed, but with more gradual response in A. aneura. Total concentration of investigated antioxidants increased in response to the first (A. melanoxylon) and second (A. aneura) heatwaves rather than drought stress alone