Drought affects the heat-hardening capacity of alpine plants as indicated by changes in xanthophyll cycle pigments, singlet oxygen scavenging, α-tocopherol and plant hormones

AbstractAlpine environments in Europe are increasingly affected by more erratic precipitation patterns, and more frequent drought and heat waves. Heat-hardening capacity is a key feature for survival of these abiotic stress factors, but it is poorly understood how heat and drought affect plant performance when combined. The main objectives of this study were (1) to determine maximum heat hardening capacity in 14 selected plant species and (2) to study how alpine plants respond to combined heat and drought stress compared to heat alone. (3) For risk assessment maximum leaf temperatures were measured in the field and (4) important methodological aspects of testing heat tolerance were evaluated. Heat hardening capacity was assessed by Tc, the heat threshold of photosystem II (PS II), and by heat tolerance tests based on visual inspection of leaf tissue damage or potential quantum efficiency of PS II (Fv/Fm). A purpose-built Heat Tolerance Testing System (HTTS) was used, which allows for controlled heat exposure of whole plants under nearly natural conditions. Additionally, in two species from contrasting habitats, Senecio incanus and Primula minima, the dynamics of heat hardening was studied during and after 8days exposure to heat (H), or to a combination of heat and severe drought (H+D) within a light-transmissive heat hardening chamber at the alpine field site. In both species, H treatment significantly increased heat tolerance (LT50), determined by the HTTS, to 58.0°C and 54.9°C, respectively, and was accompanied by elevated production of abscisic acid (ABA) and salicylic acid (SA), whereas jasmonic acid (JA) levels decreased. Under H+D the LT50 was only 56.5°C and 51.6°C, respectively, and levels of ABA were higher in S. incanus and SA lower in both species in comparison to H. Changes in xanthophyll cycle pigments, α-tocopherol and carotenoids:chlorophyll ratio were more pronounced in P. minima than in S. incanus. In P. minima both H and H+D significantly increased singlet oxygen (1O2) scavenging capacity, determined by electron paramagnetic resonance spectroscopy (EPR). In the field, the maximum half-hourly mean (HHM) leaf temperature of P. minima (32.2°C) was significantly lower than of S. incanus (46.5°C, a potentially harmful temperature). We conclude that the investigated species are well adapted to the prevailing temperature conditions in the field. They also possess an outstanding heat hardening capacity, but this can be curtailed when heat is combined with drought. As drought further increases leaf temperatures, the risk of suffering lethal heat damage of some species may increase in the future, particularly at south exposed, ruderal alpine sites with uncertain water supply

Gestión del conocimiento: perspectiva multidisciplinaria. Volumen 13

El libro “Gestión del Conocimiento. Perspectiva Multidisciplinaria”, Volumen 13 de la Colección Unión Global, es resultado de investigaciones. Los capítulos del libro, son resultados de investigaciones desarrolladas por sus autores. El libro es una publicación internacional, seriada, continua, arbitrada, de acceso abierto a todas las áreas del conocimiento, orientada a contribuir con procesos de gestión del conocimiento científico, tecnológico y humanístico. Con esta colección, se aspira contribuir con el cultivo, la comprensión, la recopilación y la apropiación social del conocimiento en cuanto a patrimonio intangible de la humanidad, con el propósito de hacer aportes con la transformación de las relaciones socioculturales que sustentan la construcción social de los saberes y su reconocimiento como bien público. El libro “Gestión del Conocimiento. Perspectiva Multidisciplinaria”, Volumen 13, de la Colección Unión Global, es resultado de investigaciones. Los capítulos del libro, son resultados de investigaciones desarrolladas por sus autores. El libro cuenta con el apoyo de los grupos de investigación: Universidad Sur del Lago “Jesús María Semprúm” (UNESUR) - Zulia – Venezuela; Universidad Politécnica Territorial de Falcón Alonso Gamero (UPTFAG) - Falcón – Venezuela; Universidad Politécnica Territorial de Mérida Kléber Ramírez (UPTM) - Mérida - Venezuela; Universidad Guanajuato (UG) - Campus Celaya - Salvatierra - Cuerpo Académico de Biodesarrollo y Bioeconomía en las Organizaciones y Políticas Públicas (CABBOPP) - Guanajuato – México; Centro de Altos Estudios de Venezuela (CEALEVE) - Zulia – Venezuela, Centro Integral de Formación Educativa Especializada del Sur (CIFE - SUR) - Zulia – Venezuela; Centro de Investigaciones Internacionales SAS (CEDINTER) - Antioquia – Colombia y diferentes grupos de investigación del ámbito nacional e internacional que hoy se unen para estrechar vínculos investigativos, para que sus aportes científicos formen parte de los libros que se publiquen en formatos digital e impreso

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Leaf anatomy of two reciprocally non-monophyletic mountain plants (Heliosperma spp.): does heritable adaptation to divergent growing sites accompany the onset of speciation?

Evolution is driven by natural selection, favouring individuals adapted in phenotypic traits to the environmental conditions at their growing site. To shed light on ecological and (epi-) genetically based differentiation between Heliosperma pusillum and Heliosperma veselskyi, two reciprocally non-monophyletic, but morphologically and ecologically divergent species from the south-eastern Alps, we studied various leaf anatomical traits and investigated chloroplast ultrastructure in leaves of the two species grown either in their natural habitat or in a common garden. The alpine H. pusillum occurs in open, wet rock habitats, whereas its close relative H. veselskyi is restricted to dry, shady habitats below overhanging rocks in the montane belt. H. pusillum exhibited higher thickness of leaves and palisade layers as adjustments and/or adaptations to higher irradiance and a higher stomatal area index reflecting better water availability. Traits were adjusted plastically, but differed between species grown in a common garden, suggesting that the differentiation between the two species is not solely based on phenotypic plasticity but also has a genetic basis. Our study thus supports the hypothesis that differentiation between the highly interfertile species is likely driven by natural selection.(VLID)452662

Data from: Natural selection drives parallel divergence in the mountain plant Heliosperma pusillum s.l.

(1) The evolution of species or ecotypes can occur gradually through neutral and adaptive genetic changes. To explore the influence of natural selection during early phases of divergence, morphological and ecological discontinuity and its adaptive significance were investigated in six pairs of alpine and independently evolved montane populations of Heliosperma pusillum .; the latter are usually taxonomically recognised at the species rank in spite of their highly doubtful debatable taxonomic value. (2) We tested whether environmental conditions – characterised by Landolt indicator values from vegetation surveys and temperature measurements – and morphology of alpine and montane populations differ discretely and in parallel across six population pairs. By reciprocal transplantation experiments in natural environments in two population pairs and in climate chambers for five population pairs we compared fitness of native vs. non-native individuals. (3) Alpine and montane populations differed in environmental conditions and morphology within each pair. Morphological differentiation occurred in parallel and correlated with environmental, but not with genetic distances. In both environments, native individuals had higher establishment success and plant size. (4) Differentiation of the independently evolved montane populations is driven by natural selection and parallel, independent adaptation in response to drought, lower irradiance and higher, less fluctuating temperatures in montane and alpine populations, respectively. Our study system exemplifies rapid, parallel evolution leading to morphologically and ecologically strongly divergent, though fully interfertile, ecotypes

Multiple auto- and allopolyploidisations marked the Pleistocene history of the widespread Eurasian steppe plant Astragalus onobrychis (Fabaceae)

The Eurasian steppes occupy a significant portion of the worldwide land surface and their biota have been affected by specific past range dynamics driven by ice ages-related climatic fluctuations. The dynamic alterations in conditions during the Pleistocene often triggered reticulate evolution and whole genome duplication events. Employing genomic, genetic and cytogenetic tools as well as morphometry we investigate the intricate evolution of Astragalus onobrychis, a widespread Eurasian steppe plant with diploid, tetraploid and octoploid cytotypes. To analyse the heteroploid RADseq dataset we employ both genotype-based and genotype-free methods that result in highly consistent results, and complement our inference with information from the plastid ycf1 region. We uncover a complex and reticulate evolutionary history, including at least one auto-tetraploidization event and two allo-octoploidization events; one of them involved also genetic contributions from other species, most likely A. goktschaicus. The present genetic structure points to the existence of four main clades within A. onobrychis, which only partly correspond to different ploidies. Time-calibrated diffusion models suggest that diversification within A. onobrychis was associated with ice age-related climatic fluctuations during the last million years. We finally argue for the usefulness of uniparentally inherited plastid markers, even in the genomic era, especially when investigating heteroploid systems

Transplants Survival

Number of seedlings recorded in natural population

Germination and Fitness recorded in climate chambers

Germination and Fitness recorded in climate chamber

Ecological Differentiation

Accompanying vegetation and the attributed Landolt indicator value