Evaluation of Brazilian wild Hevea germplasm in India for cold tolerance: Variability and character associations in juvenile growth phase

Natural rubber (Hevea brasiliensis), cultivation has been extended to non-traditional regions due to limited scope of further expansion in traditional rubber growing areas in India. These areas are often confronted with various abiotic stresses especially temperature extremes. A set of 18 wild accessions, two popular clones along with two control clones RRIM 600 and Haiken 1, were evaluated in the juvenile growth phase at the Regional Experiment Station of the Rubber Research Institute of India, Nagrakata, West Bengal, a sub-Himalayan cold prone region of India. The genotypes exhibited highly significant clonal differences (P<0.01) for all the eight quantitative traits. During the pre-winter period, the number of leaves per plant ranged from 14.2 (AC 3074) to 47.6 (MT 2229). In the post winter period maximum leaves per plant was recorded in MT 900 (29.27) comparable to the control clone Haiken 1 (28.20), while the accession AC 3293 recorded very high loss in leaves. An increase in number of whorls per plant during winter period was noted in MT 1020 as compared to Haiken 1 (0.80). Increment of plant height during winter ranged from 6.53 cm (AC 3293) to 45.01 cm (MT 1020) as compared to the control clone Haiken 1 (40.73 cm). Girth ranged from 5.36 cm (AC 3293) to 11.53 cm (MT 915) while the control clone Haiken 1 recorded a girth of 10.50 cm. Girth was significantly correlated with the other growth traits. Based on rank sum values, the accessions were ranked for overall performance and the top 20 per cent of the potential accessions showing early growth vigour were identified. These can be used for the development of cold tolerant clones

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

Genetic Variation and Structure in an Endemic Island Oak, Quercus tomentella, and Mainland Canyon Oak, Quercus chrysolepis

Premise of research. Quercus tomentella is a tree species endemic to the California Channel Islands and Isla Guadalupe. Given its distribution across six widely separated islands, significant genetic structure would be expected, despite the propensity of oaks for long-distance pollen dispersal. In comparison, its close mainland relative, Quercus chrysolepis, has a more continuous range and fewer barriers to gene flow. Methodology. We sampled Q. tomentella from all the islands in its range (N = 345) and Q. chrysolepis from five mainland sites and on the islands where it occurs (N = 100) and genotyped the trees using eight polymorphic microsatellite loci. Genetic differentiation within and between species was examined using genetic distances, analysis of molecular variance, Bayesian clustering (both spatial and nonspatial approaches), a neighbor-joining tree, and genetic discontinuities indicative of barriers to gene flow. We also looked for evidence of population bottlenecks. Pivotal results. A high level of clonality was found in Q. tomentella on Santa Catalina Island and Santa Rosa Island, but genetic variability was high in both species and at all sites, including the tiny surviving population on Isla Guadalupe. Genetic distance measures were significant between most populations of both species. The most surprising result is that the two species were not clearly differentiated, and genetic clusters identified through both spatial and nonspatial analyses were shared between species. Conclusions. The island endemic Q. tomentella and the widespread Q. chrysolepis are not well-differentiated species. Further work is needed to clarify the relationships within and among these species. Insular populations of Q. tomentella are genetically diverse and distinct; the remaining population found on Isla Guadalupe warrants protection and management to support recruitment

Interspecific and Intraspecific Pollination Patterns of Valley Oak, Quercus Lobata, in a Mixed Stand in Coastal Central California

Pollination patterns within Quercus lobata and interspecific hybridization between Q. lobata and Quercus douglasii were studied in a coastal central California mixed woodland. We first identified hybrids by means of microsatellite genotyping and assignment tests. Hybrids were rare, both among adults (4 of 190, 2.1%) and among acorns collected from Q. lobata trees (6 of 392, 1.5%). These low rates of hybridization at both early and late life history stages suggest that fertility barriers, rather than natural selection against hybrids, limit hybridization between these two species. However, hybrid adults, although rare, may facilitate gene flow between the two species. Acorns collected from a hybrid tree had both Q. lobata pollen donors (11 of 30, 37%) and Q. douglasii or hybrid pollen donors (19 of 30, 63%). After removing hybrid acorns from the analysis, we used paternity assignment to track pollination patterns within Q. lobata. Of 108 acorns, only 32 (30%) were assigned to candidate pollen donors within 200 m of the maternal tree, indicating that the majority of effective pollen travels more than 200 m. Individual trees had acorn crops with many different sires and an average effective number of pollen donors (Nep) of 219 per tree. Indirect methods using correlated paternity estimated mean pollination distances of ~100 m and mean Nep of 5.2 per tree, values much lower than those derived directly from paternity assignments