This article reviews recent literature on drought of the last millennium, followed by an update on global aridity changes from 1950 to 2008. Projected future aridity is presented based on recent studies and our analysis of model simulations. Dry periods lasting for years to decades have occurred many times during the last millennium over, for example, North America, West Africa, and East Asia. These droughts were likely triggered by anomalous tropical sea surface temperatures (SSTs), with La Ni˜ na-like SST anomalies leading to drought in North America, and El-Ni˜ no-like SSTs causing drought in East China. Over Africa, the southward shift of the warmest SSTs in the Atlantic and warming in the Indian Ocean are responsible for the recent Sahel droughts. Local feedbacks may enhance and prolong drought. Global aridity has increased substantially since the 1970s due to recent drying over Africa, southern Europe, East and South Asia, and eastern Australia. Although El Ni˜ no-Southern Oscillation (ENSO), tropical Atlantic SSTs, and Asian monsoons have played a large role in the recent drying, recent warming has increased atmospheric moisture demand and likely altered atmospheric circulation patterns, both contributing to the drying. Climate models project increased aridity in the 21 st century over most of Africa, southern Europe and the Middle East, most of the Americas, Australia, and Southeast Asia. Regions like the United States have avoided prolonged droughts during the last 50 years due to natural climate variations, but might see persistent droughts in the next 20–50 years. Future efforts to predict drought will depend on models’ ability to predict tropical SSTs. 2010 JohnWiley &Sons,Ltd.WIREs Clim Change2010 DOI:10.1002/wcc.81

Drought under Global Warming: A Review

http://digital.csic.es/bitstream/10261/216193/1/2020_Corpas_JAR_OA.pdf

H2S signaling in plants and applications in agriculture.

The present study explores the potential impact of silicon nanoparticles (Si NPs), in comparison with their bulk counterpart (silicate), on post-stress recovery performance of barley (Hordeum vulgare) seedlings under different drought stress intensities during vegetative growth. Barley plants were grown under 100% field capacity (FC), or mild (75% FC), moderate (50% FC) and severe (25% FC) drought stress levels, and were subsequently recovered by different treatments including soil application of 150 mL of Si NPs and silicate (at 125 and 250 mg Si L−1), and water. Si NPs application at 250 mg L−1 led to formation of Si NP aggregates in plant tissues, large pores in roots, and also rapid stomata closure in leaves. However, the lower Si NPs dose (125 mg Si L−1) was accompanied by a wider distribution of Si NPs in cells, and formation of a regular porosity pattern in roots i.e. more frequent pores of a smaller size. Upon recovery from all the drought stress levels, shoot biomass increased significantly in recovered plants compared to the respective non-recovered controls, and the maximum shoot biomass increase (27.3%) belonged to the moderate-stressed plants treated with Si NPs at 125 mg L−1. Exposure to Si NPs and silicate (at both doses) after all drought stress intensities caused a significant increase in total chlorophyll (up to 17.1%) and carotenoid (up to 24.1%) content of leaves except for the carotenoid content under severe drought stress. Post-drought recovery with Si NPs and silicate was linked to alterations in the plant osmolyte and metabolite profile, cellular injury and membrane stability indices, and the activity of antioxidant enzymes. Soil application of Si NPs (at a low dose of 125 mg Si L−1) showed a promising potential for post-drought recovery of barley plants via modifying plant morpho-physiological and antioxidative attributes and synthesis of specific metabolites.

Nanosilicon-based recovery of barley (Hordeum vulgare) plants subjected to drought stress

Exogenously applied proline enhances growth and productivity of drought stressed onion by improving photosynthetic efficiency, water use efficiency and up-regulating osmoprotectants

To date, an understanding of how plant growth-promoting bacteria facilitate plant growth has been primarily based on studies of individual bacteria interacting with plants under different conditions. More recently, it has become clear that specific soil microorganisms interact with one another in consortia with the collective being responsible for the positive effects on plant growth. Different plants attract different cross-sections of the bacteria and fungi in the soil, initially based on the composition of the unique root exudates from each plant. Thus, plants mostly attract those microorganisms that are beneficial to plants and exclude those that are potentially pathogenic. Beneficial bacterial consortia not only help to promote plant growth, these consortia also protect plants from a wide range of direct and indirect environmental stresses. Moreover, it is currently possible to engineer plant seeds to contain desired bacterial strains and thereby benefit the next generation of plants. In this way, it may no longer be necessary to deliver beneficial microbiota to each individual growing plant. As we develop a better understanding of beneficial bacterial microbiomes, it may become possible to develop synthetic microbiomes where compatible bacteria work together to facilitate plant growth under a wide range of natural conditions.

Recent Developments in the Study of Plant Microbiomes

Abiotic stresses, such as temperature extremes, drought, salinity, and heavy metals are major factors limiting crop productivity and sustainability worldwide. Abiotic stresses disturb plant growth and yield formation. Several chemical compounds, known as plant growth regulators (PGRs), modulate plant responses to biotic and abiotic stresses at the cellular, tissue, and organ levels. Thiourea (TU) is an important synthetic PGR containing nitrogen (36%) and sulfur (42%) that has gained wide attention for its role in plant stress tolerance. Tolerance against abiotic stresses is a complex phenomenon involving an array of mechanisms, and TU may modulate several of these. An understanding of TU-induced tolerance mechanisms may help improve crop yield under stress conditions. However, the potential mechanisms involved in TU-induced plant stress tolerance are still elusive. In this review, we discuss the essential role of TU-induced tolerance in improving performance of plants growing under abiotic stresses and potential mechanisms underlying TU-induced stress tolerance. We also highlight exploitation of new avenues critical in TU-induced stress tolerance.

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Potential Mechanisms of Abiotic Stress Tolerance in Crop Plants Induced by Thiourea.

Raynaud’s phenomenon (RP) is a multifactorial vasospastic disorder characterized by a transient, recurrent, and reversible constriction of peripheral blood vessels. RP is documented to affect up to 5% of the general population, but variation in its prevalence is commonly recognized owing to many factors, including varied definitions, gender, genetics, hormones, and region. Furthermore, RP may be idiopathic or be a clinical manifestation of an underlying illness. Patients with RP classically describe a triphasic discoloration of the affected area, beginning with pallor, followed by cyanosis, and finally ending with erythema. This change in color spares the thumb and is often associated with pain. Each attack may persist from several minutes to hours. Moreover, the transient cessation of blood flow in RP is postulated to be mediated by neural and vascular mechanisms. Both structural and functional alterations observed in the blood vessels contribute to the vascular abnormalities documented in RP. However, functional impairment serves as a primary contributor to the pathophysiology of primary Raynaud’s. Substances like endothelin-1, angiotensin, and angiopoietin-2 play a significant role in the vessel-mediated pathophysiology of RP. The role of nitric oxide in the development of this phenomenon is still complex. Neural abnormalities resulting in RP are recognized as either being concerned with central mechanisms or peripheral mechanisms. CNS involvement in RP may be suggested by the fact that emotional distress and low temperature serve as major triggers for an attack, but recent observations have highlighted the importance of locally produced factors in this regard as well. Impaired vasodilation, increased vasoconstriction, and several intravascular abnormalities have been documented as potential contributors to the development of this disorder. RP has also been observed to occur as a side effect of various drugs. Recent advances in understanding the mechanism of RP have yielded better pharmacological therapies. However, general lifestyle modifications along with other nonpharmacological interventions remain first-line in the management of these patients. Calcium channel blockers, alpha-1 adrenoreceptor antagonists, angiotensin-converting enzyme inhibitors, nitric oxide, prostaglandin analogs, and phosphodiesterase inhibitors are some of the common classes of drugs that have been found to be therapeutically significant in the management of RP. Additionally, anxiety management, measures to avoid colder temperatures, and smoking cessation, along with other simple modifications, have proven to be effective non-drug strategies in patients experiencing milder symptoms.

https://www.cureus.com/articles/73113-raynauds-phenomenon-reviewing-the-pathophysiology-and-management-strategies.pdf

Raynaud’s Phenomenon: Reviewing the Pathophysiology and Management Strategies

Titania (TiO2) is one of the most versatile materials in the field of polymer science and technology. In recent years, a large area of research has focused on the combination of TiO2 with polymers and other carbon nanostructures. Literature reports suggest that nanoscale TiO2 reinforcement gives rise to new optical, electrical, and physiochemical properties attained at extremely low TiO2 content, thus making these nanocomposites (NCs) a promising new class of materials. This review summarizes the contemporary views on the state‐of‐the‐art synthesis and applications of TiO2‐based polymer nanocomposites having different polymer matrices. The merits and demerits of various fabrication techniques have been presented alongside. Moreover, the worth of polymer/TiO2 NCs for various applications such as environmental remediation, i.e., water treatment and gas separation, biomedical, sensing, and energy sector has also been discussed. Based on the latter, one can safely anticipate that these materials hold the promise for commercial applications in widespread fields.

Polymer Nanocomposites Based on TiO2 as a Reinforcing Agent: An Overview

Atypical hemolytic uremic syndrome (HUS) is a rare but severe form of thrombotic microangiopathies (TMAs) that affects both children and adults. The clinical presentation is usually nonspecific, including a broad spectrum of symptoms ranging from abdominal pain, confusion, diarrhea, fatigue, irritability, hypertension, and lethargy. We present a case of a 36-year-old woman with medical comorbidities of asthma and pulmonary embolism who presented to our hospital in the 36th week of her pregnancy for preterm premature rupture of the membranes. The postoperative course was complicated with a sudden onset drop in hemoglobin and acute onset thrombocytopenia. Complements levels were normal while ADAMTS 13 (von Willebrand factor-cleaving protease) activity was 81% which ruled out ADAMTS 13 deficiency. No significant clinical improvement was seen after five cycles of plasmapheresis. She was later started on Eculizumab biweekly with marked improvement in biochemical and clinical status. Prompt diagnosis and treatment of atypical HUS are crucial as the prognosis is poor if untreated. The diagnosis of atypical HUS can be challenging as the classic triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury can be seen in all thrombotic microangiopathies, thus careful clinical and laboratory assessment is required to establish the diagnosis. The new treatment modality, Eculizumab, the anti-complement monoclonal antibody, has become the first-line therapy for treating atypical HUS.

Iqra Nawaz

Papers

Potential Mechanisms of Abiotic Stress Tolerance in Crop Plants Induced by Thiourea.

Raynaud’s Phenomenon: Reviewing the Pathophysiology and Management Strategies

Polymer Nanocomposites Based on TiO2 as a Reinforcing Agent: An Overview

A Case of Atypical Hemolytic Uremic Syndrome in a Pregnant Patient

Anti-inflammatory, anti-nociceptive and anti-pyretic activities of Cenchrus ciliaris L.