The effects of climate temperature and water stress on growth and several stress markers were investigated in sweet basil plants. Some growth parameters (shoot length and number of leaves) and photosynthetic chlorophyll contents were determined every two days during plant growth, and foliage leaf material was collected after 15 and 21 days of treatment. Both climate temperature and water stress inhibited sweet basil plant growth; especially, total chlorophyll levels were decreased significantly in response to high-temperature treatments. Under strong stresses, basil plants induced the synthesis and accumulation of glycine betaine (GB) as a secondary osmolyte, although at less content when compared with the proline content under the same stress conditions. Proline concentrations particularly increased in leaves of both basil stressed plants, accomplishing levels high enough to play a crucial role in cellular osmoregulation adjustment. Stress-induced accumulation of these antioxidant compounds was detected in sweet basil. Therefore, it appears that sweet basil-treated plants are able to synthesize antioxidant compounds under strong stress conditions. On the other hand, total sugar concentrations decreased in stress-treated basil plants. Both temperature and water stress treatments caused oxidative stress in the treated plants, as indicated by a significant increment in malondialdehyde (MDA) concentrations. An increase in total phenolic and flavonoid concentrations in response to water stress and a highly significant decrease in carotenoid concentrations in basil leaves were observed; flavonoids also increased under high climate temperature conditions.

The 2019 coronavirus disease (COVID-19) is a potentially fatal multisystemic infection caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Currently, viable therapeutic options that are cost effective, safe and readily available are desired, but lacking. Nevertheless, the pandemic is noticeably of lesser burden in African and Asian regions, where the use of traditional herbs predominates, with such relationship warranting a closer look at ethnomedicine. From a molecular viewpoint, the interaction of SARS-CoV-2 with angiotensin converting enzyme 2 (ACE2) is the crucial first phase of COVID-19 pathogenesis. Here, we review plants with medicinal properties which may be implicated in mitigation of viral invasion either via direct or indirect modulation of ACE2 activity to ameliorate COVID-19. Selected ethnomedicinal plants containing bioactive compounds which may prevent and mitigate the fusion and entry of the SARS-CoV-2 by modulating ACE2-associated up and downstream events are highlighted. Through further experimentation, these plants could be supported for ethnobotanical use and the phytomedicinal ligands could be potentially developed into single or combined preventive therapeutics for COVID-19. This will benefit researchers actively looking for solutions from plant bioresources and help lessen the burden of COVID-19 across the globe.

Background. Annona muricata and Khaya grandifoliola are ethnomedicinally used for the treatment of malaria and have been experimentally shown to have an anti-plasmodial effect, but the mechanisms involved are not fully understood. This study investigated the effect of the ethanol extracts of their leaves on parasitemia, radical scavenging and cytokines in Plasmodium berghei ANKA-infected BALB/c mice. Methods. BALB/c mice were infected with P. berghei and treated with chloroquine, A. muricata or K. grandifoliola extract for 4 days. The percentage of parasitemia and the level of cytokine expression were determined after treatment. Trace element, phytochemical and nitric oxide (NO) scavenging activity, 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging properties assays were done to study the antioxidant effects of AN and KG in vitro. Results. P. berghei consistently increased parasitemia in BALB/c mice. The tested doses (100-, 200-, and 400 mg/kg) of A. muricata and K. grandifoliola attenuated the P. berghei-induced elevation of parasitemia and cytokines (TNF-α, IL-5, and IL-6) in vivo during the experimental period, though not as much as chloroquine. Moreover, both extracts scavenged the DPPH and NO radicals, though A. muricata had more anti-oxidant effect than K. grandifoliola in-vitro. Conclusion. The ethanol extracts of A. muricata and K. grandifoliola reduce parasitemia in P. berghei-treated mice BALB/c by scavenging free radicals and reducing cytokines, though the extracts were not as effective as chloroquine.

This study evaluates the influences of nickel and ozone exposure individually and/ or in combination on growth performance, antioxidant activity and genes up regulation of two rice cultivars Sakha 101 and Giza 178. Ni treatment at high doses (100 µM Ni) and 75 ppb O 3 alone reduced the fresh weight, mineral content, membrane integrity and Rubisco content. There was an increase in SOD and APX activity in the shoots of rice cultivars, whereas, there was a decrease in GR and GST in the roots and shoots. In contrast combined stresses appeared to be stimulatory for growth and mineral contents, Rubisco content and antioxidant enzymes. Nonspecific lipid transfer protein and transmembrane protein genes were up regulation in rice cultivars in response to Ni stress. Carotenoid cleavage dioxygenase is upregulated in response to ozone stress; RNA pseudouridine synthase, heat shock proteins and cytochrome P450-like were upregulated in response to combined stresses. The results revealed that the interactive effects of both stresses were antagonistic on growth parameters and antioxidant activities to overcome the adverse effects of both pollutants.

Various physiological damages occur in plants upon exposure to heat stress (Hasanuzzaman et al. 2013). High temperatures (heat stress, HS) are known to inhibit enzyme activity, net photosynthetic rate (P N ), and other metabolic processes leading to physiological and biochemical alterations (Salvucci and Crafts-Brander 2004, Hassan, 2006, Zhao et al. 2008, ICPP 2014. HS uncouples enzymes and metabolic pathways leading to accumulation of harmful reactive oxygen species (ROS) which are responsible for oxidative stress (Sarieva et al. 2010). The reaction centers of PSI and PSII in chloroplasts are major sites of ROS generation (Chakraborty et al. 2011). Stomatal closure, reduction in root growth, and consequent inhibition of mineral uptake are common responses to HS (Huang and Xu 2000).Nitrogen as an essential element (Sánchez et al. 2004, Cechin and De Terezinha 2004) promotes metabolic activities, such as photosynthesis, antioxidant activities, leading to enhancing in growth and yield (Zhao et al. 2008).Due to their different physiological effects, HS and N fertilization might have interactive impacts on plants. HS reduces the rate of nutrient uptake; however, this effect could be mitigated by excessive supply of N (Altenbach et al. 2003, Zhao et al. 2008, Demmig-Adams et al. 2014. Moreover, Zhang et al. (2014) reported that N nutrition control is an important way to enhance tolerance to abiotic stress. Thus, it is important to understand how the supply of N may mitigate HS.The aim of the present experiment was to study the effects of N-fertilization on alleviation of the negative impact of HS on Chl fluorescence, P N , and stomatal conductance (g s ) of French bean plants.Seeds of French bean (Phaseolus vulgaris L.) were obtained from the Department of Agronomy, Alexandria University, Egypt. They were sown in plastic pots (20 cm 2 ), five seeds in each pot with multipurpose compost in a heated glasshouse [temperature of 24/20ºC day/night, air humidity 60-65%, 16-h photoperiod with additional irradiance of 450 μmol(photon) m -2 s -1 , total irradiance was 975 μmol(photon) m -2 s -1 ]. After appearance of expanded trifoliate leaf, 12 days after sowing (DAS), plants were thinned to one seedling per pot. Pots were then transferred to eight closed climate controlled growth chambers. Two chambers were used for N fertilization as foliar spray (three concentrations of urea: 5, 10, 15 mM). Two other