Surface canopy position determines the photosystem II photochemistry in Invasive and native prosopis congeners at Sharjah desert, UAE

Plants have evolved photoprotective mechanisms in order to counteract the damaging effects of excess light in hyper-arid desert environments. We evaluated the impact of surface canopy positions on the photosynthetic adjustments and chlorophyll fluorescence attributes (photosystem II photochemistry, quantum yield, fluorescence quenching, and photon energy dissipation), leaf biomass and nutrient content of sun-exposed leaves at the south east (SE canopy position) and shaded-leaves at the north west (NW canopy position) in the invasive Prosopis juliflora and native Prosopis cineraria in the extreme environment (hyper-arid desert area, United Arab Emirates (UAE)). The main aim of this research was to study the photoprotection mechanism in invasive and native Prosopis congeners via the safe removal—as thermal energy—of excess solar energy absorbed by the light collecting system, which counteracts the formation of reactive oxygen species. Maximum photosynthetic efficiency (Fv/Fm) from dark-adapted leaves in P. juliflora and P. cineraria was higher on NW than SE canopy position while insignificant difference was observed within the two Prosopis congeners. Greater quantum yield was observed in P. juliflora than P. cineraria on the NW canopy position than SE. With the change of canopy positions from NW to SE, the reduction of the PSII reaction center activity in the leaves of both Prosopis congeners was accelerated. On the SE canopy position, a significant decline in the electron transport rate (ETR) of in the leaves of both Prosopis congeners occurred, which might be due to the blockage of electron transfer from QA to QB on the PSII acceptor side. On the SE canopy position; Prosopis leaves dissipated excess light energy by increasing non-photochemical quenching (NPQ). However, in P. cineraria, the protective ability of NPQ decreased, which led to the accumulation of excess excitation energy (1 − qP)/NPQ and the aggravation of photoinhibition. The results also explain the role of different physiological attributes contributing to invasiveness of P. juliflora and to evaluate its liaison between plasticity of these characters and invasiveness

Different Traits Affect Salinity and Drought Tolerance during Germination of Citrullus colocynthis, a Potential Cash Crop in Arid Lands

Citrullus colocynthis, a native plant with potential uses as a feedstock for edible oil, biodiesel, and animal feed make it a potential cash crop. The importance of propagating this species under saline arid habitats necessitates understanding environmental factors affecting salinity and drought tolerance during the germination stage. Here, we assessed the impacts of seed collection time, the temperature of incubation on salinity, and drought tolerance during the seed germination stage of different accessions growing in the botanical garden of the University of Sharjah. No previous study assessed the interactive effects of these factors on the drought and salinity tolerance of this species. Three accessions (9, 10, and 13) differed in fruit and seed size and color, and germination behavior, and were selected from an earlier study. Seeds that matured in summer and winter on these accessions were treated with three salinities (0, 50, and 100 mM NaCl), and PEG levels (0, −0.3, and −0.6 MPa) and incubated at two temperatures (20/30 and 25/35 °C). The results showed significant effects of all factors (collection time, temperature, drought, and salinity) and their interactions on germination percentage. Seeds of C. colocynthis were very sensitive to salinity and drought stress, and the sensitivity depended on the time of seed collection, accession, and incubation temperature. The overall germination and tolerance to salinity and drought were significantly greater in seeds of accession 10, seeds that matured in summer, and seeds incubated at 25/35 °C. The germination in NaCl solutions was greater than in PEG solutions, indicating that seed germination was more sensitive to osmotic stress created by PEG than NaCl. Moreover, when transferred from NaCl, the recovery of ungerminated seeds was greater than in PEG solutions. This result indicates that the detrimental effect of salinity in C. colocynthis could be mainly attributed to osmotic rather than ion-toxicity effects. To adopt C. colocynthis as a cash crop or to restore degraded desert habitats, it is recommended to use seeds of drought- and salt-tolerant accessions (e.g., 10), especially those that mature in summer

Les dictionnaires Larousse

Il y a fort à parier que le Petit Larousse ait été notre premier dictionnaire, comme pour nos parents et nos grands-parents. À la fois familiers et méconnus, anciens et contemporains, les dictionnaires Larousse sont nés du génie de Pierre Larousse, un instituteur doublé d'un visionnaire dont la devise était : instruire tout le monde sur toutes choses. Ce livre nous invite à la découverte de Pierre Larousse et de son œuvre, guidés par des experts qui en sont passionnés. Chacun prospecte la région laroussienne à la recherche des richesses qu'elle recèle. On y fait des découvertes étonnantes. Ainsi, on apprend que le lexicographe barbu qu'on nous présente toujours était en outre un entrepreneur dynamique capable de brasser non seulement des mots, mais des chiffres et des stratégies. Grand maître du dictionnaire d'apprentissage, Pierre Larousse a produit une œuvre à laquelle ses successeurs ont réussi à garder toute la force d'information, au point de gagner l'ensemble de la francophonie

Assessment of Uptake, Accumulation and Degradation of Paracetamol in Spinach (Spinacia oleracea L.) under Controlled Laboratory Conditions

The occurrence and persistence of pharmaceuticals in the food chain, particularly edible crops, can adversely affect human and environmental health. In this study, the impacts of the absorption, translocation, accumulation, and degradation of paracetamol in different organs of the leafy vegetable crop spinach (Spinacia oleracea) were assessed under controlled laboratory conditions. Spinach plants were exposed to 50 mg/L, 100 mg/L, and 200 mg/L paracetamol in 20% Hoagland solution at the vegetative phase in a hydroponic system. Exposed plants exhibited pronounced phytotoxic effects during the eight days trial period, with highly significant reductions seen in the plants’ morphological parameters. The increasing paracetamol stress levels adversely affected the plants’ photosynthetic machinery, altering the chlorophyll fluorescence parameters (Fv/Fm and PSII), photosynthetic pigments (Chl a, Chl b and carotenoid contents), and composition of essential nutrients and elements. The LC-MS results indicated that the spinach organs receiving various paracetamol levels on day four exhibited significant uptake and translocation of the drug from roots to aerial parts, while degradation of the drug was observed after eight days. The VITEK® 2 system identified several bacterial strains (e.g., members of Burkhulderia, Sphingomonas, Pseudomonas, Staphylococcus, Stenotrophomonas and Kocuria) isolated from spinach shoots and roots. These microbes have the potential to biodegrade paracetamol and other organic micro-pollutants. Our findings provide novel insights to mitigate the risks associated with pharmaceutical pollution in the environment and explore the bioremediation potential of edible crops and their associated microbial consortium to remove these pollutants effectively