Instituto de Fisiología Vegetal

Reactions leading to dormancy release (DR) in 'dry', orthodox seeds are still poorly understood, as well as their dependence on moisture content (MC) and temperature. In this study, sunflower achenes were used to explore the effects of MC combined with a wide range of storage temperatures (ST°) on DR dynamics, tested at 10 °C and 25 °C. Embryo sensitivity to abscisic acid and oxygen uptake were determined and ageing indicators were assessed and complemented with dynamics for predicted viability loss. Water status was examined using sorption isotherms and the glass transition temperature (Tg). The results showed that small variations in MC and ST° had profound effects on achene dormancy and embryo responsiveness to ABA. Using a 'temperature-by-humidity' coordinate system we mapped three regions allowing DR during the glassy, rubbery, and fluid states of the achenes. Full DR (allowing germination at 10 °C and 25 °C) occurred only in the rubbery state (above Tg), and the optimal ST° for full DR dropped from 30 °C to -18 °C with MC increasing from 0.045 gH2O g-1 DW to 0.10 gH2O g-1 DW. In contrast, under both glassy and fluid states, DR was incomplete (allowing germination at 25 °C but not at 10 °C) and required warm ST° that promoted ageing.

In recent times, the population abundance of many of the native medicinal plant species in the Monte Desert in northwestern Argentina has been declining due to agricultural expansion, overgrazing, urbanization, increasing levels of harvesting, and changes in climatic conditions. Therefore, quantitative data on these species is necessary to design strategies that allow their conservation and sustainable use. This study aimed to determine the diversity patterns of some medicinal shrub species in a portion of the mountainous desert of the Calchaquí Valleys (Tucumán - Argentina). Throughout a standardized protocol, the plant communities from four localities (two sampling sites for each locality, S1 and S2) were surveyed (Ampimpa, Tío Punco, Fuerte Quemado, and Los Poleos). Relative density, relative frequency, dominance, and the species importance value index (IVI) were calculated to determine the overall species performance and dominance. Of the species identified, twelve are popularly used as medicinal. Austroflourensia fiebrigii, Pentaphorus glutinosus, Larrea cuneifolia, and Zuccagnia punctata, four medicinal plant species, were dominant in Ampimpa S1. Larrea cuneifolia, Larrea divaricata, and Z. punctata are within the medicinal plant species with the highest IVI. These plant species are used as anti-inflammatory, antirheumatic, antitumoral and to treat fungal and bacterial infections. Our study seeks to provide a significant foundation for documenting future changes in these plant communities and to promote conservation strategies and multiplication of them in situ.

Human renal tubular epithelial cell (HRTEC) primary cultures are isolated from kidneys removed from pediatric patients undergoing nephrectomies indicated by the Pediatric Nephrology Unit of the Hospital General de Pediatría Pedro de Elizalde, Buenos Aires, Argentina. Macroscopically, the normal kidney cortex is dissected from the renal medulla and cut into fragments. Cortical fragments are then digested in Hank's solution supplemented with 0.1% collagenase type 1 and filtered through a 70 µm pore size mesh to separate the renal tubules from glomeruli. Renal tubules undergo a second digestion with collagenase to isolate epithelial cells. Finally, the enzyme digestion is stopped, and the epithelial cells are grown in flasks containing RPMI 1640 with supplements under 5% CO2at 37 °C until confluence. HRTEC cells can be grown as monolayers on 96-well plates, glass coverslips into 24-well plates, or cell-culture holders coated with collagen. Also, three-dimensional human renal tubular epithelial cell (3D-HRTEC) cultures are obtained from HRTEC cells seeded on a basement membrane (BM) matrix. Cell aggregation and formation of tubular shape structures are monitored. We have used HRTEC primary cultures for many years to study the cytotoxic action caused by Shiga toxin in the pediatric kidney, which leads to pathophysiological alterations resulting in hemolytic uremic syndrome (HUS). Both HRTEC and 3D-HRTEC cultures can be used to evaluate the effects of different toxins, synthetic drugs, biological factors, hormones, etc, specifically on the human renal proximal tubule epithelium.

This study investigates the effect of inoculation with Bradyrhizobium sp. (Lotus), a symbiotic rhizobacterium, on the germination of trefoil under stress induced by copper, cadmium, and their combination. The goal is to highlight the role of Bradyrhizobium sp. (Lotus) in mitigating copper and cadmium stress and enhancing the germination of trefoil, a spontaneous fodder species. The research, conducted in Blida (Algeria) in 2024, focuses on the physiological aspects of germination, including Total Germination Count (TCG), Time to mean germination (TMG), and inhibition of germination reversibility. Statistical analysis was performed using Manova at a 5% threshold. Results indicate that Bradyrhizobium sp. (Lotus) inoculation increases TCG values and reduces the germination lag phase from +168 h to 48 h. Additionally, germination inhibition is decreased by 20 to 30% compared to non-inoculated seeds, and physiological germination parameters improve under metal stress conditions. The findings suggest that Bradyrhizobium sp. (Lotus) may mitigate copper and cadmium stress by detoxification or chelation, thereby enhancing trefoil tolerance to these metallic trace elements during the germination stage.

ABSTRACT Postharvest senescence of vegetables is characterized by the degradation of pigments and proteins. Protein degradation is often accompanied by the accumulation of amino acids and ammonium since the separated plant tissues cannot recycle nitrogen. Although it is known that treatments with low-intensity white- or red-light delay protein degradation during postharvest in kale, the effect of LED lighting on nitrogen metabolism is poorly studied. The objective of this work was to evaluate the effects of LED treatments on nitrogen metabolism during postharvest kale. Three treatments were performed: control, 20–25 µmol m−2 s−1 of white light or red light for 1 h. Nitrogen content remained unchanged. In the control, protein content decreased and was accompanied by the accumulation of amino acids and ammonium. In contrast, in both white and red LED light-treated leaves, protein content remained higher, and the accumulation of derivatives was delayed. Glutamine synthetase activity decreased more rapidly during storage in control than in treatments, which is related to a greater accumulation of ammonium. LED light treatments maintained a higher ascorbic acid content in kale leaves than in controls. This work demonstrates that low-intensity white or red LED treatments delay changes in postharvest nitrogen metabolism and improve the nutritional quality of kale leaves.

Edible fungi are unexploited natural sources of high added value biomolecules, such as phenolic compounds. This study used an innovative and green extraction method based on the quick, easy, new, cheap, reproducible (QUENCHER) process of Morchella esculenta. The QUENCHER extract had a much higher concentration of total polyphenols [(125 mg gallic acid equivalents (GAE)/g dry weight (DW)], flavonoids [38 mg catechin equivalents (CE)/g DW], flavanols [22 mg quercetin equivalents (QE)/g DW], and proanthocyanidins [44 mg CE/g DW] than the traditional aqueous extraction. In addition, antioxidant activities were evaluated by the in vitro scavenging capacity of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and iron reducing power. In the DPPH test, this phenolic richness clearly improved antioxidant activity, with an IC50 (inhibition concentration at 50%) of 0.097 mg/mL. It has also shown encouraging antibacterial qualities against resistant Gram-positive bacteria like Staphylococcus aureus (minimum inhibitory concentration varied between 6.25 and 25 μg/mL). For the acetylcholinesterase (AChE) inhibition, QUENCHER extract demonstrated strong AChE inhibition (IC50 = 0.002 mg/mL), a characteristic of significant interest in neurodegenerative disorders. These results open possibilities for using this extract as a natural antimicrobial agent, against resistant bacterial infections. Furthermore, in vitro digestion data indicates that the bioactive compounds in these extracts maintain relative stability during transit through the gastrointestinal tract, allowing for favorable bioavailability and, consequently, potential therapeutic efficacy. After 4 h of simulated digestion, over 66% of the antioxidant and anti-AChE activity was still present, indicating a degree of stability in the bioactive chemicals and an intriguing potential for bioavailability, according to in vitro digestibility experiments.