Alfonso Ortega

Antimony (Sb) is a toxic metalloid whose presence in the environment has increased in recent years due to anthropogenic activities. In soils, this element may occur as the pentavalent ion Sb(V) (antimonate) or the trivalent ion Sb(III). The latter is more abundant in nature and more harmful to living organisms. In this study, the effects of Sb(III) on a model plant of major agronomic interest – tomato – are investigated in order to elucidate which compounds or metabolic pathways may be key in the plant response to this stressor. In order to achieve this objective, tomato seedlings were cultivated hydroponically and exposed to varying concentrations of Sb(III). This approach ensured optimal availability of the metalloid to the plants. The results of the present study demonstrate that exposure to Sb(III) inhibits plant growth and triggers a range of defence mechanisms, among which proline, phytochelatins (PCs) and enzymes of the AsA/GSH cycle play a prominent role in xenobiotic detoxification. In particular, ascorbate peroxidase (APX), glutathione reductase (GR), dehydroascorbate reductase (DHAR) and monodehydroascorbate reductase (MDHAR) exhibited significant increases in both content and activity, particularly in roots compared with shoots. In addition to biochemical activity, an assessment was conducted to determine whether the expression of genes encoding these enzymes, as well as those involved in the biosynthetic pathways of the related compounds, was affected. The results of this assessment indicated the same trend. The present study underlines the pivotal function of the AsA/GSH cycle in plant defence in the context of elevated Sb(III) exposure, proposing that roots function as a barrier to restrict the translocation of this metalloid to aerial tissues. These findings may contribute to the identification of species best suited to the remediation of Sb-contaminated environments, based on the enzymes and compounds that play central roles in the defensive response described here. Studies such as the present one contribute to advancing our understanding of the mechanisms by which plants can enhance their remediation capacity and safely restore environments contaminated by xenobiotic compounds.

This study demonstrates that sunflower plants display integrated, multilevel responses to excessive lithium (Li) exposure. Li concentrations above 5 mM markedly impair germination, growth, and biomass accumulation. Li is preferentially accumulated in the shoots, showing high translocation and bioaccumulation factors, and disrupts mineral nutrient homeostasis, particularly potassium (K) and sodium (Na) uptake, while inducing oxidative stress. Although photosynthetic pigment contents decline, photosynthetic efficiency is largely maintained, except at 10 mM Li. Li treatment enhances superoxide anion (O₂^.−) and hydrogen peroxide (H₂O₂) production exclusively in leaves. Consequently, activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR), and glutathione reductase (GR) increase in leaves, whereas only APX and GR are stimulated in the roots. Nitric oxide (NO) accumulation is detected only in leaves, while hydrogen sulfide (H₂S) and glutathione (GSH) contents decline. Leaf ascorbate (AsA) levels decrease concomitantly with dehydroascorbate (DHA) accumulation. Expression analyses of catalase, DHAR, DHAR-like, and glutathione S-transferase (GST) genes confirm their involvement in Li stress responses. Moreover, global DNA methylation analyses reveal hypomethylation in leaves and hypermethylation in the roots. Overall, Li exposure induces dose- and organ-specific physiological, molecular, and epigenetic adjustments in sunflower plants under environmentally relevant concentrations and controlled experimental conditions in this study.

Industrial hemp (Cannabis sativa L.) is a multipurpose crop with growing interest due to its environmental adaptability, low input requirements, and potential contribution to sustainable agricultural systems. This study evaluated the agronomic performance of four industrial hemp varieties grown under the edaphoclimatic conditions of the Alentejo region over two consecutive growing seasons (2024 and 2025) using different sowing dates. Phenological stages, plant height and growth parameters were monitored, complemented by meteorological data obtained from IPMA. The results revealed clear differences between years. The later sowing date in 2024 promoted greater vegetative growth, resulting in taller plants, while the earlier sowing in 2025 extended the vegetative phase and delayed flowering. Varietal differences were also observed, particularly for Fibror 79, which flowered slightly later, suggesting greater photoperiod sensitivity. These patterns confirm that both thermal environment and sowing date play a decisive role in hemp phenological development. The findings also highlight the high plasticity of the crop, which demonstrated strong adaptation to the hot and dry Mediterranean summers. Overall, appropriate selection of variety and sowing date can optimize vegetative and reproductive development, representing an important strategy for sustainable agricultural systems in the Alentejo region.

Cannabis sativa L. is a versatile plant with significant medicinal, industrial, and recreational applications. Its therapeutic potential is attributed to cannabinoids like THC and CBD, whose production is influenced by environmental factors, such as radiation, temperature, and humidity. Radiation, for instance, is essential for photosynthetic processes, acting as both a primary energy source and a regulator of plant growth and development. This review covers key factors affecting C. sativa cultivation, including photoperiod, light spectrum, cultivation methods, environmental controls, and plant growth regulators. It highlights how these elements influence flowering, biomass, and cannabinoid production across different growing systems, offering insights for optimizing both medicinal and industrial cannabis cultivation. Studies indicate that photoperiod sensitivity varies among cultivars, with some achieving optimal flowering and cannabinoid production under extended light periods rather than the traditional 12/12 h cycle. Light spectrum adjustments, especially red, far-red, and blue wavelengths, significantly impact photosynthesis, plant morphology, and secondary metabolite accumulation. Advances in LED technology allow precise spectral control, enhancing energy efficiency and cannabinoid profiles compared to conventional lighting. The photoperiod plays a vital role in the cultivation of C. sativa spp., directly impacting the plant’s developmental cycle, biomass production, and the concentration of cannabinoids and terpenes. The response to photoperiod varies among different cannabis cultivars, as demonstrated in studies comparing cultivars of diverse genetic origins. On the other hand, indoor or in vitro cultivation may serve as an excellent alternative for plant breeding programs in C. sativa, given the substantial inter-cultivar variability that hinders the fixation of desirable traits.

Currently, there is an increasing presence of heavy metals and metalloids in soils and water due to anthropogenic activities. However, the biggest problem caused by this increase is the difficulty in recycling these elements and their high permanence in soils. There are plants with great capacity to assimilate these elements or make them less accessible to other organisms. We analyzed the behavior of Solanum lycopersicum L., a crop with great agronomic interest, under the stress caused by antimony (Sb). We evaluated the antioxidant response throughout different exposure times to the metalloid. Our results showed that the enzymes involved in the AsA-GSH cycle show changes in their expression level under the stress caused by Sb but could not find a relationship between the NITROSOGLUTATHIONE REDUCTASE (GSNOR) expression data and nitric oxide (NO) content in tomato roots exposed to Sb. We hypothesize that a better understanding of how these enzymes work could be key to develop more tolerant varieties to this kind of abiotic stress and could explain a greater or lesser phytoremediation capacity. Moreover, we deepened our knowledge about Glutathione S-transferase (GST) and Glutathione Reductase (GR) due to their involvement in the elimination of the xenobiotic component.

Dittrichia plants were exposed to thallium (Tl) stress (10, 50, and 100 µM) for 7 days. The Tl toxicity altered the absorption and accumulation of other nutrients. In both the roots and the leaves, there was a decline in K, Mg, and Fe content, but an increase in Ca, Mn, and Zn. Chlorophylls decreased, as did the photosynthetic efficiency, while carotenoids increased. Oxidative stress in the roots was reflected in increased lipid peroxidation. There was more production of superoxide (O₂^.−), hydrogen peroxide (H₂O₂), and nitric oxide (NO) in the roots than in the leaves, with increases in both organs in response to Tl toxicity, except for O₂^.− production in the roots, which fluctuated. There was increased hydrogen sulfide (H₂S) production, especially in the leaves. Superoxide dismutase (SOD), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR), and glutathione reductase (GR) showed increased activities, except for APX and MDHAR in the roots and GR in the leaves. The components of the ascorbate–glutathione cycle were affected. Thus, ascorbate (AsA) increased, while dehydroascorbate (DHA), reduced glutathione (GSH), and oxidized glutathione (GSSG) decreased, except for in the roots at 100 µM Tl, which showed increased GSH. These Tl toxicity-induced alterations modify the AsA/DHA and GSH/GSSG redox status. The NO and H₂S interaction may act by activating the antioxidant system. The effects of Tl could be related to its strong affinity for binding with -SH groups, thus altering the functionality of proteins and the cellular redox state.

Esca is a multi-fungal disease affecting grapevines. The objective of the study was to evaluate the physiological and molecular response of the grapevine cv. Tempranillo to esca disease, carried out in a vineyard under Mediterranean climatic conditions in western Spain. The photosynthetic pigments in the leaves decreased, with a strong decrease in the photosynthetic efficiency. The proline content increased significantly in the early stages of affected leaves, being possibly involved in the maintenance of lipid peroxidation levels in leaves, which do not increase. The phenol, flavonoid, and phenylpropanoid content decreased in esca-affected leaves, as does the total antioxidant capacity (FRAP), while the polyphenol oxidase (PPO) activity suffers a strong increase with the development of the disease. In affected grapes, the lipid peroxidation and the total phenol content decrease, but not the anthocyanin content. The ascorbate pool decreases with the disease and with time. On the other hand, pool GSH + GSSG is lower in affected leaves, but increases with time. These alterations show a clear change in the redox homeostasis. The expression of genes phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), superoxide dismutase (SOD), and chalcone synthase (ChaS1 and ChaS3) become considerably higher in response to esca, being even higher when the infection time increases. The alteration of AsA and GSH levels, phenolic compounds, PPO activity, proline content, and FRAP, together with the increase of the PAL, PPO, SOD,ChaS1, and ChaS3 gene expression, are clearly implicated in the esca response in plants. The expression of these genes, similar to the PPO activity, can be used as markers of state in the development of the disease.

Resumen Moulds are common and important allergens. They are more abundant outdoors but patients affected by mould allergy stay indoors much longer than outdoors. So, indoor sampling could help to assess the influence of the concentration of allergens in allergic symptoms. The aim of this study was to assess the relative efficiencies of two air sampling methods, viable and non viable, for the quantification of airborne indoor fungi in the homes of patients sensitized to Alternaria. Furthermore, outdoor sampling was carried out to compare results. Samples were taken over six months in Badajoz (SW Spain). Two houses were selected according to the presence of allergic patients to Alternaria. They were sampled once a month using both viable and non viable personal samplers at solar noon. A Burkard personal sampler was used to record spores and a Sampl’air AES Chemunex sampler was used for colonies. Three rooms were selected in each home: living room, kitchen and bathroom. Temperature and relative humidity were registered at each sample. Outdoor sampling was performed one day per week at the Faculty of Science, using a seven day Burkard sampler for spores and the same personal sampler for colonies. On average, 200-300 CFU/ m3 were found from more than 40 taxa identified. The highest number of colonies was recorded in the kitchen, then in the bathroom and finally in the living room. Nevertheless, there were minor differences between rooms. The houses studied showed a similar temporal pattern, with maximum values in December and minimum in January. Cladosporium colonies showed statistical differences between homes, but these differences were not found with Alternaria, Aspergillus or Penicillium colonies. Differences between rooms appeared for Alternaria colonies and Cladosporium herbarium spores. Temperature was positively correlated in most cases and relative humidity negatively with Alternaria spores. The number of spores collected was as twice as that of colonies, with an average concentration between 600-700 colonies/m3 , and nearly 1400 spores/m3 as maximum concentration. The temporal pattern of spores was similar to that found for colonies. Comparing colonies to spores, Alternaria and AspergillusPenicillium showed similar values. Notwithstanding, Cladosporium spores were nearly five times more abundant than colonies. The advantage of viable methods is the identification to species level, but they have the disadvantage that spores from some ubiquitous species, as Cladosporium, do not always grow in those media, which raises the interest to use additional non-viable methods.