Jorge Braga Ribeiro Junior

Selenium deficiency is a widespread nutritional problem worldwide, and biofortification has been proposed as a strategy to increase selenium intake through food crops. This study evaluated the effects of sodium selenate on growth, photosynthetic pigments, and selenium accumulation in sweet potato (Ipomoea batatas) plantlets micropropagated in vitro. Explants were cultured in hormone-free Murashige and Skoog medium supplemented with 0, 5, 10, 15, 20, and 25 µM sodium selenate. Plantlets grown with 5.0 µM sodium selenate showed the highest values for growth-related traits, including number of leaves, shoot length, root length, and dry biomass. Photosynthetic pigments were also enhanced at low selenium concentrations, with maximum chlorophyll and carotenoid contents observed at 5.0 µM. In contrast, higher selenium concentrations reduced plant growth and pigment accumulation, indicating phytotoxic effects. Selenium accumulation increased progressively with increasing sodium selenate concentration, reaching the highest levels at 25.0 µM. These findings indicate that 5.0 µM sodium selenate is suitable for in vitro propagation of sweet potato plantlets, whereas higher concentrations may be useful for initiating selenium biofortification strategies.

Selenium (Se) is an essential micronutrient involved in antioxidant protection, immune regulation, and human metabolic health. However, Se deficiency affects nearly 15% of the global population, reinforcing the need for effective biofortification strategies. This study evaluated the physiological and ultrastructural responses of Ipomoea batatas L. cv. Campina plantlets cultured in vitro under increasing sodium selenite concentrations. Nodal segments were grown on Murashige and Skoog (MS) medium supplemented with 0, 5, 10, 15, 20, or 25 µM Se in a completely randomized design with seven replicates. After 30 days, shoot length, leaf number, senescence, biomass, and Se accumulation were quantified. Shoot elongation remained highest in the control and at 5–15 µM Se, while green leaf number and fresh biomass peaked at 5 µM. Senescent leaves increased markedly at 25 µM, and dry biomass was greatest in the control and 5 µM treatments. Selenium accumulation increased proportionally with external concentrations. Moderate supplementation (5 µM) enhanced growth and maintained epidermal integrity, whereas higher doses induced reduced biomass, leaf senescence, and stomatal deformation. These findings demonstrate that controlled Se supplementation during micropropagation is an effective strategy for producing Se-enriched sweet potato plantlets with predictable mineral content, supporting their use in nutritional and functional food applications. Keywords: Selenium Biofortification. Ipomoea batatas. Plant Tissue Culture. Ultrastructure. In vitro Propagation. Resumo O selênio (Se) é um micronutriente essencial envolvido na proteção antioxidante, na regulação do sistema imunológico e na manutenção da saúde metabólica humana. Entretanto, a deficiência de Se afeta cerca de 15% da população mundial, reforçando a necessidade de estratégias eficazes de biofortificação. Este estudo avaliou as respostas fisiológicas e ultraestruturais de brotações de Ipomoea batatas L. cv. Campina cultivadas in vitro sob concentrações crescentes de selenito de sódio. Segmentos nodais foram cultivados em meio Murashige e Skoog (MS) suplementado com 0, 5, 10, 15, 20 ou 25 µM de Se, em delineamento inteiramente casualizado com sete repetições. Após 30 dias, foram quantificados o comprimento da parte aérea, o número de folhas verdes e senescentes, a biomassa fresca e seca e o acúmulo de Se. O alongamento dos brotos permaneceu maior no controle e entre 5 e 15 µM de Se, enquanto o número de folhas verdes e a biomassa fresca atingiram seus maiores valores em 5 µM. As folhas senescentes aumentaram significativamente em 25 µM, e a biomassa seca foi maior no controle e em 5 µM. O acúmulo de selênio aumentou proporcionalmente às concentrações externas. A suplementação moderada (5 µM) promoveu o crescimento e manteve a integridade epidérmica, enquanto doses superiores reduziram a biomassa, intensificaram a senescência foliar e causaram deformações estomáticas. Esses resultados demonstram que a suplementação controlada de Se durante a micropropagação é uma estratégia eficaz para produzir mudas de batata-doce biofortificadas com conteúdo mineral previsível, apoiando seu uso em aplicações nutricionais e alimentos funcionais. Palavras-chave: Biofortificação com Selênio. Ipomoea batatas. Cultura de Tecidos Vegetais. Ultraestrutura. Propagação in Vitro.

The Acrocomia aculeata is a promising palm tree for biofuel production, but it faces challenges related to propagation, especially due to seed dormancy. This article presents an integrative review, supported by bibliometrics, of the sexual and asexual propagation methods of the species, conducted through searches in Scopus, SciELO, and Web of Science databases. The results indicate that sexual propagation is the predominant approach in the literature, although it faces significant challenges due to seed dormancy, such as the physical resistance to embryo protrusion imposed by the operculum. Asexual propagation demonstrates great potential through micropropagation techniques, which allow obtaining genetically uniform plants in relatively short periods. The non-deep physic dormancy exhibited by the seeds interferes with germination by constraining embryo growth potential and postponing the metabolic reactivation essential for successful germination. Despite the existence of promising methods for overcoming dormancy, additional studies are needed to understand the mechanisms involved in this process. This review maps the scientific literature to highlight areas of proven research success, identify critical gaps and underexplored topics, and indicate how future investigations can support the development of efficient propagation protocols and the establishment of commercial plantations.

O girassol (Helianthus annuus L.) é uma oleaginosa de ampla importância econômica e agronômica, utilizada para diferentes finalidades, com destaque para a produção de óleo e biocombustível. No Brasil, embora ainda seja cultivado principalmente na entressafra de culturas como soja e milho, seu potencial produtivo pode ser ampliado por pesquisas voltadas ao aumento da produtividade e à redução de custos. Nesse contexto, a Terra Diatomácea (TD), material rico em silício e ainda pouco estudado como fertilizante, apresenta potencial de uso agrícola, pois o silício, embora não essencial, pode proporcionar benefícios ao desenvolvimento das plantas. Assim, objetivou-se avaliar características morfológicas, nos estádios vegetativo e reprodutivo, e fisiológicas de plantas de girassol submetidas a diferentes concentrações de TD. O experimento foi conduzido entre junho e agosto de 2022, em casa de vegetação da estação agrometeorológica da Universidade Federal do Ceará. Foram avaliadas seis concentrações de TD: 0; 3,0; 6,0; 9,0; 12,0 e 15,0 g kg⁻¹ de substrato, utilizando produto com 90% de SiO₂. As unidades experimentais foram recipientes de 20 L contendo 14 kg de composto orgânico, semeados com a cultivar Multissol. O delineamento foi inteiramente casualizado, com 12 repetições, totalizando 72 unidades experimentais. Entre as variáveis avaliadas, apenas o diâmetro de capítulo apresentou diferença significativa entre os tratamentos, parâmetro diretamente relacionado à produtividade. Conclui-se que a baixa solubilidade da TD, associada às concentrações utilizadas, possivelmente não foi suficiente para alterar a maioria das características morfológicas e fisiológicas do girassol.

Acmella oleracea, a leafy vegetable native to the Amazon region, has potential for the cosmetic, pharmaceutical and gastronomic industries. Hot environments and or low relative humidity accelerate losses of vigor and quality, making unfeasible to storage seeds of this plant. This makes necessary to develop new propagation and conservation techniques for A. oleracea. The objective was to evaluate the biometric characteristics, describe the stomata and to verify the presence or absence of epicuticular wax on the abaxial leaf epidermis of A. oleracea plantlet obtained from the conversion of synthetic seeds (SS) in vitro. The nodal segments of micropropagated plantlets, at different concentrations of 6-benzylaminopurine (BAP) (0.000; 0.025; 0.050; 0.100 and 0.200 mg l^-1), were sectioned into explants of approximately 0.3 cm, encapsulated in alginate matrix to produce SS, inoculated in test tubes with Murashige & Skoog culture medium and kept in a growth room at a temperature of 25 ± 2 ºC and a photoperiod of 16 hours. The percentage of SS conversion, number of leaves and shoots, height and root dry mass were higher in the treatments with BAP. Shoot dry mass was 54.5% higher on plants originated from SS obtained with 0.100 mg l^-1 of BAP than in the control. Anomocytic and ellipsoid-shaped stomata were well defined and epicuticular wax deposition was not observed on the abaxial epidermis of A. oleracea plantlets leaves. The stomata of A. oleracea and the absence of epicuticular wax on the leaf epidermis of this plant were similar between treatments.

Selenium (Se) is an essential micronutrient for the growth, development and metabolism of animals, including humans. It is an integral part of a set of proteins, the selenoproteins, with antioxidant action, involved in the metabolism of thyroid hormones, growth regulation, cell viability, immune system functions and reproduction. This element fulfils the same function in vegetables, although it does not play an essential role in their nutrition, so it is currently included in the group of beneficial elements. It is introduced into the food chain by ingesting plants and products derived from them. Plants assimilate Se compounds, present in the soil, mainly in the form of inorganic compounds of selenate (Se6+) and selenite (Se4+). Both have water solubility and are part of the metabolic processes that occur in humans. In view of the above, the objectives of this literature review were to present information on some of the main aspects of selenium for humans and plants, describing its forms of absorption, benefits, problems related to its deficiency and its use in food biofortification. Selenium (Se) has several benefits for plants and human health, and for humans, when administered in ideal concentrations. In addition to providing a healthy diet, it can act as an antioxidant, playing an important role in protecting against viral infections.