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Agronomic biofortification of crops with selenium (Se) is an important strategy to minimize hidden hunger and increase nutrient intake in poor populations. Selenium is an element that has several physiological and biochemical characteristics, such as the mitigation of different types of abiotic stress. Selenoproteins act as powerful antioxidants in plant metabolism through the glutathione peroxidase (GSH) pathway, and provide an increased activity for enzymatic (SOD, CAT, and APX) and non-enzymatic (ascorbic acid, flavonoids, and tocopherols) compounds that act in reactive oxygen species (ROS) scavenging system and cell detoxification. Selenium helps to inhibit the damage caused by climate changes such as drought, salinity, heavy metals, and extreme temperature. Also, Se regulates antenna complex of photosynthesis, protecting chlorophylls by raising photosynthetic pigments. However, Se concentrations in soils vary widely in the earth's crust. Soil Se availability regulates the uptake, transport, accumulation, and speciation in plants. Foliar Se application at the concentration 50 g ha−1 applied as sodium selenate increases the antioxidant, photosynthetic metabolism, and yield of several crops. Foliar Se application is a strategy to minimize soil adsorption and root accumulation. However, the limit between the beneficial and toxic effects of Se requires research to establish an optimal dose for each plant species under different edaphoclimatic conditions. In this review, we present the compilation of several studies on agronomic biofortification of plants with Se to ensure food production and food security to mitigate hidden hunger and improve the health of the population.

Made available in DSpace on 2021-06-25T10:10:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Low concentrations of selenium (Se) are beneficial for plant growth. Foliar Se application at high concentrations is toxic to plants due to the formation of reactive oxygen species (ROS). This study characterized Se toxicity symptoms using X-ray fluorescence (XRF) technique in response to foliar Se application in cowpea plants. Five Se concentrations (0, 10, 25, 50, 100 e 150 g ha−1) were sprayed on leaves as sodium selenate. The visual symptoms of Se toxicity in cowpea leaves were separated into two stages: I) necrotic points with an irregular distribution and internerval chlorosis at the leaf limb border (50–100 g ha−1); II) total chlorosis with the formation of dark brown necrotic lesions (150 g ha−1). Foliar Se application at 50 g ha−1 increased photosynthetic pigments and yield. Ultrastructural analyses showed that Se foliar application above 50 g ha−1 disarranged the upper epidermis of cowpea leaves. Furthermore, Se application above 100 g ha−1 significantly increased the hydrogen peroxide concentration and lipid peroxidation inducing necrotic leaf lesions. Mapping of the elements in leaves using the XRF revealed high Se intensity, specifically in leaf necrotic lesions accompanied by calcium (Ca) as a possible attenuating mechanism of plant stress. The distribution of Se intensities in the seeds was homogeneous, without specific accumulation sites. Phosphorus (P) and sulfur (S) were found primarily located in the embryonic region. Understanding the factors involved in Se accumulation and its interaction with Ca support new preventive measurement technologies to prevent Se toxicity in plants. São Paulo State University (UNESP), Via de Acesso Prof. Paulo Donato Castellane S/n, Postal Code 14884-900 University of São Paulo (USP), Av. Centenário, 303, São Dimas São Paulo State University (UNESP), Rua Domingos da Costa Lopes 780 São Paulo State University (UNESP), Via de Acesso Prof. Paulo Donato Castellane S/n, Postal Code 14884-900 São Paulo State University (UNESP), Rua Domingos da Costa Lopes 780

Made available in DSpace on 2020-12-12T01:28:54Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-10-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Selenium (Se) at low concentration is considered benefit element to plants. The range between optimal and toxic concentration of Se is narrow and varies among plant species. This study aimed to evaluate the phenotypic, physiological and biochemical responses of four rice genotypes (BRS Esmeralda, BRSMG Relâmpago, BRS Bonança and Bico Ganga) grown hydroponically treated with sodium selenate (1.5 mM L−1). Selenium treated plants showed a dramatically decrease of soluble proteins, chlorophylls, and carotenoids concentration, resulting in the visual symptoms of toxicity characterized as leaf chlorosis and necrosis. Selenium toxicity caused a decrease on shoot and root dry weight of rice plants. Excess Se increased the oxidative stress monitored by the levels of hydrogen peroxide and lipid peroxidation. The enzymatic antioxidant system (catalase, superoxide dismutase, and ascorbate peroxidase) increased in response to Se supply. Interestingly, primary metabolism compounds such as sucrose, total sugars, nitrate, ammonia and amino acids increased in Se-treated plants. The increase in these metabolites may indicate a defense mechanism for the osmotic readjustment of rice plants to mitigate the toxicity caused by Se. However, these metabolites were not effective to minimize the damages on phenotypic traits such as leaf chlorosis and reduced shoot and root dry weight in response to excess Se. Increased sugars profile combined with antioxidant enzymes activities can be an effective biomarkers to indicate stress induced by Se in rice plants. This study shows the physiological attributes that must be taken into account for success in the sustainable cultivation of rice in environments containing excess Se. São Paulo State University (UNESP), Ilha São Paulo State University (UNESP) University of Sao Paulo (USP) Center for Nuclear Energy in Agriculture (CENA) São Paulo State University (UNESP), Ilha São Paulo State University (UNESP) CNPq: 309380/2017–0 CNPq: 310572/2017–7

Made available in DSpace on 2020-12-12T01:10:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-03-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Selenium (Se) is an essential element for human and animal, although considered beneficial to higher plants. Selenium application at high concentration to plants can cause toxicity decreasing the physiological quality of seeds. This study aimed to characterize the Se toxicity on upland rice yield, seed physiology and the localization of Se in seeds using X-ray fluorescence microanalysis (μ-XRF). In the flowering stage, foliar application of Se (0, 250, 500, 1000, 1500, 2000 g ha−1) as sodium selenate was performed. A decrease in rice yield and an increase in seed Se concentrations were observed from 250 g Se ha−1. The storage proteins in the seeds showed different responses with Se application (decrease in albumin, increase in prolamin and glutelin). There was a reduction in the concentrations of total sugars and sucrose with the application of 250 and 500 g Se ha−1. The highest intensities Kα counts of Se were detected mainly in the endosperm and aleurone/pericarp. μ-XRF revealed the spatial distribution of sulfur, calcium, and potassium in the seed embryos. The seed germination decreased, and the electrical conductivity increased in response to high Se application rates showing clearly an abrupt decrease of physiological quality of rice seeds. This study provides information for a better understanding of the effects of Se toxicity on rice, revealing that in addition to the negative effects on yield, there are changes in the physiological and biochemical quality of seeds. São Paulo State University (UNESP), Rua Domingos da Costa Lopes 780, Postal Code 17602-496 São Paulo State University (UNESP), Postal Code 15.385-000 Federal University of Mato Grosso do Sul (UFMS), Rodovia MS-306 - Zona Rural, Postal Code 79560-000 Federal Institute of Southeast Minas Gerais Rua Monsenhor José Augusto, n. 204 - Bairro São José University of São Paulo - USP, Av. Centenário, 303, São Dimas, Postal Code 13400-970 São Paulo State University (UNESP), Rua Domingos da Costa Lopes 780, Postal Code 17602-496 São Paulo State University (UNESP), Postal Code 15.385-000 FAPESP: 15/05942-0 FAPESP: 15/19121-8 FAPESP: 16/19937-0 CNPq: 309380/2017-0

As indústrias sucroalcooleras são as responsáveis pela produção de etanol e açúcar, contudo um subproduto é gerado em grande quantidade nessa produção, a vinhaça que possui alto poder poluente e alto valor fertilizante. Grande parte da vinhaça é usada na fertirrigação, entretanto, as usinas têm encontrado dificuldades de destino da mesma devido à saturação do solo após um período de utilização. Nesta saturação do solo destaca-se a grande concentração de alguns nutrientes, principalmente do potássio, que pode prejudicar o crescimento vegetal devido ao desequilíbrio de nutrientes. O objetivo desse trabalho foi realizar o tratamento da vinhaça proveniente de uma usina sucroalcooleira com a utilização de microalgas Chlorella vulgaris (Kessler & Huss, 1992), visando reduzir alguns nutrientes presentes, principalmente o potássio, a fim de garantir um melhor reaproveitamento deste na fertirrigação dos canaviais. Os resultados mostraram a eficiência do tratamento usando microalgas na redução das concentrações de potássio, sódio e cálcio. Estas reduções fazem com que a vinhaça possua uma maior disponibilidade para ser utilizada na fertirrigação nos canaviais da própria empresa que, consequentemente, acaba reduzindo os gastos com a compra de fertilizantes minerais, fechando assim um ciclo ecológico de produção e reutilização do próprio resíduo gerado.

Made available in DSpace on 2018-12-11T17:18:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-06-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Selenium (Se) is considered a beneficial element for plants; however, in high concentrations, it causes negative effects on plant physiology and development. This study reports the first physiological, nutritional, and ultrastructural description of Se toxicity in cowpea growing under field conditions. Selenium was supplied as a foliar application of sodium selenite at varying concentrations (0, 50, 100, 200, 400, 800, 1200, and 1600 g ha−1). An increased yield was observed with the application of 50 g ha−1 Se. Application of concentrations higher than 50 g ha−1 caused leaf toxicity. Increased lipid peroxidation and hydrogen peroxide concentration and reduced total sugars, sucrose, and carotenoid concentration were observed at highest doses tested (1200 and 1600 g ha−1). Applications of more than 50 g ha−1 Se reduced the phloem diameter, caused chlorosis of the leaf blade with a coalescence of lesions, and caused pink salt deposits to appear. Lesions were observed mainly near the trichomes on the adaxial surface of the leaf blade. An analysis of the element distribution with microprobe X-ray fluorescence spectrometry (μ-XRF) revealed accumulation of Se, calcium (Ca), potassium (K), copper (Cu), and manganese (Mn) near the primary vein and in the necrotic brown areas of the leaf lesions. In contrast, Na was homogeneously distributed in the leaf tissue. São Paulo State University – UNESP, Ilha Solteira, Postal Code 15.385-000 São Paulo State University – UNESP, Tupã Postal Code 17602-496, SP University of São Paulo – USP, Postal Code 13416-000, SP The James Hutton Institute, Invergowrie School of Biosciences The University of Nottingham, Sutton Bonington São Paulo State University – UNESP, Ilha Solteira, Postal Code 15.385-000 São Paulo State University – UNESP, Tupã Postal Code 17602-496, SP FAPESP: 2015/19121-8 FAPESP: 2016/19773-8