Fluorometria, conteúdo de açúcares, crescimento e atividade de enzimas antioxidantes em plantas de Solanum lycopersicum cv. Micro-Tom em resposta a subdoses de boro
Arquivos
Data
2019-05-28
Autores
Cruz, Janaina Oliveira
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
O mineral boro (B) está relacionado a uma série de processos fisiológicos das plantas tais como: estrutura da parede celular; respiração; metabolismo de carboidratos; metabolismo de RNA; transporte de metabólitos, entre outros. O B é absorvido pelas raízes por difusão na forma de ácido bórico, sendo transportado em seguida via xilema pela taxa transpiratória e pode formar complexos estáveis com moléculas do grupo cis-hidroxila, formando complexos B-poliol que podem se movimentar no interior vegetal. A deficiência de B ocasiona rápida inibição do crescimento das raízes primárias e laterais, limitando o crescimento e divisão celular. Em vista disso, esta pesquisa tem como objetivo elucidar melhor o papel do mineral boro no metabolismo e transporte de açúcares em plantas de Solanum lycopericum cv. Micro-Tom. Para tal, foram realizados dois experimentos, o primeiro instalado em casa de vegetação no Departamento de Botânica do Instituto de Biociências de Botucatu, UNESP, SP e o outro em câmara de crescimento no Departamento de Biologia Vegetal do Instituto de Biociências, Universidade de Lisboa, Portugal. O primeiro experimento foi conduzido com delineamento de blocos ao acaso com três repetições, constituído de diferentes concentrações de boro em hidroponia. O segundo experimento foi conduzido em vasos com perlite em delineamento de blocos ao acaso com três repetições. As concentrações utilizadas em todos os experimentos foram: 0; 15,6; 31,12; 62,25; 124,5; 249 e 498 µg L-1 (controle) de boro na forma de ácido bórico. No primeiro experimento foi avaliado a atividade das enzimas superóxido dismutase (SOD), peroxidase (POD) e catalase (CAT); teor de proteínas totais solúveis; taxa da peroxidação lipídica (MDA); teores de sacarose, açúcares redutores e amido em folhas; produção de biomassa e teor de boro foliar. No segundo experimento foi avaliado a produção de biomassa, os teores de sacarose, açúcares redutores e amido em folhas e a fluorometria. No primeiro experimento foi observado que as baixas concentrações, 0 e 15,6 µg L-1 de B apresentaram os menores valores de produção de fitomassa de raiz, haste, folha, redução do crescimento absoluto e baixo teor de B foliar. Além disso, ainda ocasionou maior atividade das enzimas peroxidase e superóxido dismutase, maior taxa na produção de MDA e variações no conteúdo de amido aos 14 e 21 dias após o início dos tratamentos (DAT), açúcares redutores aos 14 e 28 DAT, e sacarose aos 7 e 21 dias após os tratamentos. No segundo experimento foi observado a não influência das diferentes concentrações de B na fluorometria; entretanto, a produção de massa (raiz, haste, folha e flor) foi maior no tratamento controle. Já os teores de açúcares, amido e açúcares redutores nos tratamentos com ausência de B e de menor concentração apresentaram maiores valores em relação ao controle. Em geral, a variação da disponibilidade de B interferiu diretamente no metabolismo e crescimento de plantas de tomate cv. Micro-Tom, em ambas as situações avaliadas.
The mineral boron (B) is related to a series of plant physiological processes such as: cell wall structure; breath; carbohydrate metabolism; RNA metabolism; transport of metabolites, among others. B is absorbed by the roots by boric acid diffusion and is then transported via the transpiratory rate xylem and can form stable complexes with cis-hydroxyl group molecules, forming B-polyol complexes that can move within the plant interior. B deficiency causes rapid inhibition of primary and lateral root growth, limiting cell growth and division. Therefore, this research aims to better elucidate the role of mineral boron in sugar metabolism and transport in Solanum lycopericum cv. Micro-Tom. To this end, two experiments were carried out, the first in a greenhouse in the Botany Department of Botucatu Bioscience Institute, UNESP, SP and the other in a growth chamber in the Department of Plant Biology of the Institute of Biosciences, University of Lisbon. Portugal. The first experiment was conducted with a randomized block design with three replications, consisting of different boron concentrations in hydroponics. The second experiment was conducted in perlite vessels in a randomized block design with three replications. The concentrations used in all experiments were: 0; 15.6; 31.12; 62.25; 124.5; 249 and 498 µg L-1 (control) of boron as boric acid. In the first experiment was evaluated the activity of the enzymes superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT); otal soluble protein content; lipid peroxidation rate (MDA); sucrose, reducing sugars and leaf starch content; biomass production and leaf boron content. In the second experiment, biomass production, sucrose, reducing sugars and starch in leaves and fluorometry were evaluated. In the first experiment it was observed that the low concentrations, 0 and 15.6 µg L-1 of B presented the lowest values of root, stem, leaf phytomass production, reduction of absolute growth and low leaf B content. In addition, it caused higher activity of the peroxidase and superoxide dismutase enzymes, higher MDA production rate and starch content variations at 14 and 21 days after the beginning of treatments (DAT), reducing sugars at 14 and 28 DAT, and sucrose. at 7 and 21 days after the treatments. In the second experiment it was observed no influence of different B concentrations on fluorometry; However, the mass production (root, stem, leaf and flower) was higher in the control treatment. Already the contents of sugars, starch and reducing sugars in the treatments without B and of lower concentration presented higher 12 12 values in relation to the control. In general, the variation of B availability directly affected the metabolism and growth of tomato cv. Micro-Tom in both situations evaluated.
The mineral boron (B) is related to a series of plant physiological processes such as: cell wall structure; breath; carbohydrate metabolism; RNA metabolism; transport of metabolites, among others. B is absorbed by the roots by boric acid diffusion and is then transported via the transpiratory rate xylem and can form stable complexes with cis-hydroxyl group molecules, forming B-polyol complexes that can move within the plant interior. B deficiency causes rapid inhibition of primary and lateral root growth, limiting cell growth and division. Therefore, this research aims to better elucidate the role of mineral boron in sugar metabolism and transport in Solanum lycopericum cv. Micro-Tom. To this end, two experiments were carried out, the first in a greenhouse in the Botany Department of Botucatu Bioscience Institute, UNESP, SP and the other in a growth chamber in the Department of Plant Biology of the Institute of Biosciences, University of Lisbon. Portugal. The first experiment was conducted with a randomized block design with three replications, consisting of different boron concentrations in hydroponics. The second experiment was conducted in perlite vessels in a randomized block design with three replications. The concentrations used in all experiments were: 0; 15.6; 31.12; 62.25; 124.5; 249 and 498 µg L-1 (control) of boron as boric acid. In the first experiment was evaluated the activity of the enzymes superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT); otal soluble protein content; lipid peroxidation rate (MDA); sucrose, reducing sugars and leaf starch content; biomass production and leaf boron content. In the second experiment, biomass production, sucrose, reducing sugars and starch in leaves and fluorometry were evaluated. In the first experiment it was observed that the low concentrations, 0 and 15.6 µg L-1 of B presented the lowest values of root, stem, leaf phytomass production, reduction of absolute growth and low leaf B content. In addition, it caused higher activity of the peroxidase and superoxide dismutase enzymes, higher MDA production rate and starch content variations at 14 and 21 days after the beginning of treatments (DAT), reducing sugars at 14 and 28 DAT, and sucrose. at 7 and 21 days after the treatments. In the second experiment it was observed no influence of different B concentrations on fluorometry; However, the mass production (root, stem, leaf and flower) was higher in the control treatment. Already the contents of sugars, starch and reducing sugars in the treatments without B and of lower concentration presented higher 12 12 values in relation to the control. In general, the variation of B availability directly affected the metabolism and growth of tomato cv. Micro-Tom in both situations evaluated.
Descrição
Palavras-chave
Nutrição, Crescimento, Enzimas, Fotossíntese, Tomate, Nutrition, Growth, Enzymes, Photosynthesis, Tomato