Ácido ascórbico como regulador da resposta antioxidante em tomateiro sob estresse salino
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Data
2019-01-18
Autores
Alves, Rita de Cássia [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Embora o ácido ascórbico (AsA) possa estar envolvido na atenuação dos efeito do estresse salino, pouco se sabe sobre os mecanismos fisiológicos e bioquímicos envolvidos, além da melhor estratégia de aplicação. O objetivo deste trabalho foi, portanto, explorar o papel do AsA via pré-tratamento de sementes; na regulação de respostas antioxidantes e no crescimento do micro-tomateiro (MT) sob estresse salino. O experimento foi conduzido em esquema fatorial 2 x 2, inteiramente casualizado, com quatro repetições. O pré-tratamento de sementes com AsA (0 e 100 mM AsA) foi realizado em sementes de MT com exposição subsequente ao estresse salino (0 e 100 mM de NaCl). Os resultados indicaram que o AsA desempenha papel na atenuação dos efeitos negativos do estresse salino através da redução do acúmulo de Na+, da peroxidação lipídica (MDA) e do concentração de H2O2, assim como, o aumento do potencial hídrico foliar, conteúdo relativo de água, clorofila total e carotenóides, atividade das enzimas antioxidantes, superóxido dismutase (SOD), catalase (CAT), ascorbato peroxidase (APX), peroxidases totais (POX), glutationa peroxidase (GPX), glutationa redutase (GR), e conteúdo de glutationa (GSH), culminando com melhor crescimento e produtividade. Assim, os resultados indicam que o pré-tratamento de sementes com AsA é uma técnica de manejo eficiente que pode ser utilizada para aliviar os efeitos deletérios e aumentar a tolerância das plantas de MT em condições de estresse salino.
Although ascorbic acid (AsA) has been known to improve plant defense systems against salt stressful-conditions, little is known about physiological and biochemistry mechanisms of AsA-mediated alleviation of salt stress, and the best management technique. The main objective of this work was, therefore, to explain the role of ascorbic acid via seed priming on antioxidant defense responses and growth regulation in tomato Micro-Tom under salt stress. The experiment was carried out using a 2 x 2 factorial completely randomized design with four replicates. In this way, seed priming with AsA (0 and 100 mM AsA) was used in Micro-Tom seeds to improve the tolerance of subsequent salt-stress exposure (0 and 100 mM NaCl). The effect of AsA priming was assessed on subsequent exposure to salt stress conditions with a physiological and biochemical approach involving antioxidant responses. Overall results indicated that AsA plays a role in alleviating the negative effects of salt stress by reduction of Na+ content, lipidic peroxidation and H2O2 content, increased leaf water potential (LWP), water-use efficiency (WUE), total chlorophyll, carotenoids, superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), peroxidase (POX), glutathione peroxidase (GPX) and glutathione reductase (GR) activities and GSH content, leading to better plant growth and higher yields. Thus, the results indicated that the seed priming with AsA is an efficient management technique that can be used to alleviate the deleterious effects of salt stress conditions and enhance salt tolerance of Micro-Tom plants.
Although ascorbic acid (AsA) has been known to improve plant defense systems against salt stressful-conditions, little is known about physiological and biochemistry mechanisms of AsA-mediated alleviation of salt stress, and the best management technique. The main objective of this work was, therefore, to explain the role of ascorbic acid via seed priming on antioxidant defense responses and growth regulation in tomato Micro-Tom under salt stress. The experiment was carried out using a 2 x 2 factorial completely randomized design with four replicates. In this way, seed priming with AsA (0 and 100 mM AsA) was used in Micro-Tom seeds to improve the tolerance of subsequent salt-stress exposure (0 and 100 mM NaCl). The effect of AsA priming was assessed on subsequent exposure to salt stress conditions with a physiological and biochemical approach involving antioxidant responses. Overall results indicated that AsA plays a role in alleviating the negative effects of salt stress by reduction of Na+ content, lipidic peroxidation and H2O2 content, increased leaf water potential (LWP), water-use efficiency (WUE), total chlorophyll, carotenoids, superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), peroxidase (POX), glutathione peroxidase (GPX) and glutathione reductase (GR) activities and GSH content, leading to better plant growth and higher yields. Thus, the results indicated that the seed priming with AsA is an efficient management technique that can be used to alleviate the deleterious effects of salt stress conditions and enhance salt tolerance of Micro-Tom plants.
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Palavras-chave
Solanum lycopersicum L., Estresse oxidativo, Pré-tratamento, Salinidade