Pré-tratamento com peróxido de hidrogênio em sementes de soja induz tolerância ao estresse por déficit hídrico
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2019-02-28
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Universidade Estadual Paulista (Unesp)
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Atualmente, devido às mudanças no regime de chuvas, a escassez de água em diversas regiões agrícolas é cada vez mais frequente. Dessa forma, o déficit hídrico se torna uma questão preocupante, especialmente no cultivo da soja, uma das mais importantes espécies agronômicas. Concomitantemente, pesquisas indicam o importante papel do peróxido de hidrogênio (H2O2) como molécula sinalizadora, capaz de induzir respostas de tolerância ao déficit hídrico. Assim, buscamos neste estudo, avaliar as respostas de plantas de soja (Glycine max L.) submetidas ao déficit hídrico após pré-tratamento com concentrações de H2O2 em sementes. Para tal, sementes de soja foram embebidas em concentrações de H2O2 (0, 10, 50, 100 e 200 mM) seguido de secagem e, posteriormente foram submetidas ao estresse osmótico com polietileno glicol (PEG -0,2 MPa) e cloreto de sódio (NaCl -0,2 MPa). Avaliou-se germinação, crescimento, acúmulo de prolina, teor de H2O2 e malondialdeído (MDA) na fase de plântulas. Para as avaliações em planta, as sementes foram embebidas apenas com 10 mM de H2O2 ou água e, condicionadas ao déficit hídrico pela interrupção da irrigação 36 dias após a semeadura. Posteriormente, foi avaliado a umidade do solo, as relações hídricas (teor relativo de água e potencial hídrico foliar), crescimento, acúmulo de prolina, conteúdo de pigmentos, teor de H2O2 e MDA. As avaliações foram realizadas em 4 períodos de estresse (0, 4 e 8 dias de restrição hídrica e, 4 dias de reidratação após o estresse máximo de 8 dias). O pré-tratamento com 10 e 50 mM de H2O2 melhorou a germinação de sementes, crescimento e acúmulo de massa seca das plântulas sob estresse osmótico e salino. Em plantas, com 36 dias, o tratamento com 10 mM de H2O2 promoveu melhorias ao prolongar o tempo para diminuição do potencial hídrico em plantas sob estresse além de induzir o crescimento de raízes em ambas as condições hídricas, porém não evitou a diminuição do crescimento da parte aérea, a redução dos pigmentos e aumento do estresse oxidativo. Dessa forma, demonstramos os efeitos positivos do uso de H2O2 no pré-tratamento de sementes de soja seguido de secagem para induzir tolerância ao déficit hídrico em plântulas. Todavia, em plantas, mais estudos são necessários para compreensão do efeito do H2O2.
Currently, due to changes in the rainfall regime, water scarcity in several agricultural regions is becoming more frequent. Thus, the water deficit becomes a matter of concern, especially in the cultivation of soybean, one of the most important agronomic species. Meanwhile, researches indicate the important role of hydrogen peroxide (H2O2.) as a signaling molecule, able to induce tolerance responses to water deficit. Thus, the purpose of this study was evaluating the responses of soybean plants (Glycine max L.) submitted to water stress after seed priming with H2O2. concentrations in seeds. Thus, soybean seeds were placed to soak in H2O2.solutions (0, 10, 50, 100 and 200 mM) followed by drying and subsequent exposition to osmotic stress with polyethylene glycol (PEG -0.2 MPa) and (NaCl -0.2 MPa). Germination, growth, proline accumulation and oxidative stress were evaluated in the seedling stage. For the plant evaluations, the seeds were only soaked with 10 mM H2O2. or water and, conditioned to the water deficit by the interruption of irrigation 36 days after sowing. Subsequently, soil moisture, water relations (relative water content and leaf water potential), growth, proline accumulation, pigment content and oxidative stress were evaluated. The evaluations were carried out in 4 stress periods (0, 4 and 8 days of water restriction and 4 days of rehydration after 8 days of maximum stress). Seed priming with 10 and 50 mM H2O2. improved germination of seeds, growth and dry mass accumulation of seedlings under osmotic and saline stress. In plants with 36 days, treatment with 10 mM H2O2 promoted improvements by prolonging the time to decrease the water potential in plants under stress, induce root growth in both water conditions from four days and reduce the content of proline and H2O2 in relation to the control, although it did not avoid the decrease of the growth, reduction of the photosynthetic pigments and increase of the oxidative stress. Thus, we demonstrated the positive effects of H2O2 use on pre-treatment of soybean seeds followed by drying to induce tolerance to water deficit in seedlings. However, in plants, further studies are required to obtain conclusive answers.
Currently, due to changes in the rainfall regime, water scarcity in several agricultural regions is becoming more frequent. Thus, the water deficit becomes a matter of concern, especially in the cultivation of soybean, one of the most important agronomic species. Meanwhile, researches indicate the important role of hydrogen peroxide (H2O2.) as a signaling molecule, able to induce tolerance responses to water deficit. Thus, the purpose of this study was evaluating the responses of soybean plants (Glycine max L.) submitted to water stress after seed priming with H2O2. concentrations in seeds. Thus, soybean seeds were placed to soak in H2O2.solutions (0, 10, 50, 100 and 200 mM) followed by drying and subsequent exposition to osmotic stress with polyethylene glycol (PEG -0.2 MPa) and (NaCl -0.2 MPa). Germination, growth, proline accumulation and oxidative stress were evaluated in the seedling stage. For the plant evaluations, the seeds were only soaked with 10 mM H2O2. or water and, conditioned to the water deficit by the interruption of irrigation 36 days after sowing. Subsequently, soil moisture, water relations (relative water content and leaf water potential), growth, proline accumulation, pigment content and oxidative stress were evaluated. The evaluations were carried out in 4 stress periods (0, 4 and 8 days of water restriction and 4 days of rehydration after 8 days of maximum stress). Seed priming with 10 and 50 mM H2O2. improved germination of seeds, growth and dry mass accumulation of seedlings under osmotic and saline stress. In plants with 36 days, treatment with 10 mM H2O2 promoted improvements by prolonging the time to decrease the water potential in plants under stress, induce root growth in both water conditions from four days and reduce the content of proline and H2O2 in relation to the control, although it did not avoid the decrease of the growth, reduction of the photosynthetic pigments and increase of the oxidative stress. Thus, we demonstrated the positive effects of H2O2 use on pre-treatment of soybean seeds followed by drying to induce tolerance to water deficit in seedlings. However, in plants, further studies are required to obtain conclusive answers.
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Memória de estresse, Germinação, Sinalização, Stress memory, Germination, Signaling