Tolerância ao défice hídrico recorrente modulado por padrões fisiológicos, bioquímicos e epigenéticos
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Data
2019-02-27
Autores
Mantoan, Luís Paulo Benetti
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Plantas que presenciam a seca podem armazenar informações sobre esta experiência, tal como uma memória ao estresse. As informações adquiridas com a memória do estresse podem ser utilizadas para aumentar a tolerância a futuros eventos de défice hídrico, porém, o crescimento das plantas pode ser limitado. O objetivo deste estudo foi investigar as respostas fisiológicas, bioquímicas e epigenéticas de Sorghum bicolor (L.) Moench durante e após o primeiro e segundo evento de défice hídrico, bem como as vantagens e desvantagens de eventos recorrentes de seca para a tolerância e crescimento. Neste estudo foram utilizados quatro tratamentos que foram: Controle, onde a irrigação foi mantida, Défice Hídrico na Fase Juvenil, onde as plantas foram submetidas a desidratação na fase juvenil seguido de reidratação, Défice Hídrico na Fase Adulta, onde a irrigação foi suspensa na fase adulta seguido de reidratação e Défice Hídrico Recorrente, onde a irrigação foi suspensa na fase juvenil e adulta seguido de reidratação. Foram avaliadas as trocas gasosas, fluorescência da clorofila a, conteúdo relativo de água na folha, densidade estomática, crescimento, enzimas atioxidativas, conteúdo de açucares totais e sacarose e ocorrência da H3K4me3 no gene Sb04g038610. Mesmo com o intervalo entre o primeiro e o segundo evento de seca, o que poderia resultar na remoção da memória do estresse formada no primeiro evento, as respostas fotossintéticas, antioxidativas, morfo-anatomicas e de estado hídrico demonstraram que plantas de S. bicolor apresentaram maior tolerância a seca durante o défice recorrente em relação às plantas submetidas a apenas um evento de défice. Além disso, plantas sob défice hídrico recorrente apresentaram maior ocorrência da marca epigenética H3K4me3 no gene Sb04g038610 durante a seca e reidratação, sendo a H3K4me3 mantida durante a reidratação de plantas submetidas ao défice hídrico único e recorrente por seis dias. Contudo, a massa seca da parte aérea e a área foliar de plantas sob seca recorrente foi reduzida em relação a plantas sob défice hídrico único. Desta forma, conclui-se que S. bicolor apresenta impressão do estresse por défice hídrico a longo prazo, pois durante o segundo evento de seca as plantas apresentam maior tolerância e presença, com posterior manutenção, da H3K4me3. Entretanto, o crescimento destas plantas é prejudicado.
Plants that experience drought can store information about this experience, such as a memory of stress. Information acquired with stress memory can be used to increase tolerance to future water deficit events, however, plant growth may be limited. The objective of this study was to investigate the physiological, biochemical and epigenetic responses of Sorghum bicolor (L.) Moench during and after the first and second water deficit event, as well as the advantages and disadvantages of recurrent drought events for tolerance and growth. Four treatments were used: Control, where irrigation was maintained, Water Deficit in the Juvenile Phase, where the plants were submitted to dehydration in the juvenile phase followed by rehydration, Water Deficit in the Adult Phase, where irrigation was suspended in the adult phase followed by rehydration and Recurrent Water Deficit, where irrigation was suspended in the juvenile and adult phases followed by rehydration. Gas exchanges, chlorophyll a fluorescence, relative leaf water content, stomatal density, plant growth, atioxidative enzymes, total sugar and sucrose content and the occurrence of H3K4me3 in the Sb04g038610 gene were evaluated. Even with the interval between the first and second drought events, which could result in the removal of the stress memory, the photosynthetic, antioxidative, morpho-anatomical and water status responses demonstrated that S. bicolor plants showed increased tolerance to drought during recurrent water deficit in relation to plants submitted to only one water deficit event. In addition, plants under recurrent drought presented a higher occurrence of the epigenetic mark H3K4me3 in the gene Sb04g038610 during drought and rehydration, with H3K4me3 being maintained during the rehydration of plants submitted to a single and recurrent drought for six days. However, dry shoot mass and leaf area of plants under recurrent drought was reduced in relation to plants under single drought conditions. In this way, it is concluded that S. bicolor presents stress imprint to water deficit to long-term, because during the second drought event the plants present greater tolerance and presence of H3K4me3, with subsequent maintenance of this epigenetic mark in rehydration.
Plants that experience drought can store information about this experience, such as a memory of stress. Information acquired with stress memory can be used to increase tolerance to future water deficit events, however, plant growth may be limited. The objective of this study was to investigate the physiological, biochemical and epigenetic responses of Sorghum bicolor (L.) Moench during and after the first and second water deficit event, as well as the advantages and disadvantages of recurrent drought events for tolerance and growth. Four treatments were used: Control, where irrigation was maintained, Water Deficit in the Juvenile Phase, where the plants were submitted to dehydration in the juvenile phase followed by rehydration, Water Deficit in the Adult Phase, where irrigation was suspended in the adult phase followed by rehydration and Recurrent Water Deficit, where irrigation was suspended in the juvenile and adult phases followed by rehydration. Gas exchanges, chlorophyll a fluorescence, relative leaf water content, stomatal density, plant growth, atioxidative enzymes, total sugar and sucrose content and the occurrence of H3K4me3 in the Sb04g038610 gene were evaluated. Even with the interval between the first and second drought events, which could result in the removal of the stress memory, the photosynthetic, antioxidative, morpho-anatomical and water status responses demonstrated that S. bicolor plants showed increased tolerance to drought during recurrent water deficit in relation to plants submitted to only one water deficit event. In addition, plants under recurrent drought presented a higher occurrence of the epigenetic mark H3K4me3 in the gene Sb04g038610 during drought and rehydration, with H3K4me3 being maintained during the rehydration of plants submitted to a single and recurrent drought for six days. However, dry shoot mass and leaf area of plants under recurrent drought was reduced in relation to plants under single drought conditions. In this way, it is concluded that S. bicolor presents stress imprint to water deficit to long-term, because during the second drought event the plants present greater tolerance and presence of H3K4me3, with subsequent maintenance of this epigenetic mark in rehydration.
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Palavras-chave
H3K4me3, “Memória” do estresse, Reidratação, Seca recorrente, Sorgo, Planta cultivada, H3K4me3, “Stress memory”, Rehydration, Recurring drought, Sorghum, Cultivated plant