Intensidade do estresse hídrico modula a expressão de aquaporinas durante a reidratação em Sorghum bicolor
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Data
2016-02-25
Autores
Schley, Thayssa Rabelo [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Espera-se que os efeitos da seca aumentem e alterem a duração do estresse hídrico nos próximos anos em diferentes regiões agrícolas. A recuperação fisiológica após o estresse hídrico ainda não é compreendida e as aquaporinas (AQPs) participam do processo de recuperação. Nosso objetivo foi avaliar se as aquaporinas estão associadas com o processo de recuperação fisiológica nas folhas após a reidratação. Plantas de Sorghum bicolor L. (Moench) foram submetidas a diferentes intensidades de estresse hídrico durante 20 dias e posterior reidratação durante 12 dias. Durante estes períodos, as variáveis de relações hídricas, fluorescência da clorofila a, trocas gasosas e a expressão dos genes PIP1,5, PIP2;2 e TIP1; 1 foram avaliados. Plantas submetidas ao déficit hídrico moderado (DHM) mostraram mesmos valores do controle em todas as variáveis fisiológicas e aumento da expressão das aquaporinas no final do déficit hídrico. Enquanto as plantas da deficiência hídrica severa (DHS) e severa progressiva (DHSP) apresentaram diminuição nas variáveis de relações hídricas, limitação estomática e não estomática da fotossíntese e baixa expressão das aquaporinas. Após a reidratação, as plantas desses tratamentos apresentam conjunto de ajustes fisiológicos que permitem o retorno da fotossíntese 144 horas após o fornecimento de água, sendo a limitação estomática a maior responsável pela recuperação. As AQPs analisadas são responsivas à reidratação somente nas plantas que não tiveram controle da reposição de água no solo (DHSP). Observamos um padrão das respostas dessas AQPs que depende da intensidade da deficiência hídrica e não da especificidade da AQP. Provavelmente elas influenciam diferentemente nos ajustes fisiológicos ocorridos durante a recuperação. Além disso, essas AQPs podem contribuir para manutenção de baixos valores de gs e consequentemente ANet, pois a recuperação dessas variáveis fisiológicas ocorre concomitantemente com a recuperação das AQPs em nível do controle 144 horas após a reidratação.
It is expected that the effects of drought increase and change the duration of water stress in the coming years in different agricultural regions. The physiological recovery after water stress is still not well understood and aquaporins (AQPs) participate in the recovery process. Our aim was evaluate whether aquaporins are associated with physiological recovery process in leaves after rehydration. Sorghum bicolor L. (Moench) plants were submitted to different intensities of water stress during 20 days and subsequent rehydration for 12 days. During these periods, variables of water relations, chlorophyll fluorescence, gas exchange and PIP1;5, PIP2;2 and TIP1;1 gene expression were evaluated. Moderate water deficit (DHM) plants showed same values of control in all physiological variables and increased aquaporins expression in the end of water deficit. While severe (DHS) and progressive severe water stress (DHSP) plants had decreased water relations, diffusive and non-diffusive limitation of photosynthesis and low aquaporins expression. After rehydration, plants of these treatments have set of physiological adjustments that enable the return of photosynthesis 144 hours after the water supply. Stomatal limitation was the most responsible for recovery. The AQPs analyzed are responsive to rehydration only in plants that did not have control of water replacement in the soil (DHSP). We observed a pattern of responses of these AQPs that depends on the intensity of water deficit and not the AQP specificity. Probably they influence differently in physiological adjustments that occur during recovery. Furthermore, these AQPs may contribute to maintaining low gs, and thus, ANet values, because the recovery of these physiological variables occurs concurrently with the recovery of AQPs 144 hours after rehydration.
It is expected that the effects of drought increase and change the duration of water stress in the coming years in different agricultural regions. The physiological recovery after water stress is still not well understood and aquaporins (AQPs) participate in the recovery process. Our aim was evaluate whether aquaporins are associated with physiological recovery process in leaves after rehydration. Sorghum bicolor L. (Moench) plants were submitted to different intensities of water stress during 20 days and subsequent rehydration for 12 days. During these periods, variables of water relations, chlorophyll fluorescence, gas exchange and PIP1;5, PIP2;2 and TIP1;1 gene expression were evaluated. Moderate water deficit (DHM) plants showed same values of control in all physiological variables and increased aquaporins expression in the end of water deficit. While severe (DHS) and progressive severe water stress (DHSP) plants had decreased water relations, diffusive and non-diffusive limitation of photosynthesis and low aquaporins expression. After rehydration, plants of these treatments have set of physiological adjustments that enable the return of photosynthesis 144 hours after the water supply. Stomatal limitation was the most responsible for recovery. The AQPs analyzed are responsive to rehydration only in plants that did not have control of water replacement in the soil (DHSP). We observed a pattern of responses of these AQPs that depends on the intensity of water deficit and not the AQP specificity. Probably they influence differently in physiological adjustments that occur during recovery. Furthermore, these AQPs may contribute to maintaining low gs, and thus, ANet values, because the recovery of these physiological variables occurs concurrently with the recovery of AQPs 144 hours after rehydration.
Descrição
Palavras-chave
Limitação difusiva, Condutância estomática, Rendimento quântico, Expressão gênica relativa, Water stress, Stomatal conductance, Quantum yield, Relative gene expression