Cálcio e sinalização do restabelecimento vegetal após estresse mecânico
Carregando...
Data
2019-02-28
Autores
Campos, Felipe Girotto [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Cálcio apresenta função estrutural, na parede celular, atua na manutenção da estabilidade da membrana plasmática e é mensageiro secundário, envolvido na regulação de processos fisiológicos do desenvolvimento e em respostas a estresses. No dano mecânico, espécies reativas de oxigênio (ERO) auxiliam no afrouxamento da parede celular e na abertura de canais de Ca2+ do reticulo endoplasmático e o aumento de Ca2+ no citoplasma gera uma cascata de sinais mediados por hormônios, ERO, peroxidases e cálcio-calmodulina. Além disso, o Ca2+ é de fundamental importância para o funcionamento do fotossistema II (PSII), uma vez que, sua variação pode interferir na cadeia transportadora de elétrons. O objetivo deste estudo foi investigar a influência da variação de cálcio na sinalização de defesa de plantas de crescimento lento e rápido e submetidas a dano mecânico. O delineamento experimental foi em blocos casualizados, com quatro repetições, em esquema fatorial, onde as plantas foram cultivadas com 0, 2 e 4 mM de Ca2+, com e sem dano mecânico e cinco épocas de avaliação, realizadas aos 0, 15, 30, 60 e 90 dias após o dano mecânico. Com a espécie de crescimento lento, Annona emarginata, foram estudados fotossíntese (fluorescência da clorofila a e trocas gasosas), massa seca total, crescimento quantitativo e peroxidação lipídica. No Solanum lycopersicum Micro-Tom, espécie de crescimento rápido, expressão de genes de estresses, enzimas antioxidantes, peroxido de hidrogênio, peroxidação lipídica, histoquímica de peroxido de hidrogênio, fotossíntese (fluorescência da clorofila a e trocas gasosas) e massa seca dos diferentes órgãos foram avaliados. Os resultados permitiram concluir que as plantas de Annona emarginata apresentaram maior resistência ao dano mecânico na presença de cálcio e foram mais sensíveis na ausência do mineral. Cultivo dessa espécie com 2 mM de cálcio na solução nutritiva completa garantiu crescimento e restabelecimento fotossintético do vegetal submetido a dano mecânico. Quanto ao Solanum lycopersicum Micro-Tom, os resultados sugerem que peroxido de hidrogênio está envolvido na resposta ao dano mecânico em plantas sem cálcio. Nessa espécie, presença de cálcio foi importante na defesa e aclimatação fotossintéica após dano mecânico e 2 mM de cálcio na solução nutritiva foram suficientes para defesa e superação do estresse por dano mecânico.
Calcium presents structural function in the cell wall, it acts in the maintenance of the stability of the plasma membrane and is secondary messenger, involved in the regulation of physiological processes of development and in responses to stresses. In mechanical damage, reactive oxygen species (ROS) assist in the loosening of the cell wall and in the opening of Ca2+ channels of the endoplasmic reticulum, and the increase of Ca2+ in the cytoplasm generates a cascade of signals mediated by hormones, ROS, peroxidases and calcium-calmodulin. In addition, Ca2+ is of fundamental importance for the functioning of photosystem II (PSII), since its variation can interfere with the electron transport chain. The objective of this study was to investigate the influence of calcium variation on defense signaling of slow and fast growing plants and submitted to mechanical damage. The experimental design was a randomized block, with four replications in a factorial design, where the plants were cultured with 0, 2 and 4 mM Ca2+ with and without mechanical damage five evaluation times were made at 0, 15, 30, 60 and 90 days after mechanical damage. With the slow-growing species, Annona emarginata, photosynthesis (chlorophyll a fluorescence and gas exchange), total dry mass, quantitative growth and lipid peroxidation were studied. The results allowed to conclude that the Annona emarginata plants presented greater resistance to the mechanical damage in the presence of calcium and were more sensitive in the absence of the mineral. Cultivation of this species with 2 mM Ca2+ in the complete nutrient solution ensured the growth and photosynthetic reestablishment of the plant submitted to mechanical damage. As for Solanum lycopersicum Micro-Tom, the results suggest that hydrogen peroxide is involved in the response to mechanical damage in plants without calcium. In this species, the presence of calcium was important in the defense and photosynthetic acclimation after mechanical damage and 2 mM Ca2+ in the nutrient solution were enough for defense and overcoming stress due to mechanical damage.
Calcium presents structural function in the cell wall, it acts in the maintenance of the stability of the plasma membrane and is secondary messenger, involved in the regulation of physiological processes of development and in responses to stresses. In mechanical damage, reactive oxygen species (ROS) assist in the loosening of the cell wall and in the opening of Ca2+ channels of the endoplasmic reticulum, and the increase of Ca2+ in the cytoplasm generates a cascade of signals mediated by hormones, ROS, peroxidases and calcium-calmodulin. In addition, Ca2+ is of fundamental importance for the functioning of photosystem II (PSII), since its variation can interfere with the electron transport chain. The objective of this study was to investigate the influence of calcium variation on defense signaling of slow and fast growing plants and submitted to mechanical damage. The experimental design was a randomized block, with four replications in a factorial design, where the plants were cultured with 0, 2 and 4 mM Ca2+ with and without mechanical damage five evaluation times were made at 0, 15, 30, 60 and 90 days after mechanical damage. With the slow-growing species, Annona emarginata, photosynthesis (chlorophyll a fluorescence and gas exchange), total dry mass, quantitative growth and lipid peroxidation were studied. The results allowed to conclude that the Annona emarginata plants presented greater resistance to the mechanical damage in the presence of calcium and were more sensitive in the absence of the mineral. Cultivation of this species with 2 mM Ca2+ in the complete nutrient solution ensured the growth and photosynthetic reestablishment of the plant submitted to mechanical damage. As for Solanum lycopersicum Micro-Tom, the results suggest that hydrogen peroxide is involved in the response to mechanical damage in plants without calcium. In this species, the presence of calcium was important in the defense and photosynthetic acclimation after mechanical damage and 2 mM Ca2+ in the nutrient solution were enough for defense and overcoming stress due to mechanical damage.
Descrição
Palavras-chave
Annona emarginata, Solanum lycopersicum Micro-Tom, expressão gênica, sistema antioxidantes, fotossíntese