Interação dos fitocromos A, B1 e B2 de tomateiro com a auxina durante a síndrome de evitação à sombra
Carregando...
Data
2020-06-08
Autores
Santos, Joel Cabral dos [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Plantas que necessitam de radiações luminosas mais intensas, quando crescidas em ambientes sombreados, desencadeiam uma série de respostas compreendidas como "síndrome de evitação à sombra" (SES). Visto que a SES é modulada principalmente pelas mudanças na proporção entre vermelho e vermelho extremo (V:VE), é evidente o envolvimento dos fitocromos na regulação desse fenômeno. É bem conhecido que as famílias do tipo A (phyA) e B (phyB) de fitocromos são os fatores mais importantes na modulação da SES. Entretanto, tem se tornado cada vez mais evidente que as auxinas são parte da sinalização dos fitocromos. Desta forma, neste trabalho estudou-se como os fitocromos A, B1 e B2 de tomateiros interagem com as auxinas durante a SES. Para tanto, utilizou-se o MT e os mutantes com baixa e alta sensibilidade à auxina diageotropica (dgt) e entire (e), respectivamente, crescidos sob luz branca ou sob baixa razão de vermelho/vermelho extremo e o MM e os mutantes em fitocromo phyA, phyB1 e phyB2 nas mesmas condições de luminosidade, mais a aplicação de auxina e do inibidor do transporte deste hormônio. Descobriu-se que o hipocótilo do dgt e do entire alongaram igualmente ao MT sob baixa V:VE. Entretanto, este alongamento nos mutantes resultou também em maior acúmulo de carbono na parte aérea. Finalmente, demonstrou-se que a SES em tomateiro é decorrente de diferentes formas de interação dos fitocromos A, B1 e B2 com as auxinas e que o NPA promove o alongamento do hipocótilo de tomateiro, ou seja, o transporte polar de auxina não é fator limitante para a SES.
Plants that require more intense light radiation, when grown in shaded environments, trigger a series of responses called "shade-avoidance syndrome" (SAS). Since SAS is mainly modulated by changes in the ratio between red and far-red (R:FR), the involvement of phytochromes in the regulation of this phenomenon is evident. It is well known that amongst families of phytochromes, type A (phyA) and B (phyB) are the most important factors in the modulation of SAS. However, it has become increasingly evident that auxins are part of the phytochrome signaling. Thus, we studied how phytochromes A, B1, and B2 of tomatoes interact with auxins during SAS. For this purpose, we used MT and two mutants with low and high sensitivity to the auxin, diageotropic (dgt) and entire (e), respectively, both grown under white light or under low red/far-red ratio; as well as MM and mutants in phytochromes phyA, phyB1, and phyB2 under the same light conditions, plus the application of auxin and its transport inhibitor. We discovered that the hypocotyl of dgt and entire also elongated equally to the MT under low R:FR. However, this elongation in the mutants also resulted in a greater accumulation of carbon in the shoot. Finally, the SAS in tomato is due to different forms of interaction between phytochromes A, B1, and B2 with auxins, and that NPA promotes the tomato hypocotyl elongation, i.e., the polar auxin transport is not a limiting factor for SAS.
Plants that require more intense light radiation, when grown in shaded environments, trigger a series of responses called "shade-avoidance syndrome" (SAS). Since SAS is mainly modulated by changes in the ratio between red and far-red (R:FR), the involvement of phytochromes in the regulation of this phenomenon is evident. It is well known that amongst families of phytochromes, type A (phyA) and B (phyB) are the most important factors in the modulation of SAS. However, it has become increasingly evident that auxins are part of the phytochrome signaling. Thus, we studied how phytochromes A, B1, and B2 of tomatoes interact with auxins during SAS. For this purpose, we used MT and two mutants with low and high sensitivity to the auxin, diageotropic (dgt) and entire (e), respectively, both grown under white light or under low red/far-red ratio; as well as MM and mutants in phytochromes phyA, phyB1, and phyB2 under the same light conditions, plus the application of auxin and its transport inhibitor. We discovered that the hypocotyl of dgt and entire also elongated equally to the MT under low R:FR. However, this elongation in the mutants also resulted in a greater accumulation of carbon in the shoot. Finally, the SAS in tomato is due to different forms of interaction between phytochromes A, B1, and B2 with auxins, and that NPA promotes the tomato hypocotyl elongation, i.e., the polar auxin transport is not a limiting factor for SAS.
Descrição
Palavras-chave
Estiolamento, Fotorreceptores, Solanum lycopersicum, Transporte polar das auxinas, Etiolation, Photoreceptors, Polar auxin transport