RESUMEN
The phytohormone auxin plays a pivotal role in governing plant growth and development. Although the TRANSPORT INHIBITOR RESPONSE1/AUXIN SIGNALING F-BOX (TIR1/AFB) receptors function in both the nucleus and cytoplasm, the mechanism governing the distribution of TIR1/AFBs between these cellular compartments remains unknown. In this study, we demonstrate that auxin-mediated oxidation of TIR1/AFB2 is essential for their targeting to the nucleus. We showed that small active molecules, reactive oxygen species (ROS) and nitric oxide (NO), are indispensable for the nucleo-cytoplasmic distribution of TIR1/AFB2 in trichoblasts and root hairs. Further studies revealed that this process is regulated by the FERONIA receptor kinase-NADPH oxidase signaling pathway. Interestingly, ROS and NO initiate oxidative modifications in TIR1C140/516 and AFB2C135/511, facilitating their subsequent nuclear import. The oxidized forms of TIR1C140/516 and AFB2C135/511 play a crucial role in enhancing the function of TIR1 and AFB2 in transcriptional auxin responses. Collectively, our study reveals a novel mechanism by which auxin stimulates the transport of TIR1/AFB2 from the cytoplasm to the nucleus, orchestrated by the FERONIA-ROS signaling pathway.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Proteínas F-Box , Ácidos Indolacéticos , Oxidación-Reducción , Proteínas Serina-Treonina Quinasas , Transducción de Señal , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Núcleo Celular/metabolismo , Proteínas F-Box/metabolismo , Regulación de la Expresión Génica de las Plantas , Ácidos Indolacéticos/metabolismo , Óxido Nítrico/metabolismo , Fosfotransferasas/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Receptores de Superficie Celular/metabolismoRESUMEN
BACKGROUND: Gamma-glutamylcysteine synthetase (γ-ECS) is a rate-limiting enzyme in glutathione biosynthesis and plays a key role in plant stress responses. In this study, the endogenous expression of the Caragana korshinskii γ-ECS (Ckγ-ECS) gene was induced by PEG 6000-mediated drought stress in the leaves of C. korshinskii. and the Ckγ-ECS overexpressing transgenic Arabidopsis thaliana plants was constructed using the C. korshinskii. isolated γ-ECS. RESULTS: Compared with the wildtype, the Ckγ-ECS overexpressing plants enhanced the γ-ECS activity, reduced the stomatal density and aperture sizes; they also had higher relative water content, lower water loss, and lower malondialdehyde content. At the same time, the mRNA expression of stomatal development-related gene EPF1 was increased and FAMA and STOMAGEN were decreased. Besides, the expression of auxin-relative signaling genes AXR3 and ARF5 were upregulated. CONCLUSIONS: These changes suggest that transgenic Arabidopsis improved drought tolerance, and Ckγ-ECS may act as a negative regulator in stomatal development by regulating the mRNA expression of EPF1 and STOMAGEN through auxin signaling.
Asunto(s)
Adaptación Fisiológica/genética , Caragana/genética , Caragana/fisiología , Deshidratación/genética , Deshidratación/fisiopatología , Sequías , Glutamato-Cisteína Ligasa/genética , Adaptación Fisiológica/fisiología , Arabidopsis/genética , Arabidopsis/fisiología , Regulación de la Expresión Génica de las Plantas , Genes de Plantas , Variación Genética , Genotipo , Glutamato-Cisteína Ligasa/fisiología , Hojas de la Planta/genética , Hojas de la Planta/fisiología , Estomas de Plantas/genética , Estomas de Plantas/crecimiento & desarrollo , Plantas Modificadas GenéticamenteRESUMEN
The drought-tolerant plant Caragana korshinskii Kom. was used to investigate the relative contribution of photorespiration and antioxidative mechanisms to water-stress adaptations across the Loess Plateau. The samples were collected from Shenmu, Yulin and Dongsheng along with the reduction of rainfall. The results showed the lower leaf water potential and the lower content of O2â¢- and malondialdehyde (MDA) were found in the plants in drier zone. H2O2 didn't show a significant difference among these sampling sites. Both photorespiratory rate (PR) and net photosynthetic rate (PN) increased with the decrease of rainfall. Low rainfall upregulated the gene expression and activities of photorespiratory enzymes. In addition, ascorbate peroxidase (APX), glutathione peroxidase (GPX) and superoxide dismutase (SOD) activity and reduced glutathione (GSH), ascorbic acid (AsA) contents increased with the decrease of rainfall, whereas catalase (CAT) activity decreased. These results indicate photorespiration could play a protective role for the photosynthetic apparatus from photoinhibition and photodamage under low rainfall levels, which could also act together with the antioxidation system to improve the tolerance to drought in C. korshinskii.