Arabidopsis seedlings are genetically endowed with the capability to follow two distinct developmental programs: photomorphogenesis in the light and skotomorphogenesis in darkness. The regulatory protein CONSTITUTIVE PHOTO-MORPHOGENIC1 (COP1) has been postulated to act as a repressor of photomorphogenesis in the dark because loss-of-function mutations of COP1 result in dark-grown seedlings phenocopying the light-grown wild-type seedlings. In this study, we tested this working model by overexpressing COP1 in the plant and examining its inhibitory effects on photomorphogenic development. Stable transgenic Arabidopsis lines overexpressing COP1 were generated through Agrobacterium-mediated transformation. Overexpression was achieved using either the strong cauliflower mosaic virus 35S RNA promoter or additional copies of the wild-type gene. Analysis of these transgenic lines demonstrated that higher levels of COP1 can inhibit aspects of photomorphogenic seedling development mediated by either phytochromes or a blue light receptor, and the extent of inhibition correlated quantitatively with the vivo COP1 levels. This result provides direct evidence that COP1 acts as a molecular repressor of photomorphogenic development and that multiple photoreceptors can independently mediate the light inactivation of COP1. It also suggests that a controlled inactivation of COP1 may provide a basis for the ability of plants to respond quantitatively to changing light signals, such as fluence rate and photoperiod. 相似文献
Wild-type Arabidopsis seedlings are capable of following two developmental programs: photomorphogenesis in the light and skotomorphogenesis in darkness. Screening of Arabidopsis mutants for constitutive photomorphogenic development in darkness resulted in the identification of three new loci designated COP8, COP10, and COP11. Detailed examination of the temporal morphological and cellular differentiation patterns of wild-type and mutant seedlings revealed that in darkness, seedlings homozygous for recessive mutations in COP8, COP10, and COP11 failed to suppress the photomorphogenic developmental pathway and were unable to initiate skotomorphogenesis. As a consequence, the mutant seedlings grown in the dark had short hypocotyls and open and expanded cotyledons, with characteristic photomorphogenic cellular differentiation patterns and elevated levels of light-inducible gene expression. In addition, plastids of dark-grown mutants were defective in etioplast differentiation. Similar to cop1 and cop9, and in contrast to det1 (deetiolated), these new mutants lacked dark-adaptive change of light-regulated gene expression and retained normal phytochrome control of seed germination. Epistatic analyses with the long hypocotyl hy1, hy2, hy3, hy4, and hy5 mutations suggested that these three loci, similar to COP1 and COP9, act downstream of both phytochromes and a blue light receptor, and probably HY5 as well. Further, cop8-1, cop10-1, and cop11-1 mutants accumulated higher levels of COP1, a feature similar to the cop9-1 mutant. These results suggested that COP8, COP10, and COP11, together with COP1, COP9, and DET1, function to suppress the photomorphogenic developmental program and to promote skotomorphogenesis in darkness. The identical phenotypes resulting from mutations in COP8, COP9, COP10, and COP11 imply that their encoded products function in close proximity, possibly with some of them as a complex, in the same signal transduction pathway. 相似文献
Low-temperature and high humidity are typical environmental factors in the plastic tunnel and solar greenhouse during the cold season that restricts plant growth and development. Herein, we investigated the impact of different combinations of low-temperature and high humidity (day/night: T1 15/10 °C?+?95%, T2 12/8 °C?+?95%, and T3 9/5 °C?+?95%) along with a control (CK 25/18 °C?+?80%) on cucumber cultivars viz: Zhongnong37 (ZN37: resistant) and Shuyanbailv (SYB: sensitive). The low-temperature and high humidity stresses increased electrolyte leakage (EL), malondialdehyde (MDA), hydrogen peroxide (H2O2) and intercellular concentration of carbon dioxide (Ci), and reduced morphological indices, relative water content (RWC), net photosynthesis rate (Pn), stomatal conductance (Gs), transpiration rate (E) and leaf pigments in both cultivars as compared to control (CK). Superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR) were decreased in cv. SYB under stress conditions as compared to cv. ZN37. Low-temperature and high humidity treatments showed an increase in proline and soluble protein content in cv. ZN37 as compared to cv. SYB. Abscisic acid (ABA) and jasmonic acid (JA) were augmented while indole-3-acetic acid (IAA), zeatin (ZT), zeatin riboside (ZR), and gibberellic acid (GA) were decreased in both cultivars. Under T3 (9/5 °C?+?95%), Pn, protoporphyrin, and ZT were extremely decreased by 71.3%, 74.3%, and 82.4%, respectively, in cv. SYB compared to control. Moreover, principal component analysis (PCA) based on physiochemical traits confirmed that cv. ZN37 had the strongest correlation with antioxidant enzymes, proline, and soluble protein content than cv. SYB under low-temperature and high humidity treatments. Our results suggest that a stress-tolerant cultivar mitigates stress damage in cucumber transplants by regulating photosynthetic efficiency, antioxidant capacity and hormonal profile when compared to a stress-sensitive cultivar.
This study investigated the effect of butanol extract of AS (ASBUE) on atherosclerosis in apolipoprotein E-deficient (ApoE−/−) mice. The mice were administered ASBUE (390 or 130 mg/kg/day) or rosuvastatin (RSV) via oral gavage for eight weeks. In ApoE−/− mice, ASBUE suppressed the abnormal body weight gain and improved serum and liver biochemical indicators. ASBUE remarkably reduced the aortic plaque area, improved liver pathological conditions, and lipid metabolism abnormalities, and altered the intestinal microbiota structure in ApoE−/− mice. In the vascular tissue of ASBUE-treated mice, P-IKKβ, P-NFκB, and P-IκBα levels tended to decrease, while IκB-α increased in high fat-diet-fed atherosclerotic mice. These findings demonstrated the anti-atherosclerotic potential of ASBUE, which is mediated by the interaction between the gut microbiota and lipid metabolism and regulated via the Nuclear Factor-kappa B (NF-κB) pathway. This work paves the groundwork for subsequent studies to develop innovative drugs to treat atherosclerosis. 相似文献