Cloning of a 9-cis-epoxycarotenoid dioxygenase gene and the responses of Caragana korshinskii to a variety of abiotic stresses.
(10/14)
Abscisic acid (ABA) regulates plant adaptive responses to various environmental stresses. Oxidative cleavage of cis-epoxycarotenoids catalyzed by 9-cis-epoxycarotenoid dioxygenase (NCED) is the main regulatory step in the biosynthesis of ABA in higher plants. Using RACE technology, a full-length cDNA-encoding NCED gene was isolated and characterized from the leaves of Caragana korshinskii (Peashrub). The 2442-bp full-length CkNCED1 had a 1818-bp ORF, which encodes a peptide of 605 amino acids. The deduced amino acid sequence of CkNCED1 protein shared high identity with other NCEDs. Southern blot analysis revealed that the gene CkNCED1 was a single copy in the genome of C. korshinskii. When C. korshinskii plants were exposed to a water deficit, ABA accumulation was followed by large increases in CkNCED1 mRNA in leaves and stems, but only a moderate increase in the roots. Conversely, rehydration of stressed leaves caused a rapid decrease in CkNCED1 mRNA and ABA levels. RT-PCR and Quantitative real-time PCR analysis showed that salt stress rapidly induced the strong expression of CkNCED1 in leaves and roots of C. korshinskii, as well as ABA accumulation. The expression of CkNCED1 and ABA accumulation was also induced by cold stress and the application of exogenous ABA. Taken together, these results suggest that CkNCED1 likely plays a primary role in the biosynthesis of ABA in C. korshinskii. (+info)
Stilbene derivatives as human 5-HT(6) receptor antagonists from the root of Caragana sinica.
(11/14)
The 5-HT(6) receptor (5-HT(6)R) is a member of the class of recently discovered 5-hydroxytryptamine (5-HT) receptors. Due to the lack of selective 5-HT(6)R ligands, the cellular signaling mechanisms of the 5-HT(6)R are poorly understood. We previously developed a cell-based high-throughput screening (HTS) method for the 5-HT(6)R and screened synthetic chemical compounds. In the present study, we expanded our screening into natural products to find novel 5-HT(6)R ligands. We found that the ethyl acetate fraction from the root of Caragana sinica (537-18BE) produced the most potent antagonistic activity. After further isolation of 537-18BE, we found that three stilbene derivatives, (+)-alpha-viniferin, miyabenol C and pallidol, are active constituents of 537-18BE inhibiting the 5-HT(6)R. Among them, (+)-alpha-viniferin showed the most potent inhibition, and miyabenol C also produced a considerable inhibition. When examined effects on other neurotransmitters for selectivity, 537-18BE and three stilbene derivatives did not produce any notable effects on 5-HT(4), 5-HT(7), or muscarinic acetylcholine M1 (M(1)) receptors. Furthermore, 5-HT(6)R antagonistic effects of (+)-alpha-viniferin, miyabenol C and pallidol were confirmed on extracellular signal-regulated kinase 1 and 2 (ERK1/2) which exerts effects in downstream pathways of 5-HT(6)R activation. (+info)
Different water use strategies of juvenile and adult Caragana intermedia plantations in the Gonghe Basin, Tibet Plateau.
(12/14)