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Cobalt-catalyzed enantioconvergent cross-coupling of C(sp 3 )-H bonds with in situ -generated sulfenate anions is achieved to access chiral sulfoxides, which are found in the structures of many biologically active agents. The more challenging aliphatic C-H bonds as well as sterically hindered substrates containing tertiary C-H bonds could also be tolerated well. Mechanistic studies indicate that the transformation could undergo a Co II S(O)R-mediated single-electron transfer with N -fluorocarboxamides, followed by a 1,5-hydrogen atom transfer and then a pivotal organocobalt(IV)-controlled enantioselective cross-coupling process. This novel asymmetric radical reaction for C-S bond construction could open a new door for the synthesis of sulfur-centered chiral compounds.

We herein report a copper-catalyzed formal [5 + 2] aza-annulation of N -fluorosulfonamides and 1,3-dienes/1,3-enynes for synthesis of structurally diverse alkene/alkyne-containing azepanes. The reaction features selective functionalization of distal unactivated C(sp 3 )-H bonds and a broad substrate scope, thus allowing the late-stage modification of pharmaceuticals and natural products. A radical mechanism involving 1,5-hydrogen atom transfer of N-radicals, facile coupling of alkyl radicals with 1,3-dienes/1,3-enynes, and the construction of azepane motifs via C-N bond formation is proposed.

Overexpression or activation of Yes-associated protein (YAP) is common in cancer cells. Thus, targeting YAP may be a strategy for cancer therapy. Licochalcone A (LicA) is a primary active compound of licorice root and is known to have medicinal effects, such as antioxidant, antibacterial, antiviral, and anticancer effects. However, the anticancer pharmacological mechanism of LicA has not been investigated in cholangiocarcinoma. In this study, we investigated the antiproliferative effect of LicA and the underlying molecular mechanism in HCCC-9810 and RBE human cholangiocarcinoma cells. Our experiments indicated that LicA suppressed the growth of cholangiocarcinoma cells through inactivation of the Hippo pathway. Pescadillo ribosomal biogenesis factor 1 (PES1) was notably upregulated and related to carcinogenesis. We also found that LicA suppressed the expression and nuclear localization of PES1, which was associated with the inhibition of YAP expression and transcriptional activity., (© 2021 Wiley Periodicals LLC.)

The novel methods for efficient plant regeneration via direct somatic embryogenesis (SE) and SE-mediated transformation system under high concentration of NAA in Ranunculus sceleratus were established. On MS media containing a high concentration of NAA (10.0 mg/L) in the dark, all inoculated explants (root, stem and leaf) formed somatic embryos at high frequencies, respectively, 66.03, 126.47 and 213.63 embryoids per explant, and 100% of the embryoids developed into plantlets on 1/2 MS rooting media. Morphological and histological analyses revealed that SE in R. sceleratus followed a classical pattern. All inoculated explants can be used as receptors for genetic transformation in R. sceleratus, through direct SE-mediated method after Agrobacterium infection. RcLEC1-B, as a marker gene, changed the number and morphology of flower organs and the development of cuticle in R. sceleratus, which indicated that the efficient transgenic system of R. sceleratus was established. To our knowledge, this is the first observation that both direct SE and transgenic transformation system, via induction of a single plant growth regulator, have been successfully constructed in R. sceleratus.

A new approach was established for the regeneration of Trichosanthes kirilowii from root, stem, and leaf explants by somatic embryogenesis (SE), involving a previously unreported SE structure, rhizoid tubers (RTBs). During SE, special rhizoids were first induced from root, stem, and leaf explants with average rhizoid numbers of 62.33, 40.17, and 11.53 per explant, respectively, on Murashige and Skoog (MS) medium (pH 4.0) supplemented with 1.0 mg/L 1-naphthaleneacetic acid (NAA) under dark conditions. Further, one RTB was formed from each of the rhizoids on MS medium (pH 4.0) supplemented with 20 mg/L thidiazuron (TDZ) under light conditions. In the suitable range (pH 4.0-9.0), a lower pH value increased the induction of rhizoids and RTBs. Approximately 37.77, 33.47, and 31.07% of in vivo RTBs from root, stem, and leaf explants, respectively, spontaneously developed into multiple plantlets on the same MS medium (supplemented with 20 mg/L TDZ) for induction of RTBs, whereas >95.00% of in vitro RTBs from each kind of explant developed into multiple plantlets on MS medium supplemented with 5.0 mg/L 6-benzylaminopurine (BAP). Morphological and histological analyses revealed that RTB is a novel type of SE structure that develops from the cortex cells of rhizoids.

Previous studies have shown that the SUP genes play important roles in flower development and plant growth and morphogenesis. In this study, we isolated and characterized a SUPERMAN-like gene DgSZFP from chrysanthemum. DgSZFP contains one conserved Cys2/His2-type zinc finger motifs in the N-terminal region and an EAR-box in C-terminus. Its expression was significantly higher in nodes, flower buds, disc stamens, and petals than in the other tissues. Overexpression of DgSZFP in tobacco resulted in enhanced branching, reduced plant height, increased the width of petal tubes, produced the staminoid petals and petaloid stamens in flowers, and enhanced the seed weight and size. In addition, DgSZFP-overexpression tobacco plants accumulated high concentrations of cytokinin and chlorophyll. These results suggest that DgSZFP may be the candidate gene for regulating branching and floral organ development in chrysanthemum., (Crown Copyright © 2014. Published by Elsevier Masson SAS. All rights reserved.)

Plant vacuolar Na(+)/H(+) antiporter genes play significant roles in salt tolerance. However, the roles of the chrysanthemum vacuolar Na(+)/H(+) antiporter genes in salt stress response remain obscure. In this study, we isolated and characterized a novel vacuolar Na(+)/H(+) antiporter gene DgNHX1 from chrysanthemum. The DgNHX1 sequence contained 1920 bp with a complete open reading frame of 1533 bp encoding a putative protein of 510 amino acids with a predicted protein molecular weight of 56.3 kDa. DgNHX1 was predicted containing nine transmembrane domains. Its expression in the chrysanthemum was up-regulated by salt stress, but not by abscisic acid (ABA). To assess roles of DgNHX1 in plant salt stress responses, we performed gain-of-function experiment. The DgNHX1-overexpression tobacco plants showed significant salt tolerance than the wild type (WT). The transgenic lines exhibited more accumulation of Na(+) and K(+) under salt stress. These findings suggest that DgNHX1 plays a positive regulatory role in salt stress response.

A drought stress-responsive Cys2/His2-type zinc finger protein gene DgZFP3 was previously isolated (Liu et al., Afr J Biotechnol 11:7781-7788, 2012b) from chrysanthemum. To assess roles of DgZFP3 in plant drought stress responses, we performed gain-of-function experiment. The DgZFP3-overexpression tobacco plants showed significant drought tolerance over the wild type (WT). The transgenic lines exhibited less accumulation of H2O2 under drought stress, more accumulation of proline and greater activities of peroxidase (POD) and superoxide dismutase than the WT under both control conditions and drought stress. In addition, there was greater up-regulation of the ROS-related enzyme genes (NtSOD and NtPOD) and stress-related genes (NtLEA5 and NtDREB) in transgenic lines under normal or drought conditons. Thus DgZFP3 probably plays a positive regulatory role in drought stress response and has the potential to be utilized in transgenic breeding to improve drought stress tolerance in plants.

The plant-specific NAC (for NAM, ATAF1, 2 and CUC2) transcription factors (TFs) have been implicated in different cellular processes involved in stress responses such as cold, high salinity or drought as well as abscisic acid (ABA) signalling. However, the roles of the chrysanthemum NAC TF genes in plant stress responses are still unclear. A full-length cDNA designated DgNAC1, containing a highly conserved N-terminal DNA-binding NAC domain, has been isolated from chrysanthemum by RACE (rapid amplification of cDNA ends). It encodes a protein of 284 amino acids residues (=~32.9 kDa) and theoretical pI of 7.13. The transcript of DgNAC1 was enriched in roots and flowers than in stems and leaves of the adult chrysanthemum plants. The gene expression was strongly induced by ABA, NaCl, drought and cold treatment in the seedlings. Subcellular localization revealed that DgNAC1:GFP fusion protein was preferentially distributed to nucleus. To assess whether DgNAC1 is a practically useful target gene for improving the stress tolerance of chrysanthemum, we ectopically over-expressed the full-length DgNAC1 cDNA in tobacco and found that the 35S:DgNAC1 transgenic tobacco exhibited a markedly increased tolerance to salt. Despite this increased salt stress tolerance, the transgenic tobacco showed no detectable phenotype defects under normal growth conditions. These results proposed that DgNAC1 is appropriate for application in genetic engineering strategies aimed at improving salt stress tolerance in chrysanthemum., (© Springer Science+Business Media B.V. 2011)

A Cys2/His2-type zinc finger protein gene, DgZFP, was isolated from chrysanthemum by rapid amplification of cDNA ends (RACE) approach. The DgZFP encodes a protein of 211 amino acids residues with a calculated molecular mass of 22.9 kDa and theoretical isoelectric point is 8.59. DgZFP contains two Cys2/His2-type zinc finger motifs, one nuclear localization domain, one Leu-rich domain, and one ethylene-responsive element-binding factor (ERF)-associated amphiphilic repression (EAR) domain. The transcript of DgZFP was enriched in flowers than in roots, stems, and leaves of the adult chrysanthemum plants. The gene expression was strongly induced by NaCl, drought and cold treatment, and weakly by ABA treatment in the seedlings. Subcellular localization revealed that DgZFP was localized preferentially distributed to nucleus. Overexpression of DgZFP improved salt tolerance and resulted in growth suppression in transgenic tobacco. We argued that DgZFP is a new member of the Cys2/His2-type zinc finger protein genes, and it maybe function as a regulator in response to salt stress in plants.