Genome-Wide Identification and Expression Analysis of <i>HSP70</i> Gene Family in <i>Chrysanthemum lavandulifolium</i> under Heat Stress

As a molecular chaperone, HSP70 is widely involved in complex activities in plants. Under high temperature, drought, high salt, low temperature, heavy metals, and other stresses, HSP70 is rapidly synthesizes, stabilizes protein and biological macromolecular structures, and improves the stress resistance of plants. In this study, 83 ClHSP70 genes in Chrysanthemum lavandulifolium were identified based on the published Chrysanthemum lavandulifolium genome database. The genes were divided into six clusters based on a phylogenetic analysis, and the gene structures, conserved motifs, and functional domains were relatively conserved. Only two collinear genes were observed, and they formed a pair of duplicating genes. Multiple abiotic stress and phytohormone response elements were observed on the ClHSP70 promoter, such as temperature, drought, methyl jasmonate, abscisic acid, and other stress-related elements, and CpG islands were found on some ClHSP70 promoters, suggesting that they may be related to methylation modifications. Tissue expression analysis showed that the ClHSP70 genes were highly expressed in the roots. In addition, the gene expression changed significantly after 1 h of heat treatment and plays an important role in plant responses to temperature stress. The results of this study provide insights on the ClHSP70 gene family members and a theoretical basis for further research on functional analyses of the ClHSP70 gene family

Genome-Wide Identification and Analysis of <i>NF-Y</i> Gene Family Reveal Its Potential Roles in Stress-Resistance in <i>Chrysanthemum</i>

Nuclear factor Y (NF-Y) is a class of transcription factors (TFs) with various biological functions that exist in almost all eukaryotes. In plants, heterotrimers composed of different NF-Y subunits are numerous and have different functions that can participate in the regulation of plant growth at various stages. However, NF-Y genes have not been systematically analyzed in chrysanthemum, only involving several NF-Y members. In this study, forty-six NF-Y members were identified from the diploid species Chrysanthemum seticuspe, including eight NF-YA members, twenty-one NF-YB members, and seventeen NF-YC members. These NF-Y genes were analyzed for their physicochemical characteristics, multiple alignments, conserved motifs, gene structure, promoter elements, and chromosomal location. Phylogenetic analysis revealed that only two gene pairs in C. seticuspe underwent gene duplication events. The Ka/Ks ratios were both less than one, indicating that the two pairs underwent purifying selection. Promoter element analysis showed that multiple abiotic stress and hormone response elements were present in the CsNF-Y genes, suggesting that these genes play an important role in the response to stress, growth, and development in plants. Further validation of candidate genes in response to drought regulation using RT-qPCR demonstrated that CsNF-Y genes in C. seticuspe play an important role in drought regulation

AICAR-Induced AMPK Activation Inhibits the Noncanonical NF-κB Pathway to Attenuate Liver Injury and Fibrosis in BDL Rats

Background. To evaluate the AMP-activated protein kinase- (AMPK-) mediated signaling and NF-κB-related inflammatory pathways that contribute to cholestatic diseases in the bile duct ligation (BDL) rat model of chronic cholestasis and verify the protective role of 5-Aminoimidazole-4-carboxamide1-β-D-ribofuranoside (AICAR) against hepatic injury and fibrosis triggered by cholestasis-related inflammation. Methods. Animals were randomly divided into three groups: sham-operated group, BDL group, and BDL+ AICAR group. Cholestatic liver injury was induced by common BDL. Two weeks later, rats in BDL+AICAR group started receiving AICAR treatment. Hepatic pathology was examined by haematoxylin and eosin (H&E) and sirius red staining and hydroxyproline assay was performed in evaluating the severity of hepatic cirrhosis. Real-time PCR and Western blot were performed for RNA gene expression of RNA and protein levels, respectively. Results. The BDL group showed liver injury as evidenced by histological changes and elevation in serum biochemicals, ductular reaction, fibrosis, and inflammation. The mRNA expression of canonical NF-κB inflammatory cytokines such as TNF-α, IL-1β, TGF-β, and the protein of noncanonical NF-κB, P100, and P52 was upregulated in the livers of BDL rats. The BDL rats with the administration of AICAR could induce AMPK activation inhibiting the noncanonical NF-κB pathway to attenuate liver injury and fibrosis in BDL rats. Conclusion. The BDL model of hepatic cholestatic injury resulting in activation of Kupffer cells and recruitment of immune cells might initiate an inflammatory response through activation of the NF-κB pathway. The AMPK activator AICAR significantly alleviated BDL-induced inflammation in rats by mainly inhibiting the noncanonical NF-κB pathway and thus protecting against hepatic injury and fibrosis triggered by BDL