Microbial pattern recognition suppresses de novo organogenesis.

De novo root regeneration (DNRR) is a developmental process that regenerates adventitious roots from wounded tissues. Phytohormone signaling pathways involved in microbial resistance are mobilized after cutting and influence de novo root regeneration. Microbes may positively or negatively influence the development and stress responses of a plant. However, most studies on the molecular mechanisms of de novo organogenesis are performed in aseptic conditions. Thus, the potential crosstalk between organ regeneration and biotic stresses is underexplored. Here, we report the development of a versatile experimental system to study the impact of microbes on DNRR. Using this system, we found that bacteria inhibited root regeneration by activation of, but not limited to, pathogen-associated molecular pattern (PAMP)-triggered immunity. Sensing bacteria-derived flagellin 22 peptide (flg22) inhibited root regeneration by interfering with the formation of an auxin maximum at the wound site. This inhibition relies on the receptor complex that recognizes microbial patterns but may bypass the requirement of salicylic acid signaling.

Endogenous salicylic acid suppresses de novo root regeneration from leaf explants.

Plants can regenerate new organs from damaged or detached tissues. In the process of de novo root regeneration (DNRR), adventitious roots are frequently formed from the wound site on a detached leaf. Salicylic acid (SA) is a key phytohormone regulating plant defenses and stress responses. The role of SA and its acting mechanisms during de novo organogenesis is still unclear. Here, we found that endogenous SA inhibited the adventitious root formation after cutting. Free SA rapidly accumulated at the wound site, which was accompanied by an activation of SA response. SA receptors NPR3 and NPR4, but not NPR1, were required for DNRR. Wounding-elevated SA compromised the expression of AUX1, and subsequent transport of auxin to the wound site. A mutation in AUX1 abolished the enhanced DNRR in low SA mutants. Our work elucidates a role of SA in regulating DNRR and suggests a potential link between biotic stress and tissue regeneration.

Topoisomerase â ¡α Gene as a Marker for Prognostic Prediction of Hepatocellular Carcinoma: A Bioinformatics Analysis.

Objective To investigate the expression of topoisomeraseⅡα (TOP2α) in hepatocellular carcinoma (HCC) and its role in predicting prognosis of HCC patients. Methods We used HCC-related datasets in UALCAN, HCCDB, and cBioPortal databases to analyze the expression and mutation of TOP2α and its co-expressed genes in HCC tissues. GO function and KEGG pathway enrichment of TOP2α and its co-expressed genes were identified. The TIMER database was used to analyze infiltration levels of immune cells in HCC. The impacts of TOP2α and its co-expression genes and the infiltrated immune cells on the survival of HCC patients were assayed by Kaplan-Meier plotter analysis. Results TOP2α and its co-expression genes were highly expressed in HCC (P< 0.001) and detrimental to overall survival of HCC patients (P< 0.001). TOP2α and its co-expression genes were mainly involved in cell mitosis and proliferation, and cell cycle pathway (ID: hsa04110, P = 0.001945). TOP2α and its co-expression genes were mutated in HCC and the mutations were significantly detrimental to overall survival (P = 0.0247) and disease-free survival (P = 0.0265) of HCC patients. High TOP2α expression was positively correlated with the infiltration of B cell (r = 0.459, P< 0.01), CD8+ T cell (r = 0.312, P< 0.01), CD4+ T cell (r = 0.370, P< 0.01), macrophage (r = 0.459, P< 0.01), neutrophil (r = 0.405, P< 0.01), and dendritic cell (r = 0.473, P< 0.01) in HCC. The CD8+ T cell infiltration significantly prolonged the 3- and 5-year survival of HCC patients (all P< 0.05), and CD4+ T cell infiltration significantly shortened the 3-, 5-, and 10-year survival of HCC patients (all P< 0.05). ConclusionTOP2α may be an oncogene, which was associated with poor prognosis of HCC patients and could be used as a biomarker for the prognostic prediction of HCC.

Structural Determination of Ruthenium Complexes Containing Bi-Dentate Pyrrole-Ketone Ligands.

A series of ruthenium compounds containing a pyrrole-ketone bidentate ligand, 2-(2'-methoxybenzoyl)pyrrole (1), have been synthesized and characterized. Reacting 1 with [(η6-cymene)RuCl2]2 and RuHCl(CO)(PPh3)3 generated Ru(η6-cymene)[C4H3N-2-(CO-C6H4-2-OMe)]Cl (2) and {RuCl(CO)(PPh3)2[C4H3N-2-(COC6H4-2-OMe)]} (3), respectively, in moderate yields. Successively reacting 2 with sodium cyanate and sodium azide gave {Ru(η6-cymene)[C4H3N-2-(CO-C6H4-2-OMe)]X} (4, X=OCN; 5, X=N3) with the elimination of sodium chloride. Compounds 2-5 were all characterized by ¹H and 13C-NMR spectra and their structures were also determined by X-ray single crystallography.

Hypervalent Iodine(III)-Induced Domino Oxidative Cyclization for the Synthesis of Cyclopenta[b]furans.

A new strategy for cyclopenta[b]furan synthesis mediated by hypervalent iodine(III) has been described. The approach employs diacetoxyiodobenzene-induced initial dehydrogenation to a putative trienone intermediate and triggered sequential cycloisomerization to form the cyclo-penta[b]furan targets.

Discovering chromatin motifs using FAIRE sequencing and the human diploid genome.

BACKGROUND: Specific chromatin structures are associated with active or inactive gene transcription. The gene regulatory elements are intrinsically dynamic and alternate between inactive and active states through the recruitment of DNA binding proteins, such as chromatin-remodeling proteins. RESULTS: We developed a unique genome-wide method to discover DNA motifs associated with chromatin accessibility using formaldehyde-assisted isolation of regulatory elements with high-throughput sequencing (FAIRE-seq). We aligned the FAIRE-seq reads to the GM12878 diploid genome and subsequently identified differential chromatin-state regions (DCSRs) using heterozygous SNPs. The DCSR pairs represent the locations of imbalances of chromatin accessibility between alleles and are ideal to reveal chromatin motifs that may directly modulate chromatin accessibility. In this study, we used DNA 6-10mer sequences to interrogate all DCSRs, and subsequently discovered conserved chromatin motifs with significant changes in the occurrence frequency. To investigate their likely roles in biology, we studied the annotated protein associated with each of the top ten chromatin motifs genome-wide, in the intergenic regions and in genes, respectively. As a result, we found that most of these annotated motifs are associated with chromatin remodeling, reflecting their significance in biology. CONCLUSIONS: Our method is the first one using fully phased diploid genome and FAIRE-seq to discover motifs associated with chromatin accessibility. Our results were collected to construct the first chromatin motif database (CMD), providing the potential DNA motifs recognized by chromatin-remodeling proteins and is freely available at http://syslab.nchu.edu.tw/chromatin.