RALF22 promotes plant immunity and amplifies the Pep3 immune signal.

Rapid alkalinization factors (RALFs) in plants have been reported to dampen pathogen-associated molecular pattern (PAMP)-triggered immunity via suppressing PAMP-induced complex formation between the pattern recognition receptor (PRR) and its co-receptor BAK1. However, the direct and positive role of RALFs in plant immunity remains largely unknown. Herein, we report the direct and positive roles of a typical RALF, RALF22, in plant immunity. RALF22 alone directly elicited a variety of typical immune responses and triggered resistance against the devastating necrotrophic fungal pathogen Sclerotinia sclerotiorum in a FERONIA (FER)-dependent manner. LORELEI (LRE)-like glycosylphosphatidylinositol (GPI)-anchored protein 1 (LLG1) and NADPH oxidase RBOHD were required for RALF22-elicited reactive oxygen species (ROS) generation. The mutation of cysteines conserved in the C terminus of RALFs abolished, while the constitutive formation of two disulfide bridges between these cysteines promoted the RALF22-elicited ROS production and resistance against S. sclerotiorum, demonstrating the requirement of these cysteines in the functions of RALF22 in plant immunity. Furthermore, RALF22 amplified the Pep3-induced immune signal by dramatically increasing the abundance of PROPEP3 transcript and protein. Supply with RALF22 induced resistance against S. sclerotiorum in Brassica crop plants. Collectively, our results reveal that RALF22 triggers immune responses and augments the Pep3-induced immune signal in a FER-dependent manner, and exhibits the potential to be exploited as an immune elicitor in crop protection.

Asymmetric Hydrosilylation of ß-Silyl Styrenes Catalyzed by a Chiral Palladium Complex.

A palladium complex coordinated with a chiral SIPHOS ligand was evaluated as an efficient catalyst for asymmetric hydrosilylation of ß-silyl styrenes with trichlorosilane and 23 1,2-bis(silyl) chiral compounds were produced. Good to excellent enantioselectivities were observed with 1-aryl-2-silyl ethanols, where the trichlorosilyl groups of the hydrosilylation products were selectively converted into a hydroxyl group in the presence of pre-installed trialkylsilyl groups. Asymmetric hydrosilylation of ß-silyl styrenes followed by methylation of the trichlorosilyl group gave stable 1,2-bis(silyl) chiral compounds 4 with excellent yields. DFT calculations of hydridopalladium B coordinated with a SIPHOS ligand, an intermediate of the hydrosilylation reaction, established the optical structures to be energy minima, and the structural information could well illustrate the enantioselectivity for the hydrosilylation reaction.

Exosomal mRNAs and lncRNAs involved in multiple myeloma resistance to bortezomib.

The bone marrow microenvironment plays an essential role in multiple myeloma (MM) progression. We aimed to explore the alterations of levels of long noncoding RNAs and messenger RNAs (mRNAs), derived from exosomes in peripheral blood, in resistance to bortezomib (Btz) of MM patients. Peripheral blood samples were collected from five Btz-resistant and five Btz-sensitive MM patients. Exosomes in patients' peripheral blood were enriched, and the profiles of long noncoding RNAs (lncRNAs) and mRNAs in exosomes were determined using deep sequencing. Bioinformatics analysis was performed to explore biological function. MTS was employed to determine the viability of Roswell Park Memorial Institute (RPMI) 8226 and LP-1 cells incubated with exosomes derived from Btz-resistant patients. Quantitative polymerase chain reaction (qPCR) was used to evaluate the levels of exosomal FFAR1, SP9, HIST1H2BG, and ITIH2. Incubation with Btz-resistant patient-derived exosomes significantly increased the viability of Btz-treated RPMI 8226 and LP-1 cells in a dose-dependent manner. We identified 482 lncRNAs and 2099 mRNAs deregulated in exosomes of the Btz-resistance group; and 78 mRNAs were enriched in DR-related pathways, including mammalian target of rapamycin, platinum drug resistance, and the cAMP and phosphoinositide 3-kinase-Akt signaling pathways. qPCR results verified the increases in FFAR1 and SP9 and decreases in HIST1H2BG and ITIH2 in Btz-resistant patient-derived exosomes. Moreover, exosomal FFAR1 and SP9 exhibited potential as independent prognostic indicators of survival of MM patients. Our study reveals significant dysregulation of exosomal RNA components in the Btz-resistant group of MM patients as well as several mRNAs that may be used as biomarkers of prognosis of MM patients that are resistant to Btz.

Electrochemical CO2 reduction on Cu and Au electrodes studied using in situ sum frequency generation spectroscopy.

As an important pathway for energy storage and a key reaction in the carbon cycle, the CO2 electrochemical reduction reaction has recently gained significant interest. A variety of catalysts have been used to approach this topic experimentally and theoretically; however, the molecular level insight into the reaction mechanism is lacking due to the complexity of the surface processes and the challenges in probing the intermediate species. In this study, CO2 reduction reactions on polycrystalline Cu and Au electrodes were investigated in 0.1 M CO2-saturated NaHCO3 solution. In situ sum frequency generation (SFG) spectroscopy has been adopted to access the intermediates and products on the metal electrodes. On the Au electrode, only linearly adsorbed CO could be detected, and the reduction produced no hydrocarbon species. On the Cu electrode, C-H stretching vibrations corresponding to surface-adsorbed ethoxy species were observed, but no CO vibrations can be detected with SFG. The results revealed that the CO randomly adsorbed on the Cu surface, and the multiple orientations of the adsorbed species may be the reason for the formation of C-C bonding. These results demonstrate direct molecular level evidence for different reaction pathways on the Cu and Au electrodes.

Genome-Wide Identification of Rapid Alkalinization Factor Family in Brassica napus and Functional Analysis of BnRALF10 in Immunity to Sclerotinia sclerotiorum.

Rapid alkalinization factors (RALFs) were recently reported to be important players in plant immunity. Nevertheless, the signaling underlying RALF-triggered immunity in crop species against necrotrophic pathogens remains largely unknown. In this study, RALF family in the important oil crop oilseed rape (Brassica napus) was identified and functions of BnRALF10 in immunity against the devastating necrotrophic pathogen Sclerotinia sclerotiorum as well as the signaling underlying this immunity were revealed. The oilseed rape genome carried 61 RALFs, half of them were atypical, containing a less conserved YISY motif and lacking a RRXL motif or a pair of cysteines. Family-wide gene expression analyses demonstrated that patterns of expression in response to S. sclerotiorum infection and DAMP and PAMP treatments were generally RALF- and stimulus-specific. Most significantly responsive BnRALF genes were expressionally up-regulated by S. sclerotiorum, while in contrast, more BnRALF genes were down-regulated by BnPep5 and SsNLP1. These results indicate that members of BnRALF family are likely differentially involved in plant immunity. Functional analyses revealed that BnRALF10 provoked diverse immune responses in oilseed rape and stimulated resistance to S. sclerotiorum. These data support BnRALF10 to function as a DAMP to play a positive role in plant immunity. BnRALF10 interacted with BnFER. Silencing of BnFER decreased BnRALF10-induced reactive oxygen species (ROS) production and compromised rape resistance to S. sclerotiorum. These results back BnFER to be a receptor of BnRALF10. Furthermore, quantitative proteomic analysis identified dozens of BnRALF10-elicited defense (RED) proteins, which respond to BnRALF10 in protein abundance and play a role in defense. Our results revealed that BnRALF10 modulated the abundance of RED proteins to fine tune plant immunity. Collectively, our results provided some insights into the functions of oilseed rape RALFs and the signaling underlying BnRALF-triggered immunity.

Characterization of tomato protein kinases embedding guanylate cyclase catalytic center motif.

Guanylate cyclases (GCs) are enzymes that catalyze the reaction to produce cyclic GMP (cGMP), a key signaling molecule in eukaryotes. Nevertheless, systemic identification and functional analysis of GCs in crop plant species have not yet been conducted. In this study, we systematically identified GC genes in the economically important crop tomato (Solanum lycopersicum L.) and analyzed function of two putative tomato GC genes in disease resistance. Ninety-nine candidate GCs containing GC catalytic center (GC-CC) motif were identified in tomato genome. Intriguingly, all of them were putative protein kinases embedding a GC-CC motif within the protein kinase domain, which was thus tentatively named as GC-kinases here. Two homologs of Arabidopsis PEPRs, SlGC17 and SlGC18 exhibited in vitro GC activity. Co-silencing of SlGC17 and SlGC18 genes significantly reduced resistance to tobacco rattle virus, fungus Sclerotinia sclerotiorum, and bacterium Pseudomonas syringae pv. tomato (Pst) DC3000. Moreover, co-silencing of these two genes attenuated PAMP and DAMP-triggered immunity as shown by obvious decrease of flg22, chitin and AtPep1-elicited Ca2+ and H2O2 burst in SlGC-silenced plants. Additionally, silencing of these genes altered the expression of a set of Ca2+ signaling genes. Furthermore, co-silencing of these GC-kinase genes exhibited stronger effects on all above regulations in comparison with individual silencing. Collectively, our results suggest that GC-kinases might widely exist in tomato and the two SlPEPR-GC genes redundantly play a positive role in resistance to diverse pathogens and PAMP/DAMP-triggered immunity in tomato. Our results provide insights into composition and functions of GC-kinases in tomato.

Probing nanoscale spatial distribution of plasmonically excited hot carriers.

Surface plasmons (SPs) of metals enable the tight focusing and strong absorption of light to realize an efficient utilization of photons at nanoscale. In particular, the SP-generated hot carriers have emerged as a promising way to efficiently drive photochemical and photoelectric processes under moderate conditions. In situ measuring of the transport process and spatial distribution of hot carriers in real space is crucial to efficiently capture the hot carriers. Here, we use electrochemical tip-enhanced Raman spectroscopy (EC-TERS) to in situ monitor an SP-driven decarboxylation and resolve the spatial distribution of hot carriers with a nanometer spatial resolution. The transport distance of about 20 nm for the reactive hot carriers is obtained from the TERS imaging result. The hot carriers with a higher energy have a shorter transport distance. These conclusions can be guides for the design and arrangement of reactants and devices to efficiently make use of plasmonic hot carriers.

Surface configuration of CO adsorbed on nanostructured Pt electrodes probed using broadband sum frequency generation spectroscopy.

Using broadband sum frequency generation (BB-SFG) spectroscopy, the effect of surface structure on the adsorption states of linearly bonded CO (COL) on a Pt electrode was thoroughly analyzed. Two overlapped SFG peaks with different linewidths and electrochemical Stark slopes were identified, which correspond to COL in different surface configurations.

Probing the edge-related properties of atomically thin MoS2 at nanoscale.

Defects can induce drastic changes of the electronic properties of two-dimensional transition metal dichalcogenides and influence their applications. It is still a great challenge to characterize small defects and correlate their structures with properties. Here, we show that tip-enhanced Raman spectroscopy (TERS) can obtain distinctly different Raman features of edge defects in atomically thin MoS2, which allows us to probe their unique electronic properties and identify defect types (e.g., armchair and zigzag edges) in ambient. We observed an edge-induced Raman peak (396 cm-1) activated by the double resonance Raman scattering (DRRS) process and revealed electron-phonon interaction in edges. We further visualize the edge-induced band bending region by using this DRRS peak and electronic transition region using the electron density-sensitive Raman peak at 406 cm-1. The power of TERS demonstrated in MoS2 can also be extended to other 2D materials, which may guide the defect engineering for desired properties.