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Phloem-feeding insects feed on plant phloem using their stylets. While ingesting phloem sap, these insects secrete saliva to circumvent plant defenses. Previous studies have shown that, to facilitate their feeding, many phloem-feeding insects can elicit the salicylic acid- (SA-) signaling pathway and thus suppress effective jasmonic acid defenses. However, the molecular basis for the regulation of the plant's defense by phloem-feeding insects remains largely unknown. Here, we show that Bt56, a whitefly-secreted low molecular weight salivary protein, is highly expressed in the whitefly primary salivary gland and is delivered into host plants during feeding. Overexpression of the Bt56 gene in planta promotes susceptibility of tobacco to the whitefly and elicits the SA-signaling pathway. In contrast, silencing the whitefly Bt56 gene significantly decreases whitefly performance on host plants and interrupts whitefly phloem feeding with whiteflies losing the ability to activate the SA pathway. Proteinprotein interaction assays show that the Bt56 protein directly interacts with a tobacco KNOTTED 1-like homeobox transcription factor that decreases whitefly performance and suppresses whiteflyinduced SA accumulation. The Bt56 orthologous genes are highly conserved but differentially expressed in different species of whiteflies. In conclusion, Bt56 is a key salivary effector that promotes whitefly performance by eliciting salicylic acid-signaling pathway. [ABSTRACT FROM AUTHOR]

The fall armyworm (FAW) Spodoptera frugiperda is a major polyphagous pest that feeds mainly on food crops, such as corn and rice, posing a serious threat to the safety of food crops worldwide. Trehalase, can degrade trehalose and the resulting products participate in the synthesis of chitin, one of the main components of outer epidermis in insects. Therefore, trehalase inhibitors have been identified as novel agents for pest control. We report the insecticidal potential of a trehalase inhibitor validamycin against FAW. Validamycin (1 µg/µL) when injected in FAW using microinjection could significantly reduce trehalase activity 48 h later, especially, the activity of soluble trehalase, then the glucose content and glycogen content also decrease. In addition, the deaths of larvae in validamycin treated group at each instar stage were higher than those in the control group, moreover, validamycin treatment increased the pupal weight and prolonged pest development. Similarly, validamycin also significantly inhibited the chitinase activity and caused the accumulation of chitin in FAW. Results of qRT-PCR showed that the expression levels of two trehalose genes (SfTRE1 and SfTRE2), which encode key enzymes in chitin biosynthesis pathway, were significantly reduced, while the expression levels of fructose-6-phosphate transaminase, glucosamine-phosphate N-acetyltransferase and chitinase genes were significantly increased. It is obvious that validamycin has an influence on physiological metabolism and development of FAW, the results obtained will be conducive to the prevention and control of FAW in the future. [ABSTRACT FROM AUTHOR]

Plasmonics is a rapidly developing field concerning light manipulation at the nanoscale with many potential applications, of which plasmonic circuits are promising for future information technology. Plasmonic waveguides are fundamental elements for constructing plasmonic integrated circuits. Among the proposed different plasmonic waveguides, metallic nanowires have drawn much attention due to the highly confined electromagnetic waves and relatively low propagation loss. Here we review the recent research progress in the waveguiding characteristics of metallic nanowires and nanowire-based nanophotonic devices. Plasmon modes of both cylindrical and pentagonal metallic nanowires with and without substrate are discussed. Typical methods for exciting and detecting the plasmons in metallic nanowires are briefly summarized. Because of the multimode characteristic, the plasmon propagation and emission in the nanowire have many unique properties, benefiting the design of plasmonic devices. A few nanowire-based devices are highlighted, including quarter-wave plate, Fabry—Pérot resonator, router and logic gates. [ABSTRACT FROM AUTHOR]

Using numerical simulation, we investigate the high-order plasmon resonances in individual nanostructures of an Ag nanorice core surrounded by an Al2O3 shell. The peak positions of localized surface plasmon resonances (LSPRs) are red-shifted exponentially with the increase of the dielectric shell thickness. This is due to the exponential decay of electromagnetic field intensity in the direction perpendicular to the interface. This exponential red-shift depends on the wavelength of the resonance peak instead of the resonance order. In addition, we find that the LSPRs in an Ag nanorice of 60-nm width can be perfectly described by a single linear function. These features make nanorice an ideal platform for sensing applications. [ABSTRACT FROM AUTHOR]

III–V quantum dot (QD) lasers monolithically grown on CMOS-compatible Si substrates are considered as essential components for integrated silicon photonic circuits. However, epitaxial growth of III–V materials on Si substrates encounters three obstacles: mismatch defects, antiphase boundaries (APBs), and thermal cracks. We study the evolution of the structures on U-shaped trench-patterned Si (001) substrates with various trench orientations by homoepitaxy and the subsequent heteroepitaxial growth of GaAs film. The results show that the formation of (111)-faceted hollow structures on patterned Si (001) substrates with trenches oriented along [110] direction can effectively reduce the defect density and thermal stress in the GaAs/Si epilayers. The (111)-faceted silicon hollow structure can act as a promising platform for the direct growth of III–V materials for silicon based optoelectronic applications. [ABSTRACT FROM AUTHOR]