Leaf monoterpene emission limits photosynthetic downregulation under heat stress in field-grown grapevine

Rising temperature is among the most remarkably stressful phenomena induced by global climate changes with negative impacts on crop productivity and quality. It has been previously shown that volatiles belonging to the isoprenoid family can confer protection against abiotic stresses. In this work, two Vitis vinifera cv. ‘Chardonnay’ clones (SMA130 and INRA809) differing due to a mutation (S272P) of the DXS gene encoding for 1-deoxy-D-xylulose-5-phosphate (the first dedicated enzyme of the 2C-methyl-D-erythritol-4-phosphate (MEP) pathway) and involved in the regulation of isoprenoids biosynthesis were investigated in field trials and laboratory experiments. Leaf monoterpene emission, chlorophyll fluorescence and gas-exchange measurements were assessed over three seasons at different phenological stages and either carried out in in vivo or controlled conditions under contrasting temperatures. A significant (p < 0.001) increase in leaf monoterpene emission was observed in INRA809 when plants were experiencing high temperatures and over two experiments, while no differences were recorded for SMA130. Significant variation was observed for the rate of leaf CO2 assimilation under heat stress, with INRA809 maintaining higher photosynthetic rates and stomatal conductance values than SMA130 (p = 0.003) when leaf temperature increased above 30 °C. At the same time, the maximum photochemical quantum yield of PSII (Fv/Fm) was affected by heat stress in the non-emitting clone (SMA130), while the INRA809 showed a significant resilience of PSII under elevated temperature conditions. Consistent data were recorded between field seasons and temperature treatments in controlled environment conditions, suggesting a strong influence of monoterpene emission on heat tolerance under high temperatures. This work provides further insights on the photoprotective role of isoprenoids in heat-stressed Vitis vinifera, and additional studies should focus on unraveling the mechanisms underlying heat tolerance on the monoterpene-emitter grapevine clone

Water-Saving Traits Can Protect Wheat Grain Number Under Progressive Soil Drying at the Meiotic Stage:A Phenotyping Approach

In wheat, water deficit during meiosis of pollen mother cells greatly reduces seed set and grain number. A promising option to avoid grain losses and maintain wheat productivity under water stress is to exploit conservative water-use strategies during reproduction. In this work, two cultivars known to be adapted to different environments were studied. Water stress, with or without a polymer spray known to reduce stomatal conductance, was applied to both cultivars just prior to meiosis. Two experiments were carried out in a phenotyping platform to (1) assess and validate daily non-destructive estimation of projected leaf area and to (2) evaluate different water-use (WU) strategies across the meiotic period and their effect on physiology and yield components. Gladius displays an elevated breakpoint (BP) in the regression of WU against fraction of transpirable soil water (FTSW) for both daily and night-time WU suggesting higher conservative whole-plant response when compared to Paragon. At the same time, Gladius maintained flag leaf gas-exchange with a significant reduction at ~ 0.2 FTSW only, suggesting an uncoupled mechanism of WU reduction that optimized the water resource available for flag leaf gas-exchange maintenance. Under progressive soil drying, seed set and grain number of tillers stressed at GS41 were significantly reduced in Paragon (p < 0.05) thus leading to lower grain yield and grain number at plant level than Gladius. Polymer-induced reduction of transpiration is potentially useful when applied to the non-conservative stressed Paragon, maintaining higher FTSW, water-use efficiency and RWC during the progressive soil drying treatment. This led to better seed set (p < 0.05) and grain number maintenance (p < 0.05) than in the stressed Paragon control. We conclude that the different conservative traits detected in this work, protect grain development around meiosis and therefore maintain grain number under water-limiting conditions. Additionally, non-conservative genotypes (often with a greater expected yield potential) can be protected at key stages by reducing their water use with a polymer spray. Thus, future efforts can integrate both crop breeding and management strategies to achieve drought-resilience during the early reproductive phase in wheat and potentially other cereals

Large-FSR Thermally Tunable Double-Ring Filters for WDM Applications in Silicon Photonics

International audience; We present the design procedure and experimental results of thermally tunable double ring resonators for integrated wavelength division multiplexing applications. A detailed analytical model specific for double rings is described, and a modified racetrack geometry using Bezier bends is used to reduce bending loss. We demonstrate devices with a free-spectral-range up to 2.4 THz ( 19 nm) around 1550 nm and nonadjacent channel rejection higher than 35 dB. The experimental results of thermally tunable double ring resonators is also presented with doped silicon integrated heaters, allowing the device to be used as a tunable filter or a switch

Ultracompact microinterferometer-based fiber Bragg grating interrogator on a silicon chip

We report an interferometer-based multiplexed fiber Bragg grating (FBG) interrogator using silicon photonic technology. The photonic-integrated system includes the grating coupler, active and passive interferometers, interferometers, a 12-channel wavelength-division-multiplexing (WDM) filter, and Ge photodiodes, all integrated on a 6x8&nbsp;mm2 silicon chip. The system also includes optical and electric interfaces to a printed board, which is connected to a real-time electronic board that actively performs the phase demodulation processing using a multitone mixing (MTM) technique. The device with active demodulation, which uses thermally-based phase shifters, features a noise figure of σ&nbsp; = &nbsp;0.13&nbsp;pm at a bandwidth of 700&nbsp;Hz, which corresponds to a dynamic spectral resolution of 4.9&nbsp;fm/Hz1/2. On the other hand, the passive version of the system, based on a 90º-hybrid coupler, features a noise figure of σ&nbsp; = &nbsp;2.55&nbsp;pm at a bandwidth of 10&nbsp;kHz, also showing successful detection of a 42&nbsp;kHz signal when setting the bandwidth to 50&nbsp;kHz. These results demonstrate the advantage of integrated photonics, which allows the integration of several systems with different demodulation schemes in the same chip and guarantees easy scalability to a higher number of ports without increasing the dimensions or the cost

Enhanced Transepithelial Permeation of Gallic Acid and (-)-Epigallocatechin Gallate across Human Intestinal Caco-2 Cells Using Electrospun Xanthan Nanofibers

Electrospun xanthan polysaccharide nanofibers (X) were developed as an encapsulation and delivery system of the poorly absorbed polyphenol compounds, gallic acid (GA) and (-)-epigallocatechin gallate (EGCG). Scanning electron microscopy was used to characterize the electrospun nanofibers, and controlled release studies were performed at pH 6.5 and 7.4 in saline buffer, suggesting that the release of polyphenols from xanthan nanofibers follows a non-Fickian mechanism. Furthermore, the X-GA and X-EGCG nanofibers were incubated with Caco-2 cells, and the cell viability, transepithelial transport, and permeability properties across cell monolayers were investigated. An increase of GA and EGCG permeability was observed when the polyphenols were loaded into xanthan nanofibers, compared to the free compounds. The observed in vitro permeability enhancement of GA and EGCG was induced by the presence of the polysaccharide nanofibers, which successfully inhibited efflux transporters, as well as by tight junctions opening

Distributed temperature sensor system based on Raman scattering using correlation-codes

A distributed sensor system employing spontaneous Raman scattering with use of correlation-coding techniques and a single-detector scheme is discussed and experimentally characterised. A sensing distance of up to 8 km is achieved with high spatial and temperature resolutions; use of correlation-coding significantly reduces measurement time and allows use of low-power laser sources

Relativistic Structure of the Deuteron: 1.Electro-disintegration and y-scaling

Realistic solutions of the spinor-spinor Bethe-Salpeter equation for the deuteron with realistic interaction kernel including the exchange of pi, sigma, omega, rho, eta and delta mesons, are used to systematically investigate relativistic effects in inclusive quasi-elastic electron-deuteron scattering within the relativistic impulse approximation. Relativistic y-scaling is considered by generalising the non relativistic scaling function to the relativistic case, and it is shown that y-scaling does occur in the usual relativistic scaling variable resulting from the energy conservation in the instant form of dynamics. The present approach of y-scaling is fully covariant, with the deuteron being described by eight components, viz. the 3S_1^{++}, 3S_1^{--}, 3D_1^{++}, 3D_1^{--}, 3P_1^{+-}, 3P_1^{-+}, 1P_1^{+-}, 1P_1^{-+} waves. It is demonstrated that if the negative relative energy states 1P_1, 3P_1 are disregarded, the concept of covariant momentum distributions N(p_0,p), with p_0=M_D/2-\sqrt{p^2+m^2}, can be introduced, and that calculations of lectro-disintegration cross section in terms of these distributions agree within few percents with the exact calculations which include the 1P_1, 3P_1 states, provided the nucleon three momentum |p|\<= 1 GeV/c; in this momentum range, the asymptotic relativistic scaling function is shown to coincide with the longitudinal covariant momentum distribution.Comment: 32 LaTeX pages, 18 eps-figures. Final version to appear in Phys. Rev.