Search

Plant roots integrate environmental signals with development using exquisite spatiotemporal control. This is apparent in the deposition of suberin, an apoplastic diffusion barrier, which regulates flow of water, solutes and gases, and is environmentally plastic. Suberin is considered a hallmark of endodermal differentiation but is absent in the tomato endodermis. Instead, suberin is present in the exodermis, a cell type that is absent in the model organism Arabidopsis thaliana. Here we demonstrate that the suberin regulatory network has the same parts driving suberin production in the tomato exodermis and the Arabidopsis endodermis. Despite this co-option of network components, the network has undergone rewiring to drive distinct spatial expression and with distinct contributions of specific genes. Functional genetic analyses of the tomato MYB92 transcription factor and ASFT enzyme demonstrate the importance of exodermal suberin for a plant water-deficit response and that the exodermal barrier serves an equivalent function to that of the endodermis and can act in its place.

We present a comparative study of two Lu-based oxide ceramics doped with Yb3+ ions, namely Yb:Lu3Al5O12 (garnet) and Yb:Lu2O3 (sesquioxide), promising for thin-disk lasers. The ceramics are fabricated using nanopowders of 3.6 at.% Yb:Lu2O3 and Al2O3 produced by laser ablation: Yb:Lu3Al5O12 – by vacuum sintering at 1800 °C for 5 h with the addition of 1 wt% TEOS as a sintering aid, and Yb:Lu2O3 – by vacuum pre-sintering at 1250 °C for 2 h followed by Hot Isostatic Pressing at 1400 °C for 2 h under Ar gas pressure of 207 MPa. The comparison includes the structure, Raman spectra, transmission, optical spectroscopy and laser operation. The crystal-field splitting of Yb3+ multiplets is revealed for Lu3Al5O12. A continuous-wave (CW) Yb:Lu3Al5O12 ceramic microchip laser generates 5.65 W at 1031.1 nm with a slope efficiency of 67.2%. In the quasi-CW regime, the peak power is scaled up to 8.83 W. The power scaling for the Yb:Lu2O3 ceramic laser is limited by losses originating from residual coloration and inferior thermal behavior. © 2020 Elsevier Ltd and Techna Group S.r.l.

© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement. We report on a mode-locked Tm,Ho:CLNGG laser emitting in the 2 µm spectral range using single-walled carbon nanotubes (SWCNTs) as a saturable absorber (SA). Pulses with duration of 98 fs are generated at 99.28 MHz repetition rate with an average output power of 123 mW, yielding a pulse energy of 1.24 nJ. Using a 0.5% output coupling, pulses as short as 67 fs, i.e., 10 optical cycles, are produced after extracavity compression with a 3-mm-thick ZnS plate.

© 2018 Optical Society of America. We report on the crystal growth, structure, Raman and optical spectroscopy of novel mixed tetragonal vanadates, Yb:Lu 1-x-y Y x La y VO 4 . Optical absorption, stimulatedemission, and gain cross-section spectra of Yb 3+ are determined for p and s polarizations. For a Yb:Lu 0.74 Y 0.23 La 0.01 VO 4 crystal, the absorption bandwidth is > 10 nm, the ? SE is 1.1 × 10 -20 cm 2 at 1013 nm, the gain bandwidth is > 40 nm (for p-polarization), and the radiative lifetime of the 2 F 5/2 state is ~305 ?s. The Stark splitting of the Yb 3+ multiplets is determined using low-temperature (6 K) spectroscopy. A diode-pumped a-cut 2 at.% Yb:Lu 0.74 Y 0.23 La 0.01 VO 4 laser generated 5.0 W at 1044 nm with a slope efficiency of 43%. The developed materials are promising for sub-100 fs mode-locked lasers at ~1 ?m.

We report on inkjet-printing of graphene saturable absorbers (SAs) suitable for passive Qswitching of ~2-μm bulk and waveguide lasers. Using graphene-SA in a microchip Tm:KLu(WO4)2 laser, 1.2 μJ/136 ns pulses are generated at 1917 nm., QC 20171030

Contains fulltext : 175490.pdf (publisher's version ) (Closed access)

© 2017 Optical Society of America. Monoclinic thulium-doped magnesium monotungstate, Tm 3+ :MgWO 4 , is promising for efficient power-scalable continuous-wave (CW) and passively Q-switched lasers at > 2 ?m. Under diode pumping at 802 nm, a compact CW laser based on Z-cut Tm:MgWO 4 generated 3.09 W at 2022-2034 nm with a slope efficiency of 50% which represents the highest output power ever achieved with this type of laser host. Stable passive Q-switching of the Tm:MgWO 4 laser is demonstrated for the first time, to the best of our knowledge, using single-walled carbon nanotubes, graphene, and Cr 2+ :ZnS saturable absorbers. Using the latter, the best performance is achieved with 16.1 ?J/13.6 ns pulses at 2017.8 nm with a maximum average output power of 0.87 W and a peak power of 1.18 kW.

© 2017 Optical Society of America. Multi-watt continuous-wave (CW) operation of tetragonal rare-earth calcium aluminate Yb:CaLnAlO 4 Ln Gd;Y) crystals in plano–plano microchip lasers was demonstrated with an almost quantum-defect-limited slope efficiency. Pumped at 978 nm by an InGaAs laser diode, a 3.4 mm long 8 at. % Yb:CaGdAlO 4 laser generated 7.79 W at 1057–1065 nm with a slope efficiency of ? 84% (with respect to the absorbed pump power). An even higher ? 91% was achieved with a 2.5 mm long 3 at. % Yb:CaYAlO 4 laser, from which 5.06 W were extracted at 1048–1056 nm. Both lasers produced linearly polarized output (?-polarization) with an almost circular diffraction-limited beam (M 2 x,y < 1.1). The output performance of the developed lasers was modeled, yielding an internal loss coefficient as low as 0.004?0.007 cm ?1 . In addition, their spectroscopic properties were revisited.

We study cryogenic laser operation of an Yb-doped KLu(WO4)2 crystal pumped with a volume Bragg grating (VBG) stabilized diode laser at 981 nm. In the continuous wave laser regime, a maximum output power of 4.31 W is achieved at 80 K with a slope efficiency of 44.0% with respect to the incident pump power. Using a 85% initial transmission Cr:YAG crystal for passive Q-switching, an average output power of 2.11 W is achieved at 100 K for a repetition rate of 19 kHz. The pulse energy, pulse duration and peak power amount to 111 ¿J, 231 ns and 0.48 kW, respectively.

Open Access

Contains fulltext : 175490.pdf (publisher's version ) (Closed access)

Contains fulltext : 175490.pdf (publisher's version ) (Closed access)

We report on a model of diode-pumped Thulium lasers passively Q-switched by a graphene saturable absorber applicable also for any other "fast" saturable absorber. It reasonably predicts the dependence of the pulse duration, pulse energy and pulse repetition frequency on the absorbed power. The model is applied in the present work for a Tm: KLuW microchip laser passively Q-switched with a multi-layer graphene saturable absorber. The laser generates similar to 1 W at 1926 nm with a slope efficiency of 39%. Stable 190 ns /4.1 mu J pulses are achieved at a pulse repetition frequency of 260 kHz. The potential of graphene for the generation of few-ns pulses at similar to 2 mu m is discussed.

We report on the growth, spectroscopic and laser characterization of a novel monoclinic laser crystal, Yb,In:KLu(WO4)(2) (Yb,In:KLuW). The absorption, stimulated-emission and gain cross-section spectra of 3.5 at% Yb, 5.5 at% In-doped KLuW are determined at room temperature with polarized light and compared with those for Yb,In:KYW, as well as singly Yb-doped KLuW and KYW crystals. It is found that the introduction of In results in a decrease of the transition cross-sections and in a spectral broadening of the absorption and emission bands. Such a broadening is more pronounced for light polarization E parallel to N-p. For Yb,In:KLuW, the maximum sigma(abs) is 9.9 x 10(-20) cm(2) at 980.9 nm for E parallel to N-m and the corresponding bandwidth of the absorption peak is 3.7 nm. The radiative lifetime for Yb3+ ions is 237 +/- 5 mu s. The stimulated emission cross-sections are sigma(SE)(m)= 2.4 x 10(-20) cm(2) at 1022.4 nm and sigma(SE)(p) = 1.3 x 10(-20) cm(2) at 1039.1 nm corresponding to an emission bandwidth of > 30 nm and > 35 nm, respectively. The diode pumped N-g-cut Yb,In:KLuW microchip laser generated 4.11 W at 1042-1048 nm with a slope efficiency of 78%. The Yb,In:KLuW crystal is very promising for the generation of sub-100 fs pulses in mode-locked lasers due to its broadband emission characteristics. (C) 2016 Elsevier B.V. All rights reserved.

Open Access

We study cryogenic laser operation of an Yb-doped KLu(WO4)2 crystal pumped with a volume Bragg grating (VBG) stabilized diode laser at 981 nm. In the continuous wave laser regime, a maximum output power of 4.31 W is achieved at 80 K with a slope efficiency of 44.0% with respect to the incident pump power. Using a 85% initial transmission Cr:YAG crystal for passive Q-switching, an average output power of 2.11 W is achieved at 100 K for a repetition rate of 19 kHz. The pulse energy, pulse duration and peak power amount to 111 ¿J, 231 ns and 0.48 kW, respectively.

We report on a detailed spectroscopic study of Eu3+ ions in the monoclinic KYb(WO4)2 crystal. The polarized room and low-temperature absorption spectra are measured. The maximum ¿abs corresponding to the 7F1 ¿ 5D1 transition is 1.32×10-20 cm2 at 534.2 nm with a bandwidth of 0.7 nm (for E || Nm). The Stark sub-levels of the excited mulitplets are determined. A Judd-Ofelt analysis is applied to the Eu3+:KYb(WO4)2 crystal to determine the probability of spontaneous transitions, radiative lifetimes and luminescence branching ratios. Within the strong configuration interaction (SCI) approxi-mation, the intensity parameters are ¿2 = 4.757, ¿4 = 2.295, ¿6 = 1.644 [10-20 cm2] and ¿f = 50160 cm¿1. The radiative lifetime of the 5D0 state is 351 µs. The maximum stimulated-emission cross-section corresponding to the 7F1 ¿ 5D1 transition is 1.44×10-20 cm2 at 703.2 nm (for E || Nm). Under UV excita-tion, the Eu3+: KYb(WO4)2 crystal provides intense red photoluminescence with CIE coordinates, x = 0.675, y = 0.325.

Influence of pre-irradiation annealing temperature on the efficiency of the subsurface color center formation in gamma-irradiated lithium fluoride nanocrystals has been studied. Increase of the annealing temperature reduces the efficiency of formation of these centers. Nanocrystals lose their ability to form subsurface color centers after pre irradiation annealing at 623 K and higher temperatures. The formed subsurface color centers are partially transformed into the usual centers of the same composition during the post-radiation annealing at certain temperatures. It has been shown that the mechanical fragmentation of lithium fluoride crystals leads to the formation of nanosized clusters in their subsurface layer. Subsurface radiation color centers which are located near the clusters are subjected to the modified crystal field. This circumstance causes strong differences between the luminescent characteristics of subsurface color centers and usual centers of the same composition in the crystal bulk, where there are no clusters. The clusters are completely destroyed after annealing the samples at 623 K and higher temperatures. The obtained results indicate that the presence of nanoclusters is a prerequisite for the formation of subsurface radiation color centers with specific fluorescent properties. The thickness of the subsurface layer, where subsurface color centers can be formed, has been estimated.

We report on the crystal growth, structural and spectroscopic investigation of a novel trigonal calcium vanadate crystal, Tm3+:Ca9La(VO4)(7). Polarized absorption, stimulated-emission and gain cross-section spectra are determined for this material. The maximum sigma(SE) corresponding to the F-3(4) -> H-3(6) transition amounts to 1.28 x 10(-20) cm(2) at 1854 nm for sigma-polarization. The measured lifetime of the Tm3+ ions in the F-3(4) state is 1.19 ms. The Judd-Ofelt analysis performed yielded intensity parameters of Omega(2) = 4.682, Omega(4) = 0.659 and Omega(6) = 0.475 [10(-20) cm(2)]. The polarized Raman spectra indicate a strong and broad band centered at 867 cm(-1). Owing to the disordered nature of Ca9La(VO4)(7), the Tm3+ ions exhibit a broad and smooth gain profile at similar to 2 mu m. The spectroscopic properties of Tm3+:Ca9La(VO4)(7) are very promising for broadly tunable and ultrashort pulse lasers near 2 mu m. (C) 2017 Optical Society of America

We report on a detailed spectroscopic study of Eu3+ ions in the monoclinic KYb(WO4)(2) crystal. The polarized room and low-temperature absorption spectra are measured. The maximum sigma(abs) corresponding to the F-7(1) -> D-5(1) transition is 1.32 x 10(-20) cm(2) at 534.2 nm with a bandwidth of 0.7 nm (for E parallel to N-m). The Stark sub-levels of the excited mulitplets are determined. A Judd-Ofelt analysis is applied to the Eu3+ :KYb(WO4)(2) crystal to determine the probability of spontaneous transitions, radiative lifetimes and luminescence branching ratios. Within the strong configuration interaction (SCI) approximation, the intensity parameters are Omega(2)=4.757, Omega(4)=2.295, Omega(6)=1.644 [10(-20) cm(2)] and Delta(f)=50160 cm(-1). The radiative lifetime of the D-5(0) state is 351 mu s. The maximum stimulated-emission cross-section corresponding to the F-7(1) -> D-5(1) transition is 1.44 x 10(-20) cm(2) at 703.2 nm (for E parallel to N-m). Under UV excitation, the Eu3+ :KYb(WO4)(2) crystal provides intense red photoluminescence with CIE coordinates, x=0.675, y=0.325. (C) 2016 Published by Elsevier B.V.

Contains fulltext : 157084.pdf (Publisher’s version ) (Closed access)

Contains fulltext : 157084.pdf (Publisher’s version ) (Closed access)

Contains fulltext : 157084.pdf (Publisher’s version ) (Closed access)

Thermal lensing is studied in monoclinic Yb:Ca4YO(BO3)(3) (Yb:YCOB) oxoborate crystals cut along the optical indicatrix axes. For all orientations, the thermal lens is positive. In the Z-cut crystal, the sensitivity factors of the thermal lens are MZ-X = 2.4 and MZ-Y = 2.8 m(-1)/W (for E parallel to X), and the astigmatism degree is as low as S/M = 14%. The positive thermal lens in Yb:YCOB is related to the large thermal expansion and strong photoelastic effect. Microchip lasers are realized with 3-mm-long X, Y, and Z-cut 15 at.% Yb:YCOB crystals. With a Z-cut crystal, maximum output power of 8.35 W is achieved at similar to 1040 nm with slope efficiency of 70%. Using various crystal cuts and output coupler transmissions, multiwatt emission in the spectral range of 1033-1091 nm is demonstrated.

Compact Yb:KLu(WO4)(2) and Yb: LuVO4 lasers diode-pumped at 978 nm are passively Q-switched by a single-layer graphene saturable absorber. The Yb:KLu(WO4)(2) laser generated 165 ns/0.49 mu J pulses at 1030 nm with 170 mW average output power and 12 % slope efficiency. With the Yb:LuVO4 laser, 152 ns/0.83 mu J pulses were achieved. The output power reached 300 mW at 1024 nm, and the slope efficiency was 10 %. Laser operation in a plano-plano cavity is achieved with both crystals with thermal lensing playing a key role in their performance. A model describing graphene Q-switched Yb lasers is developed. Our results indicate the potential of graphene for passive Q-switching of similar to 1 mu m bulk lasers.

We report on growth and detailed spectroscopic study of Eu3+-doped tetragonal sodium gadolinium double tungstate, Eu:NaGd(WO4)(2), a new promising crystal for deep-red lasers. Large-volume crystal doped with 4.9 at.% Eu is grown by Czochralski method along the [001] crystallographic direction. Absorption of Eu3+ ions is studied at room temperature (RT) and at 6 K. For the absorption band related to the F-7(1) -> D-5(1) transition suitable for pumping of Eu:NaGd(WO4)(2), the maximum cross-section is sigma(abs) = 1.2 x 10(-21) cm(2) at 535.5 nm with the full width at half maximum (FWHM) of 3.1 nm (at RT, for E parallel to a polarization). For the D-5(0) -> F-7(4) transition, the maximum stimulated-emission cross-section is sigma(SE) = 1.6 x 10(-21) cm(2) at 698.3 nm (RT, E parallel to c polarization). Lifetime of the D-5(0) state is 490 +/- 10 mu s (at RT). Under UV excitation, Eu:NaGd(WO4)(2) provides intense red emission with CIE coordinates (x = 0.671, y = 0329). (C) 2016 Elsevier B.V. All rights reserved.

Compact Yb:KLu(WO4)2 and Yb:LuVO4 lasers diode-pumped at 978 nm are passively Q-switched by a single- layer graphene saturable absorber. The Yb:KLu(WO4)2 laser generated 165 ns/0.49 ¿J pulses at 1030 nm with 170 mW average output power and 12 % slope efficiency. With the Yb:LuVO4 laser, 152 ns/0.83 ¿J pulses were achieved. The output power reached 300 mW at 1024 nm, and the slope efficiency was 10 %. Laser operation in a plano-plano cavity is achieved with both crystals with thermal lensing playing a key role in their performance. A model describing graphene Q-switched Yb lasers is developed. Our results indicate the potential of graphene for passive Q-switching of ~1 ¿m bulk lasers.

A diode-pumped Tm,Ho:KLu(WO4)2 microchip laser passively Q-switched with a Cr:ZnS saturable absorber generated an average output power of 131 mW at 2063.6 nm with a slope efficiency of 11% and a Q-switching conversion efficiency of 58%. The pulse characteristics were 14 ns / 9 ¿J at a pulse repetition frequency of 14.5 kHz. With higher modulation depth of the saturable absorber, 9 ns / 10.4 ¿J / 8.2 kHz pulses were generated at 2061.1 nm corresponding to a record peak power extracted from a passively Q-switched Tm,Ho laser of 1.15 kW. A theoretical model is presented predicting the pulse energy and duration. The simulations are in good agreement with the experimental results

Efficient and power-scalable laser operation of a vibronic Tm3+ : KLu(WO4)(2) microchip laser at similar to 2.13 mu m is demonstrated. In the continuous-wave mode under diode pumping at similar to 805 nm, this laser generated 1.17 W at 2109-2133 nm with a slope efficiency of 39%. This emission is related to the coupling of the electronic transitions of Tm3+ ions with the stretching vibrations of the WOW oxygen bonds in the monoclinic KLu(WO4)(2) crystal host appearing at similar to 379, 406, and 450 cm(-1). The achieved emission wavelength is longer, to our knowledge, than any previously reported laser based on Tm3+ or Ho3+ doped double tungstate crystals. Passive Q-switching of the vibronic Tm3+ : KLu(WO4)(2) laser is realized with a single-walled carbon nanotube (SWCNT) based saturable absorber, representing the longest wavelength in this mode of operation. In this regime, the maximum output power reached 0.70 W at 2131 nm, corresponding to a slope efficiency of 29%. The pulse characteristics were 25 ns/1.1 mu J at the pulse repetition frequency of 0.62 MHz. These are, we believe, the shortest pulses ever achieved in any lanthanide-based laser passively Q-switched by carbon nanostructures. A conventional (purely electronic transition) Tm3+ : KLu(WO4)(2) microchip laser at 1.92 mu m Q-switched by the same SWCNTs generated 40 ns/ 4.0 mu J pulses corresponding to a peak power of 0.1 kW, which is a record value for this type of laser oscillator, to our knowledge. (C) 2016 Optical Society of America

A diode-pumped Tm,Ho:KLu (WO4)(2) microchip laser passively Q-switched with a Cr:ZnS saturable absorber generated an average output power of 131 mW at 2063.6 nm with a slope efficiency of 11% and a Q-switching conversion efficiency of 58%. The pulse characteristics were 14 ns/9 mu J at a pulse repetition frequency of 14.5 kHz. With higher modulation depth of the saturable absorber, 9 ns/10.4 mu J/8.2 kHz pulses were generated at 2061.1 nm, corresponding to a record peak power extracted from a passively Q-switched Tm,Ho laser of 1.15 kW. A theoretical model is presented, predicting the pulse energy and duration. The simulations are in good agreement with the experimental results. (C) 2016 Optical Society of America

A compact intracavity-pumped microchip Ho laser is realized using stacked Tm:KLuW/Ho:KLuW crystals pumped by a laser diode at 805 nm; both crystals are cut for light propagation along the Ng optical indicatrix axis and emit with polarization along the Nm axis. Maximum CW output power of 285 mW is achieved at a wavelength of 2080 nm for 5.6 W absorbed pump power in the Tm:KLuW crystal with a maximum slope efficiency of 8.3 %. Maximum total (Tm3+ and Ho3+ emission) output of 887 mW with a slope efficiency of 23 % is achieved. Laser operation is obtained in the 1867-1900 nm spectral range corresponding to the Tm emission, while Ho emits at 2078-2100 nm, depending on the output coupling. The microchip Ho laser generates a near-circular output beam with M2 < 1.1. The compact laser setup with plane-plane cavity provides automatic mode-matching condition for the Tm and Ho laser modes.

We describe a compact Yb: YAG laser Q-switched by a graphene-based saturable absorber and pumped by a laser diode at 932 or 969 nm. The compact laser generates a maximum average output power value of 185 mW at 1032 nm with a slope efficiency value of 12%. The shortest duration of the Q-switched pulse achieved is 228 ns at a repetition frequency of 285 kHz. The maximum pulse energy amounts to 0.65 µJ.

A microchip laser is realized on the basis of a monoclinic Tm,Ho-codoped KLu(WO4)2 crystal cut for light propagation along the Ng optical indicatrix axis. This crystal cut provides positive thermal lens with extremely weak astigmatism, S/M = 4%. High sensitivity factors, M = dD/dPabs, of 24.9 and 24.1 m−1/W for the mg- and pg- tangential planes are calculated with respect to the absorbed pump power. Such thermo-optic behavior is responsible for mode stabilization in the plano-plano microchip laser cavity, as well as the demonstrated perfect circular beam profile (M2 < 1.1). Maximum continuous-wave output power of 450 mW is obtained with a slope efficiency of 31%. A set of output couplers is employed to achieve lasing in the spectral range of 2060-2096 nm. The increase of output coupler transmission results in deterioration of the laser performance attributed to the increased up-conversion losses.

Contains fulltext : 126189.pdf (Publisher’s version ) (Closed access), Global climate change has increased flooding events, which affect both natural vegetation dynamics and crop productivity. The flooded environment is lethal for most plant species because it restricts gas exchange and induces an energy and carbon crisis. Flooding survival strategies have been studied in Oryza sativa, a cultivated monocot. However, our understanding of plant adaptation to natural flood-prone environments remains scant, even though wild plants represent a valuable resource of tolerance mechanisms that could be used to generate stress-tolerant crops. Here we identify mechanisms that mediate the distinct flooding survival strategies of two related wild dicot species: Rumex palustris and Rumex acetosa. Whole transcriptome sequencing and metabolite profiling reveal flooding-induced metabolic reprogramming specific to R. acetosa. By contrast, R. palustris uses the early flooding signal ethylene to increase survival by regulating shade avoidance and photomorphogenesis genes to outgrow submergence and by priming submerged plants for future low oxygen stress. These results provide molecular resolution of flooding survival strategies of two species occupying distinct hydrological niches. Learning how these contrasting flood adaptive strategies evolved in nature will be instrumental for the development of stress-tolerant crop varieties that deliver enhanced yields in a changing climate.

Contains fulltext : 126189.pdf (Publisher’s version ) (Closed access), Global climate change has increased flooding events, which affect both natural vegetation dynamics and crop productivity. The flooded environment is lethal for most plant species because it restricts gas exchange and induces an energy and carbon crisis. Flooding survival strategies have been studied in Oryza sativa, a cultivated monocot. However, our understanding of plant adaptation to natural flood-prone environments remains scant, even though wild plants represent a valuable resource of tolerance mechanisms that could be used to generate stress-tolerant crops. Here we identify mechanisms that mediate the distinct flooding survival strategies of two related wild dicot species: Rumex palustris and Rumex acetosa. Whole transcriptome sequencing and metabolite profiling reveal flooding-induced metabolic reprogramming specific to R. acetosa. By contrast, R. palustris uses the early flooding signal ethylene to increase survival by regulating shade avoidance and photomorphogenesis genes to outgrow submergence and by priming submerged plants for future low oxygen stress. These results provide molecular resolution of flooding survival strategies of two species occupying distinct hydrological niches. Learning how these contrasting flood adaptive strategies evolved in nature will be instrumental for the development of stress-tolerant crop varieties that deliver enhanced yields in a changing climate.

Contains fulltext : 126189.pdf (Publisher’s version ) (Closed access), Global climate change has increased flooding events, which affect both natural vegetation dynamics and crop productivity. The flooded environment is lethal for most plant species because it restricts gas exchange and induces an energy and carbon crisis. Flooding survival strategies have been studied in Oryza sativa, a cultivated monocot. However, our understanding of plant adaptation to natural flood-prone environments remains scant, even though wild plants represent a valuable resource of tolerance mechanisms that could be used to generate stress-tolerant crops. Here we identify mechanisms that mediate the distinct flooding survival strategies of two related wild dicot species: Rumex palustris and Rumex acetosa. Whole transcriptome sequencing and metabolite profiling reveal flooding-induced metabolic reprogramming specific to R. acetosa. By contrast, R. palustris uses the early flooding signal ethylene to increase survival by regulating shade avoidance and photomorphogenesis genes to outgrow submergence and by priming submerged plants for future low oxygen stress. These results provide molecular resolution of flooding survival strategies of two species occupying distinct hydrological niches. Learning how these contrasting flood adaptive strategies evolved in nature will be instrumental for the development of stress-tolerant crop varieties that deliver enhanced yields in a changing climate.

Contains fulltext : 92111.pdf (publisher's version ) (Closed access)

Contains fulltext : 92111.pdf (publisher's version ) (Closed access)

A detailed description of the molecular response of Arabidopsis thaliana to submergence can aid the identification of genes that are critical to flooding survival. • Rosette-stage plants were fully submerged in complete darkness and shoot and root tissue was harvested separately after the O2 partial pressure of the petiole and root had stabilized at c. 6 and 0.1 kPa, respectively. As controls, plants were untreated or exposed to darkness. Following quantitative profiling of cellular mRNAs with the Affymetrix ATH1 platform, changes in the transcriptome in response to submergence, early darkness, and O2-deprivation were evaluated by fuzzy k-means clustering. This identified genes co-regulated at the conditional, developmental or organ-specific level. Mutants for 10 differentially expressed HYPOXIA-RESPONSIVE UNKNOWN PROTEIN (HUP) genes were screened for altered submergence tolerance. • The analysis identified 34 genes that were ubiquitously co-regulated by submergence and O2 deprivation. The biological functions of these include signaling, transcription, and anaerobic energy metabolism. HUPs comprised 40% of the co-regulated transcripts and mutants of seven of these genes were significantly altered in submergence tolerance. • The results define transcriptomic adjustments in response to submergence in the dark and demonstrate that the manipulation of HUPs can alter submergence tolerance.

The exploitation of natural variation in Arabidopsis thaliana (Arabidopsis) provides a huge potential for the identification of the molecular mechanisms underlying this variation as a result of the availability of a vast array of genetic and genomic resources for this species. Eighty-six Arabidopsis accessions were screened for natural variation in flooding tolerance. This forms the first step towards the identification and characterization of the role of candidate genes contributing to flooding tolerance. • Arabidopsis accessions at the 10-leaf stage were subjected to complete submergence in the dark. Survival curves were plotted to estimate median lethal times as a measure of tolerance. Flooding-associated survival parameters, such as root and shoot oxygen content, initial carbohydrate content and petiole elongation under water, were also measured. • There was a significant variation in submergence tolerance among Arabidopsis accessions. However, the order of tolerance did not correlate with root and shoot oxygen content or initial amounts of shoot starch and total soluble sugars. A negative correlation was observed between submergence tolerance and underwater petiole elongation. • Arabidopsis accessions show considerable variation in the ability to tolerate complete submergence, making it a good species in which to identify and characterize genes and to study mechanisms that contribute to survival under water.

The exploitation of natural variation in Arabidopsis thaliana (Arabidopsis) provides a huge potential for the identification of the molecular mechanisms underlying this variation as a result of the availability of a vast array of genetic and genomic resources for this species. Eighty-six Arabidopsis accessions were screened for natural variation in flooding tolerance. This forms the first step towards the identification and characterization of the role of candidate genes contributing to flooding tolerance. • Arabidopsis accessions at the 10-leaf stage were subjected to complete submergence in the dark. Survival curves were plotted to estimate median lethal times as a measure of tolerance. Flooding-associated survival parameters, such as root and shoot oxygen content, initial carbohydrate content and petiole elongation under water, were also measured. • There was a significant variation in submergence tolerance among Arabidopsis accessions. However, the order of tolerance did not correlate with root and shoot oxygen content or initial amounts of shoot starch and total soluble sugars. A negative correlation was observed between submergence tolerance and underwater petiole elongation. • Arabidopsis accessions show considerable variation in the ability to tolerate complete submergence, making it a good species in which to identify and characterize genes and to study mechanisms that contribute to survival under water.

A detailed description of the molecular response of Arabidopsis thaliana to submergence can aid the identification of genes that are critical to flooding survival. • Rosette-stage plants were fully submerged in complete darkness and shoot and root tissue was harvested separately after the O2 partial pressure of the petiole and root had stabilized at c. 6 and 0.1 kPa, respectively. As controls, plants were untreated or exposed to darkness. Following quantitative profiling of cellular mRNAs with the Affymetrix ATH1 platform, changes in the transcriptome in response to submergence, early darkness, and O2-deprivation were evaluated by fuzzy k-means clustering. This identified genes co-regulated at the conditional, developmental or organ-specific level. Mutants for 10 differentially expressed HYPOXIA-RESPONSIVE UNKNOWN PROTEIN (HUP) genes were screened for altered submergence tolerance. • The analysis identified 34 genes that were ubiquitously co-regulated by submergence and O2 deprivation. The biological functions of these include signaling, transcription, and anaerobic energy metabolism. HUPs comprised 40% of the co-regulated transcripts and mutants of seven of these genes were significantly altered in submergence tolerance. • The results define transcriptomic adjustments in response to submergence in the dark and demonstrate that the manipulation of HUPs can alter submergence tolerance.

A detailed description of the molecular response of Arabidopsis thaliana to submergence can aid the identification of genes that are critical to flooding survival. • Rosette-stage plants were fully submerged in complete darkness and shoot and root tissue was harvested separately after the O2 partial pressure of the petiole and root had stabilized at c. 6 and 0.1 kPa, respectively. As controls, plants were untreated or exposed to darkness. Following quantitative profiling of cellular mRNAs with the Affymetrix ATH1 platform, changes in the transcriptome in response to submergence, early darkness, and O2-deprivation were evaluated by fuzzy k-means clustering. This identified genes co-regulated at the conditional, developmental or organ-specific level. Mutants for 10 differentially expressed HYPOXIA-RESPONSIVE UNKNOWN PROTEIN (HUP) genes were screened for altered submergence tolerance. • The analysis identified 34 genes that were ubiquitously co-regulated by submergence and O2 deprivation. The biological functions of these include signaling, transcription, and anaerobic energy metabolism. HUPs comprised 40% of the co-regulated transcripts and mutants of seven of these genes were significantly altered in submergence tolerance. • The results define transcriptomic adjustments in response to submergence in the dark and demonstrate that the manipulation of HUPs can alter submergence tolerance.

The exploitation of natural variation in Arabidopsis thaliana (Arabidopsis) provides a huge potential for the identification of the molecular mechanisms underlying this variation as a result of the availability of a vast array of genetic and genomic resources for this species. Eighty-six Arabidopsis accessions were screened for natural variation in flooding tolerance. This forms the first step towards the identification and characterization of the role of candidate genes contributing to flooding tolerance. • Arabidopsis accessions at the 10-leaf stage were subjected to complete submergence in the dark. Survival curves were plotted to estimate median lethal times as a measure of tolerance. Flooding-associated survival parameters, such as root and shoot oxygen content, initial carbohydrate content and petiole elongation under water, were also measured. • There was a significant variation in submergence tolerance among Arabidopsis accessions. However, the order of tolerance did not correlate with root and shoot oxygen content or initial amounts of shoot starch and total soluble sugars. A negative correlation was observed between submergence tolerance and underwater petiole elongation. • Arabidopsis accessions show considerable variation in the ability to tolerate complete submergence, making it a good species in which to identify and characterize genes and to study mechanisms that contribute to survival under water.

Appartient à l’ensemble documentaire : Aquit1, Avec mode texte

Appartient à l’ensemble documentaire : Aquit1, Avec mode texte

We report on the first Tm-doped double tungstate microchip laser Q-switched with graphene using a Tm:KLu(WO4)2 crystal cut along the Ng dielectric axis. This laser generates a maximum average output power of 310 mW with a slope efficiency of 13%. At a repetition rate of 190 kHz the shortest pulses with 285 ns duration and 1.6 μJ energy are achieved

We report on growth and detailed spectroscopic study of Eu3ю-doped tetragonal sodium gadolinium double tungstate, Eu:NaGd(WO4)2, a new promising crystal for deep-red lasers. Large-volume crystal doped with 4.9 at.% Eu is grown by Czochralski method along the [001] crystallographic direction. Absorption of Eu3ю ions is studied at room temperature (RT) and at 6 K. For the absorption band related to the 7F1 / 5D1 transition suitable for pumping of Eu:NaGd(WO4)2, the maximum cross-section is sabs ј 1.2 _ 10_21 cm2 at 535.5 nm with the full width at half maximum (FWHM) of 3.1 nm (at RT, for E jj a polarization). For the 5D0 / 7F4 transition, the maximum stimulated-emission cross-section is sSE ј 1.6 _ 10_21 cm2 at 698.3 nm (RT, E jj c polarization). Lifetime of the 5D0 state is 490 ± 10 ms (at RT). Under UV excitation, Eu:NaGd(WO4)2 provides intense red emission with CIE coordinates (x ј 0.671, y ј 0.329)

A microchip laser is realized on the basis of a monoclinic Tm,Ho-codoped KLu(WO4)2 crystal cut for light propagation along the Ng optical indicatrix axis. This crystal cut provides positive thermal lens with extremely weak astigmatism, S/M = 4%. High sensitivity factors, M = dD/dPabs, of 24.9 and 24.1 m−1/W for the mg- and pg- tangential planes are calculated with respect to the absorbed pump power. Such thermo-optic behavior is responsible for mode stabilization in the plano-plano microchip laser cavity, as well as the demonstrated perfect circular beam profile (M2 < 1.1). Maximum continuous-wave output power of 450 mW is obtained with a slope efficiency of 31%. A set of output couplers is employed to achieve lasing in the spectral range of 2060-2096 nm. The increase of output coupler transmission results in deterioration of the laser performance attributed to the increased up-conversion losses

We describe a compact Yb: YAG laser Q-switched by a graphene-based saturable absorber and pumped by a laser diode at 932 or 969 nm. The compact laser generates a maximum average output power value of 185 mW at 1032 nm with a slope efficiency value of 12%. The shortest duration of the Q-switched pulse achieved is 228 ns at a repetition frequency of 285 kHz. The maximum pulse energy amounts to 0.65 µJ