Low Yield Limit Research Articles

Small Auxin Up RNAs influence the distribution of indole-3-acetic acid and play a potential role in increasing seed size in Euryale ferox Salisb

BackgroundAquatic Euryale ferox Salisb. is an economically important crop in China and India. Unfortunately, low yield limitations seriously hinder market growth. Unveiling the control of seed size is of remarkable importance in improvement of crops. Here, we generated a new hybrid line (HL) with larger seeds by crossing South Gordon Euryale and North Gordon Euryale (WT) which hasn’t been reported before. However, the functional genes and molecular mechanisms controlling the seed size in Euryale ferox Salisb. remain unclear. In this study, we focused on the differentially expressed genes in the auxin signal transduction pathway during fruit development between HL and WT to explore candidate regulatory genes participated in regulating seed size.ResultsBoth concentration and localization of indole-3-acetic acid (IAA) at two growth stages of fruits of WT and HL were detected by LC-MS and immunofluorescence. Although IAA content between the two lines did not differ, IAA distribution was significantly different. To elucidate the mechanism and to seek the key genes underlying this difference, RNA-seq was performed on young fruits at the two selected growth stages, and differentially expressed genes related to the auxin transduction pathway were selected for further analysis.ConclusionHybrid Euryale ferox Salisb. expressed significant heterosis, resulting in non-prickly, thin-coated, large seeds, which accounted for the significantly larger yield of HL than that of WT. Our study indicated that Small Auxin Up RNAs (SAURs) -mediated localization of IAA regulates seed size in Euryale ferox Salisb. We found that some SAURs may act as a positive mediator of the auxin transduction pathway, thereby contributing to the observed heterosis.

Anomalous Exciton Quenching in Organic Semiconductors in the Low-Yield Limit.

The dynamics of exciton quenching are critical to the operational performance of organic optoelectronic devices, but their measurement and elucidation remain ongoing challenges. Here, we present a method for quantifying small photoluminescence quenching efficiencies of organic semiconductors under steady-state conditions. Exciton quenching efficiencies of three different organic semiconductors, PC70BM, P3HT, and PCDTBT, are measured at different bulk quencher densities under continuous low-irradiance illumination. By implementing a steady-state bulk-quenching model, we determine exciton diffusion lengths for the studied materials. At low quencher densities we find that a secondary quenching mechanism is in effect, which is responsible for approximately 20% of the total quenched excitons. This quenching mechanism is observed in all three studied materials and exhibits quenching volumes on the order of several thousand cubic nanometers. The exact origin of this quenching process is not clear, but it may be indicative of delocalized excitons being quenched prior to thermalization.

Mechanical behaviour and functional properties of porous Ti-45 at. % Ni alloy produced by self-propagating high-temperature synthesis

The mechanical behaviour and shape memory effects were studied in the porous Ti-45.0 at. % Ni alloy produced by self-propagating high-temperature synthesis. It is shown that the porous Ti-45.0 at % Ni alloy is deformed by the same mechanisms as a cast Ti50Ni50 alloy. At low temperatures, the deformation of the porous alloy is realised via martensite reorientation at a low yield limit and by dislocation slip at a high yield limit. At high temperatures (in the austenite B2 phase) the porous Ti-45.0 at % Ni alloy is deformed by the stress-induced martensite at a low yield limit and by dislocation slip at a high yield limit. The pseudoelasticity effect is not found in this alloy, while the transformation plasticity and the shape memory effects are observed on cooling and heating under a constant load. The values of the transformation plasticity, and the shape memory effects, depend linearly on the stress acting on cooling and heating. The temperatures of the martensitic transformation increase linearly when the stress rises up to 80 MPa. The porous Ti-45.0 at % Ni alloy accumulates an irreversible strain on cooling and heating and demonstrates unstable functional behaviour during thermal cycling.

Stable inheritance of excellent agricultural traits induced by <sup>12</sup>C<sup>6+</sup> heavy-ions in lentil (Lens culinaris Medik.)

The lentil (Lens culinaris Medik.) belongs to the most important leguminous plants in Asia. It is a very popular and highly nutritious food. However, small pod size and low yield limit its agricultural use. Through irradiation mutagenesis of dry lentil seeds by 12C6+ ion beam, we found some lines with excellent agricultural traits in M2 progeny at doses of 90 Gy (grey), such as height increase and improvement of the number of branches and three-seed pods as well as seeds with increased grain yield. Six generations of irradiated lentils were screened for these traits. In the M8 generation, the grain yield of three high-yielding lentil lines (lines hyl-1, hyl-2, and hyl-3) reached 212.4%, 195.3% and 190.8%, respectively, of the non-irradiated controls. The results indicated that crop improvement was stable inherited across the generations. Statistical analysis revealed that the increase in grain yield was due to increased total pod number and seeds per pod. Fortunately, adverse effects of irradiation (e.g. reduced germination rates and poor pollen vitality) disappeared over the eight generations. In conclusion, we present a practical method for the improvement of lentils through radiation breeding, leading to high yielding cultivars, which could support the use of this crop in agriculture.

The velocity of ultrasound in low-carbon steel deformed at the low yield limit

The variation of a thin structure upon deformation of low-carbon steel at the yield limit is analyzed. The character of the interrelationship between the stage nature of a plastic flow of low-carbon steel and the velocity of ultrasound in it is established. It is shown that the velocity of ultrasound is a parameter for obtaining additional data on the development of plastic flow. The structural changes that exert an effect on the velocity of ultrasound in the deformation that corresponds to the yield site are studied.

A method to probe the cytoplasmic osmolality and osmotic water and solute fluxes across the cell membrane of cyanobacteria with chlorophyll a fluorescence: Experiments with Synechococcus sp. PCC7942

We present a method with which osmotic properties of the cytoplasm of cyanobacterial cells and the osmotic permeability of plasma membranes to water and solutes can be assessed from measurements of chlorophyll a fluorescence. When the electron transport of photosystem II is inhibited, the quantum yield of chlorophyll a fluorescence in cyanobacterial cells varied between a low yield limit that was attained after acclimation to darkness (state 2) and a high yield limit that was attained after acclimation to light (state 1). It was shown recently that the difference between chlorophyll a fluorescence of light‐acclimated and of dark‐acclimated cells relates quantitatively to the internal osmolality of cyanobacteria (G. C. Papageorgiou and A. Alygizaki‐Zorba. 1997. Biochim. Biophys. Acta 1335: 1‐4). In the present work we employed rapid mixing of Synechococcus sp. PCC7942 (strain PAMCOD) suspensions with solutions of defined osmolality in order to measure cell osmolality and turgor threshold, as well as water and solute fluxes across cell membranes. Concentration upshocks with sorbitol, glycine betaine, Na+ and K+ salts caused rapid (t1/2 < 10 ms) depression of fluorescence that was correlated to osmotic water outflow from the cells. The fluorescence remained depressed in all cases except for NaCl. With NaCl, the depression was transient and fluorescence recovered with an apparent time constant of 200 ms. The fluorescence rise correlates to inflows of NaCl and water.

Physical modelling of lithosphere subduction in collision zones

Physical (mechanical) modeling of continental collision is performed with a 4-layered mantle model. Compositionally distinct layers of hydrocarbons are used to model a lithosphere which consists of two crustal layers (the upper one quasi-brittle, the lower one plastic) and a plastic mantle layer. The lower crustal layer, the “crustal asthenosphere”, has a low yield limit. A low-viscosity liquid (water) represents the asthenosphere under the lithosphere. Lateral compression of the model plate by a piston is the driving mechanism of collision. Similarity criteria are satisfied in the modeling. The collisional process was investigated with various boundary conditions and values of the model parameters. The yield limit and the thickness of the “crustal asthenosphere” were varied, as well as the action of the piston on the plate: the force was applied either throughout the plate section, or on its mantle layer only (in the latter case, this layer slipped relative to the upper crust). Hence different results were obtained. A more realistic pattern seems to occur when the yield limit of the crustal asthenosphere is not too small and free sliding of the crustal layers over the mantle lithosphere is not possible. The upper crustal layer then experiences failure in the collision zone and thrusting develops there. Intensive thickening of the lower crust was observed, the mantle layer being subducted like oceanic lithosphere in a subduction zone.