Genetic diversity of wild barley (Hordeum vulgare ssp. spontaneum) and its utilization for barley improvement

Wild barley （Hordeum vulgare spp. spontaneum） is the undisputed progenitor of cultivated barley and offers considerable poten- tial as a genetic resource for barley improvement. Naturally occurring populations are distributed primarily across the Fertile Crescent, but secondary areas of diversity are also found in central Asia and Tibet. The pattern of its genetic diversity is non-random, and is structured on a global, regional and local scale. On a global scale, diversity follows ecogeography, while on a regional and local scale, it is more strongly determined by ecology. Populations growing in areas where the climate is unreliable and/or the soil is heterogeneous tend to retain the most diversity. A large number of accessions are currently conserved ex situ, but a high proportion of these have originated fi：om the Fertile Crescent. Given the likelihood of future climate change, conserving germplasm both in situ and ex situ in the various regions where the species＇ currently existing is a research priority. The value of H. vulgare spp. spontaneum for the improvement of cultivated barley lies largely in its potential contribution to the levels of attaina- ble pathogen resistance and abiotic stress tolerance.

Complexity analysis of the Portevin-Le Chatelier in an Al alloy atdifferent tem peratures

The complexity of the Portevin-Le Chatelier(PLC)effect in an Al alloy at different temperatures was ana-lyzed by modified multiscale entropy.The results show that three evolutions of entropy with scale factor,i.e.,near zero,monotonically increasing and peak-shape,were observed corresponding to the smoothcurves,type-A serrations and type-B/-C serrations,respectively.The scale factor at the peak was one-third of the average serration period.The sample entropy increased initially and then decreased withtemperature,which was opposite to the critical strain.It is also suggested that the type-A serrations cor-responded to self-organized criticality and the type-B/-C serrations corresponded to chaos through theevolutions of entropy with scale factor.

Protein and lipid characterization of wheat roots plasma membrane damaged by Fe and H₂O₂using ATR-FTIR method

In plant cells the plasma membrane is a highly elaborated structure that functions as the point of exchange with adjoining cells, cell walls and the external environment. In this study, we investigated the structure and function characteristic of wheat root plasma membrane (PM) as affected by H2O2 and Fe by using fluorescence spectroscopic and attenuated total reflectance infrared (ATR-IR) techniques. The results showed that these oxidant damaged induced an obviously reduced membrane fluidity were observed in the roots PM treated with the 200 μM H2O2, FeSO4, and FeCl3. Computer-aided software analyses of the FTIR spectrum indicated that the content of the α-helices decreased and β-sheet increased in the secondary structures of proteins after exposure to the oxidants of 200 μM H2O2, FeSO4, and FeCl3. The number of P=O and C=C bonds area declined rapidly in the lipids of the membrane under the oxidants stress. These structural alterations might explain the reason of the roots PM instability under most of the abiotic stress.

Fast genetic mapping in barley:case studies of cuticle mutants using RNA-sequencing

Barley(Hordeum vulgare L.)is one of the earliest domesticated crop species and ranked as the fourth largest cereal production worldwide.Forward genetic studies in barley have greatly advanced plant genetics during the last century;however,most genes are identified by the conventional mapping method.Array genotyping and exome-capture sequencing have also been successfully used to target the causal mutation in barley populations,but these techniques are not widely adopted because of associated costs and partly due to the huge genome size of barley.This review summarizes three mapping cases of barley cuticle mutants in our laboratory with the help of RNA-sequencing.The causal mutations have been successfully identified for two of them and the target genes are located in the pericentromeric regions.Detailed information on the mapping-by-sequencing,mapping-and-sequencing,and RNA-sequencing assisted linkage mapping are presented and some limitations and challenges on the mapping assisted by RNA sequencing are also discussed.The alternative and elegant methods presented in this review may greatly accelerate forward genetics of barley mapping,especially for laboratories without large funding.

Sand rice,a promising future crop for desert and marginal lands in northern China

The pioneer Amaranthaceae species sand rice(Agriophyllum squarrosum)is an annual psammophyte that is widely distributed in the deserts and sand fields of northern China.The well-balanced nutritional values,long consumption history,and extreme stress tolerance of sand rice have fascinated scientists,prompting its development as a climate-resilient crop.Sand rice has been successfully introduced and cultivated on sandy and loess lands over the past decade,while large-scale artificial planting has been carried out in the Ulan Buh and Tengger deserts.However,the yield is far below the maximum potential,as estimated by the highest yield per plant ever found in the Tengger desert during our survey of wild populations.The current domestication of sand rice relies mainly on natural selection and mutagenesis breeding.A few elite lines with modified agronomic traits,such as compact architecture,high productivity,reduced trichomes,and short plant stature,have been developed from natural populations and a chemical mutagenesis library.Breeding new cultivars and broader cultivation of sand rice in deserts and marginal lands will stimulate economic growth and diversify the food supply,especially for the area west of the Hu Huanyong Line,thus contributing to environmental sustainability in northern China.

Leaf-surface wax of desert plants as a potential lubricant additive

Using an MFT-R4000 tester at room temperature,the leaf-surface wax of two desert plants,Ammopiptanthus mongolicus(AM)and Reaumuria soongorica(RS),was extracted and evaluated for its potential as a lubricant additive in polyalphaolefin(PAO)for steel-steel contact.Gas chromatography-mass spectrometry analysis was performed to identify the composition of the AM leaf-surface wax,and scanning electron microscopy and X-ray photoelectron spectroscopy were used to investigate its friction mechanisms.The results suggest that the leaf-surface wax could successfully reduce the friction and wear of steel-steel sliding pairs compared with PAO containing molybdenum dithiocarbamate additives.AM,in particular,showed high-performance wear resistance and friction-reducing properties.Its excellent tribological properties were attributed to the wax composition of leaf-surface fatty acids,alcohol,and esters.

New Fractal Evidence of Pacific Plate Subduction in the Late Mesozoic, Great Xing’an Range, Northeast China

Late Mesozoic granitoids are widespread in the Great Xing’an Range(GXR), which is part of a large igneous province in eastern China. The geodynamic setting of the Late Mesozoic granitoids is still debated, and there have been two dominant models proposed, subduction and thermal erosion. This study discusses the geodynamic mechanisms from a new perspective on ages of the granitoids and fractal dimensions of their shape. Our results show that granitoids become gradually older from South GXR to North GXR to Erguna Block(EB) in the Jurassic, and opposite in the Cretaceous. The fractal dimensions of the Perimeter-area model(DAP) exhibit the same features. The values of DAP are smaller from South GXR(0.673 1) to North GXR(0.628 0) to EB(0.607 9) in the Jurassic, and larger from South GXR(0.609 6) to North GXR(0.630 2) to EB(0.639 9) in the Cretaceous. This implies that the geometrical irregularities of the granitoids are shaped by subduction rather than thermal erosion. These spatial variations could be best explained by the subduction of the Pacific Plate and consequent granitoid magmatism in the Late Mesozoic, thus providing a new fractal evidence for Pacific Plate subduction mechanism and opening a new possibility method for studing plate movement.

New method for estimating strike and dip based on structural expansion orientation for 3D geological modeling

Strike and dip are essential to the description of geological features and therefore play important roles in 3D geological modeling.Unevenly and sparsely measured orientations from geological field mapping pose problems for the geological modeling,especially for covered and deep areas.This study developed a new method for estimating strike and dip based on structural expansion orientation,which can be automatically extracted from both geological and geophysical maps or profiles.Specifically,strike and dip can be estimated by minimizing an objective function composed of the included angle between the strike and dip and the leave-one-out cross-validation strike and dip.We used angle parameterization to reduce dimensionality and proposed a quasi-gradient descent(QGD)method to rapidly obtain a near-optimal solution,improving the time-efficiency and accuracy of objective function optimization with the particle swarm method.A synthetic basin fold model was subsequently used to test the proposed method,and the results showed that the strike and dip estimates were close to the true values.Finally,the proposed method was applied to a real fold structure largely covered by Cainozoic sediments in Australia.The strikes and dips estimated by the proposed method conformed to the actual geological structures more than those of the vector interpolation method did.As expected,the results of 3D geological implicit interface modeling and the strike and dip vector field were much improved by the addition of estimated strikes and dips.