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• Mixture Gaussian Network equipped with memory modules for long-horizon prediction. • Learning from successful experience to guide the early exploration. • Clipped value expansion in the model to learn a stable critic with low overestimation bias. • Back-propagating multi-step gradients along imaginary trajectories to optimize the policy end-to-end. • Model-based deterministic policy gradient improves the sample efficiency. Model-based reinforcement learning (MBRL) approaches have demonstrated great potential in handling complex tasks with high sample efficiency. However, MBRL struggles with asymptotic performance compared to model-free reinforcement learning (MFRL). In this paper, we present a long-horizon policy optimization method, namely model-based deterministic policy gradient (MBDPG), for efficient exploitation of the learned dynamics model through multi-step gradient information. First, we approximate the dynamics of the environment with a parameterized linear combination of an ensemble of Gaussian distributions. Moreover, the dynamics model is equipped with a memory module and trained on a multi-step prediction task to reduce cumulative error. Second, successful experience is used to guide the policy at the early stage of training to avoid ineffective exploration. Third, a clipped double value network is expanded in the learned dynamics to reduce overestimation bias. Finally, we present a deterministic policy gradient approach in the model that backpropagates multi-step gradient along the imagined trajectories. Our method shows higher sampling efficiency than the state-of-the-art MFRL methods while maintaining better convergence performance and time efficiency compared to the SOAT MBRL. [ABSTRACT FROM AUTHOR]

Highlights: [•] A novel generalized semi-analytical explicit capillary force model is established. [•] Fourier series expansion is introduced to fit for the plates with arbitrary shape. [•] Incredible ability to predict the standoff height when considering chip gravity. [•] Complex phase diagram is obtained to characterize varieties of system instability. [Copyright &y& Elsevier]

Developing cultivars with improved Pi use efficiency is essential for the sustainability of agriculture as well as the environment. Phosphate starvation response (PHR) regulators have not yet been systematically studied in wheat. This study provides the detailed characteristics of PHRs in hexaploid wheat as well as other major gramineous plants at the genome-wide level. The identified PHR proteins were divided into six subfamilies through phylogeny analysis, and a total of 63 paralogous TaPHR pairs were designated as arising from duplication events, with strong purifying selection. The promoters of TaPHRs were identified as stations for many transcription factors. Protein–protein interaction network and gene ontology enrichment analysis indicated a core biological process of cellular response to phosphate starvation. The three-dimensional structures of core PHR proteins showed a high phylogenetic relationship, but amino acid deletions in core protein domains may cause functional differentiation between rice and wheat. TaPHR3 could interact with TaSPX1 and TaSPX5 proteins, which is regarded as a novel interaction mode. Under different Pi gradient treatments, TaPHR s showed low inducible expression patterns among all subfamilies. Our study is the first to comprehensively clarify the basic properties of TaPHR proteins and might accumulate basic data for improving grain yield and environmental homeostasis. [ABSTRACT FROM AUTHOR]

Temperature-sensitive genic male sterile (TGMS) line Beijing Sterility 366 (BS366) has been utilized in hybrid breeding for a long time, but the molecular mechanism underlying male sterility remains unclear. Expression arrays, small RNA, and degradome sequencing were used in this study to explore the potential role of miRNA in the cold-induced male sterility of BS366. Microspore observation showed defective cell plates in dyads and tetrads and shrunken microspores at the vacuolated stage. Differential regulation of Golgi vesicle transport, phragmoplast formation, sporopollenin biosynthesis, pollen exine formation, and lipid metabolism were observed between cold and control conditions. Pollen development was significantly represented in the 352 antagonistic miRNA-target pairs in the integrated analysis of miRNA and mRNA profiles. The specific cleavage of ARF17 and TIR1 by miR160 and miR393 were found in the cold-treated BS366 degradome, respectively. Thus, the cold-mediated miRNAs impaired cell plate formation through repression of Golgi vesicle transport and phragmoplast formation. The repressed expression of ARF17 and TIR1 impaired pollen exine formation. The results of this study will contribute to our understanding of the roles of miRNAs in male sterility in wheat. [ABSTRACT FROM AUTHOR]

Background: Histone methylation usually plays important roles in plant development through post-translational regulation and may provide a new visual field for heterosis. The histone methyltransferase gene family has been identified in various plants, but its members and functions in hybrid wheat related in heterosis is poorly studied. Results: In this study, 175 histone methyltransferase (HMT) genes were identified in wheat, including 152 histone lysine methyltransferase (HKMT) genes and 23 protein arginine methyltransferase (PRMT) genes. Gene structure analysis, physicochemical properties and subcellular localization predictions of the proteins, exhibited the adequate complexity of this gene family. As an allohexaploid species, the number of the genes (seven HKMTs orthologous groups and four PRMTs orthologous groups) in wheat were about three times than those in diploids and showed certain degrees of conservation, while only a small number of subfamilies such as ASH-like and Su-(var) subfamilies have expanded their members. Transcriptome analysis showed that HMT genes were mainly expressed in the reproductive organs. Expression analysis showed that some TaHMT genes with different trends in various hybrid combinations may be regulated by lncRNAs with similar expression trends. Pearson correlation analysis of the expression of TaHMT genes and two yield traits indicated that four DEGs may participate in the yield heterosis of two-line hybrid wheat. ChIP-qPCR results showed that the histone modifications (H3K4me3, H3K36me3 and H3K9ac) enriched in promoter regions of three TaCCA1 genes which are homologous to Arabidopsis heterosis-related CCA1/LHY genes. The higher expression levels of TaCCA1 in F1 than its parents are positive with these histone modifications. These results showed that histone modifications may play important roles in wheat heterosis. Conclusions: Our study identified characteristics of the histone methyltransferase gene family and enhances the understanding of the evolution and function of these members in allohexaploid wheat. The causes of heterosis of two-line hybrid wheat were partially explained from the perspective of histone modifications. [ABSTRACT FROM AUTHOR]

Abstract: MicroRNAs (miRNAs) represent a class of endogenous regulator for post-transcriptionally modulating gene expression. Elucidating complete miRNA repertoires for individual species is a long-desired goal in miRNA research. So far only 42 have been annotated for common wheat (Triticum aestivum) due to its large genome. Here, we employed miRDeep-P, a program developed previously for retrieving miRNAs from deep sequencing data in plants, to parse 14 sequenced small RNA libraries of wheat using expression sequence tags (ESTs) as the reference in lieu of a complete genome sequence. This effort identified 145 miRNAs along with the corresponding stem-looped precursors with many differentially expressed in development and associated with powdery mildew infection. Examination of the phylogenetic distribution of these miRNAs and their target genes revealed that many are conserved in monocots. The set of miRNAs identified in this study is thus useful to further miRNA research in wheat and other important cereal crop species. [Copyright &y& Elsevier]

• The wheat CHS family members were identified. • Several TaCHSs showed anther-specific expression patterns. • TaCHSs co-expressed with potential anther sporopollenin biosynthetic genes. • TaLAP5 (TaCHS3 , TaCHS10) and TaLAP6 (TaCHS64, TaCHS67) may be involved in the cold-induced male sterility in BS366. Chalcone synthase (CHS), also known as the plants-specific type III polyketide synthases (PKSs), catalyzes the first key step in the biosynthesis of plant flavonoids. Flavonoids are one of the most important secondary metabolites which participate in flower pigmentation and pollen fertility. Recent reports have demonstrated the role of the CHS family in plant pollen exine formation. This study focused on the potential roles of CHS in the pollen exine formation of wheat. In the present study, a genome-wide investigation of the CHS family was carried out, and 87 CHS genes were identified in wheat. TaCHS3 , TaCHS10 , and TaCHS13 are wheat orthologs of Arabidopsis LESS ADHESIVE POLLEN (LAP5); TaCHS58 , TaCHS64 , and TaCHS67 are wheat orthologs of AtLAP6. TaCHS3 , TaCHS10 , and TaCHS67 showed anther-specific patterns. The expression of TaCHS3 , TaCHS10, and TaCHS67 was positively co-expressed with sporopollenin biosynthetic genes, including TaCYP703A2 , TaCYP704B1 , TaDRL1 , TaTKPR2 , and TaMS2. Coincidently, the expression of TaCHS3 , TaCHS10, and TaCHS67 , together with those sporopollenin biosynthetic genes, were repressed at the tetrads and uninucleate stages in the temperature-sensitive genic male-sterile (TGMS) line BS366 under sterile conditions. Wheat anther-specific CHS genes might participate in the exine formation of BS366 through co-expressing with sporopollenin biosynthetic genes, which will undoubtedly provide knowledge of the roles of CHS in wheat pollen development. [ABSTRACT FROM AUTHOR]

Background: Anthocyanins contribute to coloration and antioxidation effects in different plant tissues. MYB transcription factors have been demonstrated to be a key regulator for anthocyanin synthesis in many plants. However, little information was available about the MYB genes in the halophyte species Eutrema salsugineum. Result: Here we report the identification of an important anthocyanin biosynthesis regulator EsMYB90 from Eutrema salsugineum, which is a halophyte tolerant to multiple abiotic stresses. Our phylogenetic and localization analyses supported that EsMYB90 is an R2R3 type of MYB transcription factor. Ectopic expression of EsMYB90 in tobacco and Arabidopsis enhanced pigmentation and anthocyanin accumulation in various organs. The transcriptome analysis revealed that 42 genes upregulated by EsMYB90 in 35S:EsMYB90 tobacco transgenic plants are required for anthocyanin biosynthesis. Moreover, our qRT-PCR results showed that EsMYB90 promoted expression of early (PAL, CHS, and CHI) and late (DFR, ANS, and UFGT) anthocyanin biosynthesis genes in stems, leaves, and flowers of 35S:EsMYB90 tobacco transgenic plants. Conclusions: Our results indicated that EsMYB90 is a MYB transcription factor, which regulates anthocyanin biosynthesis genes to control anthocyanin biosynthesis. Our work provides a new tool to enhance anthocyanin production in various plants. [ABSTRACT FROM AUTHOR]

Abstract The high-performance Mg-8.8Gd-3.4Y-1Zn-0.8Mn (wt%) alloy sheets were prepared by large-strain high-efficiency rolling process. The large strains with ~ 87% and ~ 91% total reduction were introduced in the hard-to-deform Mg alloy by hard-plate rolling process at 400 °C for merely 3 and 2 rolling passes. The microstructural morphology and texture were examined, and the tensile tests were performed along rolling direction (RD) and transverse direction (TD). The large-strain rolling process brings in refined grains, homogeneous dispersive LPSO phase and β phase and weakened basal texture. The anisotropy of the strength and elongation is improved after rolling. The as-rolled sample with ~ 91% total reduction exhibits excellent mechanical properties with ultimate tensile strength (UTS) of 434 MPa, tensile yield strength (TYS) of 318 MPa and elongation to failure (EL) of 10.7% parallel to the TD. By quantitating the relation between grain orientations and the deformation modes, it is confirmed that the basal slip and prismatic slip are the dominant deformation modes at the initial stage of plastic deformation, meanwhile the pyramidal slip and extension twinning are the complementary deformation modes. Highlights • The hard-to-deform Mg alloy has been rolled with a large reduction per pass (~ 70%) and a large total reduction (~ 91%). • The as-rolled Mg alloy exhibits an improved anisotropy with high strength and appreciable ductility. • The quantitative relation between grain orientations and the deformation modes has been uncovered. [ABSTRACT FROM AUTHOR]

High-performance as-extruded and peak-aged Mg-9.2Gd-3.3Y-1.2Zn-0.9Mn (wt%) alloys have been fabricated by semi-continuous casting, heat-treating, extruding and ageing processes. The effects of different heat treatments on the microstructure and mechanical properties have been investigated. Lamellar and bulk-shaped 14H-type long-period stacking ordered (LPSO) phase and few RE-rich (RE: rare earth element) particles form by different heat treatments. After hot extrusion, the heat-treated alloy with bulk-shaped LPSO phase exhibits an equal-axial microstructure, while the heat-treated alloy with lamellar LPSO phase across the grains shows bimodal grain microstructure consisting of fine equal-axial grains and coarse deformed grains. The more profuse lamellar LPSO phase in heat-treated alloy generates higher volume fraction of deformed grains and finer equal-axial grains, hence leads to higher strength but lower ductility. After ageing, the alloy with profuse LPSO and β′ phases achieves the superior mechanical properties with ultimate tensile strength (UTS) of 525 MPa, tensile yield strength (TYS) of 420 MPa and elongation to failure (EL) of 6.3%. The alloy strengthening is mainly attributed to the bimodal grain microstructure, LPSO phase, Mg 5 Gd (β) phase and β′ phase. [ABSTRACT FROM AUTHOR]

The effect of Al content on the microstructure, damping behavior and mechanical properties of Mg-xAl-0.5Ce (wt%) damping alloys was systematically studied. Al content had a great effect on the morphology features of Al 4 Ce phases. The quasi-rectangular network structure was observed in as-cast Mg-1Al-0.5Ce alloy. The Al addition promoted the dynamic recrystallization during extrusion process and led to the texture weakening, but the basal texture was sharpened with further Al addition due to the consumption of the Ce solute. The as-extruded Mg-1Al-0.5Ce alloy showed the best damping capacity among as-extruded Mg-xAl-0.5Ce alloys, which was mainly ascribed to the texture weakening. The ductility was improved with increasing Al content, while the strength was reduced. This behavior was related with the texture weakening and increasing grain sizes. The as-extruded Mg-1Al-0.5Ce alloy exhibited the excellent comprehensive performance. The peak P 2 of as-extruded alloys in the first heating run was a superimposed peak, consisting of a grain boundary relaxation peak and a recrystallization peak. The grain boundary peaks P 2 in the second heating run shifted to lower temperatures and their activation energies decreased with increasing Al content. The reasons for the variation of the grain boundary peak P 2 were discussed. [ABSTRACT FROM AUTHOR]

The ageing behavior of as-extruded Mg-1.5Gd-1.3Y-0.6Zn-0.6Mn (at%) alloy was investigated. The strength and ductility are simultaneously improved during ageing at the peak hardness platform. The alloy aged for 100 h exhibits ultrahigh ultimate tensile strength (UTS) of 538 MPa and good elongation to failure (EL) of 13.1%. [ABSTRACT FROM AUTHOR]

The 12-oxo-phytodienoic acid reductases (OPRs) are involved in the various processes of growth and development in plants, and classified into the OPRⅠ and OPRⅡ subgroups. In higher plants, only OPRⅡ subgroup genes take part in the biosynthesis of endogenous jasmonic acid. In this study, we isolated a novel OPRⅡ subgroup gene named TaOPR2 (GeneBank accession: KM216389) from the thermo-sensitive genic male sterile (TGMS) wheat cultivar BS366. TaOPR2 was predicted to encode a protein with 390 amino acids. The encoded protein contained the typical oxidored_FMN domain, the C-terminus peroxisomal-targeting signal peptide, and conserved FMN-binding sites. TaOPR2 was mapped to wheat chromosome 7B and located on peroxisome. Protein evolution analysis revealed that TaOPR2 belongs to the OPRⅡ subgroup and shares a high degree of identity with other higher plant OPR proteins. The quantitative real-time PCR results indicated that the expression of TaOPR2 is inhibited by abscisic acid (ABA), salicylic acid (SA), gibberellic acid (GA 3 ), low temperatures and high salinity. In contrast, the expression of TaOPR2 can be induced by wounding, drought and methyl jasmonate (MeJA). Furthermore, the transcription level of TaOPR2 increased after infection with Puccinia striiformis f. sp . tritici and Puccinia recondite f. sp . tritici . TaOPR2 has NADPH-dependent oxidoreductase activity. In addition, the constitutive expression of TaOPR2 can rescue the male sterility phenotype of Arabidopsis mutant opr3 . These results suggest that TaOPR2 is involved in the biosynthesis of jasmonic acid (JA) in wheat. [ABSTRACT FROM AUTHOR]

• CMAC is analyzed on the carbon content distribution and the fracture mechanics. • A calculation rule between the shift of DBTT and the carbon content is given. • Outer surface with the highest CMAC of SG channel head is studied and discussed. Fast fracture evaluation strategy is receiving earnest concern in the structural integrity analysis of nuclear equipment which subjected to the effects of neutron irradiation during operation. The increment of ductile and brittle transition temperature is mainly due to the neutron irradiation which increases the risk of brittle fracture failure. In addition to the neutron irradiation, the high carbon macro-segregation of low-alloy steels also increases the risk of brittle fracture failure as the carbon positive macro-segregation will lead to the increasing ductile and brittle transition temperature of low-alloy steels. In the present study, a conservative relationship between the carbon content and the increment of ductile and brittle transition temperature is developed based on data and is used to the brittle fracture failure analysis of the highest carbon content region in SG channel head. A special defect size is assumed considering capability of non-destructive evaluation technology in the brittle fracture failure analysis. Results show that ratio between the calculated stress intensity factor according to safety coefficient suggested by ASME design code and the critical stress intensity factor is less than one, which indicates a safe design and no risk of brittle fracture failure for steam generator channel head considering high carbon macro-segregation. [ABSTRACT FROM AUTHOR]

Developing magnesium (Mg) alloys with both high elastic modulus and damping capacity is a long-term challenge in the field of lightweight metals. Herein, it is shown that alloying with Si in Mg-Gd-Y-Zn-Mn simultaneously increased the elastic modulus and damping capacity. After Si alloying, the LPSO phase was greatly reduced and a large number of (RE + Si)-rich particles were formed. Due to the contribution of the high modulus second phases, the elastic modulus of the extruded Mg-Gd-Y-Zn-Mn alloy with a trace amount of Si was 49.3 GPa, 8 GPa greater than that of the extruded pure Mg. In addition, the extruded Mg-Gd-Y-Zn-Mn-Si alloy possessed good damping capacity at both room temperature (RT) and high temperature. At high strain amplitude, the extruded Mg-Gd-Y-Zn-Mn-Si alloy achieved a RT damping value of Q −1 > 0.01, significantly higher than the extruded pure Mg, which was related to the high density of thermal mismatch dislocations in the vicinity of the interfaces between the reinforcing phase and the α-Mg matrix. With the increasing temperature, the extruded Mg-Gd-Y-Zn-Mn-Si alloy showed obviously higher damping capacity than the extruded Si-free alloy, which was attributed to the incoherent phase interfaces, weakened texture and thermal mismatch dislocations. • Elastic modulus and damping capacity of a Mg alloy were improved simultaneously. • High Young's modulus (RE + Si)-rich particles were produced due to Si addition. • Good damping capacity at both room temperature and high temperature were obtained. [ABSTRACT FROM AUTHOR]