This study aimed to improve the measurement accuracy of the discrete element method (DEM) simulation parameters of sorghum seeds for enhanced model accuracy. We measured the intrinsic and contact parameters of sorghum seeds, extracted the outline of the seeds by 3D scanning, and used the multi-spherical particle model filling method in the EDEM (Version 2020) software to obtain the simulation model of the seeds. By simulating the free-fall, slope slip, slope rolling, and rolling experiments of sorghum seeds–photosensitive resin material, we calibrated the collision restitution coefficient of the sorghum seeds–photosensitive resin material to 0.690, static friction coefficient to 0.345, and rolling friction coefficient to 0.040. Through the steepest ascent search and central composite design experiments, we calibrated the collision restitution coefficient of sorghum seeds–sorghum seeds to 0.400, the static friction coefficient to 0.450, and the rolling friction coefficient to 0.043. The angle of repose of the parameter combination and the angle of repose of the physical experiment (33.82°) were verified, and the relative errors of the coefficients were 0.7%, 0.25%, and 0.3%, respectively, indicating that the established model had a high simulation accuracy and reliability. These results show that the established sorghum seeds model and the optimally calibrated parameter combination are effective for DEM studies on sorghum seeds.

Discrete element simulation is an effective method to reveal the interaction between tillage components and work objects. However, due to the lack of discrete element modelling parameters of maize root and its mixture with soil, existing tillage models cannot accurately simulate the farmland environment under a no-tillage system. This study developed single maize root (SMR) with different diameters and maize root-soil mixture (MRSM) DEM models based on calibrated parameters through the angle of repose (AOR) tests. First, the Plackett–Burman and the steepest climb tests were performed to identify the range of essential parameters for the AOR of the SMR. Then, the optimal parameters for the SMR and MRSR models were obtained by Box–Behnken design (BBD) testing. The results showed that the static friction coefficient of SMR-SMR and the rolling friction coefficient of SMR-SMR and SMR-steel significantly affected the AOR. In addition, the AOR of MRSM was extremely sensitive to the restitution coefficient and surface energy coefficient of root soil. Based on optimal parameters, the relative errors between the simulated and measured AOR and pixel peak values of the piles’ contour curve were less than 5% for SMR and MRSM. The error of the dynamic AOR of the measured and simulated MSRM was less than 10%. These results indicate that the parameter calibration method and the developed models can be valuable references for DEM simulation for maize stubble and tillage.

Using discrete element simulation to reveal the interaction between seed and seed metering devices (SMD) is an important method for developing SMDs. However, due to the lack of discrete element modeling (DEM) parameters of adzuki bean seeds (ABS) in existing literature, it is difficult to develop a suitable SMD. In this study, the DEM parameters of ABS were determined by a combination of physical tests and virtual calibration. Initially, the intrinsic parameters, contact parameters, and angle of repose (AOR) of ABS were measured. The parameters significantly affected AOR were then screened out by Plackett–Burman test. Furthermore, the Steepest Ascent test was used to determine the optimal interval value of significant parameters. Finally, the optimal values of significant parameters were obtained by the Box–Behnken test with an AOR of 23.93° and an error of 0 as targets. The results showed that the coefficient of static friction of ABS–ABS, coefficient of static friction of ABS-photosensitive resin plate, and coefficient of rolling friction of ABS–ABS significantly affected the AOR, and their optimal values were 0.302, 0.282, and 0.043, respectively. The verification test showed that the relative error between simulated and measured values of AOR was 0.67%. This indicated that the determined DEM parameters were accurate and reliable. The results from the study can provide a reference for the selection of DEM parameters in the mechanized seeding process of ABS.

Puccinia striiformis f. sp. tritici (Pst) is an important obligate pathogen in wheat (Triticum aestivum L.) and secretes effectors into plant cells to promote infection. Identifying host targets of effector proteins and clarifying their roles in pathogen infection is essential for understanding pathogen virulence. In this study, we identified a serine-rich effector, Pst27791, from Pst that suppresses cell death in Nicotiana benthamiana. Stable overexpression of Pst27791 in wheat suppressed reactive oxygen species accumulation and the salicylic acid-dependent defense response. Transgenic wheat expressing the RNA interference construct of Pst27791 exhibited high resistance to Pst virulent isolate CYR31, indicating its importance in pathogenesis. Pst27791 interacting with wheat rapidly accelerated fibrosarcoma (Raf)-like kinase TaRaf46 in yeast and in planta. Knocking down TaRaf46 expression in wheat attenuated Pst infection and increased wheat immunity. The overexpression of TaRaf46 decreased wheat resistance to Pst and repressed MAPK activation in wheat. Pst27791 may stabilize TaRaf46 through the inhibition of proteasome-mediated degradation in N. benthamiana. The ability of Pst27791 to enhance Pst colonization was compromised when TaRaf46 was silenced, suggesting that the virulence of Pst27791 is mediated by TaRaf46. Overall, these results indicate that Raf-like kinase TaRaf46 is exploited by the Pst effector as a negative regulator of plant immunity to promote infection in wheat.

Background: The degradation of intracellular proteins plays an essential role in plant responses to stressful environments. ClpS1 and E3 ubiquitin ligase function as adaptors for selecting target substrates in caseinolytic peptidase (Clp) proteases pathways and the 26S proteasome system, respectively. Currently, the role of E3 ubiquitin ligase in the plant immune response to pathogens is well defined. However, the role of ClpS1 in the plant immune response to pathogens remains unknown. Results: Here, wheat ( Triticum aestivum ) ClpS1 (TaClpS1) was studied and resulted to encode 161 amino acids, containing a conserved ClpS domain and a chloroplast transit peptide (1-32 aa). TaClpS1 was found to be specifically localized in the chloroplast when expressed transiently in wheat protoplasts. The transcript level of TaClpS1 in wheat was significantly induced during infection by Puccinia striiformis f. sp. tritici ( Pst ). Knockdown of TaClpS1 via virus-induced gene silencing (VIGS) resulted in an increase in wheat resistance against Pst , accompanied by an increase in the hypersensitive response (HR), accumulation of reactive oxygen species (ROS) and expression of TaPR1 and TaPR2 , and a reduction in the number of haustoria, length of infection hypha and infection area of Pst . Furthermore, heterologous expression of TaClpS1 in Nicotiana benthamiana enhanced the infection by Phytophthora parasitica . Conclusions: These results suggest that TaClpS1 negatively regulates the resistance of wheat to Pst .

Drought stress is a major factor that limits the yield and quality in wheat. In this study, we identified an orthologue of the rice gene OsDIS1 (Oryza sativa drought-induced SINA protein 1) in wheat (Triticum aestivum L.) called TaDIS1. TaDIS1 encodes a putative 301 amino acid protein with a C3HC4 RING finger conserved domain at the N-terminal and a SINA domain at the C-terminal. TaDIS1 contains three exons and two introns. qRT-PCR analysis showed that TaDIS1 expression was induced by PEG6000, NaCl, and abscisic acid (ABA) treatment. We generated TaDIS1-overexpressing transgenic Arabidopsis lines. Under drought stress conditions, the transgenic Arabidopsis plants had a lower germination rate, relative water content, and proline contents, with higher water loss, chlorophyll loss, relative electrical conductivity, and malondialdehyde contents compared with the wild type. The antioxidant enzyme (superoxide dismutase, peroxidase, and catalase) activity levels were lower in the transgenic plants. The TaDIS1-overexpressing plants had shorter roots with greater growth inhibition in response to mannitol treatment than the wild type, with increased hypersensitivity to ABA during seed germination and early seedling growth. The expression of stress-related genes in transgenic plants under drought stress suggests that TaDIS1 may function negatively in drought stress by regulating the stress response-related genes.

非生物胁迫对小麦的生长发育具有不良影响,克隆与非生物胁迫相关的基因,并对其结构及表达特性进行分析,可以为进一步探索小麦的抗逆机制和抗逆育种奠定基础.本研究利用同源克隆技术从普通小麦品种中国春中克隆了水稻E3泛素连接酶基因OsHTAS的同源基因TaHTAS-5A(GeneBank登录号:MF967573),并利用生物信息学方法对其基因序列特征进行分析;利用qRT-PCR技术对该基因在小麦不同组织及不同逆境胁迫下的表达模式进行分析;同时,对该基因的表达产物进行了亚细胞定位.结果表明,小麦TaHTAS-5A基因含有220 bp的5'UTR、1242 bp的ORF以及126 bp的3'UTR,共编码413个氨基酸;基因组分析表明,该基因全长3 819 bp,共包含4个外显子和3个内含子;缺体-四体定位表明该基因位于小麦5A染色体上;蛋白结构分析显示,TaHTAS-SA蛋白的N端包含四个跨膜结构域,C端包含一个E3泛素连接酶特有的RING finger保守结构城,具有植物E3泛素连接酶的结构特征;qRT-PCR结果显示,TaHTAS-5A对高温、低温和ABA都有响应,对干旱和盐响应不敏感;TaHTAS-5A在小麦的根、茎、叶和幼穗等不同组织中均有表达,但表达量有差异,在叶和穗中的表达量明显高于根部和茎部;亚细胞定位结果表明,TaHTAS-5A位于细胞膜上.本研究为进一步探究小麦TaHTAS-5A基因的功能奠定了基础,也为小麦非生物胁迫抗性改良提供了一定的理论依据.

Gibberellins (GA) are involved in seed development and E3 ubiquitin-ligases actively participate in GA perception and signal transduction. TaGW2-6A encodes a RING E3 ubiquitin-ligase that negatively regulates grain size. Therefore, Chinese Spring (CS) and its TaGW2-6A allelic variants (NIL31) were investigated to elucidate the relative contribution of GA to the regulation of seed development in wheat. The expression levels of GA biosynthesis and response genes were higher in NIL31 than CS, especially those of GA 3-oxidase and GASA4. The expression of TaGW2-6A exhibited the opposite pattern compared with those of the GA biosynthesis and response genes in CS and NIL31. The results showed that the GA content of NIL31 was significantly higher than that of CS. Thus, TaGW2-6A had a negative relationship on GA synthesis and response genes. Moreover, after GA treatment, CS and NIL31 exhibited the opposite phenotypes and GA contents. These results demonstrate that allelic variation in TaGW2-6A increases the seed size via the GA hormone pathway. Transcriptional analysis and cytological analysis showed that TaGW2-6A allelic variants regulated GA synthesis via GA 3-oxidases, thereby leading to the higher expression of GASA4 to control endosperm cell elongation and division during grain filling. Finally, germination experiments were performed to elucidate the relationships between TaGW2-6A and GA synthesis and response genes in wheat with full fertility. These results provide new insights into the effects of the ubiquitination system mediated by TaGW2-6A on the GA hormone signaling pathway, thereby improving our understanding of the role of TaGW2-6A in seed development in wheat.

Functional allelic variants of TaGW2 - 6A produce large grains, possibly via changes in endosperm cells and dry matter by regulating the expression of cytokinins and starch-related genes via the ubiquitin–proteasome system.

The viscoelastic properties of wheat dough are due mainly to the structure of gluten and interactions within the protein complex. We determined the effects of high-molecular-weight glutenin subunit (HMW-GS) on the polymerization of glutenin during grain development and on the secondary and micro-structures of gluten, using Xinong1718 and its four near-isogenic lines (NILs). The polymerization of glutenin was monitored based on the percentage of unextractable polymeric protein (%UPP). Xi1718-3 with the superior allele Bx17 + By18 exhibited a rapid increase in %UPP five days earlier than the other lines with variations at Glu-B1, thereby obtained the highest %UPP at maturity. The secondary structures, such as the proportion of beta-sheets and the alpha-helix/beta-sheet ratio differed significantly among the NILs. The micro-structure of gluten in NILs varied in terms of the pore size distribution and cross-linkage patterns. Significant correlations were found between %UPP with the beta-sheet content and alpha-helix/beta-sheet ratio, so these secondary structures could also be used as indicators of wheat flour quality. (C) 2016 Elsevier Ltd. All rights reserved.