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This paper introduces a conceptual framework for finite element analysis of generalized Maxwell viscoelastic materials based on the initial stress approach. The proposed method facilitates the explicit and convenient determination of mechanical parameters for viscoelastic materials by directly utilizing relaxation test data. Each time step's viscoelastic relaxation stress is treated as the initial stress, and a recursive calculation formula for the material's initial stress is established, relying solely on the relaxation stress and strain from the previous time step. Based on this, the study outlines the computational steps for initial-stress-based finite element analysis of elastic materials. The proposed algorithm's accuracy and efficiency are validated through a classical one-dimensional axial rod example. Results demonstrate that the introduced initial stress-type finite element analysis maintains the stiffness matrix equal to the initial stiffness matrix throughout the calculation process, significantly enhancing the efficiency of finite element analysis for viscoelastic materials while reducing the computational resource required. The conceptual framework improves the efficiency and accuracy of analyzing the mechanical parameters of viscoelastic materials using relaxation test data. [ABSTRACT FROM AUTHOR]

For linear viscoelastic materials, this paper proposes a finite element analysis method based on an integral constitutive relationship that can simultaneously consider the relaxation behavior of the elastic modulus and the creep Poisson's ratio. Firstly, the generalized Maxwell model is employed to depict the relaxation characteristics of the elastic modulus, while the generalized Kelvin model is used to represent the creep Poisson's ratio. Subsequently, the element relaxation stiffness matrix is established, thereby forming a convolutional finite element equation. Furthermore, the recursive calculation of the convolutional integral is derived, and the calculation steps of the finite element for viscoelasticity considering the time-dependent nature of both the elastic modulus and Poisson's ratio are established. Finally, the accuracy of the proposed algorithm is verified through two numerical examples with linear viscoelastic material. The results indicate that the proposed variable stiffness method for the finite element analysis of linear viscoelastic materials can simultaneously consider the changes in the elastic modulus and Poisson's ratio over time, thereby establishing a new path and idea for the more accurate simulation of viscoelastic materials' mechanical properties. Compared with the initial strain method for linear viscoelastic materials, the variable stiffness method proposed in this paper effectively avoids the assumption of constant stress during the micro time interval, thus significantly enhancing the finite element calculation accuracy of linear viscoelastic materials. The proposed method establishes a simulation algorithm that matches existing commercial software with viscoelastic material experiments by considering the elastic modulus and Poisson's ratio as material parameters. [ABSTRACT FROM AUTHOR]

Relatively mild xerophytic or hardening treatments can induce healthy development of plants. In the present study, as one of xerophytophysiological applications, sub-irrigation was applied to a flower plant of Eustoma grandiflorum to confirm whether the sub-irrigation improved flowering quality in addition to plant growth and physiology. As shown by the results, long-term sub-irrigation induced osmotic adjustment, with osmolyte concentration increasing 32.8 osmol m−3 (p ≤ 0.01), improved leaf photosynthetic activities, with more than 10% (p ≤ 0.05) increase in photosynthetic capacity, and promoted plant growth, with a shoot biomass increase by 27.5% (p ≤ 0.01) and a root increase by 50.5% (p ≤ 0.01). These improvements were attributed to turgor maintenance and cell water re-compartmentation into the symplasm, which were both the consequence of osmotic adjustment. The lower osmotic potential and lower relative leaf water potential at incipient plasmolysis suggested that plants in sub-irrigation plots might be more resistant to environmental stresses. Sub-irrigation also improved flower quality shown by increased anthocyanin concentration (16% up, p ≤ 0.01). Flower quality improvement might be attributed to up-regulation of the PAL gene, which could catalyze the synthesis of anthocyanins. PAL gene up-regulation might be associated with a concentration increase in salicylic acid (SA), which was suggested as a plant hormone for signaling. Sub-irrigation also affected the flower opening and closing oscillations with less changed opening size or oscillation amplitude. We adopted mathematical models and thoroughly analyzed dynamic changes in photosynthesis, plant growth, and flower opening oscillations. In conclusion, sub-irrigation was a feasible practice and could be used in E. grandiflorum culture to improve plant growth and flower opening quality. [ABSTRACT FROM AUTHOR]

Thermo-sensitive cytoplasmic male sterility (TCMS) plays a crucial role in hybrid production and hybrid breeding; however, there are few studies on molecular mechanisms related to anther abortion in the wheat TCMS line. In this study, FA99, a new wheat thermo-sensitive cytoplasmic male sterility line, was investigated. Fertility conversion analysis showed that FA99 was mainly controlled by temperature, and the temperature-sensitive stage was pollen mother cell formation to a uninucleate stage. Further phenotypic identification and paraffin section showed that FA99 was characterized by indehiscent anthers and aborted pollen in a sterile environment and tapetum was degraded prematurely during the tetrad period, which was the critical abortion period of FA99. The contents of O2−, H2O2, MDA and POD were significantly changed in FA99 under a sterile environment by the determination of physiological indexes. Furthermore, through transcriptome analysis, 252 differentially expressed genes were identified, including 218 downregulated and 34 upregulated genes. Based on KOG function classification, GO enrichment and KEGG pathways analysis, it was evident that significant transcriptomic changes in FA99 under different fertility environments, and the major differences were "phenylalanine metabolism", "phenylpropanoid biosynthesis", "cutin, suberine and wax biosynthesis", "phenylalanine, tyrosine and tryptophan biosynthesis" and "citrate cycle (TCA cycle)". Finally, we proposed an intriguing transcriptome-mediated pollen abortion and male sterility network for FA99. These findings provided data on the molecular mechanism of fertility conversion in thermo-sensitive cytoplasmic male sterility wheat. [ABSTRACT FROM AUTHOR]

Long-chain acyl-CoA synthetase (LACS), responsible for the conversion of free FAs into acyl-CoAs, is involved in multiple pathways of lipid metabolism. Although LACS genes in Arabidopsis have been well characterized, no detailed information concerning this family is available for wheat. In the present study, a systematic analysis was carried out for the wheat LACS family. As a result, 30 putative TaLACSs were identified. Expression analysis revealed that 22 Takacs were expressed in wheat anthers. Two orthologs of AtLACS1, TaLACS2 and TaLACS3, were repressed at the vacuolated stage in the cold-treated BS366 (a temperature-sensitive genic male-sterile line). Thus, TaLACS2 and TaLACS3 may function like AtLACS1 in wax biosynthesis in anthers, and the repression of both genes may be correlated with the male sterility of BS366. TaLACS5 is an ortholog of AtLACS5, which was expressed exclusively in anthers. TaLACS5 was repressed in the cold-treated BS366 at the tetrad, uninucleate, and vacuolated stages. The negative correlation between TaLACS5 and TaGAMYB-B, and the MYB domain found in the promoter sequence suggested that TaLACS5 may be negatively regulated by TaGAMYB-B to participate in wheat fertility. These findings will provide a valuable foundation for the understanding of the wheat LACS gene family in male fertility. [ABSTRACT FROM AUTHOR]

Anther dehiscence is an important process to release pollen and then is a critical event in pollination. In the wheat photo-thermo-sensitive genic male sterility (PTGMS) line, pollen cannot release from anther since the anther cannot dehisce during anther dehiscence stage in a sterile condition. In this study, we carried out RNA-sequencing to analyze the transcriptome of one wheat PTGMS line BS366 during anther dehiscence under fertile and sterile conditions to explore the mechanism. We identified 6306 differentially expressed genes (DEGs). Weighted gene co-expression network analysis (WGCNA) and KEGG analysis showed that DEGs were mainly related to "hormone signal transduction pathway" and "starch and sucrose metabolism". We identified 35 and 23 DEGs related hormone signal transduction and sucrose metabolism, respectively. Compared with conventional wheat Jing411, there were some changes in the contents of hormones, including JA, IAA, BR, ABA and GA3, and sucrose, during three anther dehiscence stages in the sterile condition in BS366. We performed qRT-PCR to verify the expression levels of some critical DEGs of the hormone signaling pathway and the starch and sucrose metabolism pathway. The results showed disparate expression patterns of the critical DEGs of the hormone signaling pathway and the starch and sucrose metabolism pathway in different conditions, suggesting these genes may be involved in the regulation of the anther dehiscence in BS366. Finally, we conducted a hypothesis model to reveal the regulation pathway of hormones and sucrose on anther dehiscence. The information provided new clues to the molecular mechanisms of anther dehiscence in wheat and improved wheat hybrid breeding. [ABSTRACT FROM AUTHOR]

Glycoside hydrolase family 9 (GH9) is a key member of the hydrolase family in the process of cellulose synthesis and hydrolysis, playing important roles in plant growth and development. In this study, we investigated the phenotypic characteristics and gene expression involved in pollen fertility conversion and anther dehiscence from a genomewide level. In total, 74 wheat GH9 genes (TaGH9s) were identified, which were classified into Class A, Class B and Class C and unevenly distributed on chromosomes. We also investigated the gene duplication and reveled that fragments and tandem repeats contributed to the amplification of TaGH9s. TaGH9s had abundant hormone-responsive elements and light-responsive elements, involving JA–ABA crosstalk to regulate anther development. Ten TaGH9s, which highly expressed stamen tissue, were selected to further validate their function in pollen fertility conversion and anther dehiscence. Based on the cell phenotype and the results of the scanning electron microscope at the anther dehiscence period, we found that seven TaGH9s may target miRNAs, including some known miRNAs (miR164 and miR398), regulate the level of cellulose by light and phytohormone and play important roles in pollen fertility and anther dehiscence. Finally, we proposed a hypothesis model to reveal the regulation pathway of TaGH9 on fertility conversion and anther dehiscence. Our study provides valuable insights into the GH9 family in explaining the male sterility mechanism of the wheat photo-thermo-sensitive genetic male sterile (PTGMS) line and generates useful male sterile resources for improving wheat hybrid breeding. [ABSTRACT FROM AUTHOR]

Thermosensitive genic male sterile (TGMS) wheat lines are the core of two-line hybrid systems. Understanding the mechanism that regulates male sterility in TGMS wheat lines is helpful for promoting wheat breeding. Several studies have obtained information regarding the mechanisms associated with male sterility at the transcriptional level, but it is not clear how the post-transcriptional process of alternative splicing might contribute to controlling male sterility. In this study, we performed genome-wide analyses of alternative splicing during the meiosis stage in TGMS line BS366 using PacBio and RNA-Seq hybrid sequencing. Cytological observations indicated that cytoskeleton assembly in pollen cells, calcium deposition in pollen and tapetal cells, and vesicle transport in tapetal cells were deficient in BS366. According to our cytological findings, 49 differentially spliced genes were isolated. Moreover, 25 long non-coding RNA targets and three bHLH transcription factors were identified. Weighted gene co-expression network analysis detected four candidate differentially spliced genes that had strong co-relation with the seed setting percentage, which is the direct representation of male sterility in BS366. In this study, we obtained comprehensive data regarding the alternative splicing-mediated regulation of male sterility in TGMS wheat. The candidates identified may provide the molecular basis for an improved understanding of male sterility. [ABSTRACT FROM AUTHOR]

It is well known that WRKY transcription factors play essential roles in plants' response to diverse stress responses, especially to drought and salt stresses. However, a full comprehensive analysis of this family in wheat is still missing. Here we used in silico analysis and identified 124 WRKY genes, including 294 homeologous copies from a high-quality reference genome of wheat (Triticum aestivum). We also found that the TaWRKY gene family did not undergo gene duplication rather than gene loss during the evolutionary process. The TaWRKY family members displayed different expression profiles under several abiotic stresses, indicating their unique functions in the mediation of particular responses. Furthermore, TaWRKY75-A was highly induced after polyethylene glycol and salt treatments. The ectopic expression of TaWRKY75-A in Arabidopsis enhanced drought and salt tolerance. A comparative transcriptome analysis demonstrated that TaWRKY75-A integrated jasmonic acid biosynthetic pathway and other potential metabolic pathways to increase drought and salt resistances in transgenic Arabidopsis. Our study provides valuable insights into the WRKY family in wheat and will generate a useful genetic resource for improving wheat breeding. [ABSTRACT FROM AUTHOR]

Developmentally programmed cell death (dPCD) is a tightly controlled biological process. In recent years, vital roles of dPCD on regulating floral organ growth and development have been reported. It is well known that flower is an essential organ for reproduction and a turning point of plants' life cycle. Hence, uncovering the complex molecular networks which regulates dPCD processes in floral organs is utmost important. So far, our understanding of dPCD on floral organ growth and development is just starting. Herein, we summarize the important factors that involved in the tapetal degeneration, pollen tube rupture, receptive synergid cell death, nucellar degradation, and antipodal cell degradation. Meanwhile, the known factors that involved in transmitting tract formation and self-incompatibility-induced PCD were also introduced. Furthermore, the genes that associated with anther dehiscence and petal senescence and abscission were reviewed as well. The functions of various types of factors involved in floral dPCD processes are highlighted principally. The regulatory panorama described here can provide us some insights about flower-specific dPCD process. • Developmentally programmed cell death (dPCD) plays essential roles in floral organ growth, development, and senescence. • dPCD process was observed in nine types of floral organs. • Regulatory networks of dPCD in floral organs were delineated in this review. [ABSTRACT FROM AUTHOR]

Programmed cell death (PCD) play essential roles in plant growth and development. Stigmatic papilla cells form an indispensable organ for plant reproduction. The lifetime of papilla cells is tightly controlled, and the developmental PCD (dPCD) process is involved in papilla cell death. Hence, papilla cell death is a good model for studying on PCD process. In this study, the dPCD signal was visualized in dying papilla cells by detecting the GUS signal of the PCD-related reporter gene BIFUNCTIONAL NUCLEASE 1 (BFN1). We found that the GUS was not expressed at young stage, but strongly expressed in papilla cells at the ageing stage, indicating the PCD process was triggered to terminate the papilla cell fate. Given this, the RNA-Seq data set, which covered the information of the whole lifespan of papilla cells, was analyzed aiming to understand which genes and pathways were involved in papilla cell death. 37 differential expressed genes (DEGs) were isolated. Moreover, the pathways related to energy production and transportation, autophagy, and plant hormone signal transduction were considered as the key pathways involved in the papilla cell death. 9 types, total of 104 transcriptional factors (TFs) were identified as well. Finally, a putative working model of papilla cell death was integrated. The findings herein will enrich the knowledge of the dPCD-mediated pathway in regulating plant organ/tissue growth, development, senescence, and death. Our study will provide some referential gene resources for studying on the dPCD in other plant organs or tissues. • Papilla cell is a good model for study on programmed cell death (PCD). • Total of 37 DEGs involved in regulating papilla cell PCD were screened out. • Nine types, total of 104 TFs involved in regulating papilla cell PCD were isolated. • A feasible networking model of papilla cell PCD was generated. [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]

Background: The JASMONATE-ZIM DOMAIN (JAZ) repressor family proteins are jasmonate co-receptors and transcriptional repressor in jasmonic acid (JA) signaling pathway, and they play important roles in regulating the growth and development of plants. Recently, more and more researches on JAZ gene family are reported in many plants. Although the genome sequencing of common wheat (Triticum aestivum L.) and its relatives is complete, our knowledge about this gene family remains vacant., Results: Fourteen JAZ genes were identified in the wheat genome. Structural analysis revealed that the TaJAZ proteins in wheat were as conserved as those in other plants, but had structural characteristics. By phylogenetic analysis, all JAZ proteins from wheat and other plants were clustered into 11 sub-groups (G1-G11), and TaJAZ proteins shared a high degree of similarity with some JAZ proteins from Aegliops tauschii, Brachypodium distachyon and Oryza sativa. The Ka/Ks ratios of TaJAZ genes ranged from 0.0016 to 0.6973, suggesting that the TaJAZ family had undergone purifying selection in wheat. Gene expression patterns obtained by quantitative real-time PCR (qRT-PCR) revealed differential temporal and spatial regulation of TaJAZ genes under multifarious abiotic stress treatments of high salinity, drought, cold and phytohormone. Among these, TaJAZ7, 8 and 12 were specifically expressed in the anther tissues of the thermosensitive genic male sterile (TGMS) wheat line BS366 and normal control wheat line Jing411. Compared with the gene expression patterns in the normal wheat line Jing411, TaJAZ7, 8 and 12 had different expression patterns in abnormally dehiscent anthers of BS366 at the heading stage 6, suggesting that specific up- or down-regulation of these genes might be associated with the abnormal anther dehiscence in TGMS wheat line., Conclusion: This study analyzed the size and composition of the JAZ gene family in wheat, and investigated stress responsive and differential tissue-specific expression profiles of each TaJAZ gene in TGMS wheat line BS366. In addition, we isolated 3 TaJAZ genes that would be more likely to be involved in the regulation of abnormal anther dehiscence in TGMS wheat line. In conclusion, the results of this study contributed some novel and detailed information about JAZ gene family in wheat, and also provided 3 potential candidate genes for improving the TGMS wheat line.