An Innovative Finite Element Geometric Modeling of Single-Layer Multi-Bead WAAMed Part

Finite element (FE) coupled thermal-mechanical analysis is widely used to predict the deformation and residualstress of wire arc additive manufacturing (WAAM) parts. In this study, an innovative single-layermulti-bead profilegeometric modeling method through the isosceles trapezoid function is proposed to build the FE model of theWAAMprocess. Firstly, a straight-line model for overlapping beads based on the parabola function was establishedto calculate the optimal center distance. Then, the isosceles trapezoid-based profile was employed to replace theparabola profiles of the parabola-based overlapping model to establish an innovative isosceles trapezoid-basedmulti-bead overlapping geometric model. The rationality of the isosceles trapezoid-based overlapping model wasconfirmed by comparing the geometric deviation and the heat dissipation performance index of the two overlappingmodels. In addition, the FE-coupled thermal-mechanical analysis, as well as a comparative experiment of thesingle-layer eight-bead deposition process show that the simulation results of the above two models agree with theexperimental results. At the same time, the proposed isosceles trapezoid-based overlappingmodels are all straightlineprofiles, which can be divided into high-quality FE elements. It can improve the modeling efficiency andshorten the simulation calculation time. The innovative modeling method proposed in this study can provide anefficient and high-precision geometricmodelingmethod forWAAMpart FE coupled thermal-mechanical analysis.

The plasmodesmata-associated β-1,3-glucanase gene GhPdBG regulates fiber development in cotton

Trichomes are specialized structures that originate from epidermal cells of organs in higher plants.The cotton fiber is a unique single-celled trichome that elongates from the seed coat epidermis.Cotton(Gossypium hirsutum)fibers and trichomes are models for cell differentiation.In an attempt to elucidate the intercellular factors that regulate fiber and trichome cell development,we identified a plasmodesmal β-1,3-glucanase gene(designated GhPdBG)controlling the opening and closing of plasmodesmata in cotton fibers.Structural and evolutionary analysis showed haplotypic variation in the promoter region of the GhPdBG gene among 352 cotton accessions,but high conservation in the coding region.GhPdBG was expressed predominantly in cotton fibers and localized to plasmodesmata(PD).Expression patterns of PdBG that corresponded to PD permeability were apparent during fiber development in G.hirsutum and G.barbadense.The PdBG-mediated opening-closure of PD appears to be involved in fiber development and may account for the contrasting fiber traits of these two species.Ectopic expression of GhPdBG revealed that it functions in regulating fiber and trichome length and/or density by modulating plasmodesmatal permeability.This finding suggests that plasmodesmal targeting of GhPdBG,as a switch of intercellular channels,regulates single-celled fiber and trichome development in cotton.

Cotton GhBRC1 regulates branching,flowering,and growth by integrating multiple hormone pathways

Cotton architecture is partly determined by shoot branching and flowering patterns.Gh BRC1 was previously identified by RNA-seq analysis of nulliplex-branching and normal-branching cotton.However,the roles of Gh BRC1 in cotton remain unclear.In the present study,investigations of nuclear localization and transcriptional activity indicated that Gh BRC1 has characteristics typical of transcription factors.Gene expression analysis showed that Gh BRC1 was highly expressed in axillary buds but displayed different expression patterns between the two branching types.Overexpression of Gh BRC1 in Arabidopsis significantly inhibited the number of branches and promoted flowering.In contrast,silencing Gh BRC1 in cotton significantly promoted seedling growth.Gh BRC1 was induced by multiple hormones,including strigolactones,which promoted seedling growth and seed germination of Arabidopsis plants overexpressing Gh BRC1.Consistent with these findings,RNA-seq analysis of virus-induced gene silencing treated cotton revealed that a large number of genes were differentially expressed between Gh BRC1-silenced and control plants,and these genes were significantly enriched in plant hormone signalling pathways.Together,our data indicates that Gh BRC1 regulates plant branching and flowering through multiple regulatory pathways,especially those regulating plant hormones,with functions partly differing from those of Arabidopsis BRC1.These results provide insights into the molecular mechanisms controlling plant architecture,which is important for breeding cotton with ideal plant architecture and high yield.

Rapid Identification of a Candidate Gene Related to Fiber Strength Using a Superior Chromosome Segment Substitution Line from Gossypium hirsutum × Gossypium barbadense via Bulked Segregant RNA-Sequencing

Cotton is the most widely cultivated commercial crop producing natural fiber around the world.As a critical trait for fiber quality,fiber strength principally determined during the secondary wall thickening period.Based on the developed BC5F3:5 CSSLs(chromosome segment substitution lines)from Gossypium hirsutum CCRI36×G.barbadense Hai 1,the superior MBI9915 was chosen to construct the secondary segregated population BC7F2 with its recurrent parent CCRI36,which was subsequently subjected to Bulk segregant RNA-sequencing(BSR-seq)for rapid identification of candidate genes related to fiber strength.A total of 4 fiber-transcriptome libraries were separately constructed and sequenced,including two parents(CCRI36 and MBI9915)and two extreme pools at 20 DPA(days post anathesis).Through multiple comparisons,536 DEGs(differentially expressed genes)were overlapped at 20 DPA.Allelic-polymorphism comparison in mRNA sequences revealed 831 highly probable SNPs between two extreme pools related to fiber strength.Linkage analysis was performed between two extreme pools with SNP-index method.Eighteen correlated regions with 1981 annotation genes were obtained between two pools at 20 DPA,of which 12 common DEGs were similarly identified both between two parents and two pools.One gene(Gh_A07G0837)in the candidate region related to fiber strength was differentially expressed in both parents and extreme pools and involved in fiber strength development through reactive oxygen species(ROS)activity.Co-expression analysis of Gh_A07G0837 showed that Gh_A07G0837 may cooperate with other genes to regulate fiber strength.The reliability of BSR-seq results was validated by the quantitative real-time PCR(qRT-PCR)experiments on 5 common DGEs 20 DPA.Co-expressed analysis results indicated that there were some genes expressed especially low in MBI9915,resulting in good fiber strength.Focusing on bulked segregant analysis on the extreme pools derived from superior CSSL population,this study indicates that BSR-seq can be efficiently applied on rapid identification of candidate genes related to fiber strength,which make contributions to our understanding of fiber quality formation in cotton.

Genome-wide identification,characterization,and expression analysis of aluminum-activated malate transporter genes(ALMTs)in Gossypium hirsutum L.

Aluminum-activated malate transporters(ALMT)are widely involved in plant growth and metabolic processes,including adaptation to acid soils,guard cell regulation,anion homeostasis,and seed development.Although ALMT genes have been identified in Arabidopsis,wheat,barley,and Lotus japonicus,little is known about its presence in Gossypium hirsutum L.In this study,ALMT gene recognition in diploid and tetraploid cotton were done using bioinformatics analysis that examined correlation between homology and evolution.Differentially regulated ALMT genetic profile in G.hirsutum was examined,using RNA sequencing and qRT-PCR,during six fiber developmental time-points,namely 5 d,7 d,10 d,15 d,20 d,and 25 d.We detected 36 ALMT genes in G.hirsutum,which were subsequently annotated and divided into seven sub-categories.Among these ALMT genes,34 had uneven distribution across 14/26 chromosomes.Conserved domains and gene structure analysis indicated that ALMT genes were highly conserved and composed of exons and introns.The GhALMT gene expression profile at different DPA(days post anthesis)in different varieties of G.hirsutum is indicative of a crucial role of ALMT genes in fiber development in G.hirsutum.This study provides basis for advancements in the cloning and functional enhancements of ALMT genes in enhancing fiber development and augmenting high quality crop production.

Analyses of the NAC Transcription Factor Gene Family in Gossypium raimondii Ulbr.:Chromosomal Location,Structure,Phylogeny,and Expression Patterns

NAC domain proteins are plant-specific transcription factors known to play diverse roles in various plant developmental processes. In the present study, we performed the first comprehensive study of the NAC gene family in Gossypium raimondii Ulbr., incorporating phylogenetic, chromosomal location, gene structure, conserved motif, and expression profiling analyses. We identified 145 NAC transcription factor （NAC-TF） genes that were phylogenetically clustered into 18 distinct subfamilies. Of these, 127 NAC-TF genes were distributed across the 13 chromosomes, 80 （55%） were preferentially retained duplicates located in both duplicated regions and six were located in triplicated chromosomal regions. The majority of NAC-TF genes showed temporal-, spatial-, and tissue-specific expression patterns based on tran- scriptomic and qRT-PCR analyses. However, the expression patterns of several duplicate genes were partially redundant, suggesting the occurrence of sub-functionalization during their evolution. Based on their genomic organization, we concluded that genomic duplications contributed significantly to the expansion of the NAC-TF gene family in G. raimondii. Comprehensive analysis of their expression profiles could provide novel insights into the functional divergence among members of the NAC gene family in G. raimondii.

Comprehensive analysis of NAC transcription factors in diploid Gossypium: sequence conservation and expression analysis uncover their roles during fiber development

Determining how function evolves following gene duplication is necessary for understanding gene expansion.Transcription factors(TFs)are a class of proteins that regulate gene expression by binding to specific cis-acting elements in the promoters of target genes,subsequently activating or repressing their transcription.In the present study,we systematically examined the functional diversification of the NAC transcription factor(NAC-TFs)family by analyzing their chromosomal location,structure,phylogeny,and expression pattern in Gossypium raimondii(Gr)and G.arboreum(Ga).The 145 and 141 NAC genes identified in the Gr and Ga genomes,respectively,were annotated and divided into 18 subfamilies,which showed distinct divergence in gene structure and expression patterns during fiber development.In addition,when the functional parameters were examined,clear divergence was observed within tandem clusters,which suggested that subfunctionalization had occurred among duplicate genes.The expression patterns of homologous gene pairs also changed,suggestive of the diversification of gene function during the evolution of diploid cotton.These findings provide insights into the mechanisms underlying the functional differentiation of duplicated NAC-TFs genes in two diploid cotton species.

Constructing a high-density linkage map for Gossypium hirsutum × Gossypium barbadense and identifying QTLs for lint percentage

To introgress the good fiber quality and yield from Gossypium barbadense into a commercial Upland cotton variety, a high‐density simple sequence repeat （SSR） genetic linkage map was developed from a BC1F1 population of Gossypium hirsutum × Gossypium barbadense. The map com-prised 2,292 loci and covered 5115.16 centiMorgan （cM） of the cotton AD genome, with an average marker interval of 2.23 cM. Of the marker order for 1,577 common loci on this new map, 90.36% agrees well with the marker order on the D genome sequence genetic map. Compared with five pub-lished high‐density SSR genetic maps, 53.14% of marker loci were newly discovered in this map. Twenty‐six quantitative trait loci （QTLs） for lint percentage （LP） were identified on nine chromosomes. Nine stable or common QTLs could be used for marker‐assisted selection. Fifty percent of the QTLs were from G. barbadense and increased LP by 1.07%–2.41%. These results indicated that the map could be used for screening chromosome substitution segments from G. barbadense in the Upland cotton background, identifying QTLs or genes from G. barbadense, and further developing the gene pyramiding effect for improving fiber yield and quality.