Evolution, gene expression profiling and 3D modeling of CSLD proteins in cotton

The plant cell wall-dynamic, strong, and adaptable-is a natural shapeshifter

Mythology is replete with good and evil shapeshifters, who, by definition, display great adaptability and assume many different forms-with several even turning themselves into trees. Cell walls certainly fit this definition as they can undergo subtle or dramatic changes in structure, assume many shapes, and perform many functions. In this review, we cover the evolution of knowledge of the structures, biosynthesis, and functions of the 5 major cell wall polymer types that range from deceptively simple to fiendishly complex. Along the way, we recognize some of the colorful historical figures who shaped cell wall research over the past 100 years. The shapeshifter analogy emerges more clearly as we examine the evolving proposals for how cell walls are constructed to allow growth while remaining strong, the complex signaling involved in maintaining cell wall integrity and defense against disease, and the ways cell walls adapt as they progress from birth, through growth to maturation, and in the end, often function long after cell death. We predict the next century of progress will include deciphering cell type-specific wall polymers; regulation at all levels of polymer production, crosslinks, and architecture; and how walls respond to developmental and environmental signals to drive plant success in diverse environments.

Genome-wide identification and functional analysis of the cellulose synthase-like gene superfamily in common oat (Avena sativa L.)

Hemicelluloses constitute approximately one-third of the plant cell wall and can be used as a dietary fiber and food additive, and as raw materials for biofuels. Although genes involved in hemicelluloses synthesis have been investigated in some model plants, no comprehensive analysis has been conducted in common oat at present. In this study, we identified and systematically analyzed the cellulose synthase-like gene (Csl) family members in common oat and investigated them using various bioinformatics tools. The results showed that there are 76 members of the oat Csl gene family distributed on 17 chromosomes, and phylogenetic analysis indicated that the 76 Csl genes belong to the CslA, CslC, CslD, CslE, CslF, CslH, and CslJ subfamilies. A total of 14 classes of cis-acting elements were identified in the promoter regions, including hormone response, light response, cell development, and defense stress elements. The collinearity analysis identified 28 pairs of segmentally duplicated genes, most of which were found on chromosomes 2D and 6A. Expression pattern analysis showed that oat Csl genes display strong tissue-specific expression; of the 76 Csl genes, 33 were significantly up-regulated in stems and 30 were up-regulated in immature seeds. The expression of most members of the AsCsl gene family is repressed by abiotic stress, while the expression of some members is up-regulated by light. Immunoelectron microscopy shows that the product of AsCsl61, a member of CslF subfamily, mediates (1,3; 1,4)-β-D-glucan synthesis in transgenic Arabidopsis. These findings provide a fundamental understanding of the structural, functional, and evolutionary features of the oat Csl genes and may contribute to our general understanding of hemicellulose biosynthesis. Moreover, this information will be helpful in designing experiments for genetic manipulation of mixed-linkage glucan (MLG) synthesis with the goal of quality improvement in oat.

Cellulose synthase-like D movement in the plasma membrane requires enzymatic activity

Cellulose Synthase-Like D (CSLD) proteins, important for tip growth and cell division, are known to generate β-1,4-glucan. However, whether they are propelled in the membrane as the glucan chains they produce assemble into microfibrils is unknown. To address this, we endogenously tagged all eight CSLDs in Physcomitrium patens and discovered that they all localize to the apex of tip-growing cells and to the cell plate during cytokinesis. Actin is required to target CSLD to cell tips concomitant with cell expansion, but not to cell plates, which depend on actin and CSLD for structural support. Like Cellulose Synthase (CESA), CSLD requires catalytic activity to move in the plasma membrane. We discovered that CSLD moves significantly faster, with shorter duration and less linear trajectories than CESA. In contrast to CESA, CSLD movement was insensitive to the cellulose synthesis inhibitor isoxaben, suggesting that CSLD and CESA function within different complexes possibly producing structurally distinct cellulose microfibrils.

Identification and bioinformatic analysis of the CaCesA/Csls family members and the expression of the CaCslD1 in the flower buds of CMS/Rf system in pepper

The cellulose synthase gene superfamily contains cellulose synthase (CesA) and cellulose synthase-like (Csl) gene families, which synthesize cellulose and hemicellulose in plant cell walls and play a crucial role in plant growth and development. However, the CesA/Csl gene family has not been reported in pepper. Therefore, the genome-wide research of the CaCesA/CaCsl gene family was conducted in pepper. In this study, a total of 39 CaCesA/CaCsls genes (10 CesAs genes and 29 Csls genes) were identified in pepper and unevenly distributed on 11 chromosomes. These CaCesA/Csls were divided into seven subfamilies (CesAs, CslAs, CslBs, CslCs, CslDs, CslEs, CslGs), and most of CaCesA/Csls genes are closely related to AtCesA/Csls genes. The cis-acting elements in the promoters of CaCesA/Csls genes are mainly related to hormone response and stress response. There are ten collinear gene pairs between the CesA/Csls gene family of pepper and Arabidopsis, and four fragment duplication gene pairs of the CaCesA/Csls genes were discovered. RNA-seq analysis shows that the majority of CaCesA/Csls are expressed in a variety of plant tissues, indicating that most CaCesA/Csls gene expression patterns are not organ-specific, and CaCslD1/D4 have the highest expression in anthers, followed by petal, ovary, and F9. RNA-seq analysis shows that most CaCesA/Csls are responsive to five hormones (IAA, GA₃, ABA, SA, and MeJA). The tissue-specific expression analysis of the CaCslD1 gene shows that the CaCslD1 gene is expressed specifically in flowers. In the flower buds IV of cytoplasmic male sterility (CMS) and its restoration of fertility (Rf) system, CaCslD1 reach the highest expression respectively. However, the relative expression level of CaCslD1 in the fertile accessions is extremely significantly higher than in the sterile accessions. This study shows an overall understanding of the CaCesA/Csls gene family and provides a new insight for understanding the function of CaCslD1 in pollen development and exploring the fertility restoration of CMS in pepper.

Species-Specific Gene Expansion of the Cellulose synthase Gene Superfamily in the Orchidaceae Family and Functional Divergence of Mannan Synthesis-Related Genes in Dendrobium officinale

Plant Cellulose synthase genes constitute a supergene family that includes the Cellulose synthase (CesA) family and nine Cellulose synthase-like (Csl) families, the members of which are widely involved in the biosynthesis of cellulose and hemicellulose. However, little is known about the Cellulose synthase superfamily in the family Orchidaceae, one of the largest families of angiosperms. In the present study, we identified and systematically analyzed the CesA/Csl family members in three fully sequenced Orchidaceae species, i.e., Dendrobium officinale, Phalaenopsis equestris, and Apostasia shenzhenica. A total of 125 Cellulose synthase superfamily genes were identified in the three orchid species and classified into one CesA family and six Csl families: CslA, CslC, CslD, CslE, CslG, and CslH according to phylogenetic analysis involving nine representative plant species. We found species-specific expansion of certain gene families, such as the CslAs in D. officinale (19 members). The CesA/Csl families exhibited sequence divergence and conservation in terms of gene structure, phylogeny, and deduced protein sequence, indicating multiple origins via different evolutionary processes. The distribution of the DofCesA/DofCsl genes was investigated, and 14 tandemly duplicated genes were detected, implying that the expansion of DofCesA/DofCsl genes may have originated via gene duplication. Furthermore, the expression profiles of the DofCesA/DofCsl genes were investigated using transcriptome sequencing and quantitative Real-time PCR (qRT-PCR) analysis, which revealed functional divergence in different tissues and during different developmental stages of D. officinale. Three DofCesAs were highly expressed in the flower, whereas DofCslD and DofCslC family genes exhibited low expression levels in all tissues and at all developmental stages. The 19 DofCslAs were differentially expressed in the D. officinale stems at different developmental stages, among which six DofCslAs were expressed at low levels or not at all. Notably, two DofCslAs (DofCslA14 and DofCslA15) showed significantly high expression in the stems of D. officinale, indicating a vital role in mannan synthesis. These results indicate the functional redundancy and specialization of DofCslAs with respect to polysaccharide accumulation. In conclusion, our results provide insights into the evolution, structure, and expression patterns of CesA/Csl genes and provide a foundation for further gene functional analysis in Orchidaceae and other plant species.

Cellulose synthase-like protein OsCSLD4 plays an important role in the response of rice to salt stress by mediating abscisic acid biosynthesis to regulate osmotic stress tolerance

Cell wall polysaccharide biosynthesis enzymes play important roles in plant growth, development and stress responses. The functions of cell wall polysaccharide synthesis enzymes in plant growth and development have been well studied. In contrast, their roles in plant responses to environmental stress are poorly understood. Previous studies have demonstrated that the rice cell wall cellulose synthase-like D4 protein (OsCSLD4) is involved in cell wall polysaccharide synthesis and is important for rice growth and development. This study demonstrated that the OsCSLD4 function-disrupted mutant nd1 was sensitive to salt stress, but insensitive to abscisic acid (ABA). The expression of some ABA synthesis and response genes was repressed in nd1 under both normal and salt stress conditions. Exogenous ABA can restore nd1-impaired salt stress tolerance. Moreover, overexpression of OsCSLD4 can enhance rice ABA synthesis gene expression, increase ABA content and improve rice salt tolerance, thus implying that OsCSLD4-regulated rice salt stress tolerance is mediated by ABA synthesis. Additionally, nd1 decreased rice tolerance to osmotic stress, but not ion toxic tolerance. The results from the transcriptome analysis showed that more osmotic stress-responsive genes were impaired in nd1 than salt stress-responsive genes, thus indicating that OsCSLD4 is involved in rice salt stress response through an ABA-induced osmotic response pathway. Intriguingly, the disruption of OsCSLD4 function decreased grain width and weight, while overexpression of OsCSLD4 increased grain width and weight. Taken together, this study demonstrates a novel plant salt stress adaptation mechanism by which crops can coordinate salt stress tolerance and yield.

Genome-wide bioinformatics analysis of Cellulose Synthase gene family in common bean (Phaseolus vulgaris L.) and the expression in the pod development

Background

CesA and Csl gene families, which belong to the cellulose synthase gene superfamily, plays an important role in the biosynthesis of the plant cell wall. Although researchers have investigated this gene superfamily in several model plants, to date, no comprehensive analysis has been conducted in the common bean.

Results

In this study, we identified 39 putative cellulose synthase genes from the common bean genome sequence. Then, we performed a bioinformatics analysis of this gene family involving sequence alignment, phylogenetic analysis, gene structure, collinearity analysis and chromosome location. We found all members possess a cellulose_synt domain. Phylogenetic analysis revealed that these cellulose synthase genes may be classified into five subfamilies, and that members in the same subfamily share conserved exon-intron distribution and motif compositions. Abundant and distinct cis-acting elements in the 2 k basepairs upstream regulatory regions indicate that the cellulose synthase gene family may plays a vital role in the growth and development of common bean. Moreover, the 39 cellulose synthase genes are distributed on 10 of the 11 chromosomes. Additionally expression analysis shows that all CesA/Csl genes selected are constitutively expressed in the pod development.

Conclusions

This research reveals both the putative biochemical and physiological functions of cellulose synthase genes in common bean and implies the importance of studying non-model plants to understand the breadth and diversity of cellulose synthase genes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12863-022-01026-0.

Genome-wide characterization of the cellulose synthase gene superfamily in Pyrus bretschneideri and reveal its potential role in stone cell formation

Members of the cellulose synthase (CesA) and cellulose synthase-like (Csl) families from the cellulose synthase gene superfamily participate in cellulose and hemicellulose synthesis in the plasma membrane. The members of this superfamily are vital for cell wall construction during plant growth and development. However, little is known about their function in pear fruit, a model for Rosaceae species and for fleshy fruit development. In our research, a total of 36 CesA/Csl family members were identified from the pear and were grouped into six subfamilies (CesA, CslB, CslC, CslD, CslE, and CslG) according to phylogenetic relationships. We performed a protein sequence physicochemical analysis, phylogenetic tree construction, a gene structure, a conserved domain, and chromosomal localization analysis. The results indicated that most of the CesA/Csl genes from pear are closely related to genes in Arabidopsis, but these families have unique characteristics in terms of their gene structure, chromosomal localization, phylogeny, and deduced protein sequences, suggesting that they have evolved through different processes. Tissue expression analysis results showed that most of the CesA/Csl genes were constitutively expressed at different levels in different organs. Furthermore, the expression levels of four genes (Pbr032894.2, Pbr016107.1, Pbr00518.1, and Pbr034218.1) tended to first increase and then decrease during fruit development, implying that these four genes may be involved in the development of stone cells of pear fruit. Our results may help elucidate the evolutionary history and functional differences of the CesA/Csl genes in pear and lay a foundation for further investigation of the CesA/Csl genes in pear and other Rosaceae species.

Biochemical and Genetic Analysis Identify CSLD3 as a beta-1,4-Glucan Synthase That Functions during Plant Cell Wall Synthesis

In plants, changes in cell size and shape during development fundamentally depend on the ability to synthesize and modify cell wall polysaccharides. The main classes of cell wall polysaccharides produced by terrestrial plants are cellulose, hemicelluloses, and pectins. Members of the cellulose synthase (CESA) and cellulose synthase-like (CSL) families encode glycosyltransferases that synthesize the β-1,4-linked glycan backbones of cellulose and most hemicellulosic polysaccharides that comprise plant cell walls. Cellulose microfibrils are the major load-bearing component in plant cell walls and are assembled from individual β-1,4-glucan polymers synthesized by CESA proteins that are organized into multimeric complexes called CESA complexes, in the plant plasma membrane. During distinct modes of polarized cell wall deposition, such as in the tip growth that occurs during the formation of root hairs and pollen tubes or de novo formation of cell plates during plant cytokinesis, newly synthesized cell wall polysaccharides are deposited in a restricted region of the cell. These processes require the activity of members of the CESA-like D subfamily. However, while these CSLD polysaccharide synthases are essential, the nature of the polysaccharides they synthesize has remained elusive. Here, we use a combination of genetic rescue experiments with CSLD-CESA chimeric proteins, in vitro biochemical reconstitution, and supporting computational modeling and simulation, to demonstrate that Arabidopsis (Arabidopsis thaliana) CSLD3 is a UDP-glucose-dependent β-1,4-glucan synthase that forms protein complexes displaying similar ultrastructural features to those formed by CESA6.

Cotton CSLD3 restores cell elongation and cell wall integrity mainly by enhancing primary cellulose production in the Arabidopsis cesa6 mutant

Overexpression of cotton cellulose synthase like D3 (GhCSLD3) gene partially rescued growth defect of atcesa6 mutant with restored cell elongation and cell wall integrity mainly by enhancing primary cellulose production. Among cellulose synthase like (CSL) family proteins, CSLDs share the highest sequence similarity to cellulose synthase (CESA) proteins. Although CSLD proteins have been implicated to participate in the synthesis of carbohydrate-based polymers (cellulose, pectins and hemicelluloses), and therefore plant cell wall formation, the exact biochemical function of CSLD proteins remains controversial and the function of the remaining CSLD genes in other species have not been determined. In this study, we attempted to illustrate the function of CSLD proteins by overexpressing Arabidopsis AtCSLD2, -3, -5 and cotton GhCSLD3 genes in the atcesa6 mutant, which has a background that is defective for primary cell wall cellulose synthesis in Arabidopsis. We found that GhCSLD3 overexpression partially rescued the growth defect of the atcesa6 mutant during early vegetative growth. Despite the atceas6 mutant having significantly reduced cellulose contents, the defected cell walls and lower dry mass, GhCSLD3 overexpression largely restored cell wall integrity (CWI) and improved the biomass yield. Our result suggests that overexpression of the GhCSLD protein enhances primary cell wall synthesis and compensates for the loss of CESAs, which is required for cellulose production, therefore rescuing defects in cell elongation and CWI.

Differences in protein structural regions that impact functional specificity in GT2 family β-glucan synthases

Most cell wall and secreted β-glucans are synthesised by the CAZy Glycosyltransferase 2 family (www.cazy.org), with different members catalysing the formation of (1,4)-β-, (1,3)-β-, or both (1,4)- and (1,3)-β-glucosidic linkages. Given the distinct physicochemical properties of each of the resultant β-glucans (cellulose, curdlan, and mixed linkage glucan, respectively) are crucial to their biological and biotechnological functions, there is a desire to understand the molecular evolution of synthesis and how linkage specificity is determined. With structural studies hamstrung by the instability of these proteins to solubilisation, we have utilised in silico techniques and the crystal structure for a bacterial cellulose synthase to further understand how these enzymes have evolved distinct functions. Sequence and phylogenetic analyses were performed to determine amino acid conservation, both family-wide and within each sub-family. Further structural analysis centred on comparison of a bacterial curdlan synthase homology model with the bacterial cellulose synthase crystal structure, with molecular dynamics simulations performed with their respective β-glucan products bound in the trans-membrane channel. Key residues that differentially interact with the different β-glucan chains and have sub-family-specific conservation were found to reside at the entrance of the trans-membrane channel. The linkage-specific catalytic activity of these enzymes and hence the type of β-glucan chain built is thus likely determined by the different interactions between the proteins and the first few glucose residues in the channel, which in turn dictates the position of the acceptor glucose. The sequence-function relationships for the bacterial β-glucan synthases pave the way for extending this understanding to other kingdoms, such as plants.

Characterization of Cellulose synthase-like D (CSLD) family revealed the involvement of PtrCslD5 in root hair formation in Populus trichocarpa

Cellulose synthase-like D (CSLD) family was characterized for their expression and functions in Populus trichocarpa. Ten members, PtrCslD1-10, were identified in the P. trichocarpa genome, and they belong to 4 clades by phylogenetic tree analysis. qRT-PCR and promoter:GUS assays in Arabidopsis and P. trichocarpa displayed divergent expression patterns of these 10 PtrCSLD genes in root hairs, root tips, leaves, vascular tissues, xylem and flowers. Among PtrCslD2, PtrCslD4, PtrCslD5, PtrCslD6, and PtrCslD8 that all exhibited expression in root hairs, only PtrCslD5 could restore the root hairless phenotype of the atcsld3 mutant, demonstrating that PtrCslD5 is the functional ortholog of AtCslD3 for root hair formation. Our results suggest more possible functions for other PtrCslD genes in poplar.

Cell Wall Enzymes in Zygnema circumcarinatum UTEX 1559 Respond to Osmotic Stress in a Plant-Like Fashion

Previous analysis of charophyte green algal (CGA) genomes and transcriptomes for specific protein families revealed that numerous land plant characteristics had already evolved in CGA. In this study, we have sequenced and assembled the transcriptome of Zygnema circumcarinatum UTEX 1559, and combined its predicted protein sequences with those of 13 additional species [five embryophytes (Emb), eight charophytes (Cha), and two chlorophytes (Chl) as the outgroup] for a comprehensive comparative genomics analysis. In total 25,485 orthologous gene clusters (OGCs, equivalent to protein families) of the 14 species were classified into nine OGC groups. For example, the Cha+Emb group contains 4,174 OGCs found in both Cha and Emb but not Chl species, representing protein families that have evolved in the common ancestor of Cha and Emb. Different OGC groups were subjected to a Gene Ontology (GO) enrichment analysis with the Chl+Cha+Emb group (including 5,031 OGCs found in Chl and Cha and Emb) as the control. Interestingly, nine of the 20 top enriched GO terms in the Cha+Emb group are cell wall-related, such as biological processes involving celluloses, pectins, lignins, and xyloglucans. Furthermore, three glycosyltransferase families (GT2, 8, 43) were selected for in-depth phylogenetic analyses, which confirmed their presence in UTEX 1559. More importantly, of different CGA groups, only Zygnematophyceae has land plant cellulose synthase (CesA) orthologs, while other charophyte CesAs form a CGA-specific CesA-like (Csl) subfamily (likely also carries cellulose synthesis activity). Quantitative real-time-PCR experiments were performed on selected GT family genes in UTEX 1559. After osmotic stress treatment, significantly elevated expression was found for GT2 family genes ZcCesA, ZcCslC and ZcCslA-like (possibly mannan and xyloglucan synthases, respectively), as well as for GT8 family genes (possibly pectin synthases). All these suggest that the UTEX 1559 cell wall polysaccharide synthesis-related genes respond to osmotic stress in a manner that is similar to land plants.

Genome-wide characterization of the cellulose synthase gene superfamily in Solanum lycopersicum

The cellulose synthase gene superfamily, which includes the cellulose synthase (CesA) and cellulose synthase-like (Csl) gene families, plays a vital role in the biosynthesis of cellulose and hemicellulose in plants. However, these genes have not been extensively studied in tomato (Solanum lycopersicum), a model for Solanaceae plants and for fleshy fruit development. Here, we identified and systematically analyzed 38 CesA/Csl family members that contained cellulose synthase domain regions, and categorized their encoded proteins into 6 subfamilies (CesA, CslA, CslB, CslD, CslE, and CslG) based on phylogenetic analysis. Most CesA/Csl genes from tomato are closely related to those from Arabidopsis, but the families have distinct features regarding gene structure, chromosome distribution and localization, phylogeny, and deduced protein sequence, indicating that they arose via different evolutionary process. Furthermore, expression analysis of CesA/Csl genes in different tissues at various developmental stages showed that most CesAs were constitutively expressed with differential expression levels in various organs; three CslD genes were expressed specifically in flowers, and four CesA and five Csl putative genes were preferentially expressed in fruits. Our results provide insight into the general characteristics of the CesA/Csl genes in tomato, and lay the foundation for further functional studies of CesA/Csl genes in tomato and other Solanaceae species.

Genome-wide identification and analysis of the evolution and expression patterns of the cellulose synthase gene superfamily in Gossypium species

The cellulose synthase gene superfamily, which includes the cellulose synthase (Ces) and cellulose synthase-like (Csl) families, is involved in the synthesis of cellulose and hemicellulose. This superfamily is critical for cotton fiber development in Gossypium species. Applying a series of bioinformatic methods, we identified 228 Ces/Csl genes from four Gossypium species (G. hirsutum, G. barbadense, G. arboreum, and G. raimondii). These genes were then grouped into 11 subfamilies based on phylogenetic relationships. A subsequent analysis of gene evolution revealed sites in CSLG and CSLJ genes that were under long-term positive selection pressure, with a posterior probability >0.95. Moreover, the d_N:d_S value for the CSLJ clade was 1.305, suggesting this subfamily was under positive selection pressure. Our data indicated that the d_N:d_S value ranged from 0.0084 to 0.9693 among the homologous Ces/Csl genes, implying they were under purifying selection pressure. Our transcriptome and qRT-PCR analyses revealed that CesA genes were more highly expressed in tetraploids than in diploids. However, the Csl expression levels exhibited the opposite trend. Furthermore, changes to promoter sequences may have influenced the expression of homologous Ces/Csl genes. Our findings may provide novel insights into the evolutionary relationships and expression patterns of the Ces/Csl genes in Gossypium species.