Search Results (27)

Dirigent proteins (DIR) are involved in lignan biosynthesis, stress responses, and disease resistance in plants. However, systematic characterization of the DIR gene family in watermelon (Citrullus lanatus) remains limited. Here, we identified 22 ClDIR genes in watermelon using bioinformatics methods, designated ClDIR1 to ClDIR22, which were unevenly distributed across eight chromosomes and classified into three subfamilies (DIR-a, DIR-b/d, DIR-e) based on phylogenetic analysis, with DIR-b/d being the largest. Synteny analysis revealed that tandem duplication primarily drove ClDIR family expansion, and collinear relationships with Arabidopsis, rice, and cucurbit species indicated evolutionary conservation. Cis-acting element analysis showed abundant stress- and hormone-responsive elements in ClDIR promoters, suggesting roles in stress regulation. Tissue-specific expression analysis demonstrated distinct patterns, with most genes highly expressed in roots. Expression profiling under 16 abiotic and biotic stresses showed 18 ClDIR genes responded to stress, with ClDIR8 differentially expressed across all conditions. qRT-PCR validation of six key genes (ClDIR5, ClDIR8, ClDIR9, ClDIR12, ClDIR16, ClDIR22) confirmed their expression patterns under high-temperature, drought, salt, and low-temperature stresses, showing a high degree of consistency with transcriptome data. Subcellular localization indicated ClDIR8 is peroxisome-localized. Yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays validated two ClDIR8-interacting proteins, Cla97C02G049920 (encoding peroxidase) and Cla97C08G152180 (encoding catalase). These findings provide insights into ClDIR genes in watermelon, highlighting ClDIR8 as a key stress-responsive candidate for further functional studies and breeding. Full article

Dirigent proteins (DIRs) are pivotal regulators of lignin/lignan biosynthesis and play multifaceted roles in plant development and stress adaptation. Despite their functional significance, DIR genes remain unexplored in Rosa chinensis, a globally important woody ornamental species. This study identified 33 RcDIRs through whole-genome analysis, including their chromosomal distribution, phylogenetic relationships, collinearity, protein and gene structure, conserved motifs, and cis-acting element distribution, and classified them into three phylogenetically independent subgroups (DIR-a, DIR-b/d, and DIR-e). Notably, the DIR-e subgroup includes an exclusive tandem cluster comprising RcDIR7-RcDIR12, representing the largest lineage-specific RcDIR expansion in R. chinensis. Structural characterization revealed that most RcDIRs exhibit a conserved single-exon architecture. Promoter cis-element analysis uncovered abundant stress-/hormone-responsive elements and three pollen-specific motifs (AAATGA, POLLEN1LELAT52, GTGANTG10), with RcDIR12 from the DIR-e cluster showing high pollen-specific regulatory potential. Experimental validation included cloning the RcDIR12 promoter from R. chinensis ‘Old Blush’, constructing proRcDIR12::GUS vectors, and conducting histochemical GUS assays with pollen viability/DAPI staining in transgenic Arabidopsis. Histochemical assays demonstrated GUS activity localization in mature trinucleate pollen grains, marking the first experimental evidence of pollen-specific DIRs in rose. Our findings not only elucidate the DIR family’s genomic organization and evolutionary innovations in R. chinensis but also establish proRcDIR12 as a molecular tool for manipulating pollen development in plants. Full article

The DIR (Dirigent) gene family plays a multifaceted role in plant growth, development, and stress responses, making it one of the key gene families for plant adaptation to environmental changes. However, research on ZmDIRs in maize remains limited. In this study, we identified a member of the maize DIR gene family, ZmDIR5, whose promoter region contains numerous elements associated with responses to abiotic stresses. ZmDIR5 is upregulated in response to waterlogging, salt, and drought stresses, and its protein is localized in the endoplasmic reticulum. Subsequent studies revealed that ZmDIR5-EMS (ethyl methane sulfonate) mutant lines exhibited reduced growth compared to WT (wild-type) plants under waterlogging, salt, and drought stress conditions. The mutant lines also demonstrated a relatively higher accumulation of malondialdehyde and reactive oxygen species, lower synthesis of proline and total lignans, and decreased antioxidant enzyme activity under these stress conditions. Additionally, the mutant lines displayed impaired sodium and potassium ion transport capabilities, reduced synthesis of abscisic acid and zeatin, and decreased expression of related genes. The mutation of ZmDIR5 also inhibited the phenylpropanoid biosynthesis pathway in maize. These results indicate that ZmDIR5 serves as a positive regulator of maize tolerance to waterlogging, salt, and drought stresses. Full article

The DIR gene family, which encodes Dirigent proteins, plays a crucial role in plant development and stress responses. However, the functions and mechanisms of this family in maize remained underexplored. This study identified ZmDIR11, a member of the maize Dirigent protein family, and explored its role in drought tolerance. ZmDIR11 shared conserved regions with homologous proteins in wheat, rice, and Arabidopsis. RT-qPCR analysis revealed that ZmDIR11 expression is upregulated in leaves under drought and PEG stress, while subcellular localization confirmed its presence in the endoplasmic reticulum. Virus-induced gene silencing (VIGS) and EMS mutagenesis demonstrated that ZmDIR11 silencing or mutation significantly reduces drought tolerance in maize seedlings, indicating its positive regulatory role. Silencing or mutation of ZmDIR11 led to decreased growth parameters (plant height, root length, fresh weight, dry weight, and chlorophyll content) under drought stress, alongside a reduced antioxidant capacity, as evidenced by increased levels of MDA and ROS and decreased activities of SOD, CAT, and POD. Furthermore, ZmDIR11 mutation impaired the synthesis of ABA and zeatin, downregulating key genes in the ABA (ZmABA1, ZmNCED3, ZmSnRK2.6) and zeatin (ZmIPT4, ZmCKO5, ZmCKO4b) pathways. Drought-responsive genes (ZmRD20, ZmRD22, ZmDREB2A) and lignan biosynthesis genes (Zm4CL, ZmC3H, ZmCAD1) are also downregulated in ZmDIR11 mutants. In conclusion, ZmDIR11 enhances drought tolerance in maize by regulating antioxidant capacity, ABA and zeatin synthesis, and lignan metabolism. This study provides new insights into the role of DIR genes in drought tolerance and offers a potential genetic resource for breeding drought-resistant maize varieties. Full article

Pulsed electric field (PEF) has previously been recognized as a method of gentle food processing, and its use has been shown to be helpful in reducing the levels of toxigenic Fusarium micromycetes developed during malting. The aim of this study was to describe the effects of PEF on gene expression and metabolite production at the pre-finishing stage of barley malting by using a novel multi-omics data-driven approach. The study helps to uncover the processes occurring in the germinated grain and discusses the up-/downregulation of genes and metabolites in relation to fungal infection and/or PEF-induced abiotic stress. Among the factors upregulated by PEF and previously described as supportive against Fusarium diseases, we identified the increased expression of genes encoding vegetative gp1-like protein, which positively correlated with flavonoids, (methylsulfanyl)prop-2-enoates, triterpenoid glycosides, and indole alkaloids. On the other hand, some genes associated with barley resistance to fungal infection were also overexpressed in the untreated control (in particular, genes encoding ethylene response factor 3-like, putrescine hydroxycinnamoyltransferase 3-like, and dirigent protein 21-like). This study provides the first ‘data-driven’ basic research results that contribute to the understanding of the role of PEF as an effective fungal decontamination strategy and allows the formulation of new hypotheses related to Fusarium pathogen crosstalk. Full article

Magnolia obovata is renowned for its unique bioactive constituents with medicinal properties traditionally used to treat digestive disorders, anxiety, and respiratory conditions. This study aimed to establish a comprehensive omics resource through untargeted metabolome and transcriptome profiling to explore biosynthesis of pharmacologically active compounds of M. obovata using seven tissues: young leaf, mature leaf, stem, bark, central cylinder, floral bud, and pistil. Untargeted metabolomic analysis identified 6733 mass features across seven tissues and captured chemo-diversity and its tissue-specificity in M. obovata. Through a combination of cheminformatics and manual screening approach, we confirmed the identities of 105 metabolites, including neolignans, such as honokiol and magnolol, which were found to be spatially accumulated in the bark tissue. RNA sequencing generated a comprehensive transcriptome resource, and expression analysis revealed significant tissue-specific expression patterns. Omics dataset integration identified T12 transcript module from WGCNA being correlated with the biosynthesis of magnolol and honokiol in M. obovata. Notably, phylogenetic analysis using transcripts from T12 module identified two laccase (Mo_LAC1 and Mo_LAC2) and three dirigent proteins from the DIR-b/d subfamily as potential candidate genes involved in neolignan biosynthesis. This research established omics resources of M. obovata and laid the groundwork for future studies aimed at optimizing and further understanding the biosynthesis of metabolites of therapeutic potential. Full article

Dirigent (DIR) genes play a pivotal role in plant development and stress adaptation. Manihot esculenta Crantz, commonly known as cassava, is a drought-resistant plant thriving in tropical and subtropical areas. It is extensively utilized for starch production, bioethanol, and animal feed. However, a comprehensive analysis of the DIR family genes remains unexplored in cassava, a crucial cash and forage crop in tropical and subtropical regions. In this study, we characterize a total of 26 cassava DIRs (MeDIRs) within the cassava genome, revealing their uneven distribution across 13 of the 18 chromosomes. Phylogenetic analysis classified these genes into four subfamilies: DIR-a, DIR-b/d, DIR-c, and DIR-e. Comparative synteny analysis with cassava and seven other plant species (Arabidopsis (Arabidopsis thaliana), poplar (Populus trichocarpa), soybean (Glycine max), tomato (Solanum lycopersicum), rice (Oryza sativa), maize (Zea mays), and wheat (Triticum aestivum)) provided insights into their likely evolution. We also predict protein interaction networks and identify cis-acting elements, elucidating the functional differences in MeDIR genes. Notably, MeDIR genes exhibited specific expression patterns across different tissues and in response to various abiotic and biotic stressors, such as pathogenic bacteria, cadmium chloride (CdCl₂), and atrazine. Further validation through quantitative real-time PCR (qRT-PCR) confirmed the response of DIR genes to osmotic and salt stress. These findings offer a comprehensive resource for understanding the characteristics and biological functions of MeDIR genes in cassava, enhancing our knowledge of plant stress adaptation mechanisms. Full article

Schima superba, commonly known as the Chinese guger tree, is highly adaptable and tolerant of poor soil conditions. It is one of the primary species forming the evergreen broad-leaved forests in southern China. Dirigent proteins (DIRs) play crucial roles in the synthesis of plant lignin and lignans, secondary metabolism, and response to adversity stress. However, research on the DIR gene family in S. superba is currently limited. This study identified 24 SsDIR genes, categorizing them into three subfamilies. These genes are unevenly distributed across 13 chromosomes, with 83% being intronless. Collinearity analysis indicated that tandem duplication played a more significant role in the expansion of the gene family compared to segmental duplication. Additionally, we analyzed the expression patterns of SsDIRs in different tissues of S. superba. The SsDIR genes exhibited distinct expression patterns across various tissues, with most being specifically expressed in the roots. Further screening identified SsDIR genes that may regulate drought stress, with many showing differential expression under drought stress conditions. In the promoter regions of SsDIRs, various cis-regulatory elements involved in developmental regulation, hormone response, and stress response were identified, which may be closely related to their diverse regulatory functions. This study will contribute to the further functional identification of SsDIR genes, providing insights into the biosynthetic pathways of lignin and lignans and the mechanisms of plant stress resistance. Full article

The remediation of copper and nickel-afflicted sites is challenged by the different physiological effects imposed by each metal on a given plant system. Pinus banksiana is resilient against copper and nickel, providing an opportunity to build a valuable resource to investigate the responding gene expression toward each metal. The objectives of this study were to (1) extend the analysis of the Pinus banksiana transcriptome exposed to nickel and copper, (2) assess the differential gene expression in nickel-resistant compared to copper-resistant genotypes, and (3) identify mechanisms specific to each metal. The Illumina platform was used to sequence RNA that was extracted from seedlings treated with each of the metals. There were 449 differentially expressed genes (DEGs) between copper-resistant genotypes (RGs) and nickel-resistant genotypes (RGs) at a high stringency cut-off, indicating a distinct pattern of gene expression toward each metal. For biological processes, 19.8% of DEGs were associated with the DNA metabolic process, followed by the response to stress (13.15%) and the response to chemicals (8.59%). For metabolic function, 27.9% of DEGs were associated with nuclease activity, followed by nucleotide binding (27.64%) and kinase activity (10.16%). Overall, 21.49% of DEGs were localized to the plasma membrane, followed by the cytosol (16.26%) and chloroplast (12.43%). Annotation of the top upregulated genes in copper RG compared to nickel RG identified genes and mechanisms that were specific to copper and not to nickel. NtPDR, AtHIPP10, and YSL1 were identified as genes associated with copper resistance. Various genes related to cell wall metabolism were identified, and they included genes encoding for HCT, CslE6, MPG, and polygalacturonase. Annotation of the top downregulated genes in copper RG compared to nickel RG revealed genes and mechanisms that were specific to nickel and not copper. Various regulatory and signaling-related genes associated with the stress response were identified. They included UGT, TIFY, ACC, dirigent protein, peroxidase, and glyoxyalase I. Additional research is needed to determine the specific functions of signaling and stress response mechanisms in nickel-resistant plants. Full article

Target spot is caused by Corynespora cassiicola, which heavily affects soybean production areas that are hot and humid. Resistant soybean genotypes have been identified; however, the molecular mechanisms governing resistance to infection are unknown. Comparative transcriptomic profiling using two known resistant genotypes and two susceptible genotypes was performed under infected and control conditions to understand the regulatory network operating between soybean and C. cassiicola. RNA-Seq analysis identified a total of 2571 differentially expressed genes (DEGs) which were shared by all four genotypes. These DEGs are related to secondary metabolites, immune response, defense response, phenylpropanoid, and flavonoid/isoflavonoid pathways in all four genotypes after C. cassiicola infection. In the two resistant genotypes, additional upregulated DEGs were identified affiliated with the defense network: flavonoids, jasmonic acid, salicylic acid, and brassinosteroids. Further analysis led to the identification of differentially expressed transcription factors, immune receptors, and defense genes with a leucine-rich repeat domain, dirigent proteins, and cysteine (C)-rich receptor-like kinases. These results will provide insight into molecular mechanisms of soybean resistance to C. cassiicola infection and valuable resources to potentially pyramid quantitative resistance loci for improving soybean germplasm. Full article

Dirigent proteins (DIRs) contribute to plant fitness by dynamically reorganizing the cell wall and/or by generating defense compounds during plant growth, development, and interactions with environmental stresses. ZmDRR206 is a maize DIR, it plays a role in maintaining cell wall integrity during seedling growth and defense response in maize, but its role in regulating maize kernel development is unclear. Association analysis of candidate genes indicated that the natural variations of ZmDRR206 were significantly associated with maize hundred-kernel weight (HKW). ZmDRR206 plays a dominant role in storage nutrient accumulation in endosperm during maize kernel development, ZmDRR206 overexpression resulted in small and shrunken maize kernel with significantly reduced starch content and significantly decreased HKW. Cytological characterization of the developing maize kernels revealed that ZmDRR206 overexpression induced dysfunctional basal endosperm transfer layer (BETL) cells, which were shorter with less wall ingrowth, and defense response was constitutively activated in developing maize kernel at 15 and 18 DAP by ZmDRR206 overexpression. The BETL-development-related genes and auxin signal-related genes were down-regulated, while cell wall biogenesis-related genes were up-regulated in developing BETL of the ZmDRR206-overexpressing kernel. Moreover, the developing ZmDRR206-overexpressing kernel had significantly reduced contents of the cell wall components such as cellulose and acid soluble lignin. These results suggest that ZmDRR206 may play a regulatory role in coordinating cell development, storage nutrient metabolism, and stress responses during maize kernel development through its role in cell wall biogenesis and defense response, and provides new insights into understanding the mechanisms of kernel development in maize. Full article

Dirigent (DIR) members have been shown to play essential roles in plant growth, development and adaptation to environmental changes. However, to date, there has been no systematic analysis of the DIR members in the genus Oryza. Here, 420 genes were identified from nine rice species to have the conserved DIR domain. Importantly, the cultivated rice species Oryza sativa has more DIR family members than the wild rice species. DIR proteins in rice could be classified into six subfamilies based on phylogeny analysis. Gene duplication event analysis suggests that whole genome/segmental duplication and tandem duplication are the primary drivers for DIR genes’ evolution in Oryza, while tandem duplication is the main mechanism of gene family expansion in the DIR-b/d and DIR-c subfamilies. Analysis of the RNA sequencing data indicates that OsjDIR genes respond to a wide range of environmental factors, and most OsjDIR genes have a high expression level in roots. Qualitative reverse transcription PCR assays confirmed the responsiveness of OsjDIR genes to the undersupply of mineral elements, the excess of heavy metals and the infection of Rhizoctonia solani. Furthermore, there exist extensive interactions between DIR family members. Taken together, our results shed light on and provide a research foundation for the further exploration of DIR genes in rice. Full article

MonocotJRLs are Poaceae-specific two-domain proteins that consist of a jacalin-related lectin (JRL) and a dirigent (DIR) domain which participate in multiple developmental processes, including disease resistance. For OsJAC1, a monocotJRL from rice, it has been confirmed that constitutive expression in transgenic rice or barley plants facilitates broad-spectrum disease resistance. In this process, both domains of OsJAC1 act cooperatively, as evidenced from experiments with artificially separated JRL- or DIR-domain-containing proteins. Interestingly, these chimeric proteins did not evolve in dicotyledonous plants. Instead, proteins with a single JRL domain, multiple JRL domains or JRL domains fused to domains other than DIR domains are present. In this study, we wanted to test if the cooperative function of JRL and DIR proteins leading to pathogen resistance was conserved in the dicotyledonous plant Arabidopsis thaliana. In Arabidopsis, we identified 50 JRL and 24 DIR proteins, respectively, from which seven single-domain JRL and two single-domain DIR candidates were selected. A single-cell transient gene expression assay in barley revealed that specific combinations of the Arabidopsis JRL and DIR candidates reduced the penetration success of barley powdery mildew. Strikingly, one of these pairs, AtJAX1 and AtDIR19, is encoded by genes located next to each other on chromosome one. However, when using natural variation and analyzing Arabidopsis ecotypes that express full-length or truncated versions of AtJAX1, the presence/absence of the full-length AtJAX1 protein could not be correlated with resistance to the powdery mildew fungus Golovinomyces orontii. Furthermore, an analysis of the additional JRL and DIR candidates in a bi-fluorescence complementation assay in Nicotiana benthamiana revealed no direct interaction of these JRL/DIR pairs. Since transgenic Arabidopsis plants expressing OsJAC1-GFP also did not show increased resistance to G. orontii, it was concluded that the resistance mediated by the synergistic activities of DIR and JRL proteins is specific for members of the Poaceae, at least regarding the resistance against powdery mildew. Arabidopsis lacks the essential components of the DIR-JRL-dependent resistance pathway. Full article

Pesticides are routinely used to prevent severe losses in agriculture. This practice is under debate because of its potential negative environmental impact and selection of resistances in pathogens. Therefore, the development of disease resistant plants is mandatory. It was shown that the rice (Oryza sativa) protein OsJAC1 enhances resistance against different bacterial and fungal plant pathogens in rice, barley, and wheat. Recently we reported possible carbohydrate interaction partners for both domains of OsJAC1 (a jacalin-related lectin (JRL) and a dirigent (DIR) domain), however, a mechanistic understanding of its function is still lacking. Here, we report crystal structures for both individual domains and the complex of galactobiose with the DIR domain, which revealed a new carbohydrate binding motif for DIR proteins. Docking studies of the two domains led to a model of the full-length protein. Our findings offer insights into structure and binding properties of OsJAC1 and its possible function in pathogen resistance. Full article

Dirigent proteins (DIR) play important roles in the biosynthesis of lignins and lignans, defensive responses, secondary metabolism, and disease resistance in plants. The DIR gene family has been identified and studied in many plants. However, the identification of DIR gene family in eggplant has not been conducted yet. Therefore, in this study, based on the available genome information of eggplant, the DIR family genes in eggplant were identified with bioinformatics methods. The expression pattern analyses of eggplant DIR family genes in different organs and stresses were also conducted to understand their biological functions. The results showed that a total of 24 DIR genes were identified in the eggplant, which were divided into three subfamilies (DIR-a, DIR-b/d, and DIR-e). Synteny analysis of DIR genes among eggplant, Arabidopsis, and rice showed that 15 eggplant DIR genes were colinear with 18 Arabidopsis DIR genes, and 16 eggplant DIR genes were colinear with 15 rice DIR genes. Phylogenetic tree analysis showed that 19 pairs of orthologous genes were identified between eggplant and pepper. The cis-acting elements analysis implied that the eggplant DIR genes contained a lot of cis-elements associated with stress and hormone response. The organ-specific expression analysis of eggplant DIR family genes revealed that only the SmDIR3 gene was highly expressed in all the 19 organs of eggplant. Some SmDIR genes, including SmDIR7, SmDIR8, SmDIR11, SmDIR14, SmDIR18, SmDIR19, SmDIR20, and SmDIR23, were not or were lowly expressed in the eggplant organs, while the other eggplant DIR family genes showed an organ-specific expression pattern. Furthermore, 19 of 24 SmDIR genes were differentially expressed in response to abiotic and biotic stresses. 5 SmDIR genes, including SmDIR3, SmDIR5, SmDIR6, SmDIR12, and SmDIR22, were differentially expressed under multiple types of abiotic and biotic stresses. Especially notable, the SmDIR22 gene was differentially expressed under three types of abiotic stresses and two types of biotic stresses, which indicated that the SmDIR22 gene plays an important role in the response to abiotic and biotic stresses. These results provide valuable evidence for a better understanding of the biological role of DIR genes in eggplant. Full article