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Gene structure and protein domain prediction of WAK2 gene in the FHB-resistant hexaploid accession 02-5B-318 and the FHB-susceptible tetraploid cv. Saragolla. Exons are represented as rectangular boxes, and introns are black lines between the exons. Green: GUB_WAK: Galacturonan-binding wall-associated receptor kinase; yellow: EGF: Calcium-binding EGF (Epidermal Growth Factor)-like domain; blue: PROTEIN KINASE: Ser/Thr Kinase cytoplasmic catalytic domain; black boxes: 3′ and 5′ UTR. Grey arrow: MITE transposon. Red arrow: 11 bp nucleotide insertion.
Source publication
Fusarium graminearum is one of the most threating pathogen of wheat, responsible for Fusarium head blight (FHB) which annually leads to yield losses, grain quality decay and accumulation of harmful mycotoxins in kernels. Host resistance represents the most effective approach to limit disease damages; however, only a limited number of resistant loci...
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Context 1
... A-genome was firstly isolated in the hexaploid 02-5B-318 accession ( Fig. S1) and in the durum wheat cv. Saragolla (Fig. S2), and physically localized on 2A chromosome by using nulli-tetrasomic aneuploid lines. Sequence isolated on 2A chromosome and associated to IWB63138 was undergone a prediction of potential genes by using Softberry software (Fig. 4) and BLAST with wheat ESTs. In the resistant parent (02-5B-318, R P) one gene was predicted accounting for a genomic sequence of 5,613 structured into 6 exons (mRNA of 2,262 bp), whereas two adjacent genes were predicted on the same DNA plus strand of the susceptible parent (Saragolla, S P): the first one accounted for a gDNA sequence ...
Context 2
... polymorphisms detected between R P and S P exerted important differences also in WAK protein structure (Fig. 4). In silico translation of 02-5B-318 mRNA resulted in an amino acidic sequence of 753 residues containing three functional domains: 1) Wall-Associated receptor kinase galacturonan-binding (GUB_WAK); 2) Calcium-binding EGF-like domain (EGF); 3) Ser/Thr kinase (catalitic domain). In contrast, the two proteins ...
Context 3
... the other hand, in the susceptible lines, two forms of WAK proteins are produced by the alternative splicing of WAK2 gene (illustrated in Fig. 4): the first one lacks the Ser/Thr kinase cytoplasmic domain, and the second one misses the EGF-transmembrane domain. According to our hypothesis, these latter are not-functional enzymes which lead to a less efficient intracellular cascade signaling. As a consequence, the mechanism of PME down-regulation is slowed, so that cell wall ...
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Key message
Four QTL for ergot resistance (causal pathogen Claviceps purpurea) have been identified in the durum wheat cultivar Greenshank.
Abstract
Claviceps purpurea is a pathogen of grasses that infects flowers, replacing the seed with an ergot sclerotium. Ergot presents a significant problem to rye, barley and wheat, in particular hybrid seed...
Fusarium head blight (FHB) is a highly destructive fungal disease of wheat to which host resistance is quantitatively inherited and largely influenced by the environment. Resistance to FHB has been associated with taller height and later maturity; however, a further understanding of these relationships is needed. An association mapping panel (AMP)...
Background
Fusarium head blight (FHB) caused by several Fusarium species, is one of the diseases causing the greatest worldwide damage to small grain cereals, especially wheat and barley. FHB outbreaks can substantially diminish grain yield and end-use quality due to sterile florets and withered, mycotoxin-contaminated grain kernels. Great effort h...
Phenotyping for quantitative resistance to Septoria tritici blotch (STB), one of the most economically devastating diseases of durum wheat (Triticum durum Desf.) in North African region, is a limiting factor for breeding progress. Here we tested main phenotypic markers of aggressiveness affecting host damage and pathogen reproduction reported in ea...
Citations
... In roots, WAK2 was somewhat inhibited, whereas LRR-RLK was activated. The biochemical modalities related to their function of recognizing various exogenous factors are different [165,166], WAK2 and LRR-RLK being described as conferring resistance against F. culmorum [167] and Blumeria graminis f. sp. tritici, respectively [168]. ...
Plant growth-promoting rhizobacteria (PGPR) applications have emerged as an ideal substitute for synthetic chemicals by their ability to improve plant nutrition and resistance against pathogens. In this study, we isolated fourteen root endophytes from healthy wheat roots cultivated in Tunisia. The isolates were identified based from their 16S rRNA gene sequences. They belonged to Bacillota and Pseudomonadota taxa. Fourteen strains were tested for their growth-promoting and defense-eliciting potentials on durum wheat under greenhouse conditions, and for their in vitro biocontrol power against Fusarium culmorum, an ascomycete responsible for seedling blight, foot and root rot, and head blight diseases of wheat. We found that all the strains improved shoot and/or root biomass accumulation, with Bacillus mojavensis, Paenibacillus peoriae and Variovorax paradoxus showing the strongest promoting effects. These physiological effects were correlated with the plant growth-promoting traits of the bacterial endophytes, which produced indole-related compounds, ammonia, and hydrogen cyanide (HCN), and solubilized phosphate and zinc. Likewise, plant defense accumulations were modulated lastingly and systematically in roots and leaves by all the strains. Testing in vitro antagonism against F. culmorum revealed an inhibition activity exceeding 40% for five strains: Bacillus cereus, Paenibacillus peoriae, Paenibacillus polymyxa, Pantoae agglomerans, and Pseudomonas aeruginosa. These strains exhibited significant inhibitory effects on F. culmorum mycelia growth, sporulation, and/or macroconidia germination. P. peoriae performed best, with total inhibition of sporulation and macroconidia germination. These finding highlight the effectiveness of root bacterial endophytes in promoting plant growth and resistance, and in controlling phytopathogens such as F. culmorum. This is the first report identifying 14 bacterial candidates as potential agents for the control of F. culmorum, of which Paenibacillus peoriae and/or its intracellular metabolites have potential for development as biopesticides.
... Fielder, however, is moderately resistant to FHB, while WL711 and Bobwhite are moderately susceptible (Han et al., 2012). Tetraploid genotypes Kronos and Altar are both susceptible to FHB (Gadaleta et al., 2019). ...
Feeding the world's ever‐increasing population requires continuous development of high‐yielding and disease‐resistant cultivars of food crops such as wheat (Triticum aestivum L.). Speed breeding, which utilizes longer photoperiod times and higher temperatures, is a technique that accelerates plant development and is rapidly being adopted by wheat breeders across the globe to fast‐track cultivar development. Plant diseases are a major threat to crop production, and breeding for disease resistance is a major goal of crop breeders. Fusarium head blight (FHB), caused by Fusarium graminearum, is a major disease of small grain cereals, affecting their yield and quality. The aim of present work was to assess if speed breeding conditions can be used to accelerate reliable assessment of FHB severity and mycotoxin deoxynivalenol (DON) accumulation in wheat varieties. We screened a set of six spring wheat genotypes with different levels of genetic resistance (two moderately susceptible, two highly susceptible, one moderately resistant, and one resistant) for their response to FHB at 14 days after inoculation (dai) and 21 dai and DON accumulation under normal versus speed breeding conditions. FHB severity and DON accumulation were found to be highly correlated at all time points under normal and speed breeding conditions. Robust differentiation between resistant and susceptible genotypes could be achieved at 14 dai rather than the normal period of 21 dai, saving at least a week in phenotyping. Combined with the accelerated growth, flowering, and maturity under these conditions, efficient FHB screening and DON evaluation under speed breeding conditions will fast‐track development of resistant wheat varieties.
... The pathogen penetrates the cell wall, and produces cell wall fragments that can be recognized and sensed by Htn1, which in turn transmits the signal downstream and activates the expression of PR genes to enhance maize resistance to leaf blight [14]. Similarly, TaWAK6 is involved in wheat resistance to leaf rust [15], and TaWAK2 enhances wheat resistance to Fusarium graminearum by binding to pectin [16], which further highlights the importance of WAKL gene family in plant disease resistance. Nevertheless, some WAKLs negatively regulate plant disease resistance. ...
Background
Sesame charcoal rot caused by Macrophomina phaseolina is one of the most serious fungal diseases in sesame production, and threatens the yield and quality of sesame. WAKL genes are important in the plant response to biotic stresses by sensing and transmitting external signals to the intracellular receptor. However, there is still a lack about the WAKL gene family and its function in sesame resistance to M. phaseolina. The aim of this study was to interpret the roles of WAKL genes in sesame resistance to M. phaseolina.
Results
In this study, a comprehensive study of the WAKL gene family was conducted and 31 WAKL genes were identified in the sesame genome. Tandem duplication events were the main factor in expansion of the SiWAKL gene family. Phylogenetic analysis showed that the sesame SiWAKL gene family was divided into 4 groups. SiWAKL genes exhibited different expression patterns in diverse tissues. Under M. phaseolina stress, most SiWAKL genes were significantly induced. Notably, SiWAKL6 was strongly induced in the resistant variety “Zhengzhi 13”. Functional analysis showed that SiWAKL6 was induced by salicylic acid but not methyl jasmonate in sesame. Overexpression of SiWAKL6 in transgenic Arabidopsis thaliana plants enhanced their resistance to M. phaseolina by inducing the expression of genes involved in the salicylic acid signaling pathway and reconstructing reactive oxygen species homeostasis.
Conclusions
Taken together, the results provide a better understanding of functions about SiWAKL gene family and suggest that manipulation of these SiWAKL genes can improve plant resistance to M. phaseolina. The findings contributed to further understanding of functions of SiWAKL genes in plant immunity.
... In roots, WAK2 was somewhat inhibited, whereas LRR-RLK was activated. The biochemical modalities related to their function of recognizing various exogenous factors are different [169,170], WAK2 and LRR-RLK being described as conferring resistance against F. culmorum [171] and Blumeria graminis f. sp. tritici, respectively [172]. ...
In recent decades, agriculture has been under strong pressure to achieve intensive levels of production. The success of this goal, largely achieved, is notably linked to the massive use of pesticides and chemical fertilizers. However, the use of these agrochemical products profoundly deteriorates the quality of soils and the environment. The challenge lies in the development of sustainable agricultural practices that harness the naturally associated microbiomes in crops, especially in cereal cultivation. This thesis aims to shed light on the complex aspects of microbial communities associated with an ancient variety of wheat, by identifying their potential beneficial effects on wheat growth and innate immunity. A total of 206 fungal isolates and 102 bacterial isolates were obtained from the rhizosphere, roots, and ears of the ancient wheat variety Florence Aurore. Among these isolates, 6 strains of Trichoderma from the rhizosphere and 14 root endophytic bacteria were selected to characterize their biofertilization potential for plant growth and their biocontrol activity against Fusarium culmorum, a predominant pathogen in Tunisia
causing economically damaging diseases. All these isolates demonstrated their
biostimulatory effectiveness in planta by increasing fresh and dry biomass as well as
chlorophyll content in wheat plants under controlled conditions. These capabilities
correlated with the ability of these strains in vitro to solubilize phosphate and zinc,
produce indolic compounds, ammonia, and hydrogen cyanide. At the same time, these strains showed biocontrol ability by eliciting systemic plant defenses in 21-day-old wheat seedlings. Similarly, the bacterial endophytes Paenibacillus polymyxa, Paenibacillus peoriae, and Pantoea agglomerans inhibited the mycelial growth, sporulation, and germination of F. culmorum macroconidia in vitro, either through direct contact or by treating the pathogen with purified intracellular fractions. These antagonistic abilities could be explained by the production of volatile organic compounds, antifungal substances, and extracellular lytic enzymes such as Amylase, Cellulase, Pectinase, Protease, and Chitinase. These observations offer promising solutions to further boost more environmentally friendly and productive cereal crops in Tunisia.
... Though WAK proteins in Arabidopsis regulate growth and development, their role in defense response is pivotal (Kohorn et al. 2014;Wagner and Kohorn 2001). For instance, in wheat, WAKs promoted resistance against Fusarium graminearum upon binding with pectin (Gadaleta et al. 2019). ...
Wall-associated kinases (WAKs) are a unique family of proteins that are predominantly localized on the plasma membrane and simultaneously bound to the cell wall. WAKs play a pivotal role in signal transduction to regulate growth, defense, and response to environmental stimuli in plants. These kinases have been identified and characterized in various plant species, however, similar information for Catharanthus roseus is scarce. C. roseus is an evergreen ornamental plant that produces a repertoire of biologically active compounds. The plant is best characterized for the production of antineoplastic monoter-penoid indole alkaloids (MIAs) namely vinblastine and vincristine. Owing to the diverse composition of phytochemicals, C. roseus is known as a "model non-model" plant for secondary metabolite research. Genome analyses showed 37 putative CrWAK genes present in C. roseus, largely localized on the plasma membrane. Phylogenetic analysis revealed six clusters of CrWAKs. Diverse cis-acting elements, including those involved in defense responses, were identified on the promotor regions of CrWAK genes. The highest binding affinity (− 12.6 kcal/mol) was noted for CrWAK-22 against tri-galacturonic acid. Tri-galacturonic acid stimulated 2.5-fold higher production of vinblastine, sixfold upregulation of the expression of ORCA3 transcription factor, and 6.14-fold upregulation of CrWAK-22 expression. Based on these results it was concluded that the expression of CrWAK genes induced by biotic elicitors may have an important role in the production of MIAs. The current findings may serve as a basis for functional characterization and mechanistic explanation of the role of CrWAK genes in the biosynthesis of MIAs upon elicitation.
... For example, UBP13 (Fig. 5e) encodes a ubiquitin-specific protease that is responsible for initial pathogen perception 60 , and UBC36 encodes an E2 ubiquitin-conjugating enzyme involved in dampening immune signaling 61 . The wall-associated receptor-like kinase gene, WAK2, also plays an important role in disease resistance 62 . Together, these genes influence the immune system and may reflect the fact that plants in cities face increased susceptibility to disease caused by different pathogens and pollutants compared to the ones living in the wild 63 . ...
Urban greening provides important ecosystem services and ideal places for urban recreation and is a serious consideration for municipal decision-makers. Among the tree species cultivated in urban green spaces, Robinia pseudoacacia stands out due to its attractive flowers, fragrances, high trunks, wide adaptability, and essential ecosystem services. However, the genomic basis and consequences of its wide-planting in urban green spaces remains unknown. Here, we report the chromosome-level genome assembly of R. pseudoacacia, revealing a genome size of 682.4 Mb and 33,187 protein-coding genes. More than 99.3% of the assembly is anchored to 11 chromosomes with an N50 of 59.9 Mb. Comparative genomic analyses among 17 species reveal that gene families related to traits favoured by urbanites, such as wood formation, biosynthesis, and drought tolerance, are notably expanded in R. pseudoacacia. Our population genomic analyses further recover 11 genes that are under recent selection. Ultimately, these genes play important roles in the biological processes related to flower development, water retention, and immunization. Altogether, our results reveal the evolutionary forces that shape R. pseudoacacia cultivated for urban greening. These findings also present a valuable foundation for the future development of agronomic traits and molecular breeding strategies for R. pseudoacacia.
... Consistent with several transcriptomic and proteomic studies [30,150], the six Trichoderma isolates induced the modulation of several plant resistance (R) genes, which was correlated with the activation of a wide range of plant defenses and a high physiological level of resistance. It is then also plausible that this resistance acquisition should be extended to pathosystems other than F. culmorum (and of which WAK2 would be one of their recognition systems [151]), such as Blumeria graminis f. sp. tritici (LRR RLK) [152], Puccinia triticina (WAK6) [153], Rhizoctonia cerealis (RLCK) [154], and those whose related receptor-like kinases encoding genes are significantly up-regulated by certain Trichoderma strains alone and/or in the presence of F. culmorum. ...
Beneficial microorganisms, including members of the Trichoderma genus, are known for their ability to promote plant growth and disease resistance, as well as being alternatives to synthetic inputs in agriculture. In this study, 111 Trichoderma strains were isolated from the rhizospheric soil of Florence Aurore, an ancient wheat variety that was cultivated in an organic farming system in Tunisia. A preliminary ITS analysis allowed us to cluster these 111 isolates into three main groups, T. harzianum (74 isolates), T. lixii (16 isolates) and T. sp. (21 isolates), represented by six different species. Their multi-locus analysis (tef1, translation elongation factor 1; rpb2, RNA polymerase B) identified three T. afroharzianum, one T. lixii, one T. atrobrunneum and one T. lentinulae species. These six new strains were selected to determine their suitability as plant growth promoters (PGP) and biocontrol agents (BCA) against Fusarium seedling blight disease (FSB) in wheat caused by Fusarium culmorum. All of the strains exhibited PGP abilities correlated to ammonia and indole-like compound production. In terms of biocontrol activity, all of the strains inhibited the development of F. culmorum in vitro, which is linked to the production of lytic enzymes, as well as diffusible and volatile organic compounds. An in planta assay was carried out on the seeds of a Tunisian modern wheat variety (Khiar) by coating them with Trichoderma. A significant increase in biomass was observed, which is associated with increased chlorophyll and nitrogen. An FSB bioprotective effect was confirmed for all strains (with Th01 being the most effective) by suppressing morbid symptoms in germinated seeds and seedlings, as well as by limiting F. culmorum aggressiveness on overall plant growth. Plant transcriptome analysis revealed that the isolates triggered several SA- and JA-dependent defense-encoding genes involved in F. culmorum resistance in the roots and leaves of three-week-old seedlings. This finding makes these strains very promising in promoting growth and controlling FSB disease in modern wheat varieties.
... In wheat, Stb6 encodes a conserved WAKL protein that manages gene-for-gene resistance against Zymoseptoria tritici in a hypersensitive responseindependent manner [41]. Furthermore, TaWAK2 has been reported to prevent penetration and spread of Fusarium graminearum by suppressing the expression of pectin methyl esterase 1 to produce a more rigid cell wall [42]. In maize, it has also been shown that qHSR1 and Htn1, which encode two WAK/WAKL proteins, are implicated in plant resistance against fungal pathogens Sporisorium reilianum and Exserohilum turcicum, respectively [43,44]. ...
Background
Tomato yellow leaf curl virus (TYLCV) is a major monopartite virus in the family Geminiviridae and has caused severe yield losses in tomato and tobacco planting areas worldwide. Wall-associated kinases (WAKs) and WAK-like kinases (WAKLs) are a subfamily of the receptor-like kinase family implicated in cell wall signaling and transmitting extracellular signals to the cytoplasm, thereby regulating plant growth and development and resistance to abiotic and biotic stresses. Recently, many studies on WAK/WAKL family genes have been performed in various plants under different stresses; however, identification and functional survey of the WAK/WAKL gene family of Nicotiana benthamiana have not yet been performed, even though its genome has been sequenced for several years. Therefore, in this study, we aimed to identify the WAK/WAKL gene family in N. benthamiana and explore their possible functions in response to TYLCV infection.
Results
Thirty-eight putative WAK/WAKL genes were identified and named according to their locations in N. benthamiana. Phylogenetic analysis showed that NbWAK/WAKLs are clustered into five groups. The protein motifs and gene structure compositions of NbWAK/WAKLs appear to be highly conserved among the phylogenetic groups. Numerous cis-acting elements involved in phytohormone and/or stress responses were detected in the promoter regions of NbWAK/WAKLs. Moreover, gene expression analysis revealed that most of the NbWAK/WAKLs are expressed in at least one of the examined tissues, suggesting their possible roles in regulating the growth and development of plants. Virus-induced gene silencing and quantitative PCR analyses demonstrated that NbWAK/WAKLs are implicated in regulating the response of N. benthamiana to TYLCV, ten of which were dramatically upregulated in locally or systemically infected leaves of N. benthamiana following TYLCV infection.
Conclusions
Our study lays an essential base for the further exploration of the potential functions of NbWAK/WAKLs in plant growth and development and response to viral infections in N. benthamiana.
... TaWAK interacts with the P. nodorum host-specific effector toxin SnTox1 and activates PCD, which facilitates infection by P. nodurum (Shi et al., 2016). WAK2 gene was also reported to be involved in quantitative resistance against Fusarium head blight (FHB) in durum wheat (Gadaleta et al., 2019). In rice, several WAKs are implicated in regulating QDR to the rice blast fungus Magnaporthe oryzae. ...
In contrast to large‐effect qualitative disease resistance, quantitative disease resistance (QDR) exhibits partial and generally durable resistance and has been extensively utilized in crop breeding. The molecular mechanisms underlying QDR remain largely unknown but considerable progress has been made in this area in recent years. In this review, we summarize the genes that have been associated with plant QDR and their biological functions. Many QDR genes belong to the canonical resistance gene categories with predicted functions in pathogen perception, signal transduction, phytohormone homeostasis, metabolite transport and biosynthesis, and epigenetic regulation. However, other “atypical” QDR genes are predicted to be involved in processes that are not commonly associated with disease resistance, such as vesicle trafficking, molecular chaperones, and others. This diversity of function for QDR genes contrasts with qualitative resistance, which is often based on the actions of nucleotide‐binding leucine‐rich repeat (NLR) resistance proteins. An understanding of the diversity of QDR mechanisms and of which mechanisms are effective against which classes of pathogens will enable the more effective deployment of QDR to produce more durably resistant, resilient crops.
... 15 Some WAKs play roles in resistance to Fusarium, including GhWAK7A, which participates in defense against Fusarium wilt in cotton by recognizing chitin 60 ; Arabidopsis RESISTANCE TO FUSARIUM OXYSPORUM 1 (RFO1), which confers resistance to multiple Fusarium races 61 ; and WAK2, which confers non-race-specific resistance to Fusarium head blight in durum wheat. 62 Both the single mutant Dcfem1 and the triple mutant Dcfem1/5/ n1 caused smaller lesions than the wild-type strain ( Figures 1B and S1J), suggesting that cfem1/5/n1 may make comparable contribution to fungal virulence on wheat and maize. CFEM8 is required for virulence in maize ( Figure 1B) but was not required for wheat floret infection. ...
The fungus Fusarium graminearum causes a devastating disease Gibberella stalk rot of maize. Our knowledge of molecular interactions between F. graminearum effectors and maize immunity factors is lacking. Here, we show that a group of cysteine-rich common in fungal extracellular membrane (CFEM) domain proteins of F. graminearum are required for full virulence in maize stalk infection and that they interact with two secreted maize proteins, ZmLRR5 and ZmWAK17ET. ZmWAK17ET is an alternative splicing isoform of a wall-associated kinase ZmWAK17. Both ZmLRR5 and ZmWAK17ET interact with the extracellular domain of ZmWAK17. Transgenic maize overexpressing ZmWAK17 shows increased resistance to F. graminearum, while ZmWAK17 mutants exhibit enhanced susceptibility to F. graminearum. Transient expression of ZmWAK17 in Nicotiana benthamiana triggers hypersensitive cell death, whereas co-expression of CFEMs with ZmWAK17ET or ZmLRR5 suppresses the ZmWAK17-triggered cell death. Our results show that ZmWAK17 mediates stalk rot resistance and that F. graminearum delivers apoplastic CFEMs to compromise ZmWAK17-mediated resistance.
