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PubMed2026

Integrated Genomics and Transcriptomics Reveal Stable Resistance Loci and Candidate Genes for Powdery Mildew in Wheat.

Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), poses a substantial threat to global wheat production. Enhancing resistance through molecular breeding necessitates a comprehensive understanding of its genetic and molecular underpinnings. This study leveraged a 2-year phenotypic evaluation of 283 diverse wheat accessions combined with genome-wide association studies (GWAS) to pinpoint stable quantitative trait loci for powdery mildew resistance. We identified 52 robust resistance loci across the wheat genome, including seven novel loci consistently detected across four environments. Comparative transcriptome profiling of resistant and susceptible wheat lines revealed 95 differentially expressed genes, predominantly enriched in defense response, signal transduction, and transcription regulation pathways. By integrating the GWAS and transcriptomic data, we precisely identified three compelling candidate genes (TaPIP5K, TaPKG, and TaORR6) on chromosome 2A, which are implicated in cell wall reinforcement, jasmonic acid signaling, and reactive oxygen species scavenging, respectively. Further validation using expression analysis corroborated their pivotal roles in resistance. Our findings provide a rich repository of validated genetic markers, promising candidate genes, and superior resistant germplasms, offering critical resources to accelerate targeted molecular breeding efforts for durable powdery mildew resistance in wheat.

Blumeria graminis f. sp. tritici↗
PubMed2024

CRISPR/Cas9-driven double modification of grapevine MLO6-7 imparts powdery mildew resistance, while editing of NPR3 augments powdery and downy mildew tolerance.

The implementation of genome editing strategies in grapevine is the easiest way to improve sustainability and resilience while preserving the original genotype. Among others, the Mildew Locus-O (MLO) genes have already been reported as good candidates to develop powdery mildew-immune plants. A never-explored grapevine target is NPR3, a negative regulator of the systemic acquired resistance. We report the exploitation of a cisgenic approach with the Cre-lox recombinase technology to generate grapevine-edited plants with the potential to be transgene-free while preserving their original genetic background. The characterization of three edited lines for each target demonstrated immunity development against Erysiphe necator in MLO6-7-edited plants. Concomitantly, a significant improvement of resilience, associated with increased leaf thickness and specific biochemical responses, was observed in defective NPR3 lines against E. necator and Plasmopara viticola. Transcriptomic analysis revealed that both MLO6-7 and NPR3 defective lines modulated their gene expression profiles, pointing to distinct though partially overlapping responses. Furthermore, targeted metabolite analysis highlighted an overaccumulation of stilbenes coupled with an improved oxidative scavenging potential in both editing targets, likely protecting the MLO6-7 mutants from detrimental pleiotropic effects. Finally, the Cre-loxP approach allowed the recovery of one MLO6-7 edited plant with the complete removal of transgene. Taken together, our achievements provide a comprehensive understanding of the molecular and biochemical adjustments occurring in double MLO-defective grape plants. In parallel, the potential of NPR3 mutants for multiple purposes has been demonstrated, raising new questions on its wide role in orchestrating biotic stress responses.

Vitis↗
PubMed2026

Marker-assisted screening of resistance to fire blight, powdery mildew, and apple scab in local apple varieties from Uzbekistan.

Apple (Malus domestica Borkh.) is one of the most economically important fruit crops worldwide; however, its production is severely constrained by major diseases, including fire blight, powdery mildew, and apple scab. Breeding disease-resistant cultivars represents a sustainable alternative to chemical control, particularly through the effective utilization of local germplasm resources from Central Asia. This study aimed to evaluate the presence and distribution of resistance-associated alleles in local apple varieties from Uzbekistan using polymorphic DNA markers. A collection of local apple accessions was screened to identify markers linked to resistance against fire blight, powdery mildew, and apple scab. The analysis revealed substantial genetic variation in resistance gene combinations among the studied varieties. The fire blight-associated marker AE10-375 was detected in 79.8% of the accessions. For powdery mildew resistance, 75.2% of the varieties carried resistance alleles corresponding to both Pl1 and Pl2 genes. Screening for apple scab resistance demonstrated that Vfa2, Vfa1, and Rvi6 were the most prevalent genes, with Vfa2 detected in 95.4% of the accessions. Regional analysis indicated that accessions from Karakalpakstan exhibited the highest proportion of genotypes harboring markers associated with resistance to multiple diseases. Six local varieties-Atlas olma, Turkish, Xuboni, Krasniy jeleznyak, Shoyi olma, and Besh barmoq-were identified as carrying resistance-associated markers for all three diseases. These findings demonstrate that local apple germplasm from Uzbekistan represents a valuable genetic resource for resistance to economically important diseases. The identified genotypes provide promising donor material for breeding programs aimed at developing cultivars with durable, broad-spectrum resistance while reducing reliance on chemical control strategies.

Malus↗
PubMed2026

Genome-Wide Identification and Characterization of the TBL Gene Family and Temporal Expression Dynamics During Powdery Mildew Infection in Cucumber (Cucumis sativus).

Cell-wall polysaccharide O-acetylation contributes to cell-wall assembly, organ development, and plant-pathogen interactions, but the cucumber TBL gene family remains poorly characterized. Here, 37 CsTBL genes were identified genome-wide and analyzed using phylogenetic, syntenic, conserved-motif, gene-structure, promoter, protein-structure, Gene Ontology, and transcriptome approaches, followed by RT-qPCR analysis after powdery mildew inoculation. All CsTBL proteins contained the conserved GDS and DxxH motifs, whereas accessory motifs and predicted structural features varied among clades. Intraspecific analysis identified dispersed, WGD/segmental, and tandem duplication categories, and cross-species synteny was more extensive with melon than with Arabidopsis. Homology-derived annotations associated CsTBL genes with cell-wall polysaccharide metabolism, Golgi/endomembrane compartments, and O-acetyltransferase activity, including six genes assigned to xylan O-acetyltransferase-related annotations. Expression profiling revealed tissue- and developmental-stage-dependent patterns, whereas the publicly available powdery mildew RNA-seq dataset provided descriptive temporal expression profiles in Podosphaera xanthii-inoculated samples. Independent RT-qPCR analysis using time-matched mock controls revealed distinct post-inoculation responses among six selected genes. Relative to the corresponding mock controls, CsTBL2 was consistently repressed; CsTBL15 showed transient induction at 1 dpi followed by repression; CsTBL24 exhibited a biphasic response; CsTBL25 was induced at all sampled post-inoculation time points; CsTBL26 showed progressive induction; and CsTBL30 reached its highest observed expression level at 3 dpi. Integrated functional annotation and expression evidence highlighted CsTBL26 as a priority candidate for further functional characterization, while CsTBL24 and CsTBL25 represented fruit-associated candidates with distinct powdery mildew responses; CsTBL30 remained an additional strongly infection-responsive candidate. These findings provide an evolutionary and expression-based framework for the functional characterization of the cucumber TBL gene family.

O-acetylation↗
PubMed2025

Avirulence depletion assay: Combining R gene-mediated selection with bulk sequencing for rapid avirulence gene identification in wheat powdery mildew.

Wheat production is threatened by multiple fungal pathogens, such as the wheat powdery mildew fungus (Blumeria graminis f. sp. tritici, Bgt). Wheat resistance breeding frequently relies on the use of resistance (R) genes that encode diverse immune receptors which detect specific avirulence (AVR) effectors and subsequently induce an immune response. While R gene cloning has accelerated recently, AVR identification in many pathogens including Bgt lags behind, preventing pathogen-informed deployment of resistance sources. Here we describe a new "avirulence depletion (AD) assay" for rapid identification of AVR genes in Bgt. This assay relies on the selection of a segregating, haploid F1 progeny population on a resistant host, followed by bulk sequencing, thereby allowing rapid avirulence candidate gene identification with high mapping resolution. In a proof-of-concept experiment we mapped the AVR component of the wheat immune receptor Pm3a to a 25 kb genomic interval in Bgt harboring a single effector, the previously described AvrPm3a2/f2. Subsequently, we applied the AD assay to map the unknown AVR effector recognized by the Pm60 immune receptor. We show that AvrPm60 is encoded by three tandemly arrayed, nearly identical effector genes that trigger an immune response upon co-expression with Pm60 and its alleles Pm60a and Pm60b. We furthermore provide evidence that Pm60 outperforms Pm60a and Pm60b through more efficient recognition of AvrPm60 effectors, suggesting it should be prioritized for wheat breeding. Finally, we show that virulence towards Pm60 is caused by simultaneous deletion of all AvrPm60 gene paralogs and that isolates lacking AvrPm60 are especially prevalent in the US thereby limiting the potential of Pm60 in this region. The AD assay is a powerful new tool for rapid and inexpensive AVR identification in Bgt with the potential to contribute to pathogen-informed breeding decisions for the use of novel R genes and regionally tailored gene deployment.

Triticum↗
PubMed1978

Taxonomic study and fermentation of producing organism and antimicrobial activity of mildiomycin.

A taxonomic study of strain B-98891, which produced an antibiotic effective against powdery mildew of barley, identified it as Streptoverticillium rimofaciens. On agar media the antibiotic, which was named mildiomycin, was only weakly active against most fungi and bacteria tested. However, it inhibited some Mycobacterium and Rhodotorula, and it showed excellent control of powdery mildew of barley plants in greenhouse tests at concentrations between 31.2 and 62.5 ppm. Rhodotorula rubra IFO 0907 was selected as the test organism for in vitro assay of mildiomycin.

Antifungal Agents↗
PubMed2026

Phylogenetic and Functional Analyses of Wheat TaMAN Genes Responding to Salinity and Pathogens.

Endo-β-1,4-mannanases (MANs) are glycoside hydrolase family 5 (GH5) enzymes that degrade cell wall mannan polysaccharides and participate in plant growth and stress adaptation. This gene family has not been systematically characterized in common wheat (Triticum aestivum L.). Here, we identified 24 TaMAN genes (TaMAN1-TaMAN24) genome-wide and analyzed their phylogeny, gene structures, chromosomal distribution, synteny, and promoter cis-acting elements. Expression profiles under biotic and abiotic stresses were investigated using public databases, salt-stress RNA-seq, and RT-qPCR. TaMAN proteins (386-475 aa) were mainly predicted to localize in the extracellular space. Phylogenetic analysis divided them into three groups, with Groups II and III representing monocot-specific expansions. Family expansion was driven primarily by whole-genome duplication, supplemented by tandem duplication on homoeologous group 6. Promoters were enriched in hormone- and stress-responsive cis-acting elements (ABRE, as-1/CGTCA-motif, W box). TaMAN1, TaMAN5, TaMAN8, TaMAN9, TaMAN16 and TaMAN19 were significantly induced by powdery mildew, while TaMAN3, TaMAN4 and TaMAN19-TaMAN22 rapidly responded to salt stress. This study provides candidate genes for disease-resistant and salt-tolerant wheat breeding.

TaMAN gene↗
PubMed2026

Novel genomic regions associated with adult-plant resistance to multiple fungal pathogens in wheat (Triticum aestivum L.) revealed by DArT marker sequencing.

Wheat is among the top three most important cereal crops globally and serves as a staple food for approximately 40% of the world's population. Fungal leaf diseases such as yellow and leaf rusts (YR, LR), septoria nodorum blotch (SNB), septoria tritici blotch (STB), and powdery mildew (PM) have a major effect on yield loss in wheat, and resistance breeding is so far the most effective strategy to minimize those losses. Adult plant resistance (APR) is a crucial component of durable disease resistance; it reduces the pathogen's infection rate, keeping disease levels below the damage threshold, even in the absence of complete immunity. Therefore, this study aimed to identify sources of resistance in a collection of 411 accessions from diverse global origins. These accessions were phenotyped across 2018-2019. DArTseq technology and Genome-wide association studies (GWAS) analysis were conducted to identify single-nucleotide polymorphisms (SNPs) associated with APR for evaluated pathogens. DArT analysis showed that wheat chromosome 2B contains genomic regions associated with resistance to SNB, and that SNPs on chromosome 3B are associated with resistance to YR. On chromosome 6 A, there is a strong potential to explore, as a shared resistance locus for YR and SNB was found. SNPs: 3,937,236, 1,056,817 were consistent in both years, meaning their association with disease resistance is reliable and repeatable. Chromosome 7D is a strong region for SNPs significantly associated with both LR and SNB resistance. While multiple disease resistance genes are present on 7D, the 610 Mb LR locus is distinct from known LR, PM, and SNB loci, making it a strong candidate for functional validation. These findings highlight the value of historical resistance sources and uncover novel genomic regions for breeding a broad-spectrum APR-based resistance. Dual-trait loci, especially those effective against both biotrophic and necrotrophic pathogens, represent a promising material for achieving durable resistance in elite wheat cultivars.

Triticum↗
PubMed2025

Barley resistance and susceptibility to fungal cell entry involve the interplay of ROP signaling with phosphatidylinositol-monophosphates.

Rho-of-plant small GTPases (ROPs) are regulators of plant polar growth and of plant-pathogen interactions. The barley ROP, RACB, is involved in susceptibility toward infection by the barley powdery mildew fungus Blumeria hordei (Bh) but little is known about the cellular pathways that connect RACB signaling to disease susceptibility. Here we identify novel RACB interaction partners of plant or fungal origin by untargeted co-immunoprecipitation of constitutively active (CA) RACB tagged by green fluorescent protein from Bh-infected barley epidermal layers and subsequent analysis by liquid chromatography-coupled mass spectrometry. Three of the immunoprecipitated proteins, a plant phosphoinositide phosphatase, a plant phosphoinositide phospholipase, and a putative Bh-effector protein, are involved in the barley-Bh-pathosystem and support disease resistance or susceptibility, respectively. RACB and its plant interactors bind to overlapping anionic phospholipid species in vitro, and in the case of RACB, this lipid interaction is mediated by its carboxy-terminal polybasic region (PBR). Fluorescent markers for anionic phospholipids show altered subcellular distribution in barley cells during Bh attack and under expression of a RACB-binding fungal effector. Phosphatidylinositol 4-phosphate, phosphatidylinositol 3,5-bisphosphate, and phosphatidylserine show a distinct enrichment at the haustorial neck region, suggesting a connection to subcellular targeting of RACB at this site. The interplay of ROPs with anionic phospholipids and phospholipid-metabolizing enzymes may thus enable the subcellular enrichment of components pivotal for success or failure of fungal penetration.

Hordeum↗
PubMed1978

Isolation and characterization of mildiomycin, a new nucleoside antibiotic.

A new antibiotic mildiomycin, strongly active against powdery mildew, was isolated from the culture filtrate of Streptoverticillium rimofaciens B-98891. It is a water-soluble basic antibiotic and was purified by ion-exchange and adsorption chromatography. The molecular formula of the purified compound was determined to be C19H30N8O9(H2O) from physical and chemical data. The UV and NMR spectra suggested that this antibiotic is a nucleoside. On acidic hydrolysis it gave 5-hydroxymethyl cytosine which has not previously been found in nucleoside antibiotics.

Antifungal Agents↗