Explore the vast range of titles available.

Some Stemphylium isolates reported from Malaysia as well as other regions of the world have been identified by morphology and blast analysis of the ITS region only, and eventually deposited in NCBI GenBank. To our knowledge, some of these isolates have been misidentified. The re-examination of identity of all Stemphylium isolates reported from Malaysia using morphological and phylogenetic analyses of the ITS and gpd, as well as phylogenetic analyses of all isolates of S. lycopersici and S. solani available in NCBI GenBank from other regions of the world indicated that a remarkable number of isolates deposited in NCBI GenBank under S. lycopersici and S. solani species were misidentified.

The root-endophytic fungus Piriformospora indica (=Serendipita indica) has been revealed for its growth-promoting effects and its capacity to induce resistance in a broad spectrum of host plants. However, the bioefficacy of this fungus had not yet been tested against any pathogen affecting onion (Allium cepa). In this study, the biocontrol potency of P. indica against onion leaf blight, an impacting disease caused by the necrotrophic fungal pathogen Stemphylium vesicarium, was evaluated. First, it was proved that colonisation of onion roots by P. indica was beneficial for plant growth, as it increased leaf development and root biomass. Most relevantly, P. indica was also effective in reducing Stemphylium leaf blight (SLB) severity, as assessed under greenhouse conditions and confirmed in field trials in two consecutive years. These investigations could also provide some insight into the biochemical and molecular changes that treatment with P. indica induces in the main pathways associated with host defence response. It was possible to highlight the protective effect of P. indica colonisation against peroxidative damage, and its role in signalling oxidative stress, by assessing changes in malondialdehyde and H2O2 content. It was also showed that treatment with P. indica contributes to modulate the enzymatic activity of superoxide dismutase, catalase, phenylalanine ammonia-lyase and peroxidase, in the course of infection. qPCR-based expression analysis of defence-related genes AcLOX1, AcLOX2, AcPAL1, AcGST, AcCHI, AcWRKY1, and AcWRKY70 provided further indications on P. indica ability to induce onion systemic response. Based on the evidence gathered, this study aims to propose P. indica application as a sustainable tool for improving SLB control, which might not only enhance onion growth performance but also activate defence signalling mechanisms more effectively, involving different pathways.

Background Stemphylium blight incited by Stemphylium botryosum poses a significant threat to lentil crops worldwide, inducing severe defoliation and causing substantial yield losses in susceptible varieties under favorable conditions. While some moderate levels of resistance have been identified within lentil germplasm, a low number of resistant cultivars are available to farmers. Adding to the common constraints of resistance breeding, a notable challenge is generating a sufficient number of spores for large-scale screenings, which are essential for pinpointing additional sources of resistance for integration into breeding programs. Therefore, there is a pressing need to improve existing screening methods and tailor them for large-scale material selection. In pursuit of this objective, a protocol for the efficient production of fungal material has been adapted. Results Optimization of fungal material production was successfully achieved by comparing the use of fungal mycelia and spores. Spore production was found to be optimal when produced on solid V8-PDA(hi) medium, while liquid Richard’s medium was identified as superior for mycelium yield. Furthermore, a refined screening method was developed by evaluating the resistance of six lentil accessions to stemphylium blight. This assessment included the use of either fungal mycelia (at densities ranging from 1 to 5 g L − 1 ) or spores (with densities ranging from 5 × 10 4 to 2 × 10 5 conidia mL − 1 ) under three different relative humidity levels (from 50 to 100%). Both humidity levels and inoculum dose significantly influenced the final disease rating (DR) and the relative Area Under the Disease Progress Curve (rAUDPC). Differences among genotypes in final symptom severity (DR) became more pronounced after inoculation with inoculum densities of 5 g L − 1 of mycelium or of 10 5 and 2 × 10 5 conidia mL − 1 of spore under 100% relative humidity. Given the challenges associated with the large-scale production of S. botryosum spores, inoculations with 5 g L − 1 of mycelium is highly recommended as a practical alternative for conducting mass-scale screenings. Conclusions The findings from this study underscore the critical importance of maintaining high level of humidity during inoculation and disease progression development for accurately assessing resistance to stemphylium blight. The optimization of mycelial production for suspension inoculation emerges as a more reliable and efficient approach for conducting large-scale screening to assess germplasm resistance against stemphylium blight in lentil crops.

• Pathogenic fungi often target the plant plasma membrane (PM) H⁺-ATPase during infection. To identify pathogenic compounds targeting plant H⁺-ATPases, we screened extracts from 10 Stemphylium species for their effect on H⁺-ATPase activity. • We identified Stemphylium loti extracts as potential H⁺-ATPase inhibitors, and through chemical separation and analysis, tenuazonic acid (TeA) as a potent H⁺-ATPase inhibitor. By assaying ATP hydrolysis and H⁺ pumping, we confirmed TeA as a H⁺-ATPase inhibitor both in vitro and in vivo. To visualize in planta inhibition of the H⁺-ATPase, we treated pH-sensing Arabidopsis thaliana seedlings with TeA and quantified apoplastic alkalization. • TeA affected both ATPase hydrolysis and H⁺ pumping, supporting a direct effect on the H⁺-ATPase. We demonstrated apoplastic alkalization of A. thaliana seedlings after short-term TeA treatment, indicating that TeA effectively inhibits plant PM H⁺-ATPase in planta. TeA-induced inhibition was highly dependent on the regulatory C-terminal domain of the plant H⁺-ATPase. • Stemphylium loti is a phytopathogenic fungus. Inhibiting the plant PM H⁺-ATPase results in membrane potential depolarization and eventually necrosis. The corresponding fungal H⁺-ATPase, PMA1, is less affected by TeA when comparing native preparations. Fungi are thus able to target an essential plant enzyme without causing self-toxicity.

Main conclusionStemphylium botryosum alters lentil secondary metabolism and differentially affects resistant and susceptible genotypes. Untargeted metabolomics identifies metabolites and their potential biosynthetic pathways that play a crucial role in resistance to S. botryosum.The molecular and metabolic processes that mediate resistance to stemphylium blight caused by Stemphylium botryosum Wallr. in lentil are largely unknown. Identifying metabolites and pathways associated with Stemphylium infection may provide valuable insights and novel targets to breed for enhanced resistance. The metabolic changes following infection of four lentil genotypes by S. botryosum were investigated by comprehensive untargeted metabolic profiling employing reversed-phase or hydrophilic interaction liquid chromatography (HILIC) coupled to a Q-Exactive mass spectrometer. At the pre-flowering stage, plants were inoculated with S. botryosum isolate SB19 spore suspension and leaf samples were collected at 24, 96 and 144 h post-inoculation (hpi). Mock-inoculated plants were used as negative controls. After analyte separation, high-resolution mass spectrometry data was acquired in positive and negative ionization modes. Multivariate modeling revealed significant treatment, genotype and hpi effects on metabolic profile changes that reflect lentil response to Stemphylium infection. In addition, univariate analyses highlighted numerous differentially accumulated metabolites. By contrasting the metabolic profiles of SB19-inoculated and mock-inoculated plants and among lentil genotypes, 840 pathogenesis-related metabolites were detected including seven S. botryosum phytotoxins. These metabolites included amino acids, sugars, fatty acids and flavonoids in primary and secondary metabolism. Metabolic pathway analysis revealed 11 significant pathways including flavonoid and phenylpropanoid biosynthesis, which were affected upon S. botryosum infection. This research contributes to ongoing efforts toward a comprehensive understanding of the regulation and reprogramming of lentil metabolism under biotic stress, which will provide targets for potential applications in breeding for enhanced disease resistance.

Stemphylium leaf spot (SLP), caused by Stemphylium vesicarium , has emerged as an increasing threat to spinach production in the United States, with widespread outbreaks reported across major spinach-growing regions over the past two decades. The objectives of this study were to: (1) evaluate global USDA spinach germplasm collections and commercial cultivars for resistance to S. vesicarium ; (2) perform genome-wide association studies (GWAS) to identify genomic regions associated with resistance; and (3) conduct genomic prediction (GP) to enhance selection accuracy. A total of 311 diverse spinach genotypes, including USDA germplasm accessions and commercial cultivars, were evaluated under greenhouse conditions at the University of Arkansas using the S. vesicarium isolate Sb-1-St001 from 2019 to 2021. The panel exhibited a wide range of disease responses. GWAS using disease severity index (DSI) values and whole-genome resequencing (WGR)-based SNP markers identified four SNPs—SOVchr1_127757911 (127,757,911 bp, Chr1), SOVchr2_21962694 (21,962,694 bp, Chr2), SOVchr4_114674293 (114,674,293 bp, Chr4), and SOVchr5_37417509 (37,417,509 bp, Chr5)—that were significantly associated with DSI for SLP resistance. Genomic prediction of DSI was performed using seven GP models across nine randomly selected SNP datasets and two GWAS-derived SNP sets. The GWAS-derived marker sets produced higher prediction accuracies in cross-population prediction, with r-values of 0.45 and 0.51 for the 4- and 18-SNP sets, respectively. These results underscore the potential of marker-assisted selection (MAS) and genomic selection (GS) to accelerate the development of spinach cultivars resistant to Stemphylium leaf spot.

Stemphylium blight (SB) is one of the most important biotic stresses of lentil, occuring in almost all major lentil-growing nations. Among 150 species recorded, Stemphylium botryosum (Wallr.) is responsible for inciting SB in lentil. It has a wide host range and perpetuate in the seeds, crop debris and secondary spread occurs through air-borne conidia. The most vulnerable stage of infection is flowering to early pod setting, so, confers a serious threat to lentil production. Environment plays pivotal role in host–pathogen dynamics and also interfere in disease management. This study involves deciphering genotype × environment interactions by utilising GGE biplot to unveil and validate durable resistant genotypes and their performance over three different locations. Primarily, from 70 lentil genotypes, 23 promising genotypes were selected based on their disease reaction (< 30%) against SB and evaluated further across the three locations for two consecutive years. The test result from GGE biplot analysis revealed that genotype exerted higher proportion of variation in SB reaction than environment. Result confirmed the presence of inconsistent genotypic response over locations and years. Selected locations grouped into three environment clusters suggesting the existence of cross over interaction with in the genotypes. Integration of GGE biplot and BLUP analysis identified G-3 (ILL10838/ILWL11/X2016S) as the “ideal” genotype whereas, G-7 (8114/10956/16–1) and G-5 (LIRL22-107/LIRL21-50–1-1–1) as “desirable” genotypes considering their static response against SB over the environment. Genotypes detected through this study could be recommended for their future deployment in lentil resistance breeding programme.

Mycovirus-infected fungi can suffer from poor growth, attenuated pigmentation, and virulence. However, the molecular mechanisms of how mycoviruses confer these symptoms remain poorly understood. Here, we report a mycovirus Stemphylium lycopersici alternavirus 1 (SlAV1) isolated from a necrotrophic plant pathogen Stemphylium lycopersici that causes altered colony pigmentation and hypovirulence by specifically interfering host biosynthesis of Altersolanol A, a polyketide phytotoxin. SlAV1 significantly down-regulates a fungal polyketide synthase (PKS1), the core enzyme of Altersolanol A biosynthesis. PKS1 deletion mutants do not accumulate Altersolanol A and lose pathogenicity to tomato and lettuce. Transgenic expression of SlAV1 open-reading frame 3 (ORF3) in S. lycopersici inhibits fungal PKS1 expression and Altersolanol A accumulation, leading to symptoms like SlAV1-infected fungal strains. Multiple plant species sprayed with mycelial suspension of S. lycopersici or S. vesicarium strains integrating and expressing ORF3 display enhanced resistance against virulent strains, converting the pathogenic fungi into biocontrol agents. Hence, our study not only proves inhibiting a key enzyme of host phytotoxin biosynthesis as a molecular mechanism underlying SlAV1-mediated hypovirulence of Stemphylium spp., but also demonstrates the potential of mycovirus-gene integrated fungi as a potential biocontrol agent to protect plants from fungal diseases.

The purple spot disease of asparagus is the most important disease in German asparagus growing regions. Two different Stemphylium species, S. vesicarium and the closely related species S. botryosum, are described as causal pathogens. Because of the strong phenotypical similarities the morphological differentiation is very difficult. Therefore the development of a suitable alternative to distinguish these species is an important need. The aim of this study was to develop a molecular and genetic based differentiation method for S. vesicarium and S. botryosum, and to analyze asparagus samples from Germany with this method to identify the prevalent causal agent of the purple spot disease in Germany. The sequences of three different DNA-markers were compared to get the most appropriate basis. Additionally to the commonly used ITS regions, parts of the protein-coding genes gapdh (glyceraldehyde-3-phosphate-dehydrogenase) and cytochrome b were analysed. The most significant difference between the two species was a 3 kb intron present in the S. botryosum cytochrome b region but not in S. vesicarium. This difference showed to be suitable for the distinction of these two Stemphylium species by a simple PCR-reaction. In addition to the qualitative analysis, the frequencies of these species were detected directly from asparagus field samples with the help of qPCR. In all german samples collected in 2010, 2011, 2013 and 2014 only S. vesicarium could be identified.

A new fungal disease affecting wheat in Egypt, known as Stemphylium leaf spot, caused by Stemphylium vesicarium Wallr (Simmons) is reported. From all symptomatic wheat leaves, S. vesicarium was the most frequently isolated fungus (71.9%). The isolated pathogen was identified based on morphological characteristics together with molecular diagnosis. The Stemphylium isolate AUMC 15115 in this study was clustered at the same branch as Stemphylium mali CBS 122640, ex-type material (Synonym = Stemphylium vesicarium). At the Smart Agriculture Clinic Project, Sids Agricultural Research Station, Agricultural Research Centre, Beni Suef governorate, 12 cultivars of wheat were assessed in pot experiments for their resistance to Stemphylium leaf spot during the 2020 and 2021 growing seasons. Overall, distinct variations were observed in all examined cultivars in response to S. vesicarium infection. The Sakha 95 cultivar exhibited a minimal infection rate (disease incidence was 6.7, 3.3% and disease severity being, 0.7, 0.5%, respectively in the two growing seasons) and was classified as resistant. In contrast, Beni Suef 5 had the highest percent of infection (63.3, 66.7%), disease severity (38.5, 40.3%) and was classified as susceptible. In resistant cultivars, there was an increase in total phenol content, polyphenol oxidase (PPO), peroxidase (POD), and superoxide dismutase (SOD) activities. Conversely, there was a reduction in electrolyte leakage percentage and hydrogen peroxide (H2O2) accumulation. However, the number of protein bands in resistant wheat cultivars exhibited a more significant increase than susceptible ones, particularly in the Sakha 95, which displayed the highest number of proteins.