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Sugarcane smut, a serious disease caused by the fungus Sporosorium scitamineum, can result in 30% to 100% cane loss. The most affordable and efficient measure of preventing and handling sugarcane smut disease is to select disease-resistant varieties. A comprehensive evaluation of disease resistance based on the incidence of smut disease is essential during the selection process, necessitating the rapid and accurate identification of sugarcane smut. Traditional identification methods, which rely on visual observation of symptoms, are time-consuming, costly, and inefficient. To address these limitations, we present the lightweight sugarcane smut detection model (YOLOv5s-ECCW), which incorporates several innovative features. Specifically, the EfficientNetV2 is incorporated into the YOLOv5 network to achieve model compression while maintaining high detection accuracy. The convolutional block attention mechanism (CBAM) is added to the backbone network to improve its feature extraction capability and suppress irrelevant information. The C3STR module is used to replace the C3 module, enhancing the ability to capture global large targets. The WIoU loss function is used in place of the CIoU one to improve the bounding box regression's accuracy. The experimental results demonstrate that the YOLOv5s-ECCW model achieves a mean average precision (mAP) of 97.8% with only 4.9 G FLOPs and 3.25 M parameters. Compared with the original YOLOv5, our improvements include a 0.2% increase in mAP, a 54% reduction in parameters, and a 70.3% decrease in computational requirements. The proposed model outperforms YOLOv4, SSD, YOLOv5, and YOLOv8 in terms of accuracy, efficiency, and model size. The YOLOv5s-ECCW model meets the urgent need for the accurate real-time identification of sugarcane smut, supporting better disease management and selection of resistant varieties. [ABSTRACT FROM AUTHOR]

The cultivation of wheat in North America represents a relatively recent endeavour, spanning a mere 150 years. This relatively brief period of its recent cultivation has allowed the opportunity to document the threats and diseases farmers had to face from the start. In this minireview, our primary objective is to provide a detailed exploration of the historical context on how we end up effectively managing what was once among the most destructive and hard to manage diseases affecting wheat, namely, common bunt (covered smut). This review delves into the early research efforts dedicated to understanding the biology of the causal pathogens and developing effective management approaches. These efforts encompass a wide spectrum of potential methods, ranging from seed treatments to cropping practices, and the development of genetic resistance. Throughout this exploration, we will also spotlight the remarkable scientific success story that has unfolded within the Canadian context. In essence, this review aims to provide a scientific examination of the history, challenges and innovative approaches associated with mitigating the impact of bunt pathogens on wheat cultivation in North America, and future challenges. [ABSTRACT FROM AUTHOR]

We analyzed smut fungi (Ustilaginales) parasitizing nine poaceous hosts from three districts (Shangla, Mansehra, and Dir Upper) of Khyber Pakhtunkhwa Province, Pakistan. Eight taxa were identified in two genera using both morphological and molecular techniques by amplifying ITS and LSU regions. We describe Ustilago pseudosyntherismae sp. nov. on Digitaria sanguinalis and Dactylis glomerata as new to science and U. neocopinata as a new record for Pakistan. We provide updated distribution records for six smut species viz. U. maydis, U. tritici, Sporisorium cruentum, S. moniliferum, S. reilianum, and S. schweinfurthianum. [ABSTRACT FROM AUTHOR]

Background and Objectives: Flour color changes caused by contamination like fungal‐damaged kernels can be determined by several methods, but many existing methods are time‐consuming and require specialized training. In this study, a commercial flatbed scanner was used to quickly detect and quantify the abundance of black specks derived from smutty grains in wheat flour samples. Findings: Our method easily classified flour samples into several categories, as clean flour, marginally clean, or contaminated, by using varied levels of %area‐smut. From our set of calibration flour samples, clean flour samples were located below 0.025% area‐smut. Marginal flours were defined as flours having %area‐smut from 0.025% to 0.050%. Notably, contaminated flour had %area‐smut greater than 0.05%. Moreover, the flour color brightness parameter (L) was determined using the scanner and was found to be inversely related to the %area‐smut. In addition, the number of smutty seeds manually detected in 250 g whole‐grain samples was correlated to the %area‐smut found in the flour. Conclusions: Therefore, this method represents a rapid and reliable way to distinguish clean flour from flour milled from wheat containing various levels of smut contamination. Significance and Novelty: This method was developed and validated using wheat samples collected from the field and contained a range of smut contamination. Although specks could easily be detected and counted, we found that speck counts varied with scanner resolution setting. Therefore, an alternate parameter referred to as "%area‐smut" was calculated and resulted in more consistent values per sample regardless of scanner resolution. Additionally, the flour color parameter, L*, was determined for each scanned image using imaging processing software. This color parameter, L*, was well correlated with those measured with a reference hand‐held colorimeter. [ABSTRACT FROM AUTHOR]

Rice serves as a staple food across various continents worldwide. The rice plant faces significant threats from a range of fungal, bacterial, and viral pathogens. Among these, rice false smut disease (RFS) caused by Villosiclava virens is one of the devastating diseases in rice fields. This disease is widespread in major ricegrowing regions such as China, Pakistan, Bangladesh, India, and others, leading to significant losses in rice plantations. Various toxins are produced during the infection of this disease in rice plants, impacting the fertilization process as well. This review paper lightens the disease cycle, plant immunity, and infection process during RFS. Mycotoxin production in RFS affects rice plants in multiple ways, although the exact phenomena are still unknown. [ABSTRACT FROM AUTHOR]

Sugarcane smut, a serious disease caused by the fungus Sporosorium scitamineum, can result in 30% to 100% cane loss. The most affordable and efficient measure of preventing and handling sugarcane smut disease is to select disease-resistant varieties. A comprehensive evaluation of disease resistance based on the incidence of smut disease is essential during the selection process, necessitating the rapid and accurate identification of sugarcane smut. Traditional identification methods, which rely on visual observation of symptoms, are time-consuming, costly, and inefficient. To address these limitations, we present the lightweight sugarcane smut detection model (YOLOv5s-ECCW), which incorporates several innovative features. Specifically, the EfficientNetV2 is incorporated into the YOLOv5 network to achieve model compression while maintaining high detection accuracy. The convolutional block attention mechanism (CBAM) is added to the backbone network to improve its feature extraction capability and suppress irrelevant information. The C3STR module is used to replace the C3 module, enhancing the ability to capture global large targets. The WIoU loss function is used in place of the CIoU one to improve the bounding box regression’s accuracy. The experimental results demonstrate that the YOLOv5s-ECCW model achieves a mean average precision (mAP) of 97.8% with only 4.9 G FLOPs and 3.25 M parameters. Compared with the original YOLOv5, our improvements include a 0.2% increase in mAP, a 54% reduction in parameters, and a 70.3% decrease in computational requirements. The proposed model outperforms YOLOv4, SSD, YOLOv5, and YOLOv8 in terms of accuracy, efficiency, and model size. The YOLOv5s-ECCW model meets the urgent need for the accurate real-time identification of sugarcane smut, supporting better disease management and selection of resistant varieties.

Premise: In frequently burned southeastern USA pine‐grassland communities, wiregrass (Aristida stricta and A. beyrichiana) are dominant bunchgrasses whose flowers are infected during flowering by a smut fungus (Langdonia walkerae). We hypothesized that because prescribed fire timing affects wiregrass flowering patterns, it could affect smut incidence (occurrence of smut on plants) and severity of infection in inflorescences and spikelets. Because soil order could influence plant susceptibility, we hypothesized that these patterns would differ between soil orders. We hypothesized differences between species as representative of geographic variation in this ecosystem. Methods: We surveyed the incidence and severity of L. walkerae in wiregrass populations (85 populations at 14 sites) that had been prescription burned at different times during the previous year. We used binomial regressions to test whether incidence and severity differed by burn day, soil order, or species, with site as a random effect. Results: Fires that occurred in the winter were associated with significantly lower incidence than fires later in the year (as the months progressed into summer). Plants growing on Spodosol soils were significantly less likely to be infected than those on other soils. More variation in incidence, however, was explained by site, suggesting that site‐specific characteristics were important. Smut severity in inflorescences and spikelets was greater overall in populations of A. stricta than in southern populations (A. beyrichiana). Conclusions: Our findings indicate that fire timing and soil order affect L. walkerae incidence in wiregrass plants, but neither appears to be associated with greater severity. Patterns of smut infection are related to site history and geographic variation. [ABSTRACT FROM AUTHOR]

Abstract To elucidate the mechanisms underlying the resistance to smut of different sugarcane cultivars, endophytic bacterial and fungal compositions, functions and metabolites in the stems of the sugarcane cultivars were analyzed using high-throughput sequencing techniques and nontargeted metabolomics. The results showed that the levels of ethylene, salicylic acid and jasmonic acid in sugarcane varieties that were not sensitive to smut were all higher than those in sensitive sugarcane varieties. Moreover, endophytic fungi, such as Ramichloridium, Alternaria, Sarocladium, Epicoccum, and Exophiala species, could be considered antagonistic to sugarcane smut. Additionally, the highly active arginine and proline metabolism, pentose phosphate pathway, phenylpropanoid biosynthesis, and tyrosine metabolism in sugarcane varieties that were not sensitive to smut indicated that these pathways contribute to resistance to smut. All of the above results suggested that the relatively highly abundant antagonistic microbes and highly active metabolic functions of endophytes in non-smut-sensitive sugarcane cultivars were important for their relatively high resistance to smut.

To elucidate the mechanisms underlying the resistance to smut of different sugarcane cultivars, endophytic bacterial and fungal compositions, functions and metabolites in the stems of the sugarcane cultivars were analyzed using high-throughput sequencing techniques and nontargeted metabolomics. The results showed that the levels of ethylene, salicylic acid and jasmonic acid in sugarcane varieties that were not sensitive to smut were all higher than those in sensitive sugarcane varieties. Moreover, endophytic fungi, such as Ramichloridium, Alternaria, Sarocladium, Epicoccum, and Exophiala species, could be considered antagonistic to sugarcane smut. Additionally, the highly active arginine and proline metabolism, pentose phosphate pathway, phenylpropanoid biosynthesis, and tyrosine metabolism in sugarcane varieties that were not sensitive to smut indicated that these pathways contribute to resistance to smut. All of the above results suggested that the relatively highly abundant antagonistic microbes and highly active metabolic functions of endophytes in non-smut-sensitive sugarcane cultivars were important for their relatively high resistance to smut. [ABSTRACT FROM AUTHOR]

The present study was aimed to determine the genetic variability of sugarcane smut pathogen (Sporisorium scitamineum) in Sri Lanka to support an effective crop improvement program for sugarcane smut disease resistance. Eighty-three isolates of S. scitamineum were collected from 15 different sugarcane varieties grown in seven sugarcane cultivating areas in Sri Lanka. DNA sequencing of PCR products obtained by specific (i.e., bE 4 and bE 8) and universal (i.e., ITS 1 and ITS 4) primers showed 99% sequence similarity among the collected S. scitamineum isolates. Genetic diversity was determined using 16 inter-simple sequence repeat (ISSR) primers. It produced 104 amplified DNA fragments which are 100% polymorphic. The polymorphic information content (PIC) value of ISSR markers varied from 0.25 to 0.46 with an average of 0.37. The results revealed a moderate degree of genetic diversity among the S. scitamineum isolates. The genetic differentiation coefficient (Gst) was estimated to be 0.241 in the studied fungal population, suggesting 24% of the total genetic variation originates between the populations, and 76% originates within the populations. Geneflow (Nm) was calculated as 1. 572, indicating that gene flow occurs across populations at a faster rate. The collected isolates clustered into five genetically distinct groups having no relationship with their geographical origin. The results confirmed a considerable genetic variation among the collected isolates from major sugarcane growing areas in Sri Lanka. Therefore, it is proposed to use a mixture of S. scitamineum isolates collected from all sugarcane growing areas when screening for smut-resistant sugarcane varieties. [ABSTRACT FROM AUTHOR]

[Objectives] This study was conducted to clarify the outbreak and disaster characteristics of Sesamia inferens Walker and smut in cane-growing regions in the low-latitude plateau of Yunnan Province, where there is continuous high temperature and drought in spring and summer. [Methods] A systematic investigation and analysis was conducted on different varieties in different types of fields in 16 cane-growing regions with outbreak of S. inferens and smut in Yunnan from 2019 to 2021. [Results] The outbreak of S. inferens and smut in cane-growing regions in the low-latitude plateau of Yunnan Province resulted in an average percent of dry hearts in the range of 17.3% -56.3%, and as high as 84.0% in severe cases. 70% thiamethoxam seed treatment dispersible powder and clothianidin or thi-amethoxam fertilizer granules were ineffective against S. inferens, while 10% monosultap • thiamethoxam or 10% clothianidin • monosultap granules had a significant control efficacy on S. inferens. The average diseased plant rate ranged from 14.8% to 89.7% in susceptible varieties with smut, and was as high as 100% in severe cases. ROC 1, Yuetang 93-159, Yuetang 00-236, and Liucheng 05-136 had strong resistance, with an average diseased plant rate of 0 -5.5% and the highest rate of 7.6%. S. inferens and smut both broke out in cane-growing regions with an altitude below 1 200 m. It is recommended to pay attention to disease and pest monitoring in cane-growing regions with an altitude below 1 200 m, and combine it with the management of new plants and ratoon plants to effectively prevent and control the first and second generation of S. inferens-infested seedlings from March to May. It is also recommended to strengthen the promotion and application of excellent disease-resistant varieties, so as to achieve a reasonable distribution of varieties and fundamentally control the outbreak and epidemic of sugarcane smut. [Conclusions] This study provides a basis for the effective prevention and control of catastrophic S. inferens and smut caused by extreme climate. [ABSTRACT FROM AUTHOR]

The common smut of corn, caused by Ustilago maydis, reduces the yield and quality of maize forage. When heavy infestations of corn smut occur, grain yields can be so severely decreased that the most viable economic alternative may be to harvest and ensile the crop. Only a couple of studies have attempted to investigate the influence of aerobic exposure on the nutritive value and aerobic stability of silage, which is prepared from smut-infected maize. In this study, individual whole corn plants were harvested by hand. The plants were distributed into three treatments: 0% infected, 50% infected, and 100% infected. The fresh forage was ensiled in triplicate for a 90-day period. Aerobic exposure lasted for 28 days. Samples were taken on the day of opening and on the 3rd, 7th, 14th, and 28th days. Near infrared spectroscopy (NIRS) calibration equations were used for the prediction of qualitative indicators. Silage prepared from 100% smut-infected maize had comparatively poor quality with dry matter loss, increasing pH and the low amount of starch. It was also distinguished with significant temperature increases from days 15 to 18 of aerobic exposure. Silage prepared from 50% smut-infected maize did not show significant quality changes over the period of the experiment, although it had inferior quality compared to the silage prepared from smut-free maize. While silage prepared from smut-infected maize had an overall worse quality than silage prepared from non-infected maize, it should not have an adverse effect on livestock health or production. [ABSTRACT FROM AUTHOR]

Aims It is known that Thecaphora frezii produces peanut smut that generates numerous economic losses. For this reason, it is a priority to search for control strategies. In this sense, we investigated the lipid profile of this pathogen, as possible antifungal targets, regarding polar lipid composition, fatty acid profile, and transcriptional regulation of genes involved in each stage of the development. Method and Results Lipids from T. frezii teliospores, basidiospores, and hyphae were analyzed by HPLC/CAD and CG/FID. We found differences in the unsaturation levels as well as in the long-chain fatty acids along the stages. Phosphatidylcholine was the main component in the three development stages, followed by cardiolipins. Phosphatidylinositol, phosphatidylethanolamine, and lyso-phosphatidylethanolamine were found in similar amounts in all stages. Although ergosterol was not detected, we found two unsaponifiable lipids. In addition, we found transcripts that encode 28 enzymes involved in the biosynthesis of three lipids by RNA-Seq. Conclusions Thecaphora frezii shows changes in the composition of membrane lipids in different ontogenetic stages as well as in the expression of transcripts for enzymes involved in lipid biosynthesis. [ABSTRACT FROM AUTHOR]

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Abnormal symptoms were observed on Anemone flaccida in Korea, indicating an infection caused by smut fungi. Morphological and molecular analyses of the strain KNUF-UB were consistent with previous reports of Urocystis eranthidis. Therefore, this is the first report of smut caused by U. eranthidis on A. flaccida in Korea.

Wheat (Triticum aestivum L.) encounters 15–20% yield loss due to fungal diseases. A study was carried out to analyse the allelic variations in functional genes associated with multiple fungal disease resistance, viz. rusts, smuts and powdery mildew in 58 contrasting wheat genotypes. The experiments were conducted at Chaudhary Charan Singh Haryana Agricultural University, Hisar, Haryana during 2020–21. A set of 29 simple sequence repeat (SSR) markers was selected for screening, out of which 24 markers showed amplifications (82.7%) and 23 showed polymorphism (95.83%) with a total of 46 alleles. Alleles per locus varied from 1 to 3 with a mean of 1.96 alleles per locus. At a similarity coefficient of 0.66, dendrogram grouped all the genotypes into 2 major clusters. Two and three dimensional plots also confirmed the distribution. Results showed that genotypes PBW 725 and WH 1268 were found to be most diverse at a similarity coefficient of 77%. SSR polymorphism rates were analysed using polymorphism information content, expected heterozygosity, marker index, discriminating power and resolving power values, where first two ranged from 0.03–0.65, and later three ranged from 0.03–1.94, 0.03–0.66 and 0.03–2.00, respectively. Based on these results, 8 proficient markers, viz. Barc232, Swm271, Xbarc124, Xbarc32, Xwmc44, Xgwm296, Gpw5029 and Xwmc557 are suggested for Indian wheat fungal disease resistance profiling. Among these, first two markers (Barc232 and Swm271) were detected in most (57) of the genotypes which are associated with ut6 and Lr75 genes, providing resistance to loose smut and leaf rust, respectively. This study can further help in gene pyramiding for producing multiple disease resistant genotypes.

Sugarcane smut seriously endangers sugarcane production, resulting in reduced sugarcane yield and sucrose loss. It is dispered through wind and soil, its teliospores could survive for more than half a year in hot and dry conditions. Rhizosphere microecology is a micro-ecosystem in which roots are closely related to soil. The environmental factors of the system, such as soil microorganisms, root exudates and soil physicochemical properties, have an extremely important impact on the growth and development of plant. Similarly, the development and prevention and control of plant diseases is also closely related. The research on characteristics of sugarcane rhizosphere micro-ecosystem and the internal relationship between it and sugarcane smut is conducive to the early prevention of sugarcane smut and the exploration of biocontrol resources. This paper summarizes the previous research progress from the following these aspects: the occurrence and harm of sugarcane smut, the relationship between plant rhizosphere microecology and diseases, sugarcane rhizosphere microecology and smut control. It aims to provide reference for the research of sugarcane rhizosphere microecology, the excavation of excellent biological control resources and the efficient control of sugarcane smut. [ABSTRACT FROM AUTHOR]

Sugarcane smut caused by the basidiomycetous fungus Sporisorium scitamineum is one of the most devastating diseases that affect sugarcane production, globally. At present, the most practical and effective management strategy for the disease is the cultivation of resistant cultivars. In this connection, a detailed understanding of the host's defense mechanism in response to smut isolates with varying degrees of virulence at the molecular level would facilitate the development of reliable and durable smut-resistant sugarcane varieties. Hence, in this study, a comparative whole transcriptome analysis was performed employing Illumina RNA-seq in the smut susceptible cultivar Co 97009 inoculated with two distinct S. scitamineum isolates, Ss97009 (high-virulent) and SsV89101 (low-virulent) during the early phases of infection (2 dpi and 5 dpi) and at the phase of sporogenesis (whip emergence) (60 dpi). Though the differential gene expression profiling identified significant transcriptional changes during the early phase of infection in response to both the isolates, the number of differentially expressed genes (DEGs) were more abundant at 60 dpi during interaction with the high virulent isolate Ss97009, as compared to the low virulent isolate SsV89101. Functional analysis of these DEGs revealed that a majority of them were associated with hormone signaling and the synthesis of defense-related metabolites, suggesting a complex network of defense mechanisms is being operated in response to specific isolates of the smut pathogen. For instance, up-regulation of hormone-related genes, transcription factors, and flavonoid biosynthesis pathway genes was observed in response to both the isolates in the early phase of interaction. In comparison to early phases of infection, only a few pathogenesis-related proteins were up-regulated at 60 dpi in response to Ss97009, which might have rendered the host susceptible to infection. Strikingly, few other carbohydrate metabolism-associated genes like invertases were up-regulated in Ss97009 inoculated plants during the whip emergence stage, representing a shift from sucrose storage to smut symptoms. Altogether, this study established the major switching of defense signaling pathways in response to S. scitamineum isolates with different virulence attributes and provided novel insights into the molecular mechanisms of sugarcane-smut interaction. [ABSTRACT FROM AUTHOR]

Sporisorium scitamineum, a biotrophic basidiomycete fungus, causes the ravaging sugarcane smut disease globally in almost all sugarcane growing countries. The fungus spans around three distinct developmental stages, viz., diploid teliospores, haploid sporidia and dikaryotic mycelia, during its life cycle. The yeast-like and non-pathogenic haploid sporidia represent two opposite mating types: MAT-1 and MAT-2. Discrimination of these mating type haploids is essential for long-term preservation and maintenance of true-to-type isolate/pathotype, genetic investigations and to understand how the fusion of non-pathogenic, compatible mating type haploids turn into virulent dikaryotic mycelia. Hitherto, only the mating-based phenotyping assay is used for discrimination of opposite mating type haploids. In the present study, a quick and reliable PCR-based assay was developed for the first time for discriminating the distinct mating types (MAT-1 and MAT-2) of the S. scitamineum by targeting the unique regions of bE/bW mating type genes. Among the different primer sets evaluated, two sets, viz., bE1F1/bE1-2R1 and bE2F2/bE1-2R1 that target bE mating type genes, precisely differentiated the MAT-1 and MAT-2 mating type haploids of two S. scitamineum isolates, Ss97009 (high virulent) and SsV89101 (less virulent). The pathogenicity of distinct developmental stages, viz., haploid sporidia, dikaryotic mycelia and teliospores, and the life cycle transitions of these two S. scitamineum isolates in planta were analyzed by phenotyping and microscopy, respectively. Quantitative real-time PCR was used to estimate the pathogen biomass of plants inoculated with individual haploid sporidia (MAT-1 and MAT-2), mixture of haploid sporidia and teliospores of Ss97009 and SsV89101. These results altogether have substantiated the virulence nature of these two isolates and established the significance of fusion of opposite mating type haploids in causing smut disease in sugarcane. Overall, this simple and efficient PCR-based discrimination assay of haploids would serve as a valuable tool for genomic and functional studies of S. scitamineum. [ABSTRACT FROM AUTHOR]

The basidiomycete fungus Sporisorium scitamineum is the causative agent of sugarcane smut disease. Mating between two strains of the opposite mating type is essential for filamentous growth and infection in sugarcane plants. However, the mechanisms underlying mating and pathogenicity are still not well understood. In this work we used gene disruption to investigate the role of Ssubc2, the gene encoding a kinase regulator in S. scitamineum. Deletion of Ssubc2 did not alter the haploid cell morphology or growth rate in vitro or tolerance to stress, but mutants with both alleles deleted lost mating ability and infectivity. Deletion of one Ssubc2 allele in a pair with a wildtype strain resulted in impaired mating and reduced virulence. Transcriptome profiling revealed that about a third of genes underwent reprogramming in the wild types during mating. Although gene expression reprogramming occurred in the pairing of Ssubc2-null mutants, their transcriptomic profile differed significantly from that of the wild types, in which 625 genes differed from those present in the wild types that seemed to be among the required genes for a successful mating. These genes include those known to regulate mating and pathogenicity, such as components of the MAPK pathway and hgl1. Additionally, a total of 908 genes were differentially expressed in an outof-control manner in the mutants. We conclude that SsUbc2 functions as a key factor to coordinate the reprogramming of gene expression at the global level and is essential for the transition from monokaryotic basidial growth to dikaryotic hyphal growth through mating. [ABSTRACT FROM AUTHOR]

Sugarcane smut caused by the basidiomycetous fungus Sporisorium scitamineum is one of the most devastating diseases that affect sugarcane production, globally. At present, the most practical and effective management strategy for the disease is the cultivation of resistant cultivars. In this connection, a detailed understanding of the host’s defense mechanism in response to smut isolates with varying degrees of virulence at the molecular level would facilitate the development of reliable and durable smut-resistant sugarcane varieties. Hence, in this study, a comparative whole transcriptome analysis was performed employing Illumina RNA-seq in the smut susceptible cultivar Co 97009 inoculated with two distinct S. scitamineum isolates, Ss97009 (high-virulent) and SsV89101 (low-virulent) during the early phases of infection (2 dpi and 5 dpi) and at the phase of sporogenesis (whip emergence) (60 dpi). Though the differential gene expression profiling identified significant transcriptional changes during the early phase of infection in response to both the isolates, the number of differentially expressed genes (DEGs) were more abundant at 60 dpi during interaction with the high virulent isolate Ss97009, as compared to the low virulent isolate SsV89101. Functional analysis of these DEGs revealed that a majority of them were associated with hormone signaling and the synthesis of defense-related metabolites, suggesting a complex network of defense mechanisms is being operated in response to specific isolates of the smut pathogen. For instance, up-regulation of hormone-related genes, transcription factors, and flavonoid biosynthesis pathway genes was observed in response to both the isolates in the early phase of interaction. In comparison to early phases of infection, only a few pathogenesis-related proteins were up-regulated at 60 dpi in response to Ss97009, which might have rendered the host susceptible to infection. Strikingly, few other carbohydrate metabolism-associated genes like invertases were up-regulated in Ss97009 inoculated plants during the whip emergence stage, representing a shift from sucrose storage to smut symptoms. Altogether, this study established the major switching of defense signaling pathways in response to S. scitamineum isolates with different virulence attributes and provided novel insights into the molecular mechanisms of sugarcane-smut interaction.

Pathogen infection seriously affects plant development and crop productivity, sometimes causing total crop failure. In this study, artificial stab inoculation was used to inoculate sugarcane smut. The changes in leaf gas exchange, chlorophyll fluorescence variables, and related defense enzyme activities were measured in sugarcane cultivar ROC22 after pathogen infection. The results showed that the net photosynthetic rate (Pn), stomatal conductance (gs), and transpiration rate (Tr) downregulated in the first three days after smut infection and upregulated on the fourth day; intercellular CO2 concentration (Ci) increased in the first three days of smut infection and reduced on the fourth day. The chlorophyll fluorescence parameters, i.e., Fo, Fm, Fv/Fm, Fs, and Fv′/Fm′ decreased at the initial stage of pathogen infection but increased rapidly up to 3 days after smut infection. It can be seen that sugarcane seedlings showed a positive response to pathogen infection. The correlation coefficient relationship between Pn, gs, and Tr reached above 0.800, showing a significant correlation; Ci was positively correlated with Fv′/Fm′ and ΦPSII, reaching above 0.800 and showing a significant correlation; Fo positively correlated with Fv/Fm, Fs, and ETR; Fv /Fm was positively correlated with Fv′/Fm′; Fs significantly correlated with Fv′/Fm′; and Fv′/Fm′ positively correlated with ΦPSII. After inoculation with smut, the related defense enzymes, i.e., POD, SOD, PPO, and PAL, were increased and upregulated; photosynthetic parameters can be associated with an increase in enzymatic activities. The results of this study will help to further study of the response mechanism to smut in the sugarcane growing period and provide a theoretical reference for sugarcane resistance to smut breeding. [ABSTRACT FROM AUTHOR]

Life cycle of the dimorphic sugarcane smut fungi, Sporisorium scitamineum , involves recognition and mating of compatible saprophytic yeast-like haploid sporidia (MAT-1 and MAT-2) that upon fusion, develop into infective dikaryotic mycelia. Although the dimorphic transition is intrinsically linked with the pathogenicity and virulence of S. scitamineum , it has never been studied using a proteomic approach. In the present study, an iTRAQ-based comparative proteomic analysis of three distinct stages was carried out. The stages were: the dimorphic transition period - haploid sporidial stage (MAT-1 and MAT-2); the transition phase (24 h post co-culturing (hpc)) and the dikaryotic mycelial stage (48 hpc). Functional categorization of differentially abundant proteins showed that the most altered biological processes were energy production, primary metabolism, especially, carbohydrate, amino acid, fatty acid, followed by translation, post-translation and protein turnover. Several differentially abundant proteins (DAPs), especially in the dikaryotic mycelial stage were predicted as effectors. Taken together, key molecular mechanisms underpinning the dimorphic transition in S. scitamineum at the proteome level were highlighted. The catalogue of stage-specific and dimorphic transition-associated-proteins and potential effectors identified herein represents a list of potential candidates for defective mutant screening to elucidate their functional role in the dimorphic transition and pathogenicity in S. scitamineum. Being the first comparative proteomics analysis of S. scitamineum , this study comprehensively examined three pivotal life cycle stages of the pathogen: the non-pathogenic haploid phase, the transition phase, and the pathogenic dikaryotic mycelial stage. While previous studies have reported the sugarcane and S. scitamineum interactions, this study endeavored to specifically identify the proteins responsible for pathogenicity. By analyzing the proteomic alterations between the haploid and dikaryotic mycelial phases, the study revealed significant changes in metabolic pathway-associated proteins linked to energy production, notably oxidative phosphorylation, and the citrate cycle. Furthermore, this study successfully identified key metabolic pathways that undergo reprogramming during the transition from the non-pathogenic to the pathogenic stage. The study also deciphered the underlying mechanisms driving the morphological and physiological alterations crucial for the S. scitamineum virulence. By studying its life cycle stages, identifying the key metabolic pathways and stage-specific proteins, it provides unprecedented insights into the pathogenicity and potential avenues for intervention. As proteomics continues to advance, such studies pave the way for a deeper understanding of plant-pathogen interactions and the development of innovative strategies to mitigate the impact of devastating pathogens like S. scitamineum. [Display omitted] • Proteome of Sporisorium scitamineum is distinct in the dimorphic transition stage. • Dimorphic transition involves global reprogramming in proteomic profiles. • Oxidative phosphorylation and citrate cycle are induced to meet the energy demands. • Carbohydrate metabolism is strongly downregulated in the dikaryotic mycelial stage. • Abundance of certain effectors increases in the dikaryotic mycelial stage. [ABSTRACT FROM AUTHOR]

Genome comparison between the maize pathogens Ustilago maydis and Sporisorium reilianum revealed a large diversity region (19-1) containing nearly 30 effector gene candidates, whose deletion severely hampers virulence of both fungi. Dissection of the S. reilianum gene cluster resulted in the identification of one major contributor to virulence, virulence-associated gene 2 (vag2; sr10050). Quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) experiments revealed high expression of vag2 during biotrophic growth of S. reilianum. Using the yeast secretion trap assay, we confirmed the existence of a functional signal peptide allowing protein secretion via the conventional secretory pathway. We identified the cytoplasmic maize chorismate mutase ZmCM2 by yeast two-hybrid screening as a possible interaction partner of Vag2. Interaction of the two proteins in planta was confirmed by bimolecular fluorescence complementation. qRT-PCR experiments revealed vag2-dependent downregulation of salicylic acid (SA)-induced genes, which correlated with higher SA levels in plant tissues colonized by Δvag2 deletion strains relative to S. reilianum wildtype strains. Metabolite analysis suggested rewiring of pathogen-induced SA biosynthesis by preferential conversion of the SA precursor chorismate into the aromatic amino acid precursor prephenate by ZmCM2 in the presence of Vag2. Possibly, the binding of Vag2 to ZmCM2 inhibits the back reaction of the ZmCM2-catalyzed interconversion of chorismate and prephenate, thus contributing to fungal virulence by lowering the plant SA-induced defenses. [ABSTRACT FROM AUTHOR]

This study was aimed at evaluating the antifungal activity of leaf extracts of neem, bitterleaf and their mixture against Ustilago scitamineum (Syd.), the pathogen of sugarcane smut disease. A suspension of mancozeb, carbendazim+maneb, matalaxy l+ carboxin + flurathiocarb, pyroquilon, benomyl, chlothalonil and flutriafol are effective as a dip in controlling the disease. However, the listed synthetic fungicides led to emergence of resistant strains of the pathogen and also cause environmental pollution. Hot water treatment of the cane setts at 52º C for 30 minutes before planting is also effective, but this can cause serious injuries on sugarcane farmers if not carefully practiced. Pour Plate method was used to determine antifungal effect of 10, 20 and 30 g/ 100 ml concentrations of aqueous and ethanolic leaf extracts of neem, bitterleaf and their mixture on radial growth of U. scitamineum for 6 days. The tested leaf extracts inhibited mycelial growth of U. scitamineum in vitro, with the ethanolic leaf extracts being more potent at some of the concentrations tested in this study. In conclusion, gradient of antifungal efficacy of the tested leaf extracts against U. scitamineum was: mixed leaf extracts > neem leaf extracts >bitterleaf leaf extracts at all the concentrations used.

Sugarcane is one of the most important industrial crops globally. It is the second largest source of bioethanol, and a major crop for biomass-derived electricity and sugar worldwide. Smut, caused by Sporisorium scitamineum , is a major sugarcane disease in many countries, and is managed by smut-resistant varieties. In China, smut remains the single largest constraint for sugarcane production, and consequently it impacts the value of sugarcane as an energy feedstock. Quantitative trait loci (QTLs) associated with smut resistance and linked diagnostic markers are valuable tools for smut resistance breeding. Here, we developed an F1 population (192 progeny) by crossing two sugarcane varieties with contrasting smut resistance and used for genome-wide single nucleotide polymorphism (SNP) discovery and mapping, using a high-throughput genotyping method called "specific locus amplified fragment sequencing (SLAF-seq) and bulked-segregant RNA sequencing (BSR-seq). SLAF-seq generated 148,500 polymorphic SNP markers. Using SNP and previously identified SSR markers, an integrated genetic map with an average 1.96 cM marker interval was produced. With this genetic map and smut resistance scores of the F1 individuals from four crop years, 21 major QTLs were mapped, with a phenotypic variance explanation (PVE) > 8.0%. Among them, 10 QTLs were stable (repeatable) with PVEs ranging from 8.0 to 81.7%. Further, four QTLs were detected based on BSR-seq analysis. aligning major QTLs with the genome of a sugarcane progenitor Saccharum spontaneum , six markers were found co-localized. Markers located in QTLs and functional annotation of BSR-seq-derived unigenes helped identify four disease resistance candidate genes located in major QTLs. 77 SNPs from major QTLs were then converted to Kompetitive Allele-Specific PCR (KASP) markers, of which five were highly significantly linked to smut resistance. The co-localized QTLs, candidate resistance genes, and KASP markers identified in this study provide practically useful tools for marker-assisted sugarcane smut resistance breeding. [ABSTRACT FROM AUTHOR]

Background: Sporisorium scitamineum is the causative agent of smut disease in sugarcane. The tricky life cycle of S. scitamineum consists of three distinct growth stages: diploid teliospores, haploid sporidia and dikaryotic mycelia. Compatible haploid sporidia representing opposite mating types (MAT-1 and MAT-2) of the fungus fuse to form infective dikaryotic mycelia in the host tissues, leading to the development of a characteristic whip shaped sorus. In this study, the transition of distinct stages of in vitro life cycle and in planta developmental stages of S. scitamineum are presented by generating stable GFP transformants of S. scitamineum. Methods and results: Haploid sporidia were isolated from the teliospores of Ss97009, and the opposite mating types (MAT-1 and MAT-2) were identified by random mating assay and mating type-specific PCR. Both haploid sporidia were individually transformed with pNIIST plasmid, harboring an enhanced green fluorescent protein (eGFP) gene and hygromycin gene by a modified protoplast-based PEG-mediated transformation method. Thereafter, the distinct in vitro developmental stages including fusion of haploid sporidia and formation of dikaryotic mycelia expressing GFP were demonstrated. To visualize in planta colonization, transformed haploids (MAT-1gfp and MAT-2gfp) were fused and inoculated onto the smut susceptible sugarcane cultivar, Co 97009 and examined microscopically at different stages of colonization. GFP fluorescence-based analysis presented an extensive fungal colonization of the bud surface as well as inter- and intracellular colonization of the transformed S. scitamineum in sugarcane tissues during initial stages of disease development. Noticeably, the GFP-tagged S. scitamineum led to the emergence of smut whips, which established their pathogenicity, and demonstrated initial colonization, active sporogenesis and teliospore maturation stages. Conclusion: Overall, for the first time, an efficient protoplast-based transformation method was employed to depict clear-cut developmental stages in vitro and in planta using GFP-tagged strains for better understanding of S. scitamineum life cycle development. [ABSTRACT FROM AUTHOR]

Spring barley resistance to diseases can reduce yield losses and amount of the applied plant protection products, and, accordingly, the costs for its cultivation. One of the most important tasks and conditions of the breeding process is the expansion of the genetic diversity of sources of resistance to unfavorable environmental conditions and the development of the varieties that possess resistance to pathogens. On the territory of the Rostov region, the most harmful and economically significant diseases of spring barley are helminth-spore spots and stone smut. The purpose of the current study was to identify the spring barley varieties resistant to helminth-sporiosis and smut. There have been presented the 3-year results on assessment of the domestic and foreign spring barley varieties for resistance to leaf diseases and smut. There have been studied 117 domestic and foreign varieties. The immunological properties of the spring barley varieties were studied in a field infectious nursery. The seed infection with spores was carried out by the S. Dimitrov's method using a nutrient environment. Sowing of the inoculated seeds was carried out at the end of the optimal terms. The analysis was carried out according to the number of infected stems. The infectious nursery with helminth-sporiosis was set up according to the Methodological recommendations (2008). On the basis of the current study, according to the immunological assessment, the varieties were divided into different groups of resistance to the studied pathogens. The genotypes with high immunological resistance degree to the complex of pathogens are of the greatest breeding value. There have been identified the sources of resistance to two pathogens. These are the varieties ‘Ratnik', ‘Zernogradsky 73', ‘Azov', ‘Kumir', ‘Elf', ‘Tan 1', ‘Zernogradsky 35', ‘Vikont' (Russia), ‘Getman', ‘Odessa 22' (Ukraine), ‘Viking' (Sweden). The identified sources of spring barley resistance to smut and spot diseases have been recommended for use in breeding programs for immunity.

Smut is a serious disease in Job's tears, also known as adlay, and contributes to the reduction of crop yield in agricultural fields. In this study, the key pathogenic fungi in adlay smut disease were first identified by internal transcribed spacer region (ITS) high-throughput sequencing and then used to elucidate the composition and diversity of the fungal community in adlay smut. Results indicate that an abundance of operational taxonomic units (OTUs) were detected in the infected involucres of flowering plants and the OTUs were classified to nine phyla, 20 classes, 45 orders, 90 families and 119 genera. A total of 4 986 OTUs clustered together, sharing six core OTUs in all samples, while 145 OTUs were shared among four geographical groups. The Shannon and Simpson indices ranged from 0.137–1.629 and 0.357–0.970, respectively. Community diversity ranked as Anshun (AS)>Qinglong (QL)>Xingren (XR)>Xingyi (XY) among the four geographical groups by Shannon and Simpson indices, exhibiting complex community diversities among accessions and geographical groups. The richness and diversity data imply a weak relationship between the accession community richness and geographical origins of samples. Two closely related fungal genera, Sporisorium and Ustilago, were implicated as causes of smut disease. The genus Sporisorium appears to be more commonly found among accessions and thus is more likely to be the fungal pathogen causing smut in adlay. This work can facilitate strategies to control and prevent smut infection to improve adlay yield.

The present investigation was conducted at El-Mattana Agricultural Research Station, Luxor Governorate, Egypt during two successive seasons 2018/2019 (plant cane) and 2019/2020 (first ratoon) to screening of eighteen sugarcane genotypes s for the lesser sugarcane borer, smut, streak and mosaic diseases resistance under natural infection and elimination of sensitive genotypes from sugarcane breeding program and to evaluate the performance of some sugarcane genotypes based on principal components analysis biplot and genetic components; heritability and genetic advance for the studied traits. The experimental design used was a randomized complete block design with three replicates. Results show all studied traits varied significantly among evaluated different genotypes in the plant cane and first ratoon. Cane yield of five and two genotypes in plant cane and first ratoon, respectively, gave significantly the highest mean values of cane yield as compare with check variety. Bored stalks% and bored joints % varied significantly among evaluated genotypes. It found high positive correlation between bored stalks% and bored joints and brix% in the positive direction. Plant height and stalk diameter were positively correlated with cane yield, not only smut, mosaic and streak diseases but also bored stalks and bored joints were negatively correlated with cane and sugar yield and negatively correlated sucrose%, purity% and recovery%. The differences between the estimates of GCV and PCV was comparatively narrow for all the characters (except stalk diameter and Mosaic disease) suggesting the possibility of affective selection of these traits and indicating high prospects for genetic progress through selection under the conditions of this investigation.

Sugarcane is one of the most important industrial crops globally. It is the second largest source of bioethanol, and a major crop for biomass-derived electricity and sugar worldwide. Smut, caused by Sporisorium scitamineum, is a major sugarcane disease in many countries, and is managed by smut-resistant varieties. In China, smut remains the single largest constraint for sugarcane production, and consequently it impacts the value of sugarcane as an energy feedstock. Quantitative trait loci (QTLs) associated with smut resistance and linked diagnostic markers are valuable tools for smut resistance breeding. Here, we developed an F1 population (192 progeny) by crossing two sugarcane varieties with contrasting smut resistance and used for genome-wide single nucleotide polymorphism (SNP) discovery and mapping, using a high-throughput genotyping method called “specific locus amplified fragment sequencing (SLAF-seq) and bulked-segregant RNA sequencing (BSR-seq). SLAF-seq generated 148,500 polymorphic SNP markers. Using SNP and previously identified SSR markers, an integrated genetic map with an average 1.96 cM marker interval was produced. With this genetic map and smut resistance scores of the F1 individuals from four crop years, 21 major QTLs were mapped, with a phenotypic variance explanation (PVE) > 8.0%. Among them, 10 QTLs were stable (repeatable) with PVEs ranging from 8.0 to 81.7%. Further, four QTLs were detected based on BSR-seq analysis. aligning major QTLs with the genome of a sugarcane progenitor Saccharum spontaneum, six markers were found co-localized. Markers located in QTLs and functional annotation of BSR-seq-derived unigenes helped identify four disease resistance candidate genes located in major QTLs. 77 SNPs from major QTLs were then converted to Kompetitive Allele-Specific PCR (KASP) markers, of which five were highly significantly linked to smut resistance. The co-localized QTLs, candidate resistance genes, and KASP markers identified in this study provide practically useful tools for marker-assisted sugarcane smut resistance breeding.

To understand the beneficial interaction of sugarcane rhizosphere actinobacteria in promoting plant growth and managing plant diseases, this study investigated the potential role of sugarcane rhizospheric actinobacteria in promoting plant growth and antagonizing plant pathogens. We isolated 58 actinobacteria from the sugarcane rhizosphere, conducted plant growth-promoting (PGP) characteristics research, and tested the pathogenic fungi in vitro. Results showed that BTU6 (Streptomyces griseorubiginosus), the most representative strain, regulates plant defense enzyme activity and significantly enhances sugarcane smut resistance by regulating stress resistance-related enzyme (substances (POD, PAL, PPO, TP) in sugarcane) activity in sugarcane. The genomic evaluation indicated that BTU6 has the ability to biosynthesize chitinase, β-1,3-glucanase, and various secondary metabolites and plays an essential role in the growth of sugarcane plants under biotic stress. Potential mechanisms of the strain in improving the disease resistance of sugarcane plants and its potential in biodegrading exogenous chemicals were also revealed. This study showed the importance of sugarcane rhizosphere actinobacteria in microbial ecology and plant growth promotion.

The common smut of corn, caused by Ustilago maydis, reduces the yield and quality of maize forage. When heavy infestations of corn smut occur, grain yields can be so severely decreased that the most viable economic alternative may be to harvest and ensile the crop. Only a couple of studies have attempted to investigate the influence of aerobic exposure on the nutritive value and aerobic stability of silage, which is prepared from smut-infected maize. In this study, individual whole corn plants were harvested by hand. The plants were distributed into three treatments: 0% infected, 50% infected, and 100% infected. The fresh forage was ensiled in triplicate for a 90-day period. Aerobic exposure lasted for 28 days. Samples were taken on the day of opening and on the 3rd, 7th, 14th, and 28th days. Near infrared spectroscopy (NIRS) calibration equations were used for the prediction of qualitative indicators. Silage prepared from 100% smut-infected maize had comparatively poor quality with dry matter loss, increasing pH and the low amount of starch. It was also distinguished with significant temperature increases from days 15 to 18 of aerobic exposure. Silage prepared from 50% smut-infected maize did not show significant quality changes over the period of the experiment, although it had inferior quality compared to the silage prepared from smut-free maize. While silage prepared from smut-infected maize had an overall worse quality than silage prepared from non-infected maize, it should not have an adverse effect on livestock health or production.

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Sporisorium scitamineum is a teleomorphic, biotrophic fungus causing the globally prevalent sugarcane smut disease in sugarcane. The severity of the disease depends on two major factors, viz. degree of resistance in the host genotype and virulence level of the pathogen. Hence, in this study, temporal transcriptomic expression of potential pathogenicity-associated genes of two distinctly virulent S. scitamineum isolates, viz. SsV89101 (low virulent) and Ss97009 (high virulent) were analyzed during interaction with a smut susceptible sugarcane cv. Co 97009 at six different time intervals. The pathogenicity-associated genes profiled in this study comprises 14 plant cell wall degrading enzymes (PCWDEs) and ten candidates secreted effector protein-coding (CSEPs) genes. Absolute quantification of pathogen biomass and comparative expression profiling analyses of these pathogenicity-associated genes during host–pathogen interaction indicated that there was a significant variation between low and high virulent isolates. More precisely, the higher and early expression (24 hpi) of certain PCWDEs, viz. Chitinase-1 and Laccase, and the CSEPs, viz. SUC2, SRT1 and CMU1 during the colonization of high virulent isolate suggested that they might possibly play a major role in facilitating faster and successful pathogen ingress, and tissue colonization than the less-virulent isolate. Transcript expression profiling of Chitinase and Laccases were also in correlation with their corresponding enzyme activity assays. Comprehensively, this quantitative temporal expression analysis has provided critical insights into the early expression of pathogenicity-associated genes and their putative role in attributing to higher virulence. Moreover, this study provides valuable clues for the screening of candidate virulence determinants for further functional characterization of the test pathogen isolates used for the evaluation of smut resistance in breeding clones. [ABSTRACT FROM AUTHOR]

On the fields with infectious backgrounds more than one thousands of varieties and samples of collection and breeding material of winter wheat are annually estimated for resistance to six diseases (brown and yellow rust, leaf blotch, powdery mildew, loose and kernel smut). Among the collection material there have been identified the samples tolerant and resistant to all studied diseases as well as the samples with complex resistance to 3–6 pathogens (e. g. “Maris Kinsman”, “Tucan”, “Liwilla”, “KS93V76”, “PL 178383” and others). Such varieties of the Inter-Station Variety Testing (ISVT) from Russia, Ukraine, Germany, France as “Etana”, “Kurs”, “Rotaks”, “Solokha”, “Shestopalovka” cannot be artificially infected with the diseases. There has been identified a small percentage among the present varieties and collection samples tolerant to such diseases as powdery mildew, leaf blotch and kernel smut. The winter soft wheat varieties developed in the FSBSI “ARC “Donskoy” both widely cultivated in production, and introduced for study in the SVT in recent years, are characterized by a high resistance to 2–4 studied diseases. These are the varieties “Tanais”, “Rostovchanka 7”, “Aksiniya”, “Nakhodka” which are recommended to plant after fallow forecrops and the varieties “Krasa Dona”, “Ermak”, “Donskoy Syurpriz”, “Don 107”, “Izyuminka”, “Asket”, “Lidiya” which are recommended to plant after non-fallow forecrops. The identified resistant varieties are recommended for wide cultivation, and the sources of resistance to a complex of the main harmful diseases on the Nizhny Don can be used in the breeding programs on immunity.

Pathogen infection seriously affects plant development and crop productivity, sometimes causing total crop failure. In this study, artificial stab inoculation was used to inoculate sugarcane smut. The changes in leaf gas exchange, chlorophyll fluorescence variables, and related defense enzyme activities were measured in sugarcane cultivar ROC22 after pathogen infection. The results showed that the net photosynthetic rate (Pn), stomatal conductance (gs), and transpiration rate (Tr) downregulated in the first three days after smut infection and upregulated on the fourth day; intercellular CO2 concentration (Ci) increased in the first three days of smut infection and reduced on the fourth day. The chlorophyll fluorescence parameters, i.e., Fo, Fm, Fv/Fm, Fs, and Fv′/Fm′ decreased at the initial stage of pathogen infection but increased rapidly up to 3 days after smut infection. It can be seen that sugarcane seedlings showed a positive response to pathogen infection. The correlation coefficient relationship between Pn, gs, and Tr reached above 0.800, showing a significant correlation; Ci was positively correlated with Fv′/Fm′ and ΦPSII, reaching above 0.800 and showing a significant correlation; Fo positively correlated with Fv/Fm, Fs, and ETR; Fv /Fm was positively correlated with Fv′/Fm′; Fs significantly correlated with Fv′/Fm′; and Fv′/Fm′ positively correlated with ΦPSII. After inoculation with smut, the related defense enzymes, i.e., POD, SOD, PPO, and PAL, were increased and upregulated; photosynthetic parameters can be associated with an increase in enzymatic activities. The results of this study will help to further study of the response mechanism to smut in the sugarcane growing period and provide a theoretical reference for sugarcane resistance to smut breeding.

Smutted Bermudagrass (Cynodon dactylon L.) plants with diseased spikelets and completely deformed inflorescences covered with black teliospores were collected from five locations at the borders of plantations in Kafr El-Sheikh province, Egypt, in April 2018. The fungus was isolated from infected plants and identified as Ustilago cynodontis (Passerini) Henn. based on its cultural and morphological characteristics, molecular techniques, and pathogenicity tests. Slender colonies of U. cynodontis with irregular edges were observed on potato dextrose agar (PDA) after 6 days at 28°C. The mature teliospores were examined by scanning electron microscopy. Crystal-like structures with a pyramidal shape were observed to be produced by the fungus in culture. The crystals were further examined using an energy dispersive spectroscopy system connected to the scanning electron microscope and their dimensions were measured (18 ± 2 µm × 16 ± 2 µm × 19 ± 2 µm). PCR analysis with internal transcribed spacer (ITS) specific primers yielded an amplicon that shared a 99% identity with U. cynodontis sequences in GenBank. Phylogenetic analysis indicated that the Egyptian isolate of U. cynodontis shared the greatest similarity with isolates of U. cynodontis from Ethiopia, Iran, India, United States, Mexico, Spain, and China. Inoculation of Bermudagrass with the isolated fungus resulted in symptoms of smut similar to those observed in the field. To our knowledge, this is the first report concerning the occurrence and characterization of U. cynodontis, the causal agent of Bermudagrass smut, in Egypt. [ABSTRACT FROM AUTHOR]

Genome comparison between the maize pathogens Ustilago maydis and Sporisorium reilianum revealed a large diversity region (19-1) containing nearly 30 effector gene candidates, whose deletion severely hampers virulence of both fungi. Dissection of the S. reilianum gene cluster resulted in the identification of one major contributor to virulence, virulence-associated gene 2 (vag2; sr10050). Quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) experiments revealed high expression of vag2 during biotrophic growth of S. reilianum. Using the yeast secretion trap assay, we confirmed the existence of a functional signal peptide allowing protein secretion via the conventional secretory pathway. We identified the cytoplasmic maize chorismate mutase ZmCM2 by yeast two-hybrid screening as a possible interaction partner of Vag2. Interaction of the two proteins in planta was confirmed by bimolecular fluorescence complementation. qRT-PCR experiments revealed vag2-dependent downregulation of salicylic acid (SA)-induced genes, which correlated with higher SA levels in plant tissues colonized by Δvag2 deletion strains relative to S. reilianum wildtype strains. Metabolite analysis suggested rewiring of pathogen-induced SA biosynthesis by preferential conversion of the SA precursor chorismate into the aromatic amino acid precursor prephenate by ZmCM2 in the presence of Vag2. Possibly, the binding of Vag2 to ZmCM2 inhibits the back reaction of the ZmCM2-catalyzed interconversion of chorismate and prephenate, thus contributing to fungal virulence by lowering the plant SA-induced defenses.

Sugar cane smut (Sporisorium scitamineum) interactions have been traditionally considered from the plant’s point of view: How can resistant sugar cane plants defend themselves against smut disease? Resistant plants induce several defensive mechanisms that oppose fungal attacks. Herein, an overall view of Sporisorium scitamineum’s mechanisms of infection and the defense mechanisms of plants are presented. Quorum sensing effects and a continuous reorganization of cytoskeletal components, where actin, myosin, and microtubules are required to work together, seem to be some of the keys to a successful attack. [ABSTRACT FROM AUTHOR]

Investigation of plant–microbe interactions greatly benefit from genetically tractable partners to address, molecularly, the virulence and defense mechanisms. The smut fungus Ustilago maydis is a model pathogen in that sense: efficient homologous recombination and a small genome allow targeted modification. On the host side, maize is limiting with regard to rapid genetic alterations. By contrast, the model plant Arabidopsis thaliana is an excellent model with a vast amount of information and techniques as well as genetic resources. Here, we present a transformation protocol for the Brassicaceae smut fungus Thecaphora thlaspeos. Using the well-established methodology of protoplast transformation, we generated the first reporter strains expressing fluorescent proteins to follow mating. As a proof-of-principle for homologous recombination, we deleted the pheromone receptor pra1. As expected, this mutant cannot mate. Further analysis will contribute to our understanding of the role of mating for infection biology in this novel model fungus. From now on, the genetic manipulation of T. thlaspeos, which is able to colonize the model plant A. thaliana, provides us with a pathosystem in which both partners are genetically amenable to study smut infection biology. [ABSTRACT FROM AUTHOR]

There are only two previous citations since the 20th Century of this smut species for Romania. However, this relates to herbarium material collected for the first time in 1957 in Târgu Mureș recorded by K. Vánky (according dataset: The Fungal Collection at the Botanische Staatssammlung München) and to the second collecting in 1978 in Valea lui Mihai-Șimian, Brașov by Negrean G. (according dataset: The Fungal Collection at the Senckenberg Museum für Naturkunde Görlitz). In the present paper the interaction between the phytopathogenic fungus Ustilago syntherismae and the plant at which it infects, Digitaria sanguinalis, has been studied. Aspects related to the phenotypic expression (symptoms) manifested by Digitaria sanguinalis under field conditions and to the morphological characteristics of the spores of the fungus Ustilago syntherismae are presented. The observations took place in the period 2018-2020.Further research is required to investigate the current distribution of the loose smut - Ustilago syntherismae (Schweinitz) Peck on Digitaria sanguinalis (L.) Scop.in Romania. [ABSTRACT FROM AUTHOR]