Powdery Mildew Disease Research Articles

Morphological and molecular characterization of Neoerysiphe galeopsidis causing powdery mildew on Lagopsis supina in central China

Lagopsis supina (Xia Zhi Cao) is a widely distributed and cultivated herbal plant that has been extensively used as a traditional Chinese medicine, Tibetan medicine and Mongolian medicine for disease treatments for centuries. While the bioactive compounds of L. supina are extensively studied, the fungal pathogens of this plant are still obscure. In 2021, powdery mildew signs and symptoms were observed on leaves of L. supina in Xinxiang City, Henan Province, China. However, the causal pathogen had not been identified. Therefore, morphological characteristics and molecular analysis was applied to identify the powdery mildew pathogen. The sequence of the internal transcribed spacer (ITS) region of the fungus was obtained and showed 99.83% identity with the previously reported Neoerysiphe galeopsidis. The virulence of this phytopathogen on L. supina was confirmed by utilizing Koch’s postulates. Therefore, we identified the causal pathogen as N. galeopsidis. Based on biological and molecular characterization, this is the first comprehensive report of powdery mildew caused by N. galeopsidis on L. supina in central China. The occurrence of powdery mildew disease on L. supina may detract from the plant’s medical and ornamental value. The identification and confirmation of N. galeopsidis on L. supina expands the knowledge of this causal agent and will support efforts towards future control and management of powdery mildews.

Powdery mildew caused by Erysiphe corylacearum: An emerging problem on hazelnut in Italy.

Erysiphe corylacearum has recently been reported in northern Italy (Piedmont) and other European countries as the causal agent of a new emerging powdery mildew on hazelnut. This disease is much more dangerous than the common hazelnut powdery mildew caused by Phyllactinia guttata as it significantly reduces yield and quality of hazelnuts. This study aimed to perform morphological and molecular characterization of the fungal isolates from powdery mildew-infected plants in the Piedmont Italian region. Additionally, genetic diversity studies and pathogenicity tests were conducted. Thirty-six fungal isolates originating from symptomatic hazelnut plants exhibiting specific powdery mildew symptoms on the superior leaf side were identified morphologically as E. corylacearum. Single- and multilocus sequence typing of five loci (ITS, rpb2, CaM, GAPDH and GS) assigned all isolates as E. corylacearum. Multilocus and GAPDH phylogenetic studies resulted in the most efficient characterization of E. corylacearum. Studied fungal isolates were able to cause new emerging powdery mildew disease by fulfilling Koch's postulates. The emergence of powdery mildew disease in Italy revealed the E. corylacearum subgrouping, population expansion, and high nucleotide similarity with other recently identified E. corylacearum hazelnut isolates. To contain this harmful disease and inhibit the fungus spread into new geographical zones, it will be necessary to implement more rigorous monitoring in neighboring hazelnut plantations near infected hazelnuts, use sustainable fungicides and search for new biocontrol agents.

Detection of the Presence of Powdery Mildew Resistance -Associated Genes (Ren1, Ren3, and Ren9) in Vitis labrusca L. Genotypes

Powdery mildew disease (Erysiphe necator Schwein) is a significant threat to grape cultivation in vineyards. Severe yield and quality losses could occur in vineyards when this pathogen is not managed correctly. Several commercial grape varieties are highly susceptible to powdery mildew. Therefore, large quantities of fungicides are applied throughout the growing season. In addition to yields and quality, new grapevine varieties that are genetically resistant to powdery mildew are required for sustainable viticulture. This study was conducted through molecular screening of powdery mildew resistance genes in nine different Vitis labrusca L. genotypes (TEG-Vl-1, TEG-Vl-2, TEG-Vl-3, TEG-Vl-4, TEG-Vl-5, TEG-Vl-6, TEG-Vl-7, TEG-Vl-8, and TEG-Vl-9) grown in the Black Sea Region of Türkiye. After PCR amplifications using Ren1, Ren3 and Ren9 locus-specific primers, Ren1, and Ren 9 genes were detected in three genotypes (TEG-Vl-1, TEG-Vl-3, and TEG-Vl-4). However, the Ren3 gene was not detected in any genotypes. It was concluded based on present findings that Vitis labrusca L. genotypes with resistance genes could be used as genetic resources in grapevine breeding programs and significant economic benefits can be provided accordingly.

Genome-Wide Identification and Expression Profile Analysis of the Phenylalanine Ammonia-Lyase Gene Family in Hevea brasiliensis.

The majority of the world's natural rubber comes from the rubber tree (Hevea brasiliensis). As a key enzyme for synthesizing phenylpropanoid compounds, phenylalanine ammonia-lyase (PAL) has a critical role in plant satisfactory growth and environmental adaptation. To clarify the characteristics of rubber tree PAL family genes, a genome-wide characterization of rubber tree PALs was conducted in this study. Eight PAL genes (HbPAL1-HbPAL8), which spread over chromosomes 3, 7, 8, 10, 12, 13, 14, 16, and 18, were found to be present in the genome of H. brasiliensis. Phylogenetic analysis classified HbPALs into groups I and II, and the group I HbPALs (HbPAL1-HbPAL6) displayed similar conserved motif compositions and gene architectures. Tissue expression patterns of HbPALs quantified by quantitative real-time PCR (qPCR) proved that distinct HbPALs exhibited varying tissue expression patterns. The HbPAL promoters contained a plethora of cis-acting elements that responded to hormones and stress, and the qPCR analysis demonstrated that abiotic stressors like cold, drought, salt, and H2O2-induced oxidative stress, as well as hormones like salicylic acid, abscisic acid, ethylene, and methyl jasmonate, controlled the expression of HbPALs. The majority of HbPALs were also regulated by powdery mildew, anthracnose, and Corynespora leaf fall disease infection. In addition, HbPAL1, HbPAL4, and HbPAL7 were significantly up-regulated in the bark of tapping panel dryness rubber trees relative to that of healthy trees. Our results provide a thorough comprehension of the characteristics of HbPAL genes and set the groundwork for further investigation of the biological functions of HbPALs in rubber trees.

Studies on powdery mildew disease of advanced mutants lines in menthol mint

Studies on powdery mildew disease of advanced mutants lines in menthol mint

POWDERY MILDEW OF MANGO: CURRENT STATUS, PERSPECTIVE AND EMERGING TOOLS FOR MANAGEMENT

Mango (Mangifera indica) is an important fruit crop that belongs to the family Anacardiacae. It is considered the most delicious fruit cultivated around the tropical and sub-tropical regions of the world. In Pakistan, mango ranked second in terms of production after citrus. It plays a vital role in enriching the economy of the country. However, its production is hampered by several biotic and abiotic stresses. Fungal pathogens are a major threat to the successful production of mangoes. Powdery mildew, caused by the fungus Pseudoidium anacardii (formerly Oidium mangifera), poses a significant threat to mango crops worldwide, leading to substantial losses in yield. Previous studies confirmed that around 20-25% of yield losses in mango production occur due to powdery mildew disease, with 100% of disease incidence in major mango-growing regions. The most severe losses occur when flowering and growth flushes become infected, especially during cool and dry weather conditions. Optimal disease development typically happens within a temperature range of 11–14 °C minimum and 27–31 °C maximum, coupled with relative humidity levels of 64–72%. Despite the widespread impact, and influence of climate change, losses are increasing day by day. There is a lack of comprehensive research on the symptoms, biology, and control measures. Control is difficult due to the emergence of resistant strains and the varying levels of susceptibility of mango varieties. Therefore, it is crucial to implement integrated management techniques to control powdery mildew. To address this issue, various approaches, such as chemical control, biological control, and Nanotechnology are being employed as management strategies. This review included a brief explanation of different management strategies used against the powdery mildew of mango concerning previous studies.

Isoquinoline alkaloids from endophytic fungus Aspergillus puniceus and their potential as inhibitors for tobacco powdery mildew

The isoquinoline alkaloids have attracted widespread attention from chemists and biologists. With the aims of screening for biological compounds produced by fungi, three new (1–3), together with four known (4–7) isoquinolines were isolated from the cigar tobacco-derived endophytic fungus Aspergillus puniceus in this study. Their structures were determined by means of HRESIMS and NMR spectroscopic studies. Interestingly, the antifungal activity test revealed that compound 5 showed high antifungal activity against G. cichoracearum (DC) (the main pathogen of tobacco powdery mildew disease) with an inhibition rate of 76.3% ± 5.0. Compared to the negative control, compounds 1–4, 6, and 7 also showed notable anti-G. cichoracearum activities with inhibition rates in the range of 38.5–56.9%. The isolation of the above isoquinolines may provide materials for the study of more potent antifungal inhibitors and contribute to an improved utilisation of cigar tobacco-derived endophytic fungi.

Genome-wide association study and haplotype analysis reveal novel candidate genes for resistance to powdery mildew in soybean.

Powdery mildew disease (PMD) is caused by the obligate biotrophic fungus Microsphaera diffusa Cooke & Peck (M. diffusa) and results in significant yield losses in soybean (Glycine max (L.) Merr.) crops. By identifying disease-resistant genes and breeding soybean accessions with enhanced resistance, we can effectively mitigate the detrimental impact of PMD on soybeans. We analyzed PMD resistance in a diversity panel of 315 soybean accessions in two locations over 3 years, and candidate genes associated with PMD resistance were identified through genome-wide association studies (GWAS), haplotype analysis, qRT-PCR, and EMS mutant analysis. Based on the GWAS approach, we identified a region on chromosome 16 (Chr16) in which 21 genes form a gene cluster that is highly correlated with PMD resistance. In order to validate and refine these findings, we conducted haplotype analysis of 21 candidate genes and indicated there are single nucleotide polymorphisms (SNPs) and insertion-deletions (InDels) variations of Glyma.16G214000, Glyma.16G214200, Glyma.16G215100 and Glyma.16G215300 within the coding and promoter regions that exhibit a strong association with resistance against PMD. Subsequent structural analysis of candidate genes within this cluster revealed that in 315 accessions, the majority of accessions exhibited resistance to PMD when Glyma.16G214300, Glyma.16G214800 and Glyma.16G215000 were complete; however, they demonstrated susceptibility to PMD when these genes were incomplete. Quantitative real-time PCR assays (qRT-PCR) of possible candidate genes showed that 14 candidate genes (Glyma.16G213700, Glyma.16G213800, Glyma.16G213900, Glyma.16G214000, Glyma.16G214200, Glyma.16G214300, Glyma.16G214500, Glyma.16G214585, Glyma.16G214669, Glyma.16G214700, Glyma.16G214800, Glyma.16G215000, Glyma.16G215100 and Glyma.16G215300) were involved in PMD resistance. Finally, we evaluated the PMD resistance of mutant lines from the Williams 82 EMS mutations library, which revealed that mutants of Glyma.16G214000, Glyma.16G214200, Glyma.16G214300, Glyma.16G214800, Glyma.16G215000, Glyma.16G215100 and Glyma.16G215300, exhibited sensitivity to PMD. Combined with the analysis results of GWAS, haplotypes, qRT-PCR and mutants, the genes Glyma.16G214000, Glyma.16G214200, Glyma.16G214300, Glyma.16G214800, Glyma.16G215000, Glyma.16G215100 and Glyma.16G215300 were identified as highly correlated with PMD resistance. The candidate genes identified above are all NLR family genes, and these discoveries deepen our understanding of the molecular basis of PMD resistance in soybeans and will be useful for guiding breeding strategies.

Effectiveness of Rhodococcus erythropolis strain OPI-01 on the fungal development in winter wheat

Abstract. Behzad A, Diakite S, Astarkhanova TS, Pakina EN, Allen D, Mohammadi PM, Diarra O, Saquee FS. 2024. Effectiveness of Rhodococcus erythropolis strain OPI-01 on the fungal development in winter wheat. Biodiversitas 25: 1063-1070. One of the means of sustainable wheat production is using bacterial pesticides, which can synthesize phytohormonal substances with antibacterial and antifungal action. Therefore, the work aimed to study the effect of different doses of a new growth regulator Restart, ZH (Rhodococcus erythropolis D strain OPI-01) on winter wheat yield. The findings of field experiments on the effect of plant growth regulator R. erythropolis strain OPI-01 method of pre-sowing treatment of seeds (at 0.1 L/t and 0.2 L/t), and soil spraying just before sowing (-0.5 l/ha) revealed that on average, during the 2020-2021 and 2021-2022 seasons, the number of productive stems increased by a margin of 23-30, the number of grains in 1 ear increased in the experimental units by 16.2-19.4%, and the length of the ear by 0.3-0.7cm, gluten varied from 32.3 to 33.8%, yield increased from 27.8-33.0% relative to the control. Disease severity and incidence of powdery mildew, brown rust and Septoria disease in plots amended withR. erythropolis strain OPI-01 was 2-fold less than in the control plots. Research trials show the efficacy of R. erythropolis strain OPI-01 under field conditions as a plant growth regulator and a potential microbial fungicide against some foliar diseases of winter wheat. It would be exciting to study the mechanism of R. erythropolis on wheat pathogens in vitro and in planta which are still less developed in the literature.

Field-Deployed Spectroscopy from 350 to 2500 nm: A Promising Technique for Early Identification of Powdery Mildew Disease (Erysiphe necator) in Vineyards

This study explores spectroscopy in the 350 to 2500 nm range for detecting powdery mildew (Erysiphe necator) in grapevine leaves, crucial for precision agriculture and sustainable vineyard management. In a controlled experimental vineyard setting, the spectral reflectance on leaves with varying infestation levels was measured using a FieldSpec 4 spectroradiometer during July and September. A detailed assessment was conducted following the guidelines recommended by the European and Mediterranean Plant Protection Organization (EPPO) to quantify the level of infestation; categorising leaves into five distinct grades based on the percentage of leaf surface area affected. Subsequently, spectral data were collected using a contact probe with a tungsten halogen bulb connected to the spectroradiometer, taking three measurements across different areas of each leaf. Partial Least Squares Regression (PLSR) analysis yielded coefficients of determination R2 = 0.74 and 0.71, and Root Mean Square Errors (RMSEs) of 12.1% and 12.9% for calibration and validation datasets, indicating high accuracy for early disease detection. Significant spectral differences were noted between healthy and infected leaves, especially around 450 nm and 700 nm for visible light, and 1050 nm, 1425 nm, 1650 nm, and 2250 nm for the near-infrared spectrum, likely due to tissue damage, chlorophyll degradation and water loss. Finally, the Powdery Mildew Vegetation Index (PMVI) was introduced, calculated as PMVI = (R755 − R675)/(R755 + R675), where R755 and R675 are the reflectances at 755 nm (NIR) and 675 nm (red), effectively estimating disease severity (R2 = 0.7). The study demonstrates that spectroscopy, combined with PMVI, provides a reliable, non-invasive method for managing powdery mildew and promoting healthier vineyards through precision agriculture practices.

Genetic variability and association study of SSR markers for yield and powdery mildew disease in pea (Pisum sativum)

Makhyatmubi, one of the most popular local varieties of field pea (Pisum sativum L.) in Manipur has morpho- physiological bottlenecks such as tall nature and high susceptibility to fungus Erysiphe pisi causing powdery mildew disease. Therefore, an experiment was conducted during winter (rabi) seasons of 2018–19 and 2020–21 at College of Post-Graduate Studies in Agricultural Sciences (Central Agricultural University, Imphal, Manipur), Umiam, Meghalaya to generate genetic variability by hybridization of Makhyatmubi with Prakash variety which is a well-known powdery mildew resistant variety in India and possesses several contrasting characters. Fruitful heterosis was estimated with highest record in number of pods per plant (114.75%) and seed yield per plant (108.04%). These two characters also showed high PCV, GCV, heritability and GAM. Number of pods per plant (0.95) was found to have highest positive significant correlation with seed yield per plant. MP-5 and MP-119 recorded superior performance in several characters under study. For the association study of simple sequence repeats (SSR) markers, easily scorable polymorphic markers were selected for surveying association with the traits. Results revealed that SSR marker AA122 may be associated with seed yield and number of pods per plant while marker AA136 with number of seeds per pod. A5 marker was found to be associated with the powdery mildew disease. Hence, it can be employed for marker assisted selection (MAS) to identify and select pea genotypes exhibit resistance to powdery mildew disease.

Bioactive carbohydrate from potato peels: A sweet inducer that mediate resistance against powdery mildew disease of cucumber through phytohormonal alterations

Large volumes of nutritive wastes are generated by food industries, which can be used in the production of bioactive compounds of commercial values. The waste generated by potato chips industries contains high quantities of insoluble starch, high concentrations of total suspended solids and chemical oxygen demand, or environmental issues. In this study, the starch extracted from the potato peels was subjected to bioconversion of isomaltose-oligosaccharide by enzymatic method and further eluted isomatlose by liquid chromatography-mass spectrometry. The structural elucidation of isomaltose was confirmed by 1H NMR and 13C NMR spectroscopy. The purified isomaltose displayed excellent in vitro antifungal action against Erysiphe cichoracearum and Fusarium oxysporum at concentrations 1.0 and 2.5 mg/ml, respectively. Notably, cucumber-seeds primed with isomaltose (2.5 and 5.0 mg/mL) concentrations recorded a significant improvement of germination (91.5 and 89 %) and vigor (2210.93 and 2015.7) over the untreated control. Subsequently, the isomaltose-primed cucumber plants challenged with powdery mildew pathogen showed enhanced protection of 63% in comparison with pathogen alone-induced plants. This enhanced growth parameters and induced resistance in cucumber may be fairly contributed by the upregulation of phytohormone levels in primed plants observed in this study. Taken together, this study is unique in the use of bioactive isomaltose from potato peels, which could enable us to minimize the agro-industrial wastes and most importantly could help to develop new formulations for sustainable crop protection strategies.

Evaluation and genetic dissection of the powdery mildew resistance in 558 wheat accessions

Powdery mildew, a widespread and destructive wheat disease caused by the fungal pathogen Blumeria graminis f. sp. tritici (Bgt), results in significant yield losses globally. Employing host resistance is the most cost-effective and environmentally sustainable approach to managing this disease. Assessing the resistance levels of wheat germplasms and understanding the genetic underpinnings of this resistance is crucial. In this study, we evaluated the seedling resistance to powdery mildew in 558 wheat accessions, along with the presence of resistance genes Pm1, Pm2, Pm4, Pm5, Pm6, Pm8, Pm12, Pm21, Pm24, Pm41, Pm42, Pm45, Pm47, Pm60, and Pm69 using various Bgt isolates and associated diagnostic markers. The study revealed that out of 558 wheat accessions tested, only 25 showed resistance to the Bgt isolate E09, highlighting a general lack of powdery mildew resistance among the evaluated accessions. Furthermore, these 25 accessions exhibited a significantly different resistance spectrum to 25 additional Bgt isolates. Notably, seven of these accessions were resistant to all the tested isolates, indicating they possess Pm genes with broad-spectrum resistance. Molecular analysis using closely linked or diagnostic markers revealed diverse resistance gene profiles: 249 accessions harbored a single tested Pm gene, 75 accessions possessed combinations of Pm genes, and 234 accessions lacked any of the tested genes. Pm8 was the most frequently detected gene, present in 27.42% of accessions, whereas Pm5, Pm12, Pm24, Pm41, Pm42, Pm45, Pm47 and Pm69 were not detected. Among the seven accessions resistant to all 26 tested isolates, Pm21 was detected in four accessions (HengS29, Chang 4640, Xinong 556, and ML728). Pm2 and Pm60 were identified in Emai 18 and Xinmai 296, respectively. Interestingly, none of the tested genes were detected in Emai 16, suggesting the presence of potentially novel Pm gene(s) conferring broad-spectrum resistance. These findings offer valuable insights for the strategic dissemination of these resistant accessions and for targeted breeding programs aimed at combating powdery mildew.

Weather Based Forewarning Model for Powdery Mildew Disease of Mustard

Powdery mildew disease is the most important disease of mustard (Brassica Juncea) which is highly sensitive to weather condition particularly temperature and humidity. To ascertain the relationship between weather variables and powdery mildew disease of mustard crop at Sardarkrushinagar, weekly powdery mildew data of 12 years (2010-11 to 2021-22) was collected from Centre for Oilseed Research, S.D. Agricultural University, Sardarkrushinagar. The data were pooled over the year and correlated with corresponding weather parameters recorded in Agromet Observatory, S.D. Agricultural University, Sardarkrushinagar. The forewarning regression equation was developed with the help of weather variables to predict the disease incidence. The results revealed that the maximum and minimum temperature ranged 26.2 to 38.1oC and 8.7 to 18.5oC respectively found congenial for disease incidence. The weather variables like maximum temperature (Tmax) and minimum temperature (Tmin) correlated significantly positive with powdery mildew disease. While morning relative humidity (RH I) and evening relative humidity (RH II) correlated significantly negative with disease severity. The impact of rainfall (RF), sunshine hour (SSH) and wind speed (WS) found positive but non-significant on powdery mildew disease. The weather variables those have significant relationship with powdery mildew disease, were used to develop multiple regression model. The regression equation Y = 62.837 + 8.072*Tmax – 3.919*RH1 developed with maximum temperature and morning relative humidity caused up to 96 % variability in the powdery mildew disease. Hence the combined effect of Tmax and RH1 was more pronounced and most influencing weather parameters on powdery mildew disease. Therefore, model could be used for predicting the powdery mildew disease well in advance.

A severity estimation method for lightweight cucumber leaf disease based on DM-BiSeNet

Accurately estimating the severity of cucumber diseases is crucial for improving cucumber quality and minimizing economic losses. Deep learning techniques have shown promising results in automatically extracting disease image features for severity estimation. However, existing methods still face challenges in accurately estimating disease severity under complex backgrounds and achieving real-time performance.This paper presents a lightweight severity estimation method called DM-BiSeNet to address these challenges. The proposed method utilizes BiSeNet V2 as the base network and incorporates depthwise separable convolutional blocks to optimize the detail branch. A simplified MobileNet V3 network is also constructed to optimize the semantic branch. The model training process is accelerated using the AdamW optimizer. To evaluate the performance of DM-BiSeNet, a dataset consisting of cucumber powdery mildew and downy mildew disease images collected in natural scenes is utilized. Experimental results demonstrate that DM-BiSeNet achieves higher accuracy in severity estimation, with an R2 value of 0.9407 and an RMSE of 1.0680, outperforming the comparison methods. Moreover, DM-BiSeNet exhibits a complexity of 1.54 GFLOPs and is capable of reasoning 94 disease images per second.The proposed DM-BiSeNet model offers a lightweight and effective solution for accurate and rapid severity estimation of cucumber diseases under complex backgrounds. It provides a valuable technical tool for quantitative disease estimation, offering significant potential for practical applications.

Effect of Weather Parameters on Development of Powdery Mildew of Ber (Ziziphus mauritiana) Caused by Oidium erysiphoides

India’s one of the most popular fruits is the ber (Ziziphus mauritiana Lamk.). Ziziphus mauritiana is sometimes referred to as Indian plum or desert apple. Oidium erysiphoides f. sp. Ziziphi, which causes powdery mildew of ber, is more common and a threat in northern states. The white powdery coating on leaves and fruits affects the photosynthesis and growth & development, respectively. This disease results in 50-60% loss in fruit yield and reduces market value of the produce. In the present study, the effect of abiotic environmental elements such as temperature, relative humidity, wind speed, and others were observed and they had a significant impact on the progression of powdery mildew disease. In the study, which was carried out on two ber cultivars viz., Gola and Kaithali, the disease progression on both cultivars showed a significantly negative correlation with maximum (Tmax) and minimum temperature (Tmin) and a significantly positive correlation with morning (RHm) and evening relative humidity (RHe). The favourable weather variables were observed viz., Tmax above 20.3 °C, Tmin around 9.9 °C and RHm was more than 80%. The ber cultivar Gola was more susceptible to disease development than Kaithali, with Gola having the highest disease intensity.

Evaluation of Coriander (Coriandrum sativum L.) Genotypes for Powdery Mildew Disease (Erysiphe polygoni DC) Resistance

Coriander (Coriandrum sativum L.) is short and bushy crop of Apiaceae family with linalool as aromatic compound, this crop is used mainly as culinary spice in India. Majorly this coriander crop is associated with powdery mildew (Erysiphe polygoni DC) disease incidence, causes serious problem in many parts of India. Screening for resistant source through artificial inoculation method which was an eco-friendly approach conductedduring Rabi-2022 at Department of Biotechnology and Crop Improvement, University of Horticultural Sciences, Bagalkot. 35 coriander accessions where are collected from Karnataka, Gujarat and Andhra Pradesh. Percent Disease Index (PDI %) was calculated for four weeks after inoculation and scored based on disease rating scale. Among them only eight genotypes (Surabhi, Asian (A-5), Mrityunjaya, Kalaburagi local, Nutan, Caribe, Samarat Ashok and Pokhara) showed slower powdery mildew symptoms (PDI value of 3.9 to 5.4%) after third week of inoculation but in fourth week all the 35 genotypes falls under susceptible (PDI more then 100%) and highly susceptible category which represents the high virulence nature of powdery mildew strain.

Biological control of wheat powdery mildew disease by the termite-associated fungus Aspergillus chevalieri BYST01 and potential role of secondary metabolites.

Wheat powdery mildew, caused by the biotrophic pathogen Blumeria graminis f. sp. tritici (Bgt) is a serious fungal disease. Natural metabolites produced by microorganisms are beneficial biological control agents to inhibit Bgt. In the present study, we investigated the effects of Aspergillus chevalieri BYST01 on wheat powdery mildew. A strain isolated from the termite was identified as A. chevalieri BYST01 by morphological characteristics and phylogenetic analysis. The fermentation broth of BYST01 showed good biocontrol effect on the Bgt in vivo with the control efficiencies of 81.59% and 71.34% under the protective and therapeutic tests, respectively. Four known metabolites, including the main compound physcion (30 mg/L), were isolated from the fermentation broth of BYST01 extracted with ethyl acetate. Importantly, under a concentration of 0.1 mM, physcion repressed conidial germination of Bgt with an inhibition rate of 77.04% in vitro and showed important control efficiencies of 80.36% and 74.64% in vivo under the protective and therapeutic tests, respectively. Hence, the BYST01 showed important potential as a microbial cell factory for the high yield of the green natural fungicide physcion. Finally, the biosyntheticgene clusters responsible for physicon production in BYST01 was predicted by analyzing a chromosome-scale genome obtained usinga combination of Illumina, PacBio, and Hi-C sequencing technologies. Aspergillus chevalieri BYST01 and its main metabolite physcion had a significant control effect on wheat powdery mildew. The biosynthesis pathway of physcion in BYST01 was predicted. © 2023 Society of Chemical Industry.

Chemical Control of Powdery Mildew of Bigleaf Hydrangea

The efficacy of the fungicide pydiflumetofen + difenoconazole (Postiva) was evaluated at varying application rates and intervals for the control of powdery mildew (Golovinomyces orontii, formerly Erysiphe polygoni) in bigleaf hydrangea (Hydrangea macrophylla ‘Nikko Blue’). Container-grown hydrangeas were arranged in a completely randomized design with six single-plant replications. Experiments were done in 2022 and 2023 under both greenhouse and shade house conditions (56% shade). Powdery mildew in hydrangea was developed naturally. Pydiflumetofen + difenoconazole at 1.1, 1.6, and 2.2 ml·L−1 and a standard fungicide azoxystrobin + benzovindiflupyr (Mural) at 0.5 g·L−1 were sprayed to runoff on 2-, 4-, and 6-week intervals. Plants that were not treated with fungicide served as the control. Plants were evaluated weekly for disease severity (0% to 100% foliage affected) and defoliation (0% to 100% defoliation). The season-long area under the disease progress curve (AUDPC) and defoliation progress curve (AUDFC) were calculated for the evaluation period. The initial and final plant height and width were recorded, and height and width increase were determined. Pydiflumetofen + difenoconazole and azoxystrobin + benzovindiflupyr significantly reduced final disease severity, AUDPC, and defoliation both in the greenhouse and shade house compared with control plants. In both greenhouse trials and the 2022 shade house trial, AUDFC was reduced in all treatments compared with the control plants. However, AUDFC was not reduced by all treatments in the 2023 shade house trial. Pooled over application intervals, the low rate of pydiflumetofen + difenoconazole was as effective as the medium and high rates of pydiflumetofen + difenoconazole and azoxystrobin + benzovindiflupyr in reducing final powdery mildew severity and AUDPC both in the greenhouse and shade house in both 2022 and 2023. No significant differences between application intervals were noted in final disease severity and progress. Control of powdery mildew with fungicides failed to increase plant dimensions (i.e., plant height and width) compared with the no fungicide control. Because all application rates and intervals of pydiflumetofen + difenoconazole provided comparable powdery mildew disease control, it is suggested that using a low rate of pydiflumetofen + difenoconazole with the longest application interval (6 weeks) is the most cost-effective approach for managing powdery mildew in bigleaf hydrangeas.

Metagenomic study reveals hidden relationships among fungal diversity, variation of plant disease, and genetic distance in Cornus florida (Cornaceae).

Understanding patterns of plant-microbe interactions across plant species and populations is a critical yet poorly characterized aspect in the field of plant pathology. Microbial DNA sequences present as contaminants in omics data of plants obtained using next-generation sequencing methods provide a valuable source to explore the relationships among endophytic microbial diversity, disease and genetic differentiation of host plants, and environmental variation, but few such studies have been conducted. The flowering dogwood tree (Cornus florida L.), an ecologically important species in North America, is threatened by powdery mildew and dogwood anthracnose diseases, and knowledge of the microbial diversity harbored within genetically and environmental distinct populations of this species remains largely unknown. We conducted a metagenomics study utilizing the sequences of RAD-tag/genotype-by-sequence libraries from leaf tissues of C. florida to examine such host-fungus interactions across the dogwood's US range. We performed various combinations of alignments to both host and pathogen genomes to obtain filtered sets sequences for metagenomics analysis. Taxonomic assignments were determined on each filtered set of sequences, followed by estimation of microbial diversity and correlation to environment and host-genetic variation. Our data showed that microbial community composition significantly differed between visually healthy and diseased sites. Several microbial taxa known to interact with dogwood were identified from these sequences. We found no correlation between microbial diversity and relative abundances of sequences aligning to draft genomes of either pathogen causing powdery mildew or dogwood anthracnose. We found a significant relationship between differences of fungal communities and geographic distances of plant populations, suggesting roles of environments in shaping fungal communities in leaf tissues. Significant correlations between the genetic differentiation of plant samples and fungal community dissimilarity (beta diversity) were also observed in certain sets of our analyses-suggesting the possibility of a relationship between microbial community composition and plant genetic distance. This relationship persisted in significance even after controlling for significant effects of geographic-bioclimatic variation of microbial diversity. Our results suggest that both genetics and the environment play a significant role in shaping foliar fungal communities. Our findings underscore the power of leveraging hidden microbial sequences within datasets originally collected for plant genetic studies to understand plant-pathogen interactions.