Induced systemic protection to powdery mildew in cucumber by phosphate and potassium fertilizers: effects of inoculum concentration and post-inoculation treatment

1995 ◽  
Vol 17 (3) ◽  
pp. 247-251 ◽  
Author(s):  
M. Reuveni ◽  
V. Agapov ◽  
R. Reuveni
Keyword(s):  
Powdery Mildew ◽  
Post Inoculation ◽  
Inoculum Concentration ◽  
Inoculation Treatment

scholarly journals Ampelomyces strains isolated from diverse powdery mildew hosts in Japan: Their phylogeny and mycoparasitic activity, including timing and quantifying mycoparasitism of Pseudoidium neolycopersici on tomato

PLoS ONE ◽  
2021 ◽  
Vol 16 (5) ◽  
pp. e0251444
Author(s):  
Márk Z. Németh ◽  
Yuusaku Mizuno ◽  
Hiroki Kobayashi ◽  
Diána Seress ◽  
Naruki Shishido ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Host Plants ◽  
Morphological Characteristics ◽  
Post Inoculation ◽  
Powdery Mildew Fungus ◽  
Rdna Its ◽  
Pseudoidium Neolycopersici ◽  
Tomato Powdery Mildew ◽  
Internal Transcribed Spacer Rdna ◽  
Complete Collapse

A total of 26 Ampelomyces strains were isolated from mycelia of six different powdery mildew species that naturally infected their host plants in Japan. These were characterized based on morphological characteristics and sequences of ribosomal DNA internal transcribed spacer (rDNA-ITS) regions and actin gene (ACT) fragments. Collected strains represented six different genotypes and were accommodated in three different clades of the genus Ampelomyces. Morphology of the strains agreed with that of other Ampelomyces strains, but none of the examined characters were associated with any groups identified in the genetic analysis. Five powdery mildew species were inoculated with eight selected Ampelomyces strains to study their mycoparasitic activity. In the inoculation experiments, all Ampelomyces strains successfully infected all tested powdery mildew species, and showed no significant differences in their mycoparasitic activity as determined by the number of Ampelomyces pycnidia developed in powdery mildew colonies. The mycoparasitic interaction between the eight selected Ampelomyces strains and the tomato powdery mildew fungus (Pseudoidium neolycopersici strain KTP-03) was studied experimentally in the laboratory using digital microscopic technologies. It was documented that the spores of the mycoparasites germinated on tomato leaves and their hyphae penetrated the hyphae of Ps. neolycopersici. Ampelomyces hyphae continued their growth internally, which initiated the atrophy of the powdery mildew conidiophores 5 days post inoculation (dpi); caused atrophy 6 dpi; and complete collapse of the parasitized conidiphores 7 dpi. Ampelomyces strains produced new intracellular pycnidia in Ps. neolycopersici conidiophores ca. 8–10 dpi, when Ps. neolycopersici hyphae were successfully destroyed by the mycoparasitic strain. Mature pycnidia released spores ca. 10–14 dpi, which became the sources of subsequent infections of the intact powdery mildew hyphae. Mature pycnidia contained each ca. 200 to 1,500 spores depending on the mycohost species and Ampelomyces strain. This is the first detailed analysis of Ampelomyces strains isolated in Japan, and the first timing and quantification of mycoparasitism of Ps. neolycopersici on tomato by phylogenetically diverse Ampelomyces strains using digital microscopic technologies. The developed model system is useful for future biocontrol and ecological studies on Ampelomyces mycoparasites.

scholarly journals Potential Role of Photosynthesis in the Regulation of Reactive Oxygen Species and Defence Responses to Blumeria graminis f. sp. tritici in Wheat

2020 ◽  
Vol 21 (16) ◽  
pp. 5767
Author(s):  
Yuting Hu ◽  
Shengfu Zhong ◽  
Min Zhang ◽  
Yinping Liang ◽  
Guoshu Gong ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Salicylic Acid ◽  
Powdery Mildew ◽  
Reactive Oxygen ◽  
Post Inoculation ◽  
Oxygen Species ◽  
Chlorophyll Fluorescence Parameters ◽  
H2o2 Accumulation ◽  
Pathogenesis Related ◽  
Defence Responses

Photosynthesis is not only a primary generator of reactive oxygen species (ROS) but also a component of plant defence. To determine the relationships among photosynthesis, ROS, and defence responses to powdery mildew in wheat, we compared the responses of the Pm40-expressing wheat line L658 and its susceptible sister line L958 at 0, 6, 12, 24, 48, and 72 h post-inoculation (hpi) with powdery mildew via analyses of transcriptomes, cytology, antioxidant activities, photosynthesis, and chlorophyll fluorescence parameters. The results showed that H2O2 accumulation in L658 was significantly greater than that in L958 at 6 and 48 hpi, and the enzymes activity and transcripts expression of peroxidase and catalase were suppressed in L658 compared with L958. In addition, the inhibition of photosynthesis in L658 paralleled the global downregulation of photosynthesis-related genes. Furthermore, the expression of the salicylic acid-related genes non-expressor of pathogenesis related genes 1 (NPR1), pathogenesis-related 1 (PR1), and pathogenesis-related 5 (PR5) was upregulated, while the expression of jasmonic acid- and ethylene-related genes was inhibited in L658 compared with L958. In conclusion, the downregulation of photosynthesis-related genes likely led to a decline in photosynthesis, which may be combined with the inhibition of peroxidase (POD) and catalase (CAT) to generate two stages of H2O2 accumulation. The high level of H2O2, salicylic acid and PR1 and PR5 in L658 possible initiated the hypersensitive response.

scholarly journals Lagged Association Between Powdery Mildew Leaf Severity, Airborne Inoculum, Weather, and Crop Losses in Strawberry

2013 ◽  
Vol 103 (8) ◽  
pp. 811-821 ◽  
Author(s):  
O. Carisse ◽  
V. Morissette-Thomas ◽  
H. Van der Heyden
Keyword(s):  
Powdery Mildew ◽  
Linear Relationship ◽  
Leaf Area ◽  
Crop Loss ◽  
Independent Data ◽  
Weather Variables ◽  
Inoculum Concentration ◽  
Crop Losses ◽  
Model Based ◽  
Airborne Inoculum

Knowledge about epidemiology and the impact of disease on yield is fundamental for establishing effective management strategies. The purpose of this study was to investigate the relationship between foliar strawberry mildew severity, Podosphaera aphanis airborne inoculum concentration, weather, and subsequent crop losses for day-neutral strawberry. The experiment was conducted at three, five, and four sites in 2006, 2007, and 2008, respectively, for a total of 12 epidemics. At each site, data were collected on 25 plants at 2-day intervals from the end of May to early October for a total of 60 to 62 samplings annually. First, seasonal crop losses were statistically described; then, a lagged regression model was developed to describe crop losses from the parameters that were significantly associated with losses. There was a strong positive linear relationship between seasonal crop losses and the area under the leaf disease progress curve (R2 = 0.90) and daily mean airborne conidia concentration (R2 = 0.86), and a negative linear relationship between crop losses and time to 5% loss (R2 = 0.76) and time to 5% leaf area diseased (R2 = 0.61). Among the 53 monitoring- and weather-based variables analyzed, percent leaf area diseased, log10-transformed airborne inoculum concentration, and weather variables related to temperature were significantly associated with crop losses. However, polynomial distributed lag regression models built with weather variables were not accurate in predicting losses, with the exception of a model based on a combined temperature and humidity variable, which provided accurate prediction of the data used to construct the model but not of independent data. Overall, the model based on log10-transformed airborne inoculum concentration did not provide accurate crop loss predictions. The model built using percent leaf area diseased with a time lag of 8 days (n = 4) and a polynomial degree of 2 provided a good description of the crop-loss data used to construct the model (r = 0.99 and 0.90) and of independent data (r = 0.92). For the 12 epidemics studied, 5% crop loss was reached when an average of 17% leaf area diseased was observed since the beginning of symptom development. These results indicate that information on foliar powdery mildew must be considered when making strawberry powdery mildew management decisions.

scholarly journals Genetic Dissection of the Powdery Mildew Resistance in Wheat Breeding Line LS5082 Using BSR-Seq

2021 ◽  
Author(s):  
Liru Wu ◽  
Tong Zhu ◽  
Huagang He ◽  
Xinyou Cao ◽  
Haosheng Li ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Differentially Expressed Genes ◽  
Dominant Gene ◽  
Wheat Breeding ◽  
Differentially Expressed ◽  
Post Inoculation ◽  
Breeding Line ◽  
Seedling Resistance ◽  
Physical Position ◽  
Chromosome Arm

Abstract Wheat powdery mildew is a destructive disease seriously threatening yield and quality. Comprehensive dissection of new resistance-related loci/genes is necessary to control this disease. LS5082 is a Chinese wheat breeding line with resistance to powdery mildew. Genetic analysis indicated that a single dominant gene, tentatively designated PmLS5082, conferred seedling resistance to different Bgt isolates. Bulked segregant RNA-seq (BSR-seq) was carried out to map the R gene PmLS5082 and profile differentially expressed genes associated with PmLS5082. PmLS5082 was mapped to chromosome arm 2BL and flanked by the markers WGGBH612-5 and YTU19-005 with genetic distances of 0.3 and 0.4 cM, respectively. The physical position was subsequently locked into the interval of 710.3-711.0 Mb. PmLS5082 differs from the catalogued Pm genes on chromosome arm 2BL in its resistant spectrum, physical position and origin, suggesting it is most likely a new Pm gene. Through COG and KEGG analysis, differentially expressed genes associated with PmLS5082 were profiled, and six genes in PmLS5082 interval were confirmed to be associated with PmLS5082 via RT-qPCR, using an additional set of wheat samples and time-course analysis post-inoculation with Bgt. In order to transfer PmLS082 to different genetic backgrounds using marker-assisted selection (MAS), closely linked markers, including Kompetitive Allele-Specific PCR (KASP) markers, were evaluated and nine markers were confirmed to be widely applicable for MAS in different genetic backgrounds.

Expression of quantitative resistance to Colletotrichum gloeosporioides in Stylosanthes scabra at different inoculum concentrations and day-night temperatures

1990 ◽  
Vol 41 (1) ◽  
pp. 89 ◽  
Author(s):  
S Chakraborty
Keyword(s):  
Colletotrichum Gloeosporioides ◽  
Quantitative Resistance ◽  
Controlled Environment ◽  
Post Inoculation ◽  
Inoculum Concentration ◽  
Coefficient Of Concordance ◽  
Uninoculated Control ◽  
Number Of Leaves ◽  
Stylosanthes Scabra ◽  
Pasture Legume

Expression of quantitative resistance to anthracnose was studied following inoculation of accessions of the tropical pasture legume Stylosanthes scabra with five different concentrations of Colletotrichum gloeosporioides conidia and at five day-night temperatures in separate experiments. According to Kendall's coefficient of concordance for rankings of accessions at the various inoculum concentrations, resistance in all six accessions was expressed consistently at 102,103, 104, 105 and 106 conidia/ml for race 3 but not for race 4a. Anthracnose severity did not increase with an increase in the inoculum concentration from l05 to 106 conidia/ml for either of the two races. Height and number of leaves/plant in the uninoculated control increased significantly at 30-25�C when glasshouse-grown seedlings were transferred to four controlled environment cabinets maintained at one of the four day-night temperatures of 30-25,32-22,30-15 or 34-14�C. Accessions were subjected to one of the four day-night temperatures for a 3 week pre- and 2 week post-inoculation exposures was not significant, predisposition of some accessions to anthracnose resulted in a significant accession X exposure interaction.

scholarly journals Powdery Mildew-Induced Hormonal and Photosynthetic Changes in Barley Near Isogenic Lines Carrying Various Resistant Genes

2020 ◽  
Vol 21 (12) ◽  
pp. 4536 ◽  
Author(s):  
Diana Saja ◽  
Anna Janeczko ◽  
Balázs Barna ◽  
Andrzej Skoczowski ◽  
Michał Dziurka ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Chlorophyll A ◽  
Chlorophyll A Fluorescence ◽  
Post Inoculation ◽  
Near Isogenic Lines ◽  
Leaf Reflectance ◽  
Isogenic Lines ◽  
Fluorescence Measurements ◽  
Resistant Genes ◽  
Psii Activity

The present work focused on the characterization of some physiological mechanisms activated upon powdery mildew inoculation of the susceptible barley cultivar Ingrid and its near-isogenic lines (NILs) carrying various resistant genes (Mla, Mlg and mlo). After inoculation with Blumeria graminis f. sp. hordei (Bgh), measurements of leaf reflectance and chlorophyll a fluorescence were performed 3 and 7 day post-inoculation (dpi), while hormone assays were made 7 dpi. Bgh-inoculated resistant genotypes were characterized by lowered leaf reflectance parameters that correlated with carotenoids (CRI) and water content (WBI) in comparison to inoculated Ingrid. The PSII activity (i.e., Fv/Fm, ETo/CSm and P.I.ABS) strongly decreased in susceptible Ingrid leaves when the disease symptoms became visible 7 dpi. In Mla plants with visible hypersensitive spots the PSII activity decreased to a lesser extent. Inoculation resulted in a very slight decrease of photosynthesis at later stage of infection in Mlg plants, whereas in resistant mlo plants the PSII activity did not change. Chlorophyll a fluorescence measurements allowed presymptomatic detection of infection in Ingrid and Mla. Changes in the homeostasis of 22 phytohormones (cytokinins, auxins, gibberellins and the stress hormones JA, SA and ABA) in powdery mildew inoculated barley are discussed in relation to resistance against this biotrophic pathogen.

Fungicide Physical Mode of Action: Impacts on Suppression of Hop Powdery Mildew

Plant Disease ◽  
2021 ◽  
Author(s):  
Briana Claassen ◽  
Sierra N Wolfenbarger ◽  
David H. Gent
Keyword(s):  
Powdery Mildew ◽  
Disease Control ◽  
Post Infection ◽  
Mode Of Action ◽  
Field Experiments ◽  
Field Studies ◽  
Post Inoculation ◽  
Complete Control ◽  
Application Timing ◽  
Zones Of Inhibition

Understanding of the physical mode of action of fungicides allows for more efficient and effective application of fungicides and can improve disease control. Greenhouse and field studies were conducted to explore the pre-and post-infection duration and translocative properties of fungicides commonly used to control hop powdery mildew, caused by Podosphaera macularis. In greenhouse studies, application made 24 h before inoculation were almost 100% effective at suppressing powdery mildew, regardless of the fungicide evaluated. However, percent control of powdery mildew based on the number of pathogen colonies per leaf varied significantly between fungicides with increasing time from inoculation to application, ranging from 50 to 100% disease control (SE 0.168 and 0, respectively) depending on the fungicide. Fluopyram or fluopyram + trifloxystrobin were particularly efficacious, suppressing nearly all powdery mildew development independent of application timing. In translocation studies, fluopyram and flutriafol were the most effective treatments in each of two separate experiments, resulting in zones of inhibition of 1036 and 246.3 mm2, respectively, on adaxial leaf surfaces when a single droplet of each fungicide was applied to the abaxial surface of leaves. In field experiments, all fungicide treatments provided nearly complete control of powdery mildew infection when applied prior to inoculation. Levels of disease control decreased with time depending on treatment, showing trends similar to those observed in greenhouse studies. In the 2017 field experiments high levels of disease control (>75%) were observed at post-inoculation timepoints for all treatments tested, whereas the same fungicides were more sensitive to application timing in a different year. Findings from this research indicate that differences in efficacy between fungicides are relatively small when applications are made preventatively, but post-infection activity and translaminar movement of certain fungicides may render some more effective depending on application coverage and pre-existing infection.

Comparative transcriptome profiling of Chinese wild grapes provides insights into powdery mildew resistance

2021 ◽  
Author(s):  
Chen Jiao ◽  
Xuepeng Sun ◽  
Xiaoxiao Yan ◽  
Xiaozhao Xu ◽  
Qin Yan ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Powdery Mildew ◽  
Fungal Pathogen ◽  
Fatty Acid Biosynthesis ◽  
Transcriptome Profiling ◽  
Wine Industry ◽  
Post Inoculation ◽  
Comparative Transcriptome ◽  
Genes Encoding ◽  
Stage Analysis

Erysiphe necator, the fungal pathogen of grape powdery mildew disease, poses a great threat to the grape fruit market and wine industry. To better understand the molecular basis of grape responses to E. necator, we performed comparative transcriptome profiling on two Chinese wild grape accessions with varying degrees of resistance to E. necator. A total of 2,856, 2,678 and 1,542 differentially expressed genes (DEGs) were identified in the susceptible Vitis pseudoreticulata ‘Hunan-1’ at 6, 24, and 96 hours post-inoculation of E. necator, respectively, while 1,921, 2,498 and 3,249 DEGs were identified in the resistant V. quinquangularis ‘Shang-24’. ‘Hunan-1’ had substantially larger fraction of down-regulated genes than ‘Shang-24’ at every infection stage. Analysis of DEGs revealed that up-regulated genes were mostly associated with defense response and disease resistance-related metabolite biosynthesis, while signaling genes were significantly suppressed in ‘Hunan-1’. Interestingly, fatty acid biosynthesis and elongation related genes were suppressed by the fungus in ‘Shang-24’ but somehow induced in ‘Hunan-1’, consistent with that E. necator is likely a fatty acid auxotroph that requires lipids from the host. Moreover, genes involved in biosynthesis and signaling of phytohormones, such as jasmonic acid and cytokinin, as well as genes encoding protein kinases and NLR proteins were differentially responded to E. necator in the two wild grapes. The variation of gene regulation associated with nutrient uptake by the fungus and with signaling transduction and pathogen recognition suggests a multi-layered regulatory network that works in concert to defend fungal pathogen infections.

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