scholarly journals Pulsed Water Mists for Suppression of Strawberry Powdery Mildew

Plant Disease ◽  
2021 ◽  
Vol 105 (1) ◽  
pp. 71-77
Author(s):  
Belachew Asalf ◽  
Rodrigo B. Onofre ◽  
David M. Gadoury ◽  
Natalia A. Peres ◽  
Arne Stensvand
Keyword(s):  
Powdery Mildew ◽  
Fungal Pathogens ◽  
Meteoric Water ◽  
Free Water ◽  
High Tunnel ◽  
Water Films ◽  
Leaf Surfaces ◽  
High Plastic ◽  
Relevant Degree ◽  
Plant Surfaces

Powdery mildew (Podosphaera aphanis) is a destructive and widespread disease of strawberry (Fragaria × ananassa), especially when susceptible cultivars are grown in high plastic tunnels or glasshouses. Many powdery mildews thrive in humid environments but free water films on plant surfaces can inhibit conidial germination of some species. We hypothesized that P. aphanis might be directly suppressed by rain through the action of water films and meteoric water. In repeated experiments, the hydrophobic conidia of P. aphanis collected on the surface of water droplets, resulting in their removal when the droplets rolled over the leaf surfaces and fell to the ground. Meteoric water and water films also damaged conidiophores. Brief midday water mists applied in pulses lasting 1 min each four times per day were as effective as multiple fungicide treatments in suppressing powdery mildew. Rapid drying of the pulsed mists resulted in effective suppression of powdery mildew without consequent increases of fungal pathogens that might benefit from water films. The timing and duration of water sprinkling has been refined to the point where it can provide a commercially relevant degree of suppression of powdery mildew on strawberry in a high-tunnel production system.

scholarly journals Evaluation of Strawberry Species and Cultivars for Powdery Mildew Resistance in Open-field and High Tunnel Production Systems

HortScience ◽  
2013 ◽  
Vol 48 (9) ◽  
pp. 1125-1129 ◽  
Author(s):  
Colleen Kennedy ◽  
Tomas N. Hasing ◽  
Natalia A. Peres ◽  
Vance M. Whitaker
Keyword(s):  
Powdery Mildew ◽  
Open Field ◽  
Production Systems ◽  
Gulf Coast ◽  
Free Water ◽  
Sources Of Resistance ◽  
High Tunnel ◽  
Elite Group ◽  
Genotype Effect ◽  
Research And Education

Many breeders have turned to wild relatives in search of beneficial traits such as disease resistance. In strawberry, the wild octoploid species Fragaria virginiana and F. chiloensis are fully interfertile with the cultivated species, F. ×ananassa, and are therefore potential sources of resistance. Powdery mildew may increase in economic importance in Florida in the near future as a result of the use of high tunnels and rowcovers for freeze protection, which limit free water and provide a favorable environment for disease development. The objective of this study was to screen an elite group of wild strawberry accessions for resistance to powdery mildew under two production systems. In 2010–11 and 2012–13, wild accessions, commercial standard cultivars, and susceptible controls were planted in open-field and high tunnel environments at the Gulf Coast Research and Education Center in Balm, FL. Although there was a significant year × genotype effect, some taxa showed high levels of resistance that were consistent across years. There was a high correlation for ratings of powdery mildew between the high tunnel and the open field for all genotypes (r = 0.89, P < 0.001). This information may be useful for breeders, because sources of resistance to powdery mildew are available within the tested genotypes. However, some accessions are highly susceptible to powdery mildew, and this must be considered when using these genotypes in breeding programs.

scholarly journals Disruption of barley immunity to powdery mildew by an in-frame Lys-Leu deletion in the essential protein SGT1

Genetics ◽  
2020 ◽  
Vol 217 (2) ◽  
Author(s):  
Antony V E Chapman ◽  
Matthew Hunt ◽  
Priyanka Surana ◽  
Valeria Velásquez-Zapata ◽  
Weihui Xu ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Fungal Pathogens ◽  
Novel Mutation ◽  
Exome Capture ◽  
Resistance Locus ◽  
Hordeum Vulgare L ◽  
Powdery Mildew Fungus ◽  
Pathogen Effectors ◽  
Cell Processes ◽  
Disease Resistances

Abstract Barley (Hordeum vulgare L.) Mla (Mildew resistance locus a) and its nucleotide-binding, leucine-rich-repeat receptor (NLR) orthologs protect many cereal crops from diseases caused by fungal pathogens. However, large segments of the Mla pathway and its mechanisms remain unknown. To further characterize the molecular interactions required for NLR-based immunity, we used fast-neutron mutagenesis to screen for plants compromised in MLA-mediated response to the powdery mildew fungus, Blumeria graminis f. sp. hordei. One variant, m11526, contained a novel mutation, designated rar3 (required for Mla6 resistance3), that abolishes race-specific resistance conditioned by the Mla6, Mla7, and Mla12 alleles, but does not compromise immunity mediated by Mla1, Mla9, Mla10, and Mla13. This is analogous to, but unique from, the differential requirement of Mla alleles for the co-chaperone Rar1 (required for Mla12 resistance1). We used bulked-segregant-exome capture and fine mapping to delineate the causal mutation to an in-frame Lys-Leu deletion within the SGS domain of SGT1 (Suppressor of G-two allele of Skp1, Sgt1ΔKL308–309), the structural region that interacts with MLA proteins. In nature, mutations to Sgt1 usually cause lethal phenotypes, but here we pinpoint a unique modification that delineates its requirement for some disease resistances, while unaffecting others as well as normal cell processes. Moreover, the data indicate that the requirement of SGT1 for resistance signaling by NLRs can be delimited to single sites on the protein. Further study could distinguish the regions by which pathogen effectors and host proteins interact with SGT1, facilitating precise editing of effector incompatible variants.

scholarly journals Occurrence of Powdery Mildew Caused by Blumeria graminis f. sp. poae on Poa pratensis in China

Plant Disease ◽  
2020 ◽  
Author(s):  
Mo Zhu ◽  
Jie Ji ◽  
Wenqi Shi ◽  
YongFang Li
Keyword(s):  
Powdery Mildew ◽  
Germ Tube ◽  
Poa Pratensis ◽  
Perennial Grass ◽  
Morphological Characteristics ◽  
Signs And Symptoms ◽  
Its Region ◽  
Width Ratio ◽  
Leaf Surfaces ◽  
Length Width

Poa pratensis, known as bluegrass, is a perennial grass and one of the best varieties with highly valued pasture and turf grass uses. It is widely grown on golf courses and used for lawns in squares and parks (Luo et al. 2020). During April and May 2020, powdery mildew-like signs and symptoms were observed on leaves of P. pratensis in Muye Park, Xinxiang city (35.3°N; 113.9°E), Henan Province, China. White or grayish powdery masses in spots- or coalesced lesions were abundant on the adaxial surfaces of leaves and covered up to 90 % of the leaf area. Some of the mildew-infested leaves appeared chlorotic or began senescence. Mildew-infested leaves were collected to microscopically observe the morphological characteristics of this pathogen. Conidiophores were composed of foot cells, followed by one or two cells, and conidia. The ellipsoid- shaped conidia (n = 50) were 25 - 36 × 10 - 15 μm (length × width), on average 30 × 13 μm, with a length/width ratio of 2.3. Foot-cells (n = 15) were 30 - 44 μm long and 7 - 15 μm wide. On leaf surfaces, germinated conidia produced a short primary germ tube and then a long secondary germ tube that finally differentiated into a hooked appressorium. Chasmothecia were not found. Based on these morphological characteristics, the pathogen was initially identified as B. graminis f. sp. poae, the known forma specialis (f. sp.) of B. graminis on P. pratensis (Braun and Cook 2012; Troch et al. 2014). Mycelia of the pathogen were scraped from infected leaves and total genomic DNA was isolated using the method described previously (Zhu et al. 2019). The rDNA internal transcribed spacer (ITS) region was amplified applying primer pairs ITS1/ITS4 (White et al. 1990). The amplicon was cloned and sequenced by Invitrogen (Shanghai, China). The obtained sequence for the pathogen was deposited into GenBank under Accession No. MT892956 and was 100 % identical (549/549 bp) to B. graminis on P. pratensis (AB273530) (Inuma et al. 2007). In addition, the phylogenetic analysis clearly showed that the identified fungus and B. graminis f. sp. poae were clustered in the same branch. To perform pathogenicity analysis, leaf surfaces of eight healthy plants were inoculated by dusting fungal conidia from diseased leaves. Eight non-inoculated plants served as a control. The non-inoculated and inoculated plants were separately maintained in two growth chambers (humidity, 60 %; light/dark, 16 h/8 h; temperature, 18 ℃). Twelve to fourteen days after inoculation, B. graminis signs were visible on inoculated leaves, while control plants remained healthy. The pathogenicity assays were repeated twice and showed same results. Therefore, based on the morphological characteristics and molecular analysis, the pathogen was identified and confirmed as B. graminis f. sp. poae. This pathogen has been reported on P. pratensis in Switzerland and Japan (Inuma et al. 2007). This is, to our best knowledge, the first disease note reporting B. graminis on P. pratensis in China. Because the hybridization of B. graminis formae speciales (ff. spp.). allow the pathogens to adapt to new hosts, P. pratensis may serve as a primary inoculum reservoir of B. graminis to threaten other species, including cereal crops (Klingeman et al. 2018; Menardo et al. 2016). In addition, powdery mildew may negatively affect the yield and quality of grasses. Our report expands the knowledge of B. graminis f. sp. poae and provides the fundamental information for future powdery mildew control.

scholarly journals Expression of the Membrane-Associated Resistance Protein RPW8 Enhances Basal Defense Against Biotrophic Pathogens

2007 ◽  
Vol 20 (8) ◽  
pp. 966-976 ◽  
Author(s):  
Wenming Wang ◽  
Alessandra Devoto ◽  
John G. Turner ◽  
Shunyuan Xiao
Keyword(s):  
Salicylic Acid ◽  
Powdery Mildew ◽  
Fungal Pathogens ◽  
Coiled Coil ◽  
Small Gtpase ◽  
Cauliflower Mosaic Virus ◽  
R Genes ◽  
Amino Terminal ◽  
Small Proteins ◽  
Enhanced Resistance

The powdery mildew resistance genes RPW8.1 and RPW8.2 from Arabidopsis differ from the other isolated plant resistance (R) genes in their predicted protein domains and their resistance spectrum. The two homologous RPW8 genes encode small proteins featuring a predicted amino-terminal transmembrane anchor domain and a coiled-coil domain and confer resistance to a broad spectrum of powdery mildews. Here, we show that Arabidopsis plants expressing the RPW8 genes have enhanced resistance to another biotrophic pathogen, Hyaloperonospora parasitica, raising the possibility that the RPW8 genes may function to enhance salicylic-acid-dependent basal defenses, rather than as powdery-mildew-specific R genes. When overexpressed from their native promoters, the RPW8 genes confer enhanced resistance to the Cauliflower mosaic virus, but render plants more susceptible to the necrotrophic fungal pathogens Alternaria and Botrytis spp. Furthermore, we show that the RPW8 proteins appear to be localized to the endomembrane system, overlapping with the endoplasmic reticulum–associated small GTPase SAR1, and accumulate to higher levels in response to application of exogenous salicylic acid, one of the signaling molecules of plant defense.

scholarly journals Ontogenic Resistance of Leaves and Fruit, and How Leaf Folding Influences the Distribution of Powdery Mildew on Strawberry Plants Colonized by Podosphaera aphanis

2014 ◽  
Vol 104 (9) ◽  
pp. 954-963 ◽  
Author(s):  
Belachew Asalf ◽  
David M. Gadoury ◽  
Anne Marte Tronsmo ◽  
Robert C. Seem ◽  
Andrew Dobson ◽  
...  
Keyword(s):  
New York ◽  
Powdery Mildew ◽  
Rapid Development ◽  
Differential Susceptibility ◽  
Rapid Acquisition ◽  
Age Related ◽  
Significant Difference ◽  
Leaf Surfaces ◽  
Ontogenic Resistance ◽  
Strawberry Cultivars

Ontogenic or age-related resistance has been noted in many pathosystems but is less often quantified or expressed in a manner that allows the concept to be applied in disease management programs. Preliminary studies indicated that leaves and fruit of three strawberry cultivars rapidly acquired ontogenic resistance to the powdery mildew pathogen, Podosphaera aphanis. In the present study, we quantify the development of ontogenic resistance in controlled inoculations of 10 strawberry cultivars using diverse isolates of P. aphanis in New York and Florida, USA, and in Norway. We report the differential and organ-specific development of ontogenic resistance in the receptacle and externally borne strawberry achenes. We further report that rapid development of ontogenic resistance prior to unfolding of emergent leaves, rather than differential susceptibility of adaxial versus abaxial leaf surfaces, may explain the commonly observed predominance of powdery mildew on the lower leaf surfaces. Susceptibility of leaves and fruit declined exponentially with age. Receptacle tissue of berries inoculated at four phenological stages from bloom to ripe fruit became nearly immune to infection approximately 10 to 15 days after bloom, as fruit transitioned from the early green to the late green or early white stage of berry development, although the achenes remained susceptible for a longer period. Leaves also acquired ontogenic resistance early in their development, and they were highly resistant shortly after unfolding and before the upper surface was fully exposed. No significant difference was found in the susceptibility of the adaxial versus abaxial surfaces. The rapid acquisition of ontogenic resistance by leaves and fruit revealed a narrow window of susceptibility to which management programs might be advantageously adapted.

scholarly journals A Pattern Recognition Tool for Quantitative Analysis of In Planta Hyphal Growth of Powdery Mildew Fungi

2005 ◽  
Vol 18 (9) ◽  
pp. 906-912 ◽  
Author(s):  
U. Seiffert ◽  
P. Schweizer
Keyword(s):  
Growth Rate ◽  
Pattern Recognition ◽  
Quantitative Analysis ◽  
Powdery Mildew ◽  
Growth Rates ◽  
Fungal Pathogens ◽  
Hyphal Growth ◽  
Blumeria Graminis ◽  
In Planta ◽  
Powdery Mildew Fungi

The development of fungal pathogens can be quantified easily at the level of spore germination or penetration. However, the exact quantification of hyphal growth rates after initial, successful host invasion is much more difficult. Here, we report on the development of a new pattern recognition software (HyphArea) for automated quantitative analysis of hyphal growth rates of powdery mildew fungi on plant surfaces that usually represent highly irregular and noisy image backgrounds. By using HyphArea, we measured growth rates of colonies of the barley powdery mildew, Blumeria graminis f. sp. hordei, on susceptible and induced-resistant host plants. Hyphal growth was not influenced by the resistance state of the plants up to 48 h postinoculation. At later time points, growth rate increased on susceptible plants, whereas it remained restricted on induced-resistant plants. This difference in hyphal growth rate was accompanied by lack of secondary haustoria formation on induced-resistant plants, suggesting that induced resistance in barley against Blumeria graminis is caused mainly by reduced penetration rates of primary as well as secondary appressoria leading, finally, to fewer and lessdeveloped fungal colonies. No evidence was found for reduced nutrient-uptake efficiency of the primary haustoria in induced-resistant leaves, which would be expected to have resulted in reduced hyphal growth rates during the first 48 h of the interaction.

scholarly journals Host adaptation through hybridization: Genome analysis of triticale powdery mildew reveals unique combination of lineage-specific effectors

2021 ◽  
Author(s):  
Marion Claudia Müller ◽  
Lukas Kunz ◽  
Johannes Peter Graf ◽  
Seraina Schudel ◽  
Beat Keller
Keyword(s):  
Powdery Mildew ◽  
Fungal Pathogens ◽  
Genetic Basis ◽  
Reference Genome ◽  
Resistance Breeding ◽  
Host Adaptation ◽  
Allelic Series ◽  
Hybrid Genome ◽  
Long Read ◽  
Bona Fide

The emergence of new fungal pathogens through hybridization represents a serious challenge for agriculture. Hybridization between the wheat mildew (Blumeria graminis f.sp. tritici) and rye mildew (B.g. f.sp. secalis) pathogens have led to the emergence of a new mildew form (B.g. f.sp. triticale) growing on triticale, a man-made amphiploid crop derived from crossing rye and wheat which was originally resistant to the powdery mildew disease. The identification of the genetic basis of host-adaptation in triticale mildew has been hampered by the lack of a reference genome. Here we report the 141.4 Mb reference assembly of triticale mildew isolate THUN-12 derived from long-read sequencing and genetic map-based scaffolding. All eleven triticale mildew chromosomes were assembled from telomere-to-telomere and revealed that 19.7% of the hybrid genome was inherited from the rye mildew parental lineage. We identified lineage-specific regions in the hybrid, inherited from the rye or wheat mildew parental lineages, that harbour numerous bona fide candidate effectors. We propose that the combination of lineage-specific effectors in the hybrid genome is crucial for host-adaptation, allowing the fungus to simultaneously circumvent the immune systems contributed by wheat and rye in the triticale crop. In line with this we demonstrate the functional transfer of the SvrPm3 effector from wheat to triticale mildew, a virulence effector that specifically suppresses resistance of the wheat Pm3 allelic series. This transfer is the likely underlying cause for the observed poor effectiveness of several Pm3 alleles against triticale mildew and exemplifies the negative implications of pathogen hybridizations on resistance breeding.

scholarly journals Potential of genetic resistance of new table grape hybrids to fungal pathogens

2021 ◽  
Vol 34 ◽  
pp. 02001
Author(s):  
Elena Ilnitskaya ◽  
Marina Makarkina ◽  
Valeriy Petrov
Keyword(s):  
Powdery Mildew ◽  
Downy Mildew ◽  
Resistance Genes ◽  
Dna Markers ◽  
Fungal Pathogens ◽  
Genetic Resistance ◽  
Plasmopara Viticola ◽  
Table Grape ◽  
Table Grapes ◽  
Hybrid Forms

Downy mildew (Plasmopara viticola) and powdery mildew (Erysiphe necator) are the most common and economically significant fungal diseases in vineyards. The task of this work is to study the genotypes of new promising hybrid forms of table grapes for the presence of resistance genes to downy mildew (Rpv10 and Rpv3) and powdery mildew (Ren9) using DNA-markers. The study was carried out on table grape hybrids under the working names Agat dubovskiy, Akelo, Arabella, Artek, Dubovskiy rozovyi, Gamlet, Ispolin, Kishmish dubovskiy, Kurazh, Pestryi, Valensiya and registered variety Liviya. The studied genes were analyzed using markers UDV305 and UDV737 (Rpv3), GF09-46 (Rpv10), CenGen6 (Ren9). The following cultivars were used as reference genotypes: Saperavi severnyi (carries Rpv10 gene) and Regent (Rpv3 and Ren9). It was established that Rpv3 gene is carried by hybrids Kishmish dubovskiy, Agat dubovskiy, Kurazh, Valensiya, Akelo, Gamlet, Dubovskiy rozovyi, Pestryi. Ren9 gene was found in Artek, Agat dubovskiy, Kurazh, Ispolin, Valensiya, Arabella, Gamlet, Dubovskiy rozovyi, Pestryi. The Rpv10 gene was not detected in any of the analyzed grapevine samples. genotypes Agat dubovskiy, Kurazh, Gamlet, Dubovskiy rozovyi, Pestryi, Valensiya carry Rpv3 and Ren9 genes simultaneously. These grapevines have an elegant bunch and large berries that are attractive to consumers.

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