Fungal effector genes involved in the suppression of chitin signaling as novel targets for the control of powdery mildew disease via a nontransgenic RNA interference approach.

Background: Chitin is a crucial component of fungal cell walls and an effective elicitor of plant immunity; however, phytopathogenic fungi have developed virulence mechanisms to counteract the activation of this plant defensive response. In this study, the molecular mechanism of chitin-induced suppression through effectors involved in chitin deacetylases (CDAs) and their degradation (EWCAs) was investigated with the idea of developing novel dsRNA-biofungicides to control the cucurbit powdery mildew caused by Podosphaera xanthii.

Results: The molecular mechanisms associated with the silencing effect of the PxCDA and PxEWCAs genes were first studied through dsRNA cotyledon infiltration assays, which revealed a ≈80% reduction in fungal biomass and a 50% decrease in gene expression.

Rational Design of a Potential New Nematicide Targeting Chitin Deacetylase.

In a previously published study, the authors devised a molecular topology QSAR (quantitative structure-activity relationship) approach to detect novel fungicides acting as inhibitors of chitin deacetylase (CDA). Several of the chosen compounds exhibited noteworthy activity. Due to the close relationship between chitin-related proteins present in fungi and other chitin-containing plant-parasitic species, the authors decided to test these molecules against nematodes, based on their negative impact on agriculture.

RNAi Technology: A New Path for the Research and Management of Obligate Biotrophic Phytopathogenic Fungi.

Powdery mildew and rust fungi are major agricultural problems affecting many economically important crops and causing significant yield losses. These fungi are obligate biotrophic parasites that are completely dependent on their hosts for growth and reproduction. Biotrophy in these fungi is determined by the presence of haustoria, specialized fungal cells that are responsible for nutrient uptake and molecular dialogue with the host, a fact that undoubtedly complicates their study under laboratory conditions, especially in terms of genetic manipulation.

A Loop-Mediated Isothermal Amplification Assay for the Identification of in Strawberry.

Gray mold in strawberry is caused by multiple species of , including , , , and . The species and are widespread in production regions of the eastern United States and Germany, and their distinction is important for disease management strategies. Currently, the only way to differentiate these species in field samples is by PCR, which is time consuming, labor intensive, and costly.

Suppression of Chitin-Triggered Immunity by a New Fungal Chitin-Binding Effector Resulting from Alternative Splicing of a Chitin Deacetylase Gene.

Phytopathogenic fungi have evolved mechanisms to manipulate plant defences, such as chitin-triggered immunity, a plant defensive response based on the recognition of chitin oligomers by plant-specific receptors. To cope with chitin resistance, fungal pathogens have developed different strategies to prevent chitin recognition, such as binding, breaking, or modifying immunogenic oligomers. In powdery mildew fungi, the activity of chitin deacetylase (CDA) is crucial for this purpose, since silencing of the gene leads to a rapid activation of chitin signalling and the subsequent suppression of fungal growth.

Rational Design of Chitin Deacetylase Inhibitors for Sustainable Agricultural Use Based on Molecular Topology.

Fungicide resistance is a major concern in modern agriculture; therefore, there is a pressing demand to develop new, greener chemicals. Chitin is a major component of the fungal cell wall and a well-known elicitor of plant immunity. To overcome chitin recognition, fungal pathogens developed different strategies, with chitin deacetylase (CDA) activity being the most conserved.

Chitin Deacetylase, a Novel Target for the Design of Agricultural Fungicides.

Fungicide resistance is a serious problem for agriculture. This is particularly apparent in the case of powdery mildew fungi. Therefore, there is an urgent need to develop new agrochemicals.

Gene Mining for Conserved, Non-Annotated Proteins of Identifies Novel Target Candidates for Controlling Powdery Mildews by Spray-Induced Gene Silencing.

The powdery mildew fungus is one of the most important limiting factors for cucurbit production worldwide. Despite the significant efforts made by breeding and chemical companies, effective control of this pathogen remains elusive to growers. In this work, we examined the suitability of RNAi technology called spray-induced gene silencing (SIGS) for controlling cucurbit powdery mildew.

Resistance to the SDHI Fungicides Boscalid and Fluopyram in Populations from Commercial Cucurbit Fields in Spain.

Powdery mildew is caused by , and is one of the most important diseases that attacks Spanish cucurbit crops. Fungicide application is the primary control tool; however, its effectiveness is hampered by the rapid development of resistance to these compounds. In this study, the EC values of 26 isolates were determined in response to the succinate dehydrogenase inhibitor (SDHI) fungicides boscalid and fluopyram.

A haustorial-expressed lytic polysaccharide monooxygenase from the cucurbit powdery mildew pathogen Podosphaera xanthii contributes to the suppression of chitin-triggered immunity.

Podosphaera xanthii is the main causal agent of cucurbit powdery mildew and a limiting factor of crop productivity. The lifestyle of this fungus is determined by the development of specialized parasitic structures inside epidermal cells, termed haustoria, that are responsible for the acquisition of nutrients and the release of effectors. A typical function of fungal effectors is the manipulation of host immunity, for example the suppression of pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI).

A Hybrid Genome Assembly Resource for , the Main Causal Agent of Powdery Mildew Disease in Cucurbits.

is the main causal agent of powdery mildew in cucurbits and, arguably, the most important fungal pathogen of cucurbit crops. Here, we present the first reference genome assembly for . We performed a hybrid genome assembly, using reads from Illumina NextSeq550 and PacBio Sequel S3.

Fungicide Resistance in Powdery Mildew Fungi.

Powdery mildew fungi (Erysiphales) are among the most common and important plant fungal pathogens. These fungi are obligate biotrophic parasites that attack nearly 10,000 species of angiosperms, including major crops, such as cereals and grapes. Although cultural and biological practices may reduce the risk of infection by powdery mildew, they do not provide sufficient protection.

Monitoring Methyl Benzimidazole Carbamate-Resistant Isolates of the Cucurbit Powdery Mildew Pathogen, , Using Loop-Mediated Isothermal Amplification.

Powdery mildew, caused by the fungus , is one of the most economically important diseases affecting cucurbit crops in Spain. Currently, chemical control offers the most efficient management of the disease; however, isolates resistant to multiple classes of site-specific fungicides have been reported in the Spanish cucurbit powdery mildew population. In previous studies, resistance to the fungicides known as methyl benzimidazole carbamates (MBCs) was found to be caused by the amino acid substitution E198A on β-tubulin.

Detection of White Root Rot in Avocado Trees by Remote Sensing.

White root rot, caused by the soilborne fungus , is an important constraint to production for a wide range of woody crop plants such as avocado trees. The current methods of detection of white root rot are based on microbial and molecular techniques, and their application at orchard scale is limited. In this study, physiological parameters provided by imaging techniques were analyzed by machine learning methods.

Heteroplasmy for the Cytochrome b Gene in Podosphaera xanthii and its Role in Resistance to QoI Fungicides in Spain.

In Spain, management of the cucurbit powdery mildew pathogen Podosphaera xanthii is strongly dependent on chemicals such as quinone outside inhibitor (QoI) fungicides. In a previous report, widespread resistance to QoI fungicides in populations of P. xanthii in south-central Spain was documented, but the molecular mechanisms of resistance remained unclear.

The Functional Characterization of Podosphaera xanthii Candidate Effector Genes Reveals Novel Target Functions for Fungal Pathogenicity.

Podosphaera xanthii is the main causal agent of powdery mildew disease in cucurbits. In a previous study, we determined that P. xanthii expresses approximately 50 Podosphaera effector candidates (PECs), identified based on the presence of a predicted signal peptide and the absence of functional annotation.

Resistance to the SDHI Fungicides Boscalid, Fluopyram, Fluxapyroxad, and Penthiopyrad in Botrytis cinerea from Commercial Strawberry Fields in Spain.

Gray mold, caused by the necrotrophic fungus Botrytis cinerea., is one of the most economically important diseases of strawberry. Gray mold control involves the application of fungicides throughout the strawberry growing season; however, B.

Characterization of Resistance to Six Chemical Classes of Site-Specific Fungicides Registered for Gray Mold Control on Strawberry in Spain.

Botrytis cinerea, causal agent of the gray mold disease, is one of the most economically important fungal pathogens of strawberry worldwide. In Spain, as in other parts of the world, management of gray mold control primarily involves the application of fungicides. To determine the fungicide resistance of the Spanish strawberry field population, 367 B.

Monitoring Resistance to SDHI Fungicides in Botrytis cinerea From Strawberry Fields.

Succinate dehydrogenase inhibitor (SDHI) fungicides have been used to control gray mold of strawberry for more than a decade, and selection for resistance in the causal agent Botrytis cinerea has become a threat to producers. In total, 2,570 B. cinerea isolates were collected from strawberry fields in the eastern United States across three seasons and their sensitivity to the SDHI materials boscalid, fluopyram, fluxapyroxad, and penthiopyrad was assessed.

Independent Emergence of Resistance to Seven Chemical Classes of Fungicides in Botrytis cinerea.

Gray mold, caused by the fungal pathogen Botrytis cinerea, is one of the most destructive diseases of small fruit crops and control is largely dependent on the application of fungicides. As part of a region-wide resistance-monitoring program that investigated 1,890 B. cinerea isolates from 189 fields in 10 states of the United States, we identified seven isolates (0.

Location-Specific Fungicide Resistance Profiles and Evidence for Stepwise Accumulation of Resistance in Botrytis cinerea.

The fungicide resistance profiles to seven chemical classes of fungicides were investigated in 198 Botrytis cinerea isolates from five blackberry fields and 214 B. cinerea isolates from 10 strawberry fields of North and South Carolina. Populations of B.

First Report of Pilidium concavum Causing Tan-brown Rot on Strawberry Nursery Stock in South Carolina.

Pilidium concavum (Desm.) Höhn. [synanamorph: Hainesia lythri (Desm.

First Report of Fludioxonil Resistance in Botrytis cinerea from a Blackberry Field in Georgia.

Botrytis cinerea Pers. is an important plant-pathogenic fungi responsible for gray mold on more than 230 plant species worldwide, including blackberry (Rubus). One of the main strategies to control the disease involves the application of different classes of fungicides.

Fungicide Resistance Profiles in Botrytis cinerea from Strawberry Fields of Seven Southern U.S. States.

The sensitivity to seven chemical classes of fungicides was investigated in 1,810 Botrytis cinerea isolates collected from strawberry blossoms and fruit in 181 strawberry fields from seven southern states in the United States across 2 years. Ten isolates were examined from each field. Fungicide sensitivity assays were carried out based on visual assessment of diametrical mycelial growth after 4 days of incubation on media amended with discriminatory doses of fungicides in microtiter plates.