Dual transcriptional characterization of spinach and Peronospora effusa during resistant and susceptible race-cultivar interactions.

Background: Spinach downy mildew, caused by the obligate oomycete pathogen, Peronospora effusa remains a major concern for spinach production. Disease control is predominantly based on development of resistant spinach cultivars. However, new races and novel isolates of the pathogen continue to emerge and overcome cultivar resistance.

Draft genome sequences for four isolates of the hemp () fungal pathogen .

Four isolates of , collected from diseased hemp () plants over a period of 2 years and shown to be pathogenic on were examined in this study. Their genome sizes ranged between 42.8 and 44.

Transmission of Spinach Downy Mildew via Seed and Infested Leaf Debris.

Spinach downy mildew, caused by the obligate oomycete pathogen , is a worldwide constraint on spinach production. The role of airborne sporangia in the disease cycle of is well established, but the role of the sexual oospores in the epidemiology of is less clear and has been a major challenge to examine experimentally. To evaluate seed transmission of spinach downy mildew via oospores in this study, isolated glass chambers were employed in two independent experiments to grow out oospore-infested spinach seed and noninfested seeds mixed with oospore-infested crop debris.

Skim resequencing finely maps the downy mildew resistance loci and in spinach cultivars whale and Lazio.

Commercial production of spinach ( L.) is centered in California and Arizona in the US, where downy mildew caused by is the most destructive disease. Nineteen typical races of have been reported to infect spinach, with 16 identified after 1990.

Characterization of Blast Resistance in a Diverse Rice Panel from Sub-Saharan Africa.

There is a recent unparalleled increase in demand for rice in sub-Saharan Africa, yet its production is affected by blast disease. Characterization of blast resistance in adapted African rice cultivars can provide important information to guide growers and rice breeders. We used molecular markers for known blast resistance genes ( genes; = 21) to group African rice genotypes ( = 240) into similarity clusters.

Resequencing worldwide spinach germplasm for identification of field resistance QTLs to downy mildew and assessment of genomic selection methods.

Downy mildew, commercially the most important disease of spinach, is caused by the obligate oomycete . In the past two decades, new pathogen races have repeatedly overcome the resistance used in newly released cultivars, urging the need for more durable resistance. Commercial spinach cultivars are bred with major R genes to impart resistance to downy mildew pathogens and are effective against some pathogen races/isolates.

Mapping and selection of downy mildew resistance in spinach cv. whale by low coverage whole genome sequencing.

Spinach () is a popular leafy vegetable crop and commercial production is centered in California and Arizona in the US. The oomycete causes the most important disease in spinach, downy mildew. A total of nineteen races of are known, with more than 15 documented in the last three decades, and the regular emergence of new races is continually overcoming the genetic resistance to the pathogen.

Genome-wide association study and genomic prediction of white rust resistance in USDA GRIN spinach germplasm.

White rust, caused by , is one of the major yield-limiting diseases of spinach () in some major commercial production areas, particularly in southern Texas in the United States. The use of host resistance is the most economical and environment-friendly approach to managing white rust in spinach production. The objectives of this study were to conduct a genome-wide associating study (GWAS), to identify single nucleotide polymorphism (SNP) markers associated with white rust resistance in spinach, and to perform genomic prediction (GP) to estimate the prediction accuracy (PA).

Foliar Diseases and the Associated Fungi in Rice Cultivated in Kenya.

We conducted a survey to assess the occurrence and severity of rice blast and brown spot diseases on popular cultivars grown in the Busia, Kirinyaga, and Kisumu counties of Kenya in 2019. Working with agricultural extension workers within rice production areas, we interviewed farmers ( = 89) regarding their preferred cultivars and their awareness of blast disease, as this was the major focus of our research. We scored the symptoms of blast and brown spot and assessed the lodging, plant height, and maturity of the crops (days after planting).

Early Detection of the Spinach Downy Mildew Pathogen in Leaves by Recombinase Polymerase Amplification.

Downy mildew of spinach, caused by , is a major economic threat to both organic and conventional spinach production. Symptomatic spinach leaves are unmarketable and spinach with latent infections are problematic because symptoms can develop postharvest. Therefore, early detection methods for could help producers identify infection before visible symptoms appear.

Ancestral Chromosomes for Family Peronosporaceae Inferred from a Telomere-to-Telomere Genome Assembly of .

Downy mildew disease of spinach, caused by the oomycete , causes major losses to spinach production. In this study, the 17 chromosomes of were assembled telomere-to-telomere, using Pacific Biosciences high-fidelity reads. Of these, 16 chromosomes are complete and gapless; chromosome 15 contains one gap bridging the nucleolus organizer region.

Integrated Strategies for Durable Rice Blast Resistance in Sub-Saharan Africa.

Rice is a key food security crop in Africa. The importance of rice has led to increasing country-specific, regional, and multinational efforts to develop germplasm and policy initiatives to boost production for a more food-secure continent. Currently, this critically important cereal crop is predominantly cultivated by small-scale farmers under suboptimal conditions in most parts of sub-Saharan Africa (SSA).

High resolution mapping and candidate gene identification of downy mildew race 16 resistance in spinach.

Background: Downy mildew, the most devastating disease of spinach (Spinacia oleracea L.), is caused by the oomycete Peronospora effusa [=P. farinosa f.

Comparative genome analyses of four rice-infecting Rhizoctonia solani isolates reveal extensive enrichment of homogalacturonan modification genes.

Background: Plant pathogenic isolates of Rhizoctonia solani anastomosis group 1-intraspecific group IA (AG1-IA) infect a wide range of crops causing diseases such as rice sheath blight (ShB). ShB has become a serious disease in rice production worldwide. Additional genome sequences of the rice-infecting R.

Fine mapping and molecular marker development of the Fs gene controlling fruit spines in spinach (Spinacia oleracea L.).

The Fs gene, which controls spinach fruit spines, was fine mapped to a 0.27 Mb interval encompassing four genes on chromosome 3. There are two types of fruit of spinach (Spinacia oleracea L.

Genome Wide Association Studies in Multiple Spinach Breeding Populations Refine Downy Mildew Race 13 Resistance Genes.

Downy mildew, caused by the oomycete , is the most economically important disease on spinach. Fourteen new races of have been identified in the last three decades. The frequent emergence of new races of continually overcome the genetic resistance to the pathogen.

Phylogenetic Analysis, Vegetative Compatibility, Virulence, and Fungal Filtrates of Leaf Curl Pathogen from Celery.

Leaf curl of celery, caused by sensu lato, has been reported in the United States. A multilocus phylogenetic analysis with three genes was conducted with a collection of isolates from celery ( = 23) and noncelery ( = 29) hosts to evaluate their taxonomic position within sensu lato. The three DNA regions used for phylogenetic analysis included the introns of the glutamine synthase and glyceraldehyde-3-phosphate dehydrogenase genes, and the partial sequence of the histone3 gene.

Sporangiospore Viability and Oospore Production in the Spinach Downy Mildew Pathogen, .

Downy mildew of spinach, caused by the obligate pathogen , remains the most important constraint in the major spinach production areas in the United States. This disease can potentially be initiated by asexual sporangiospores via "green bridges", sexually derived oospores from seed or soil, or dormant mycelium. However, the relative importance of the various types of primary inoculum is not well known.

Three New Fungal Leaf Spot Diseases of Spinach in the United States and the Evaluation of Fungicide Efficacy for Disease Management.

Leaf spot diseases of spinach, caused by , has become a major production constraint in several production areas, including Texas, in recent years. Leaf spot symptoms were observed in several fields in Texas in 2016 and 2017, with typical anthracnose-like symptoms and leaves with small, circular, and sunken lesions that appeared similar to injury from windblown sand. The lesions were plated on potato dextrose agar, from which fungal cultures were recovered.

Characterization of Leaf Spot Pathogens from Several Spinach Production Areas in the United States.

Leaf spot diseases have become a major concern in spinach production in the United States. Determining the causal agents of leaf spots on spinach, their prevalence and pathogenicity, and fungicide efficacy against these pathogens is vital for effective disease management. Spinach leaves with leaf spots were collected from Texas, California, Arizona, and South Carolina from 2016 to 2018, incubated in a moist chamber, and plated on potato dextrose and tryptic soy agar media.

Dynamics of Race Structures of the Rice Blast Pathogen Population in Heilongjiang Province, China From 2006 Through 2015.

Rice blast caused by the fungus is one of the most destructive diseases of rice. Its control through the deployment of host resistance genes would be facilitated by understanding the pathogen's race structure. Here, dynamics of race structures in this decade in Heilongjiang province were characterized by Chinese differential cultivars.

Characterization of Foliar Web Blight of Spinach, Caused by Pythium aphanidermatum, in the Desert Southwest of the United States.

A unique foliar disease of spinach, determined to be caused by Pythium aphanidermatum, was observed on spinach in Yuma County, AZ and Imperial County, CA desert spinach production areas in both 2015 and 2016. The foliar symptoms of the disease included water-soaked foliage, rapid collapse of young plants, and white, aerial, cottony mycelia. The disease was associated with hot (27 to 42°C) and wet conditions associated with overhead irrigation under high-density plantings (>8.

Fine mapping and candidate gene screening of the downy mildew resistance gene RPF1 in Spinach.

A SLAF-BSA approach was used to locate the RPF1 locus. The three most likely candidate genes were identified which provide a basic for cloning the resistance gene at the RPF1 locus. Spinach downy mildew is a globally devastating oomycete disease.