Phylodynamic Insights into Global Emergence and Diversification of the Tomato Pathogen pv. .

The emergence of plant pathogens is often associated with waves of unique evolutionary and epidemiological events. pv. is one of the major pathogens causing bacterial spot disease of tomatoes.

as a Model System for Studying Pathogen Emergence and Evolution.

In this review, we highlight studies in which whole-genome sequencing, comparative genomics, and population genomics have provided unprecedented insights into past and ongoing pathogen evolution. These include new understandings of the adaptive evolution of secretion systems and their effectors. We focus on pathosystems that have seen intensive study and improved our understanding of pathogen emergence and evolution, particularly in the context of host specialization: citrus canker, bacterial blight of rice, and bacterial spot of tomato and pepper.

Bacterial Mutation During Seasonal Epidemics.

Rapidly evolving bacterial pathogens pose a unique challenge for long-term plant disease management. In this study, we investigated the types and rate of mutations in bacterial populations during seasonal disease epidemics. Two phylogenetically distinct strains of the bacterial spot pathogen, , were marked, released in tomato fields, and recaptured at several time points during the growing season.

Effect of Cucurbit Host, Production Region, and Season on the Population Structure of in Florida.

, the causal agent of Cucurbit downy mildew (CDM), is one of the most important diseases affecting cucurbit production in the United States. This disease is especially damaging to Florida production areas, as the state is a top producer of many cucurbit species. In addition, winter production in central and south Florida likely serves as a likely source of inoculum for spring and summer cucurbit production throughout the eastern United States, where CDM is unable to overwinter in the absence of a living host.

Whole-Genome-Sequence-Based Classification of pv. and Computational Analysis of the Type III Secretion System.

spp. infect a wide range of annual and perennial plants. Bacterial blight in young seedlings of spp.

Potential of Novel Magnesium Nanomaterials to Manage Bacterial Spot Disease of Tomato in Greenhouse and Field Conditions.

Bacterial spot of tomato is among the most economically relevant diseases affecting tomato plants globally. In previous studies, non-formulated magnesium oxide nanoparticles (nano-MgOs) significantly reduced the disease severity in greenhouse and field conditions. However, the aggregation of nano-MgO in liquid suspension makes it challenging to use in field applications.

Effective Management of Powdery Mildew in Cantaloupe Plants Using Nighttime Applications of UV Light.

Ultraviolet light at wavelengths from 254 to 283 nm/has been reported to effectively suppress powdery mildews in several crops, including some cucurbits. Its use to suppress powdery mildew () specifically in cantaloupe has not been previously reported. We evaluated the foregoing technology in cantaloupe fields for suppression of powdery mildew and possible effects on plant growth and yield.

Strength in Numbers: Density-Dependent Volatile-Induced Antimicrobial Activity by .

For most of the 20th century, was the only known bacterium associated with bacterial spot of tomato in Florida. quickly replaced , mainly because of production of three (BCNs) against ; however, outcompeted even when the three known BCNs were deleted. Surprisingly, we observed antimicrobial activity against in the BCN triple mutant when the triple mutant was grown in Petri plates containing multiple spots but not in Petri plates containing only one spot.

Interaction Studies Between f. Sp. on Different Isolines of Tomato Cv. Tasti Lee.

The gene in tomato confers resistance to , and , the most common tropical root-knot nematode (RKN) species found in Florida. wilt (Fol) is another major problem in Florida tomatoes which may interact with RKN and cause more plant damage. To study the interactions between RKN, Fusarium, and in tomato, two greenhouse experiments were conducted.

Future of Bacterial Disease Management in Crop Production.

Bacterial diseases are a constant threat to crop production globally. Current management strategies rely on an array of tactics, including improved cultural practices; application of bactericides, plant activators, and biocontrol agents; and use of resistant varieties when available. However, effective management remains a challenge, as the longevity of deployed tactics is threatened by constantly changing bacterial populations.

Identification of Genes in pv. That Are Host Limiting in Tomato.

pv. strain causes a leaf spot on a sp. and is closely related to pv.

Breeding for Resistance to Fusarium Wilt of Tomato: A Review.

For over a century, breeders have worked to develop tomato () cultivars with resistance to Fusarium wilt () caused by the soilborne fungus f. sp. .

Duration of Downy Mildew Control Achieved with Fungicides on Cucumber Under Florida Field Conditions.

Cucurbit production in Florida is impacted by downy mildew on a yearly basis. Cucurbit downy mildew (CDM), caused by , is one of the most devastating cucurbit diseases and can lead to complete yield loss. Nearly continuous production of cucurbits occurs temporally throughout Florida, which puts extensive pressure on the pathogen population to select for individuals that are resistant to fungicides in use labeled for CDM.

Whole genome sequences reveal the Xanthomonas perforans population is shaped by the tomato production system.

Modern agricultural practices increase the potential for plant pathogen spread, while the advent of affordable whole genome sequencing enables in-depth studies of pathogen movement. Population genomic studies may decipher pathogen movement and population structure as a result of complex agricultural production systems. We used whole genome sequences of 281 Xanthomonas perforans strains collected within one tomato production season across Florida and southern Georgia fields to test for population genetic structure associated with tomato production system variables.

A centenary for bacterial spot of tomato and pepper.

Disease Symptoms: Symptoms include water-soaked areas surrounded by chlorosis turning into necrotic spots on all aerial parts of plants. On tomato fruits, small, water-soaked, or slightly raised pale-green spots with greenish-white halos are formed, ultimately becoming dark brown and slightly sunken with a scabby or wart-like surface.

Host Range: Main and economically important hosts include different types of tomatoes and peppers.

Supplemental Fumigant Placement Improves Root Knot and Fusarium Wilt Management for Tomatoes Produced on a Raised-Bed Plasticulture System in Florida's Myakka Fine Sand.

Fresh-market tomatoes are produced on a raised-bed plasticulture system that relies heavily on soil-applied preplant fumigants for the management of soilborne pathogens, nematodes, and weeds. Since the transition from methyl bromide to alternative fumigants, growers have experienced a resurgence of several soilborne pests and pathogens, including root-knot nematode caused by spp. and Fusarium wilt caused by f.

Epidemiology, diversity, and management of bacterial spot of tomato caused by Xanthomonas perforans.

Tomato is an important crop grown worldwide. Various plant diseases cause massive losses in tomato plants due to diverse biotic agents. Bacterial spot of tomato (BST) is a worldwide disease that results in high losses in processed and fresh tomato.

Magnesium Oxide Nanomaterial, an Alternative for Commercial Copper Bactericides: Field-Scale Tomato Bacterial Spot Disease Management and Total and Bioavailable Metal Accumulation in Soil.

Copper (Cu) is the most extensively used bactericide worldwide in many agricultural production systems. However, intensive application of Cu bactericide have increased the selection pressure toward Cu-tolerant pathogens, including , the causal agent of tomato bacterial spot. However, alternatives for Cu bactericides are limited and have many drawbacks including plant damage and inconsistent effectiveness under field conditions.

Need for speed: bacterial effector XopJ2 is associated with increased dispersal velocity of Xanthomonas perforans.

Bacterial spot caused by Xanthomonas perforans (Xp) is an economically important disease in tomato. Previous studies have shown that the recently isolated Xp strains have acquired and retained the effector gene, xopJ2, which has been reported to increase fitness of the pathogen in the field. To elucidate the fitness benefit of xopJ2, we quantified the effect of xopJ2 on the dispersal and evolution of Xp populations on tomato.

Draft Genome Sequences of Pseudomonas syringae pv. tomato Strains J4 and J6, Isolated in Florida.

pv. tomato causes bacterial speck in tomato. We report the genome sequences of two pv.

Characterization and elimination of linkage-drag associated with Fusarium wilt race 3 resistance genes.

Reducing the size of the I-3 introgression resulted in eliminating linkage-drag contributing to increased sensitivity to bacterial spot and reduced fruit size. The I-7 gene was determined to have no effect on bacterial spot or fruit size, and germplasm is now available with both the reduced I-3 introgression and I-7. Tomato (Solanum lycopersicum) production is increasingly threatened by Fusarium wilt race 3 (Fol3) caused by the soilborne fungus, Fusarium oxysporum f.

Phylogenomic Analysis of a 55.1-kb 19-Gene Dataset Resolves a Monophyletic that Includes the Species Complex.

Scientific communication is facilitated by a data-driven, scientifically sound taxonomy that considers the end-user's needs and established successful practice. In 2013, the community voiced near unanimous support for a concept of that represented a clade comprising all agriculturally and clinically important species, including the species complex (FSSC). Subsequently, this concept was challenged in 2015 by one research group who proposed dividing the genus into seven genera, including the FSSC described as members of the genus , with subsequent justification in 2018 based on claims that the 2013 concept of is polyphyletic.

Assessing Changes and Associations in the Population Across Florida Commercial Tomato Fields Via a Statewide Survey.

Before 1991, was the causal agent of bacterial spot of tomato in Florida but was quickly replaced by . The population has changed in genotype and phenotype despite lack of a clear selection pressure. To determine the current population in Florida, we collected 585 strains from 70 tomato fields, representing 22 farms across eight counties, in the Florida tomato production region.