David J Norman

University of Florida | UF · College of Agricultural and Life Sciences

Background Tomato (Solanum lycopersicum) is a globally significant crop that faces challenges from various pathogens, including Phytoplasma solani. Phytoplasmas are obligate parasitic bacteria that disrupt plant metabolism and manipulate host defenses. Our current understanding of tomato-Phytoplasma solani interaction is very limited and currently...

This recovery plan is one of several disease-specific documents produced as part of the National Plant Disease Recovery System (NPDRS) called for in Homeland Security Presidential Directive Number 9 (HSPD-9). The purpose of the NPDRS is to ensure that the tools, infrastructure, communication networks, and capacity required to mitigate the impact of...

Potato (Solanum tuberosum L.) ranks fourth among the most important staple food in the world. Ralstonia solanacearum (phylotype [phy] IIB, sequevar [seq] 1 and 2), also known as R3B2, the causal agent of brown rot disease on potato, is extremely damaging, causing great economical losses to potato in temperate regions. It is thought that members of...

The blueberry industry, a fast-growing industry in Florida, is threatened by bacterial wilt, caused by the Ralstonia solanacearum species complex (RSSC). In 2016, distinct RSSC populations were found in Florida causing disease in blueberry. Currently, there are no tools that discriminate between RSSC populations pathogenic to blueberry and other RS...

Blueberry production is expanding rapidly in the United States and globally. In 2016, bacterial wilt was discovered in Florida blueberry production. Because of the international movement of plants, this disease poses a significant risk to production. The purpose of this project was to evaluate the resistance of blueberry species and cultivars to th...

The bacterial wilt pathogens in the Ralstonia solanacearum species complex (RSSC) have broad but finite host ranges. Population genetic surveys of RSSC pathogens show that many sequevars (subspecies groups) are predominantly recovered from wilting solanaceous plants. In contrast, strains in the IIB-4 sequevar have been isolated from plants in over...

The bacterial wilt pathogens in the Ralstonia solanacearum species complex (RSSC) have broad but finite host ranges. Population genetic surveys of RSSC pathogens show that many sequevars (subspecies groups) are predominantly recovered from wilting solanaceous plants. In contrast, strains in the IIB-4 sequevar have been isolated from plants in over...

Pathogen management commonly includes environmental regulation and sanitization. There are limited numbers of effective registered bactericides. In 3 years of greenhouse trials, PostivaTM, a premix of pydiflumetofen (6.9%) and difenoconazole (11.5%), was tested for activity against xanthomonas leafspot of geranium, zinnia, ficus and bacterial wilt...

Ralstonia pseudosolanacearum (Rps), previously known as R. solanacearum phylotypes I and III is one of the causal agents of bacterial wilt, a devastating disease that afects more than 250 plant species. Emerging Rps strains were identifed infecting new hosts. P824 Rps strain was isolated from blueberry in Florida. Rps strains including PD7123 were...

This series of Key Plant, Key Pests publications is designed for Florida gardeners, horticulturalists, and landscape professionals to help identify common pests associated with common Florida flora. This new 4-page publication of the UF/IFAS Environmental Horticulture Department provides information and general management recommendations for leaf a...

Brown rot of potatoes caused by Ralstonia solanacearum is common in developing countries. Historically, brown rot losses in the United States have been restricted to southern states. This trend will most likely change with new Ralstonia introductions and temperature variability. A cold tolerant Ralstonia strain was used in this study to compare res...

Ralstonia solanacearum is the causal agent of bacterial wilt in numerous species of plants. Here, we report the whole-genome sequence of three phylogenetically diverse R. solanacearum strains, P816, P822, and P824, reported for the first time as causal agents of an emerging blueberry disease in Florida.

This series of Key Plant, Key Pests publications are designed for Florida gardeners, horticulturalists, and landscape professionals to help identify common pests associated with common Florida flora. This publication, the sixth in the Key Plant, Key Pests series, helps identify the most common pests found on the Azalea. This publication provides in...

English ivy has grown in popularity over the last few years as both an indoor and outdoor ornamental vining plant. While English ivy is very disease resistant, there are a few major diseases that will cause economic loss in production and landscape plantings. This 6-page document will assist residential or commercial property owners in identifying...

Pothos is a tropical ornamental vine that has been grown commercially in the US for almost 100 years and is used for a variety of aesthetic purposes. This 5-page publication addresses identification and treatment of common diseases encountered during greenhouse production of pothos. Written by David J. Norman and G. Shad Ali and published by the UF...

Biological control is an eco-friendly strategy for mitigating and controlling plant diseases with negligible effects on human health and environment. Biocontrol agents are mostly isolated from field crops, and microbiomes associated with wild native plants is underexplored. The main objective of this study was to characterize the bacterial isolates...

Background Most current methods for constructing guide RNAs (gRNA) for the CRISPR/Cas9 genome editing system, depend on traditional cloning using specific type IIS restriction enzymes and DNA ligation. These methods consist of multiple steps of cloning, and are time consuming, resource intensive and not flexible. These issues are particularly exace...

Strains of the Ralstonia solanacearum species complex in the phylotype IIB group are capable of causing Bacterial Wilt disease in potato and tomato at temperatures lower than 24°C. The capability of these strains to survive and to incite infection at temperatures colder than their normally tropical boundaries represents a threat to United States ag...

A strain of Ralstonia solanacearum was associated with wilting and blight of flowering ornamentals grown from cuttings that originated in Guatemala. This isolate, UW757, could wilt geranium, Osteospermum spp., and mandevilla, but was more aggressively virulent on tomato. Although it rarely caused symptoms, after inoculation UW757 colonized the stem...

Bacterial biological control agents (BCA) are largely used as live products to control plant pathogens. However, due to variable environmental and ecological factors, live BCA usually fail to produce desirable results against foliar pathogens. In this study, we investigated the potential of cell-free culture filtrates of 12 different bacterial BCA...

This report investigates population structure and genetic variability of Phytophthora spp. isolated from botanically diverse plants in Florida. Internal transcribed spacer-based molecular phylogenetic analyses indicate that Phytophthora isolates recovered from ornamental plants in Florida represent a genetically diverse population and that a majori...

Plant growth-promoting rhizobacteria (PGPRs) release soluble and volatile compounds, which are implicated in antibiosis, cell signalling, induction of resistance and tolerance in plants against biotic and abiotic stresses. Due to public concerns about the potential environmental hazards of chemical use in agriculture, exploration of PGPRs for alter...

Xanthomonas axonopodis pv. poinsettiicola is traditionally identified as the primary causal agent of bacterial leaf spot on poinsettia (family Euphorbiaceae). Sixty-seven strains of xanthomonads isolated from lesions associated with several species within the family Euphorbiaceae were collected over a 64-year period. The pathogenicity of these stra...

Application of nanoparticles for controlling plant pathogens is a rapidly emerging area in plant disease management, and nanoparticles synthesis methods that are economical and eco-friendly are extensively investigated. In this project, we investigated the potential of silver nanoparticles (AgNPs) synthesized with aqueous extract of Artemisia absin...

Ralstonia solanacearum is the causal agent of bacterial wilt of solanaceous plants. In the USA the disease is of economic importance in potato, tomato and tobacco crops. Strains of the Race 3 Biovar 2 (R3B2) can infect tomato and potato at low temperatures and are not established in North America, thus posing a threat to its agriculture. In previou...

Ralstonia solanacearum, the causal agent of bacterial wilt, is a genetically diverse bacterial plant pathogen present in tropical and subtropical regions of the world that infects more than 200 plant species, including economically important solanaceous crops. Most strains of R. solanacearum are only pathogenic at temperatures between 25 to 30[degr...

Ralstonia solanacearum is the causal agent of bacterial wilt, one of the most destructive bacterial plant diseases. We present the whole-genome sequence of the strain P673 (phylotype IIB, sequevar 4). This strain is capable of producing disease in tomato plants at low temperatures. P673 has 311 unique genes.

Ralstonia solanacearum is the causal agent of bacterial wilt, one of the most destructive bacterial plant diseases. We present the whole-genome sequence of the strain P673 (phylotype IIB, sequevar 4). This strain is capable of producing disease in tomato plants at low temperatures. P673 has 311 unique genes.

A bacterial spot of rose (Rosa spp.) caused by a xanthomonad was observed in Florida and Texas. Ten representative strains collected from the two states between 2004 and 2010 were used to determine the taxonomic position of this rose pathogen. Fatty acid methyl ester analysis was performed and a nearly 2-kb 16S-23S rRNA intergenic spacer along with...

While edible figs are grown agronomically for delicious fruit, many Ficus species have been commercialized for decorative, ornamental purposes. These horticultural Ficus varieties are used for interiorscape houseplant décor and for outdoor landscape design. This article provides guidelines for the identification and treatment of diseases that may b...

The genus Duranta is in the Verbenaceae family and contains a number of cultivated shrubs and small trees and is native to Mexico, Florida in the USA and parts of South America. Duranta erecta (common names: Golden dewdrop, Gold mound, Pigeon berry and Skyflower) is used extensively in southern states of the US as ornamental shrub and has replaced...

A comprehensive analysis of 175 Xanthomonas axonopodis pv. dieffenbachiae strains isolated from ten Araceae hosts was done to identify pathogen variation. The strains were subjected to repetitive extragenic palindromic sequence polymerase chain reaction (Rep-PCR) and four major phylogenetic clusters were generated. A subset of forty strains isolate...

This is the first comprehensive study of a collection of Ralstonia solanacearum strains from the southeastern United States to be characterized based on biovar, pathogenicity, hypersensitive reaction on tobacco, and phylogenetic analyses of the egl sequence. Rigorous phylogenetic analysis of the commonly used egl gene produced robust phylogenies th...

Because of its attractive, long-lasting flowers, Anthurium is popular as both an exotic cut-flower crop and as a flowering potted-plant crop. Growers most often report two bacterial diseases and three fungal diseases in their commercial greenhouse environments. This article provides guidelines to identify and treat diseases that may be encountered...

AdditionAl index words. cut foliage, fern anthracnose, leatherleaf fern Fern anthracnose, Colletotrichum acutatum, is a highly contagious disease in commercial ferneries causing the immature fronds of leatherleaf fern to become unmarketable for floral use. This research identifies sources that could disseminate primary inoculum, examines pathways o...

A novel hypersensitive resistance (HR) in Capsicum baccatum var. pendulum against the bacterial spot of pepper pathogen, Xanthomonas gardneri, was introgressed into C. annuum cv. Early Calwonder (ECW) to create the near-isogenic line designated as ECW-70R. A corresponding avirulence gene avrBs7, in X. gardneri elicited a strong HR in ECW-70R. A hom...

R. solanacearum strain UW551, classified as R3B2 can infect tomato and potato plants at low temperatures. R3B2 are not known to be established in the US, however, in our study we identified several R3B2 entering North America in geranium plants. We selected several strains frequently entering the United States and some considered endemic to study t...

Xanthomonas strains causing bacterial spot on tomato have been classified into four different species. We have sequenced type strains belonging to B, C and D groups and compared the draft genomes against a previously sequenced X. euvesicatoria (Xcv85-10) strain and other available genomes of xanthomonads. We are analyzing pathogenicity clusters inc...

Endospore forming bacteria were collected from root samples of 35 genera of bedding plants growing in established commercial landscape beds in Central Florida. One hundred twenty-nine bacterial strains associated with 14 species were identified using fatty acid analysis (Microbial Identification System, MIDI). All strains were evaluated for in vitr...

Ralstonia solanacearum causes bacterial wilt on a wide range of plant hosts. Most strains of R. solanacearum are nonpathogenic below 20°C; however, Race 3 Biovar 2 (R3B2) strains are classified as quarantine pathogens because of their ability to infect crops, cause disease, and survive in temperate climates. We have identified race 1 biovar 1 Phylo...

Additional index words. bactericide, Euphorbia pulcherrima, Pelargonium Abstract. This study is the first report of using titanium dioxide (TiO 2) to control Xanthomonas bacterial blight on geranium and leaf spot on poinsettia. Potted zonal geranium 'Patriot Bright Violet' and poinsettia 'Snowcap' were grown in a greenhouse and treated with a folia...

Figure S2: 1a) Phylogenetic tree based on MUMi indices; 1b) Distance matrix based on MUMi indices. MUMi program was used to calculate pairwise distances between draft genomes and reference Xanthomonas genomes.

Figure S4: AvrBs2-based HR assay confirms translocation of novel effectors. Hypersensitive response reaction indicating presence of translocation signal was recorded 24 hrs after inoculation on pepper cv. ECW20R with candidate effectors xopZ2 (a), avrBs1 (b), xopG (d), xopAM (e), xopAO (f) conjugated in race 6 strain along with control race 6 stra...

Table S5: Evidence of the horizontal gene transfer using Alien_hunter analysis.

Table S7: Domain architecture and distribution of proteins with HD-GYP, GGDEF and/or EAL domains encoded by genomes of different Xanthomonas strains.

Table S10: Genes unique to Xg. Genes of special interest are highlighted in red and yellow.

Table S1: General features of the sequencing data and of the de novo assemblies of draft genomes of Xv, Xp and Xg using individual sequencing methods.

Table S9: Genes common to all pepper pathogens but absent from Xp.

Table S3: Whole genome comparisons using MUMmer dnadiff program. % coverage of the aligned contigs and % identities of the respective contigs against reference genomes has been shown for each draft genome.

Table S6: Genes/contigs representing T6SS in draft genomes as compared to Xcv.

Table S8: Genes unique to Xp, grouped in clusters.

Bacterial spot of tomato and pepper is caused by four Xanthomonas species and is a major plant disease in warm humid climates. The four species are distinct from each other based on physiological and molecular characteristics. The genome sequence of strain 85-10, a member of one of the species, Xanthomonas euvesicatoria (Xcv) has been previously re...

This study is the first report of using titanium dioxide (TiO2) to control Xanthomonas bacterial blight on geranium and leaf spot on poinsettia. Potted zonal geranium 'Patriot Bright Violet' and poinsettia 'Snowcap' were grown in a greenhouse and treated with a foliar spray of TiO2 at 25 and 75 mM, respectively, twice. Titanium-treated and control...

Introduction Production Conditions and Environments Foliage Plant Propagation Foliage Plant Production Postproduction The Future Literature Cited

Figure S5: PCR results for gene xacPNP.

Figure S7: topology of clade in Fig. 3 with bootstrap values.

Figure S1: whole chromosome alignments of XauB and XauC scaffolds against XAC.

Table S6: names, organisms, locus tags, and accession numbers for the nucleotide sequences used to build the pth gene phylogeny ( Fig. 3 ).

Table S2: genes shared by XAC, XauB, and XauC but that are not found in other fully sequenced Xanthomonas and Xylella genomes.

Table S3: List of XAC-specific regions.

Figure S4: gene diagrams showing the contents of all 25 XAC-specific regions.

Citrus canker is a disease that has severe economic impact on the citrus industry worldwide. There are three types of canker, called A, B, and C. The three types have different phenotypes and affect different citrus species. The causative agent for type A is Xanthomonas citri subsp. citri, whose genome sequence was made available in 2002. Xanthomon...

Ralstonia solanacearum was isolated from diseased pothos (Epipremnum aureum) cuttings imported to Florida from Costa Pica. Epipremnum aureum has not previously been described as a host of R. solanacearum. Bacterial isolates were identified by standard bacteriological tests, FAME analysis (MIDI (R)), metabolic profile (Biolog (R)), and by PCP using...

Each year, large volumes of ornamental and food plant propagative stock are imported into the North America; occasionally, Ralstonia solanacearum is found systemically infecting this plant material. In this study, 107 new R. solanacearum strains were collected over a 10-year period from imported propagative stock and compared with 32 previously cha...

Sixty-one cultivars of geraniums, including zonal, regal, ivy, and scented, were tested for susceptibility to three strains of Ralstonia solanacearum: a race 1, biovar 1 (R1B1) strain P597 isolated from tomato in Florida, a R1B1 strain P673 obtained from pothos originated from Costa Rica, and a race 3, biovar 2 (R3B2) strain UW551 isolated from ger...