Insight Into the Microbial Co-occurrence and Diversity of 73 Grapevine () Crown Galls Collected Across the Northern Hemisphere.

Crown gall (CG) is a globally distributed and economically important disease of grapevine and other important crop plants. The causal agent of CG is or strains that harbor a tumor-inducing plasmid (pTi). The microbial community within the CG tumor has not been widely elucidated and it is not known if certain members of this microbial community promote or inhibit CG.

The Ecology of Agrobacterium vitis and Management of Crown Gall Disease in Vineyards.

Agrobacterium vitis is the primary causal agent of grapevine crown gall worldwide. Symptoms of grapevine crown gall disease include tumor formation on the aerial plant parts, whereas both tumorigenic and nontumorigenic strains of A. vitis cause root necrosis.

Grape Cultivar and Sap Culture Conditions Affect the Development of Xylella fastidiosa Phenotypes Associated with Pierce's Disease.

Xylella fastidiosa is a xylem-limited bacterium in plant hosts and causes Pierce's disease (PD) of grapevines, which differ in susceptibility according to the Vitis species (spp.). In this work we compared X.

Characterization of the Xylella fastidiosa PD1311 gene mutant and its suppression of Pierce's disease on grapevines.

Xylella fastidiosa causes Pierce's disease (PD) on grapevines, leading to significant economic losses in grape and wine production. To further our understanding of X. fastidiosa virulence on grapevines, we examined the PD1311 gene, which encodes a putative acyl-coenzyme A (acyl-CoA) synthetase, and is highly conserved across Xylella species.

Distribution of Agrobacterium vitis in Grapevines and Its Relevance to Pathogen Elimination.

Agrobacterium vitis, the cause of crown gall disease on grapevine, survives internally in vines and can be spread in cuttings for propagation. The possibility of generating pathogen-free vines through tissue culture makes it essential to understand the distribution of the pathogen in grapevines. A highly sensitive magnetic capture hybridization procedure along with real-time polymerase chain reaction were used to measure the distribution of tumorigenic A.

Inhibition of Grape Crown Gall by Agrobacterium vitis F2/5 Requires Two Nonribosomal Peptide Synthetases and One Polyketide Synthase.

Agrobacterium vitis nontumorigenic strain F2/5 is able to inhibit crown gall disease on grapevines. The mechanism of grape tumor inhibition (GTI) by F2/5 has not been fully determined. In this study, we demonstrate that two nonribosomal peptide synthetase (NRPS) genes (F-avi3342 and F-avi5730) and one polyketide synthase gene (F-avi4330) are required for GTI.

Potential complications when developing gene deletion clones in Xylella fastidiosa.

Background: The Gram-negative xylem-limited bacterium, Xylella fastidiosa, is an important plant pathogen that infects a number of high value crops. The Temecula 1 strain infects grapevines and induces Pierce's disease, which causes symptoms such as scorching on leaves, cluster collapse, and eventual plant death. In order to understand the pathogenesis of X.

Characterization of the Xylella fastidiosa PD1671 gene encoding degenerate c-di-GMP GGDEF/EAL domains, and its role in the development of Pierce's disease.

Xylella fastidiosa is an important phytopathogenic bacterium that causes many serious plant diseases including Pierce's disease of grapevines. X. fastidiosa is thought to induce disease by colonizing and clogging xylem vessels through the formation of cell aggregates and bacterial biofilms.

An Sfp-type PPTase and associated polyketide and nonribosomal peptide synthases in Agrobacterium vitis are essential for induction of tobacco hypersensitive response and grape necrosis.

An Sfp-type phosphopantetheinyl transferase (PPTase) encoding gene F-avi5813 in Agrobacterium vitis F2/5 was found to be required for the induction of a tobacco hypersensitive response (HR) and grape necrosis. Sfp-type PPTases are post-translation modification enzymes that activate acyl-carry protein (ACP) domains in polyketide synthases (PKS) and peptidyl-carrier protein (PCP) domains of nonribosomal peptide synthases (NRPS). Mutagenesis of PKS and NRPS genes in A.

A host-specific biological control of grape crown gall by Agrobacterium vitis strain F2/5: its regulation and population dynamics.

Nontumorigenic Agrobacterium vitis strain F2/5 is able to prevent crown gall caused by tumorigenic A. vitis on grape but not on other plant species such as tobacco. Mutations in a quorum-sensing transcription factor, aviR, and in caseinolytic protease (clp) component genes clpA and clpP1 resulted in reduced or loss of biological control.

LhnR and upstream operon LhnABC in Agrobacterium vitis regulate the induction of tobacco hypersensitive responses, grape necrosis and swarming motility.

The characterization of Tn5 transposon insertional mutants of Agrobacterium vitis strain F2/5 revealed a gene encoding a predicted LysR-type transcriptional regulator, lhnR (for 'LysR-type regulator associated with HR and necrosis'), and an immediate upstream operon consisting of three open reading frames (lhnABC) required for swarming motility, surfactant production and the induction of a hypersensitive response (HR) on tobacco and necrosis on grape. The operon lhnABC is unique to A. vitis among the sequenced members in Rhizobiaceae.

Identification of an operon, Pil-Chp, that controls twitching motility and virulence in Xylella fastidiosa.

Xylella fastidiosa is an important phytopathogenic bacterium that causes many serious plant diseases, including Pierce's disease of grapevines. Disease manifestation by X. fastidiosa is associated with the expression of several factors, including the type IV pili that are required for twitching motility.

LasR receptor for detection of long-chain quorum-sensing signals: identification of N-acyl-homoserine lactones encoded by the avsI locus of Agrobacterium vitis.

Bacterial biosensor strains have greatly facilitated the rapid discovery, isolation, and study of quorum-sensing systems. In this study, we determined the relative sensitivity of a LasR-based E. coli bacterial bioluminescence biosensor JM109 (pSB1075) for 13 diverse long-chain N-acyl-homoserine lactones (AHLs) including oxygen-substituted and -unsubstituted AHLs containing 14, 16, and 18 carbons and with and without double bonds.

Resistance to crown gall disease in transgenic grapevine rootstocks containing truncated virE2 of Agrobacterium.

A truncated form of the Ti-plasmid virE2 gene from Agrobacterium tumefaciens strains C58 and A6, and A. vitis strain CG450 was transferred and expressed in somatic embryos of grapevine rootstocks 110 Richter (Vitis rupestris × V. berlandieri), 3309 Couderc (V.

Twitching motility and biofilm formation are associated with tonB1 in Xylella fastidiosa.

A mutation in the Xylella fastidiosa tonB1 gene resulted in loss of twitching motility and in significantly less biofilm formation as compared with a wild type. The altered motility and biofilm phenotypes were restored by complementation with a functional copy of the gene. The mutation affected virulence as measured by Pierce's disease symptoms on grapevines.

Grapevine xylem sap enhances biofilm development by Xylella fastidiosa.

Xylella fastidiosa is able to form biofilms within xylem vessels of many economically important crops. Vessel blockage is believed to be a major contributor to disease development caused by this bacterium. This report shows that Vitis riparia xylem sap increases growth rate and induces a characteristic biofilm architecture as compared with biofilms formed in PD2 and PW media.

Quorum-sensing signal production by Agrobacterium vitis strains and their tumor-inducing and tartrate-catabolic plasmids.

Agrobacterium vitis strains, their tumor-inducing (pTi) and tartrate utilization (pTr) plasmid transconjugants and grapevine tumors were analyzed for the presence of N-acyl-homoserine lactones (AHLs). All wild-type A. vitis strains produced long-chain signals.

Genome sequences of three agrobacterium biovars help elucidate the evolution of multichromosome genomes in bacteria.

The family Rhizobiaceae contains plant-associated bacteria with critical roles in ecology and agriculture. Within this family, many Rhizobium and Sinorhizobium strains are nitrogen-fixing plant mutualists, while many strains designated as Agrobacterium are plant pathogens. These contrasting lifestyles are primarily dependent on the transmissible plasmids each strain harbors.

A gene cluster in Agrobacterium vitis homologous to polyketide synthase operons is associated with grape necrosis and hypersensitive response induction on tobacco.

Here, we identify a cluster of eight genes on chromosome 2 of Agrobacterium vitis that is associated with the ability of the bacterium to cause a hypersensitive response on tobacco and a necrosis of grape shoot explants. Three of these genes share a high level of structural and sequence similarity to clusters of genes in other bacteria that encode the enzymes for biosynthesis of polyketides and long-chain polyunsaturated fatty acids. No similar gene clusters were discovered in sequenced genomes of other members of Rhizobiales.

Autoaggregation of Xylella fastidiosa cells is influenced by type I and type IV pili.

Autoaggregation of widely dispersed Xylella fastidiosa cells into compact cell masses occurred over a period of hours following 7 to 11 days of growth in microfluidic chambers. Studies involving the use of mutants defective in polarly positioned type I (fimA-negative), type IV (pilB-negative), or both type I and IV (fimA- and pilO-negative) pili revealed the importance and role of pili in the autoaggregation process.

Isolation of Streptomycin-Resistant Isolates of Erwinia amylovora in New York.

Streptomycin is currently the only antibiotic registered for the control of fire blight, a devastating disease of apple (Malus), pear (Pyrus), and other rosaceous plants caused by the bacterium Erwinia amylovora. Resistance of E. amylovora to streptomycin was first identified in California pear orchards in 1971 and is currently endemic in many parts of the United States.

Mutations in type I and type IV pilus biosynthetic genes affect twitching motility rates in Xylella fastidiosa.

Xylella fastidiosa possesses both type I and type IV pili at the same cell pole. By use of a microfluidic device, the speed of twitching movement by wild-type cells on a glass surface against the flow direction of media was measured as 0.86 (standard error [SE], 0.

Twitching motility among pathogenic Xylella fastidiosa isolates and the influence of bovine serum albumin on twitching-dependent colony fringe morphology.

Fourteen Xylella fastidiosa isolates from grapevines exhibiting Pierce's disease symptoms in California, Texas, and South Carolina were examined for type IV pilus-mediated twitching motility, a phenotype previously observed in a Temecula isolate from California. All isolates except one from South Carolina (SC 19A97) exhibited colonies with a peripheral fringe on PW agar, a feature indicative of twitching motility; however, when individual cells of SC 19A97 were examined at higher magnifications twitching motility was observed. The presence and width of colony peripheral fringes were related to the amount of bovine serum albumin (BSA) present in the medium; no or low levels of BSA (0-1.

Type I and type IV pili of Xylella fastidiosa affect twitching motility, biofilm formation and cell-cell aggregation.

Xylella fastidiosa, an important phytopathogenic bacterium, causes serious plant diseases including Pierce's disease of grapevine. It is reported here that type I and type IV pili of X. fastidiosa play different roles in twitching motility, biofilm formation and cell-cell aggregation.