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Nonpathogenic strain ARK-1 of Rhizobium vitis has antagonistic activity against a tumorigenic (Ti) strain of R. vitis and works as a biocontrol agent, but the temporal dynamics of the bacterial colonization in plants needs to be understood. Here we showed that the incidence of galls induced by Ti strain was reduced to about 60% when both upper and lower positions on the grapevine stem were inoculated with ARK-1 3 cm from the site that was inoculated with Ti 5 days later. A bacterial cell detection assay in the grapevine tissue revealed that ARK-1 moved at least 3 cm in 5 days. [ABSTRACT FROM AUTHOR]

Rhizobium vitis: strain VAR03-1 is a biological control agent that suppresses grapevine crown gall disease caused by a tumorigenic strain of R. vitis (Ti). Both acetosyringone-induced expression of a virulence gene and the growth of Ti were suppressed in vitro when it was cultivated in the VAR03-1 culture filtrate. These inhibitory effects were reduced by high-temperature treatment or incubation for 72 h. Both activities were detected in the high molecular weight fraction (> 100 kDa) of the filtrate. Our results suggest that the antagonistic effects of VAR03-1 on Ti are mediated by large particle(s) released in the culture media. [ABSTRACT FROM AUTHOR]

Mildew resistance locus o (Mlo) is a specific seven-transmembrane gene family that confers resistance against several abiotic and biotic stresses in plants. In this study, we identified nine Mlo-like loci, VfMlo- like3243 ( Vitis flexuosa powdery- mildew resistance locus o-like3243), VfMlo- like4098, VfMlo- like5057, VfMlo- like6833, VfMlo- like7881, VfMlo- like8120, VfMlo- like14439, VfMlo- like14557, and VfMlo- like18484, which showed differential expression upon transcriptome analysis conducted using next generation sequencing (NGS) of V. flexuosa infected with Elsinoe ampelina. These genes are 1773-2548 bp long and encode deduced full-length proteins of 482-587 amino acids. The predicted amino acid sequences of all genes show typical Mlo domains containing seven highly conserved transmembrane domains, a calmodulin-binding domain and 30 important amino acid residues for Mlo function. While 3 VfMlo-like genes were downregulated, 5 VfMlo-like genes were up-regulated in grapevines infected with Erysiphe necator, among which four ( VfMlo- like6833, VfMlo- like8120, VfMlo- like14439 and VfMlo- like18484) are orthologous to the AtMlo2, AtMlo6 and AtMlo12 genes involved in powdery mildew susceptibility. All genes except VfMlo- like17881 showed upregulated expression at 48 hpi after infection of Rhizobium vitis. The results revealed that the tested genes are related in responses to pathogens of grapevines and can be utilized as useful resources for investigating their roles in disease resistant responses in grapevines. [ABSTRACT FROM AUTHOR]

Crown gall-affected grapevine samples were collected during 2009-2010 from major vineyards, located in different Turkish provinces. One hundred and three bacterial strains were obtained from 88 vineyards and 18 grapevine varieties; they were tumorigenic when inoculated in tobacco, sunflower and Datura stramonium plants and were identified as liliizobium vitis using biochemical and physiological tests as well as PCR and specific primers. Nineteen R. vitis strains presented a number of anomalous biochemical and physiological characters. PCR and opine-specific primers revealed the presence of octopine/cucumopine-type plasmid in 82 R. vitis strains, nopaline-type plasmids in IS strains and vitopine-type plasmids in three strains. Clonal relationship of strains was determined using Pulsed Field Gel Electrophoresis following digestion of genomic DNA with the restriction endonuclease Pmel. The greatest genetic diversity was fouuid for the strains from Denizli, Ankara and Nevşehir provinces. Nopaline and vitopine-types of Rliizobium vitis were detected for the first time in Turkey. [ABSTRACT FROM AUTHOR]

Nucleotide binding site-leucine-rich repeat (NBS-LRR) genes are the largest gene resistance family in plants. Resistance to Pseudomonas syringae 5 (RPS5) is a member of the NBS-LRR family. RPS5 and its homologs are important disease resistance genes in plants including Arabidopsis. This study identified nine loci of RPS5-like genes in Vitis flexuosa that showed differential expression from transcriptome analysis by next generation sequencing (NGS) of V. flexuosa infected with Elsinoe ampelina based on structural analyses: VfRPS5-like1059 (Vitis flexuosa resistance to Pseudomonas syringae 5-like 1059), VfRPS5-like1833, VfRPS5-like4135, VfRPS5-like4833, VfRPS5-like6172, VfRPS5-like13564, VfRPS5-like20585, VfRPS5-like55532, and VfRPS5-like62178. These genes, 2236-4762 bp in length, exhibited the structure of a coiled coil-nucleotide binding site-leucine-rich repeat (CC-NBS-LRR) resistance gene. The predicted amino acid sequences of all nine genes contained typical NBS domains. Chromosomal localization revealed that the nine genes were located in six chromosomes of the V. flexuosa pseudo-genome. Of the nine loci, only VfRPS5-like55532 showed upregulated expression against all tested pathogens at all tested time points, except 24 h postinoculation (hpi) for E. ampelina. All tested genes also showed differential expression against major grapevine fungal and bacterial pathogens. The results presented herein will also serve as a useful reference dataset for functional analysis and utilization in molecular breeding of resistant grapevines. [ABSTRACT FROM AUTHOR]

Forty-one strains of Rhizobium vitis, either tumorigenic (Ti) or nonpathogenic, were characterized using multilocus sequence analysis (MLSA) of the partial nucleotide sequences of pyrG, recA, and rpoD. The strains separated into seven clades. Rhizobium vitis (Ti) strains isolated from Japan were divided into five genetic groups (A to E), and nonpathogenic R. vitis strains were divided into two genetic groups (F and G). This result suggests that there are new genetic groups of R. vitis in Japan. Among these groups, members of A and B groups are widely distributed throughout Japan. [ABSTRACT FROM AUTHOR]

Crown gall is a globally distributed and economically important disease of grapevine and other important crop plants. The causal agent of grapevine crown gall is tumorigenic Allorhizobium vitis (Ti) strains that harbor a tumor-inducing plasmid (pTi). The epidemic of grapevine crown gall has not been widely elucidated. In this study, we investigated the genetic diversity of 89 strains of Ti and nonpathogenic A. vitis to clarify their molecular epidemiology. Multi-locus sequence analysis (MLSA) of the partial nucleotide sequences of pyrG, recA, and rpoD was performed for molecular typing of A. vitis strains isolated from grapevines with crown gall symptoms grown in 30 different vineyards, five different countries, mainly in Japan, and seven genomic groups A to F were obtained. The results of MLSA and logistic regression indicated that the population of genetic group A was significantly related to a range of prefectures and that the epidemic of group A strains originated mainly in Hokkaido in Japan through soil infection. Moreover, group E strains could have been transported by infected nursery stocks. In conclusion, this study indicates that both soil infection and transporting of infected nursery stocks are working as infection source in Hokkaido. [ABSTRACT FROM AUTHOR]

Objective: To gain insights into the virulence suppressive mechanism of a nonpathogenic strain of Rhizobium vitis ARK-1, we co-inoculated ARK-1 with a tumorigenic (Ti) strain of R. vitis to examine the expression of two essential virulence genes (virA and virG) and one non-essential gene (virD3) of the Ti strain at the wound site of grapevine. Results: Co-inoculation of ARK-1 with a Ti strain VAT03-9 at a 1:1 cell ratio into grapevine shoots resulted in significantly lower expression of the virulence genes virA, virD3, and virG of VAT03-9 at 1 day after inoculation compared with those when shoots were inoculated only with VAT03-9. ARK-1 was not able to catabolize acetosyringone, which is the plant-derived metabolites inducing the entire vir regulon in Ti strains, suggesting the direct effect of ARK-1 on the induction of broad range of vir genes of R. vitis Ti strains. [ABSTRACT FROM AUTHOR]