"Candidatus Phlomobacter fragariae" Is the Prevalent Agent of Marginal Chlorosis of Strawberry in French Production Fields and Is Transmitted by the Planthopper Cixius wagneri (China).

ABSTRACT Marginal chlorosis has affected strawberry production in France for about 15 years. A phloem-restricted uncultured bacterium, "Candidatus Phlomobacter fragariae," is associated with the disease. A large-scale survey for marginal chlorosis in French strawberry production fields and nurseries by polymerase chain reaction amplification of "Ca.

Spiralin is not essential for helicity, motility, or pathogenicity but is required for efficient transmission of Spiroplasma citri by its leafhopper vector Circulifer haematoceps.

Spiralin is the most abundant protein at the surface of the plant pathogenic mollicute Spiroplasma citri and hence might play a role in the interactions of the spiroplasma with its host plant and/or its insect vector. To study spiralin function, mutants were produced by inactivating the spiralin gene through homologous recombination. A spiralin-green fluorescent protein (GFP) translational fusion was engineered and introduced into S.

Glucose and trehalose PTS permeases of Spiroplasma citri probably share a single IIA domain, enabling the spiroplasma to adapt quickly to carbohydrate changes in its environment.

Spiroplasma citri is a plant-pathogenic mollicute phylogenetically related to Gram-positive bacteria. Spiroplasma cells are restricted to the phloem sieve tubes and are transmitted from plant to plant by the leafhopper vector Circulifer haematoceps. In the plant sieve tubes, S.

'Candidatus phytoplasma phoenicium' sp. nov., a novel phytoplasma associated with an emerging lethal disease of almond trees in Lebanon and Iran.

Almonds (Prunus amygdalus) represent an important crop in most Mediterranean countries. A new and devastating disease of almond trees in Lebanon was recently reported, characterized by the development of severe witches'-brooms on which no flowers or fruits developed, and leading to tree death within a few years. A phytoplasma was detected in diseased trees by PCR amplification of rRNA operon sequences, and RFLP patterns of amplified DNA indicated that the phytoplasma belonged to the pigeon pea witches'-broom (PPWB) group.

Spiroplasma citri, a plant pathogenic molligute: relationships with its two hosts, the plant and the leafhopper vector.

Spiroplasma citri, the type species of the genus Spiroplasma (Spiroplasmataceae, Mollicutes), is restricted to the phloem sieve tubes and transmitted by phloem sap-feeding insects, as is characteristic of the phytopathogenic mollicutes. The spiroplasmas are the only mollicutes showing motility and helical morphology, apparently mediated by a contractile fibrillar cytoskeleton bound to the inner surface of the spiroplasmal membrane. MreB genes, which are involved in cell-shape determination, have been identified in S.

New plasmid vectors for specific gene targeting in Spiroplasma citri.

In Spiroplasma citri gene inactivation through homologous recombination has been achieved by using the replicative, oriC plasmid pBOT1 as the disruption vector. However, plasmid recombination required extensive passaging of the transformants and, in most cases, recombination occurred at oriC rather than at the target gene. In the current study, we describe a new vector, in which the oriC fragment was reduced to the minimal sequences able to promote plasmid replication.

Effect of polyclonal, monoclonal, and recombinant (single-chain variable fragment) antibodies on in vitro morphology, growth, and metabolism of the phytopathogenic mollicute Spiroplasma citri.

Antibodies are known to affect the morphology, growth, and metabolism of mollicutes and thus may serve as candidate molecules for a plantibody-based control strategy for plant-pathogenic spiroplasmas and phytoplasmas. Recombinant single-chain variable fragment (scFv) antibodies are easy to engineer and express in plants, but their inhibitory effects on mollicutes have never been evaluated and compared with those of polyclonal and monoclonal antibodies. We describe the morphology, growth, and glucose metabolism of Spiroplasma citri in the presence of polyclonal, monoclonal, and recombinant antibodies directed against the immunodominant membrane protein spiralin.

Fructose operon mutants of Spiroplasma citri.

Fructose-negative mutants of Spiroplasma citri wild-type strain GII-3 were selected by two methods. The first method is based on the selection of spontaneous xylitol-resistant mutants, xylitol being a toxic fructose analogue. Five such mutants were obtained, but only one, xyl3, was unable to use fructose and had no phosphoenolpuryvate:fructose phosphotransferase system (fructose-PTS) activity.