Search results for "phytoplasma"

A Review of the Most Common and Economically Important Diseases That Undermine the Cultivation of Tomato Crop in the Mediterranean Basin

2021

Tomato (Solanum lycopersicum L.), family Solanaceae, has become in the past fifty years one of the most important and extensively grown horticultural crops in the Mediterranean region and throughout the world. In 2019, more than 180 million tonnes of tomato have been produced worldwide, out of which around 42 million tonnes in Mediterranean countries. Due to its genetic properties, tomato is afflicted by numerous plant diseases induced by fungal, bacterial, phytoplasma, virus, and viroid pathogens. Not only is its genetic inheritance of great importance to the management of the numerous tomato pathogens, but equally as important are also the present climate changes, the recently revised phy…

Epidemiological investigations and molecular characterization of ‘candidatus phytoplasma solani’ in grapevines, weeds, vectors and putative vectors i…

2020

Bois noir is caused by &lsquo

Phylogenetic relationships among Flavescence doree strains and related phytoplasmas determined by heteroduplex mobility assay and sequence of ribosom…

2003

Heteroduplex mobility assay (HMA) and DNA sequencing were performed on Flavescence doree (FD) phytoplasma strains and related phytoplasmas belonging to the elm yellows group. Part of the ribosomal RNA gene operon and a nonribosomal DNA region were utilized for phylogenetic analyses. Two FD strains, FD92 and FD-D, detected in France and Italy, respectively, were identical in both DNA fragments, confirming previous results. Other FD strains were all very similar and most closely resembled ALY, an Italian alder phytoplasma. Phytoplasmas associated with German Palatinate grapevine yellows were shown to form a distinct subcluster, also different from the elm yellows phytoplasma subcluster. Strai…

Grapevine infectious diseases in Sicily

2008

INVESTIGATIONS ON ‘CANDIDATUS PHYTOPLASMA SOLANI’ IN WESTERN SICILY, SOUTHERN ITALY

2016

‘Candidatus Phytoplasma solani’, belonging to the 16SrXII-A subgroup, is associated with grapevine Bois Noir (BN). It is usually transmitted by Hyalesthes obsoletus from a wide range of weeds to grapevine, which is considered a dead-end host. Moreover, other alternative vectors can play a role in the epidemiology of the disease. In Sicily, the presence of BN was reported in 1996, both on typical and on newly introduced cultivars. Furthermore, high BN incidence was observed on native grape cultivars grown close to ‘Chardonnay’ vineyards. In summer 2014 and 2015, the spread and the severity of BN were recorded in a 10 year-old vineyard located in San Giuseppe Jato (PA, Western Sicily), grown …

Sympatric diversification vs. immigration: deciphering host-plant specialization in a polyphagous insect, the stolbur phytoplasma vector Hyalesthes o…

2012

The epidemiology of vector transmitted plant diseases is highly influenced by dispersal and the host-plant range of the vector. Widening the vector's host range may increase transmission potential, whereas specialization may induce specific disease cycles. The process leading to a vector's host shift and its epidemiological outcome is therefore embedded in the frameworks of sympatric evolution vs. immigration of preadapted populations. In this study, we analyse whether a host shift of the stolbur phytoplasma vector, Hyalesthes obsoletus from field bindweed to stinging nettle in its northern distribution range evolved sympatrically or by immigration. The exploitation of stinging nettle has l…

Virescence of tenweeks stock associated to phytoplasma infection in Sicily

2007

In April 2007, a severe disease occurred in Sicily (Italy) in a glasshouse cultivation of tenweeks stock belonging to the cultivar White-Beach. Plants were stunted and rosetted, and the flowers were of small size and characterized by virescence symptoms. Phytoplasma presence and identity was detected by applying PCR/RFLP techniques and sequencing of 16S ribosomal gene. Phytoplasmas were identified as belonging to ribosomal subgroup 16SrII-A, never reported before in Italy and showed 99% of homology with ‘Candidatus Phytoplasma aurantifolia’ and related phytoplasmas. This is the first report of a phytoplasma disease of tenweeks stock. Considering that this Brassicaceae ornamental species is …

INFLUENCE OF CITRATE NANOPARTICLES ON PHOTOCHEMICAL ACTIVITY, RESISTANCE TO PATHOGENS AND PRODUCTIVITY OF WHEAT

2021

In field experiments, increase the quantum efficiency of PSII (Fv/Fp), the Rfd-values (the chlorophyll fluorescence vitality indices) and the content of photosynthetic pigments in wheat leaves at pretreatment of wheat seeds with solutions of citrate nanoparticles has been shown. The green weight of plants at bacterial and phytoplasmas infecting at pretreatment with solutions of citrate nanoparticles, was increase, than without pre-treatment, in order: GeNPs>I-Se>SeNPs>VNPs as it has been shown. The Fv/Fp-values in leaves infected with phytoplasmas of plants at pretreatment of VNPs or I-Se solutions were more, than without pretreatment. The Fv/Fp-value in leafs with bacterial infecting at pr…

The syndrome "basses richesses" of sugar beet in France is associated with different pathogen types and insect vectors

2007

International audience; The syndrome “basses richesses” (SBR) of sugar beet in France is associated with two phloem-restricted uncultivable bacteria: a stolbur phytoplasma and a y-3 proteobacteria. The known vector of proteobacteria is a cixiid planthopper, Pentastiridius leporinus (Hemiptera Cixiidae), formerly shown to transmit both the prokaryotes. The role of P. leporinus and of two other planthopper species, Cixius wagneri and Hyalesthes obsoletus, in spreading the two pathogens to sugar beet were compared and quantified. Because of its abundance and high infection rates with proteobacterium, P. leporinus was confirmed to be the economic vector of SBR disease. P. leporinus and C. wagne…

Association with the Syndrome "Basses Richesses" of Sugar Beet of a Phytoplasma and a Bacterium-Like Organism Transmitted by a Pentastiridius sp.

2002

The syndrome “basses richesses” of sugar beet (SBR) was first observed in 1991 in Burgundy, France. A cixiid planthopper, Pentastiridius beieri, has been proved to be involved in the transmission to sugar beet of a stolbur phytoplasma, which could be detected in some affected plants. In 2000, periwinkle and sugar beet exposed to field-collected cixiids developed symptoms similar to SBR on sugar beet. Use of 4′-6-diamidino-2-phenylindole (DAPI) staining and transmission electron microscopy confirmed the presence of phytoplasma in some of the plants, which were also positive for this pathogen in a polymerase chain reaction (PCR) analysis. A phloem-restricted gram-negative bacteria was seen i…