1,354,099 research outputs found
Multi-gene analysis for differentiation of aster yellows phytoplasmas infecting carrots in Serbia. Annals of Applied Biology, 154(2): 219-229.
No full textDuring a survey of large carrot fields in Serbia, plants showing leaf reddening
and/or yellowing, adventitious shoot production and reduction in taproot size
and quality were observed in a low percentage of plants. To verify phytoplasma
association with the described symptoms and to carry out pathogen differentiation,
PCR assays followed by restriction fragment length polymorphism (RFLP)
analyses and/or sequencing of phytoplasma 16Sr DNA and ribosomal protein
genes l22 and s3, tuf, putative aa kinase plus ribosomal recycling factor genes
and DNA helicase gene were carried out. Phytoplasmas belonging to 16SrI-A
and 16SrI-B ribosomal subgroups and to rpI-A and rpI-B ribosomal protein
subgroups, respectively, were identified by RFLP analyses in 13 of 15 symptomatic
plants tested. No amplification was obtained with non-symptomatic
carrot samples. The identification was confirmed by sequence analyses of the
phytoplasma genes studied. In two carrot samples, presence of interoperon
sequence heterogeneity was detected and phytoplasma strains were identified
as belonging to 16SrI group but were not assigned to any 16S rRNA or ribosomal
protein subgroup. This research allowed the first molecular identification
of phytoplasmas infecting carrot in Serbia using several molecular
markers, and it indicates that under field conditions in non-epidemic outbreaks
a certain amount of genetic mutation may occur in conserved genes of
these prokaryotes
Developing a method for phytoplasma identification in cactus pear samples from California.
No full textCactus pear plants showing proliferation and stunting of cladodes in Californian cultivations were tested in order to define a molecular
methodology for reliable phytoplasma detection. After several unsuccessful trials a simple extraction method was developed
to reduce the mucilage content in nucleic acid preparations that was seriously affecting pathogen detection. Nested PCR on
16S ribosomal gene and RFLP analyses together with sequencing of obtained amplicons allow to verify the presence in symptomatic
plants of 16SrV-A and 16SrI-B phytoplasmas respectively related to ‘Candidatus Phytoplasma ulmi’ and ‘Ca. P. asteris’
‘Candidatus Phytoplasma omanense’, a phytoplasma associated with witches’ broom of Cassia italica (Mill.) Lam. in Oman.
No full textSamples from plants of Cassia italica exhibiting typical witches’-broom symptoms (Cassia
witches’-broom; CWB) were examined for the presence of plant pathogenic phytoplasmas by
PCR amplification using universal phytoplasma primers. All affected plants yielded positive results.
RFLP analyses of rRNA gene products indicated that the phytoplasmas detected were different
from those described previously. Phylogenetic analysis of 16S rRNA gene sequences
confirmed that CWB represents a distinct lineage and shares a common ancestor with
‘Candidatus Phytoplasma phoenicium’. Molecular comparison revealed that the 16S rRNA gene
sequences of the four CWB strains (IM-1, IM-2, IM-3 and IM-4) identified in symptomatic C.
italica samples were nearly identical (99.6–100% similarity). The closest relatives were members
of the pigeon pea witches’-broom phytoplasma ribosomal group (16SrIX; 95–97% sequence
similarity). On the basis of unique 16S rRNA gene sequences and biological properties, the
phytoplasma associated with witches’-broom of C. italica in Oman represents a coherent but
discrete novel phytoplasma, ‘Candidatus Phytoplasma omanense’, with GenBank/DDBJ/EMBL
accession number EF666051 representing the reference strain
Molecular evidence of phytoplasmas in winter oilseed rape, tomato and corn seedlings.
No full textTo evaluate the seed transmission of phytoplasmas in three herbaceous hosts material from different geographical origin but all collected from infected or symptomatic mother plants was used. Almost 1,000 seeds were germinated under controlled conditions and 652 seedlings were obtained. Samples were grouped in 214 samples and 74 of them resulted positive to phytoplasma presence after three to 90 days from germination by nested PCR assays on 16S ribosomal gene. All the tested species i.e. winter oilseed rape, tomato and corn resulted carrying phytoplasmas belonging to the ribosomal groups retrieved in the infected mother plants
Identification and GroEL gene characterization of green petal phytoplasma infecting strawberry in Italy
No full textThe presence of phytoplasmas in strawberry showing malformation of the fruits together with the typical green petals symptoms was detected in some North Western Italy cultivations. Nucleic acids extracted from these plants were used in nested-PCR assays with primers amplifying 16S rDNA and GroEL sequences specific for phytoplasmas. Bands of 1.2 kb were obtained in both cases after nested-PCR assays and RFLP analyses allowed to classify the detected phytoplasmas in the aster yellows subgroup 16SrI-C, the GroELI grouping confirm all the strains from strawberry to be identical to each other and to GroELI-VI group. This is the first multigene molecular identification of strawberry green petals phytoplasmas in Italy
Identification of 16SrIX group phytoplasmas infecting Colombian periwinkles and molecular characterization on several genes.
No full textVirescence of tenweeks stock associated to phytoplasma infection in Sicily
No full textIn 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 widely grown in Italy, it could play an important role in spreading these phytoplasmas, new for Italy
Molecular identification of phyitoplasmas onfecting myrtle plantation in Sardinia (Italy)
No full textA new phytoplasma associated with witches’ -broom of Cassia italica in Oman.
No full textIn several Oman locations plants of Cassia italica exhibit witches’ broom symptoms. Samples were collected from four locations,
and examined for phytoplasma presence. PCR amplification using ribosomal phytoplasma primers followed by RFLP analyses
indicates that the phytoplasmas present in these samples were undistinguishable from each other, but differed from those reported
in the literature. RFLP and phylogenetic analysis of 16S rRNA gene plus spacer sequence confirmed that the closest phytoplasma
relatives were members of the pigeon pea witches’ broom phytoplasma ribosomal group (16SrIX), sharing a 93-97% sequence
similarity. Nested PCR experiments using primers amplifying the gene coding for ribosomal protein S3 provided amplification
from phytoplasmas detected in C. italica, after sequencing 600 bp in this gene the higher homology showed was 78% with phytoplasmas
related to ‘Candidatus Phytoplasma phoenicium’ and 77% with phytoplasmas belonging to ribosomal group 16SrIX
Molecular identification of “Bois Noir” phytoplasmas in grapevine in Bulgaria.
No full textField inspection in 4 vineyards located near Plovdiv (Bulgaria) allows observation of yellows symptom presence. PCR/RFLP
analyses on 16S ribosomal gene identified phytoplasmas belonging to 16SrXII-A ribosomal subgroup in both symptomatic grapevines
and bindweed growing in infected vineyard. Grapevine mother plant and young plants were also infected suggesting that,
even if this is the first report of this disease in Bulgaria, the environment is epidemically affected
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