1,721,116 research outputs found
Phytoplasma cultivation: problems and solutions
No full textOver fifty years had elapsed since Doi’s publication (1967) on the presence of mycoplasma-like organisms (MLO) now known as phytoplasmas in the sieve tubes of plants showing hormone imbalance and malformations. These phloem-limited bacteria are transmitted by plant sap-feeding insects and are classified based on molecular analysis techniques on the 16S ribosomal gene at the level of the 'Candidatus' genus (Bertaccini et al., 2018). The few scattered evidences of cultivation possibility were recently confirmed by using media based on those successfully used for human and animal mycoplasma cultivation
Phytoplasma cultivation: State of the art
No full textThe possibility to grow on artificial media phytoplasmas isolated from micropropagated infected periwinkle shoots and from field-infected tissues is a recent achievement. Isolation and cultivation together with biochemical and biological characterization of some phytoplasmas was consistently obtained. Colonies of phytoplasmas belonging to diverse ribosomal groups were obtained such as those related to a ‘Candidatus Phytoplasma pruni’- related isolate from cassava plants with frog skin diseased, ‘Ca. P. asteris’ and ‘Ca. P. solani’ from diverse infected host plants such as grapevine and coconut palms. Antisera production and their preliminary diagnostic use was also achieved for some of these isolates. Further phytoplasmas were also isolated in liquid and solid media from date palm and citrus tissues. Seed transmission in corn of aster yellows phytoplasmas was confirmed by isolation from seedlings of viable phytoplasma cells
Phytoplasma cultivation: lights and shadows
No full textThe possibility to grow phytoplasmas in complex media was first demonstrated using micropropagated infected periwinkle shoots and then carried out employing naturally infected field collected plant samples. Phytoplasmas belonging to diverse ribosomal groups were isolated from infected grapevine and coconut palm tissues and in some cases also from asymptomatic tissues, especially from trees or plants growing in severely infected areas. In particular aster yellows and “stolbur” phytoplasmas, group 16SrI and 16SrXII respectively, were consistently grown among other phytoplasmas from the different plant sources employed and the first biochemical and biological characterization of some of these isolates was obtained
Seed transmission of phytoplasmas in tomato and chilli varieties commonly grown in Mauritius
No full textTomato and chilli leaf samples were collected from plants showing stunting, reduced leaf size, leaf yellowing and leaf and fruit
distortions in different localities across Mauritius. Disease incidence at field level ranged from 5 to 60% in tomato and from 10
to 50% in chilli. The presence of 16SrI phytoplasmas was detected in 80% symptomatic tomato and 75% symptomatic chilli
plants. Seeds from mature tomato and chilli fruits collected from phytoplasma positive mother plants were sown under insect
proof conditions. After 4 to 6 weeks, germinated seedlings were checked for the presence of phytoplasmas. A total of 1% tomato
and 4.2% chilli seedlings were positive to 16SrI phytoplasmas. This is the first report of phytoplasmas in chilli and also of
phytoplasma transmission through seeds in both tomato and chilli in Mauritius
Molecular markers for differentiation of a ‘Candidatus Phytoplasma solani’ strain associated with “bois noir” disease in Sicily
No full text
Phytoplasma cultivation
No full textThe possibility to grow phytoplasmas in complex media as the mycoplasmas
was ruled out for more than 40 years due to the inconsistency of the first
isolation trials. The use of micropropagated infected periwinkle shoots first and
tissues infected directly from the fields on artificial media was recently confirmed.
Isolation and cultivation together with the first biochemical and biological characterization
of some phytoplasmas were consistently obtained. Phytoplasmas were
successfully grown from grapevine, cassava and coconut palm tissues severely
infected and in some cases also from asymptomatic tissues from trees or plants
growing in severely infected areas. Phytoplasmas from diverse ribosomal groups
were isolated in particular from cassava with frog skin the detected prokaryotes in
culture were molecularly identified as belonging to the 16SrIII group as in the original
plants. Aster yellows and ‘stolbur’ phytoplasmas, group 16SrI and 16SrXII,
respectively, were consistently grown from diverse host plants such as grapevine
and coconut palms. Seed transmission in corn of aster yellows phytoplasmas was
also confirmed by isolation from seedlings of viable cells. The growth and biochemical
and biological characterization of these bacteria is therefore the most
important recent step in the study of phytoplasmas that will allow to improve their
knowledge and to carry out focused management in the field in order to reduce their
impact on cultivated and wild crops worldwide
Molecular characterization of “bois noir” phytoplasma strains in a single vineyard in central Serbia
Full text linkGrapevine “bois noir” (BN) is a phytoplasma disease widely present in large numbers of viticultural regions of the world, and it can result in heavy reductions in yield and grape juice quality. BN is associated with the presence of ‘Candidatus Phytoplasma solani’ (BN), transmitted from herbaceous plants to grapevine by polyphagous insect vectors. In the Euro-Mediterranean Region, phloem-feeding Hemiptera of the Cixiidae family are the vectors of “stolbur” phytoplasmas and in particular, the plant hopper Hyalesthes obsoletus Signoret is the main responsible for BN transmission to grapevine. Adult of H. obsoletus can feed on various herbaceous plants, but only a few species are selected to complete their life cycle. The different ability to induce epidemic outbreak is often associated with molecularly differentiable phytoplasmas usually enclosed in the same taxon. A study was therefore carried out to verify the presence of molecular variability of BN strains in a restricted environment such as a vineyard located in the central Serbia planted with different grapevine varieties
Identification of epidemic “flavescence dorée” molecular variants in Emilia-Romagna and Veneto regions
No full textThe study of the genetic variability of phytoplasmas is a fundamental tool to clarify their epidemiology and to implement an effective monitoring and management of their associated diseases. “Flavescence dorée” (FD), a threatening disease of grapevine associated to phytoplasmas belonging to 16SrV group and their insect vector(s), is distributed within the most important European wine-producing areas, and has severe effects on both vineyard productivity and landscape management. FD is a quarantine disease in Europe, mainly transmitted by the ampelophagous leafhopper Scaphoideus titanus and, despite the efforts to contain the pathogen dissemination, the disease is still epidemic in several viticultural areas of Northern Italy. Based on sequence and restriction fragment length polymorphism (RFLP) analysis of the 16S rRNA gene two FD ribosomal groups were described as present in Italy during the last century: 16SrV-C and 16SrV-D. However, the sequencing of non-ribosomal loci, such as secY, map and rpsC, allowed the identification over the years of several variants within the FD phytoplasma populations. A multilocus analysis approach was carried out on symptomatic FD-infected samples collected in Emilia-Romagna and Veneto regions, in different areas where the disease is spreading in the last 2-3 years. The geographic distribution of the two strains was confirmed to be different, with areas (Treviso province) with the prevalence of FD-C and others (Verona and Modena provinces) with only FD-D strains presence. Interestingly, FD-D phytoplasmas were identified for the first time also in a vineyard located in Modigliana (Forlì-Cesena province) and surrounded by forests. The molecular analyses allowed the identification of genetic variants among FD-D populations in both regions, that is quite a novel finding for these phytoplasmas that showed, since their first molecular identification in 1996, very little variability. In particular, the sequencing of secY amplicons highlighted the presence of the same SNP in samples of cultivars Teroldego and Trebbiano collected in Verona province and in grapevines cultivar Sangiovese located in Modigliana (Forlì-Cesena province). On the other hand, among the FD-C phytoplasma strains, the highest variability was shown on rpsC gene, that highlighted 5 restriction profiles after RFLP analyses on samples from cultivar Glera collected in Treviso and Belluno provinces. The epidemiology of the disease is therefore still to be monitored, especially since it is now involving different vectors/plant hosts species that are very likely responsible for the emergence of these FD variants. Therefore, a continuous and capillary monitoring of the presence and emergence of FD strains associated with the disease in the areas where it is present is necessary for the application of the most appropriate and stringent control measures aimed to avoid their epidemic spreading
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