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Assunta Bertaccini

Associate Professor

Department of Agricultural and Food Sciences

Academic discipline: AGR/12 Plant Pathology


Keywords: molecular characterization plant diseases bacteria phytoplasmas pathogen-elimination diagnostic

Phytoplasmas and bacteria presence is worldwide spread in several ecosystems: research performed are aimed to verify the presence of bacteria and the definition of association with phytoplasma presence of morphological and functional anomalies in plants of different species by phytoplasma molecular identification. Classical isolation and morpho-serological and molecular identification identification of these pathogens are carried out. Beside the classification based on ribosomal gene 16S research to verify the taxonomic value of other phytoplasma genes are carried out. In particular variability of genes coding for important pathogen functions such as those related to the immunodominant membrane complex (Amp) that are inportant in phytoplasma insect transmission and of tuf gene related to basic phytoplasma proteinosinthesis. Further researches are carried out to verify the taxonomic relevance of rpS3 and SecY genes together with 16S for the production of diagnostic tools that can be emplyoed for the detection and identification of quarantine phytoplasmas. Sudies on phytoplasma transmission by new insect vectors  species and to verify seed transmissibility are also performed.
Research to study the effectiveness of molecules different from antibiotics for their activity against phytoplasmas are carried out on in vivo and in vitro grown shoots towards the improvement of phytoplasama disease managment. Epidemiological studies using molecular markers are also carried out to determine the cycles of the most important phytoplasma and bacterial diseases (grapevine, fruit trees, ornamental and forest trees).

The presence of bacteria and phytoplasmas is increasingly widespread in many ecosystems. The alterations associated with the presence of these phytopathogenic prokaryotes are different and purpose of the research is to verify the binding of them with morpho-functional abnormalities present in plant species important from an economic point of view or biologically. Visual plant examination will be carried out and appropriate laboratory investigations in order to identify bacteria and phytoplasmas and determine the main bio-morphologic characteristics of infected plants. Such research will take advantage of the most advanced knowledge in the field of biotechnology, taking into account epidemiological and economic aspects related to this type of diseases: biological assays, isolation of axenic cultures, techniques of optical and electron microscopy, use of molecular probes, gene amplification (PCR), restriction fragment length polymorphism analyses (RFLP) and sequencing of nucleic acids . The study will involve important plant species such as hardwoods (elm, willow, Acacia, chestnut, etc.) and evergreen coniferous trees like pine and fir trees on which to date phytoplasmas were not clearly related to specific syndromes (' Candidatus Phytoplasma pini '). It will be taken into consideration also other species such as maize, prickly pear, Forsythia, rose, cyclamen, sweet pepper, silene, cassava, oil palm and others detected during the research. Also herbaceous or shrub plant disease will be studied since they may be sources of infection for other agronomically relevant species. Search will be also carried our on potential natural vectors such as psyllids and leafhoppers. The research material is subjected to extraction of nucleic acids, nested-PCR with primers specific for phytoplasmas ribosomal gene and RFLP analysis and identification of phytoplasmas is carried out through comparison with samples of phytoplasmas already identified. Other non-conserved regions of the genome of phytoplasma genes such as tuf, rp,  amp and others will be studied when necessary for strain identification. Sequence comparison will be carried out with the phytoplasma strains reported in the literature and whose sequences are available in GenBank, and other databases. Surveys will be carried out to detect the presence of insect potential natural carriers of  phytoplasmas identified from time to time. In addition, research will be carried out to confirm the transmissibility of phytoplasmas through  the seed in order to validate and confirm preliminary observations  on some species such as alfalfa, tomato, corn, sesami and lime. To verify the possibility of elimination of phytoplasma from infected plants in some trials will be carried out in a host-pathogen systems under controlled environment (micropropagation). Different substances such as RIPs, therpenes and plasma of different origin will be tested.  Visual control and through gene amplification assay with  nested PCR to check for the presence of DNA of the pathogen after default periods from the beginning of treatment will be performed. Viability of phytoplasmas will also be verified in case of positive results to molecular assays in treated plants. Similar trials using also BCAs will be carried out on woody plants (fruit trees and grapevine) in order to verify the practical application of these molecules in containment of bacterial diseases as well.

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