Boscia D

Loconsole G

Martelli G.P

Palmisano F

Potere O

Saponari M

Savino V.N

LOCONSOLE, GIULIANA

SAVINO, Vito Nicola

Martelli G. P

Saponari M.

Archivio istituzionale della ricerca - Università di Bari

S4.38 Journal of Plant Pathology (2014), 96 (4, Supplement), S4.29-S4.39A XYLELLA FASTIDIOSA STRAIN WITH UNIQUE BIOLO-GY AND PHYLOGENY IS ASSOCIATED WITH A SEVERE DISEASE OF OLIVE IN SOUTHERN APULIA. G. Loconsole1, D. Boscia1, F. Palmisano2, V. Savino3, O. Potere3, G.P. Martelli3, M. Saponari1. 1Istituto per la Protezione Sostenibile delle Piante UOS Bari, CNR, via Amendola 165/A, 70126 – Bari, Italy. 2Centro di Ri-cerca, Formazione e Sperimentazione in Agricoltura, Via Cisternino 281, 70100 - Locorotondo (BA), Italy. 3Dipartimento di Scienze del Suolo, della Pianta e degli Alimenti, Università degli Studi di Bari Aldo Moro, Via Amendola 165/A, 70126 - Bari, Italy. E-mail: g.lo-console@ba.ivv.cnr.itIn October 2013, an outbreak of Xylella fastidiosa was detected in the Salento peninsula (Apulia, south-eastern Italy) in olive groves that were severely affected by a disease denoted “olive quick decline syndrome”. Surveys carried out throughout the region revealed the presence of new outbreaks, all restricted to the province of Lecce, the site of the first X. fastidiosa discovery. Investigations carried out showed that olive is the prevailing susceptible hosts, but infections were also found in oleander, some stone fruits and ornamentals. By converse, grapevines and citrus trees growing in the heavily con-taminated area, were always negative in laboratory assays and free from symptoms of Pierce’s disease and citrus variegated chlorosis. Preliminary genetic analysis based on 13 housekeeping genes, in-cluding those used for multi locus sequence typing (MLST), dem-onstrated that the olive isolate of X. fastidiosa is genetically related with the subspecies pauca, but clearly distinct from the other strains comprised this cluster. A novel, hitherto undescribed “Sequence Type” profile (http://pubmlst.org/xfastidiosa/), was therefore as-signed to the olive strain based on MLST analysis. Multiple align-ments of DNA sequences of bacterial isolates recovered from all susceptible hosts so far known, showed high nucleotide identity, suggesting that the infections are caused by the same strain. In con-clusion, the data so far collected about the natural host range and the genetics of the bacterial isolates under study, strongly support the notion that the olive isolate of X. fastidiosa represents a novel strain, for which the name “strain CoDiRO” has been proposed.BACTERIAL COMMUNITIES OF CITRUS PLANTS AFFECT-ED BY HUANGLONGBING AND CANDIDATUS LIBERI-BACTER ASIATICUS CONCENTRATION. A. Campisano1, C.P. Strano2, P. Bella2, G. Licciardello3, Z. Deng4, X. Deng5, R. La Rosa2, V. Catara2. 1Research and Innovation Centre, Fondazione Edmund Mach (FEM), S. Michele all’Adige (TN), Italy.2Department of Agricultural and Food Science, University of Catania, Italy.3Science and Technology Park of Sicily, Catania, Italy. 4National Center of Cit-rus Improvement, Hunan University of Agriculture, Changsha, P.R. China. 5Laboratory of Citrus Huanglongbing Research, Department of Plant Pathology, South China Agricultural University, Guangzhou, P.R. China. E-mail: vcatara@unict.it Huanglongbing (HLB) is the most devastating disease of cit-rus worldwide. This vector-transmitted disease is associated with phloem-limited fastidious alphaproteobacteria of the genus “Can-didatus Liberibacter” that are of quarantine concern for the Eu-ropean and Mediterranean region. Investigation in the countries where the disease is present is a way to improve our knowledge in view of a potential invasion. In China HLB is associated to “Ca. L. asiaticus” (Las). During field surveys in Guandong province, China, we collected young shoots of Buddha’s hand (Citrus medica var. sarcodactylis) and ‘Shatangju mandarin’ (Citrus reticulata) in orchards with a HLB infection history. Bulk samples of leaf mid-ribs and bark from single plants were separately processed. Total genomic DNA, including microbial DNA, was extracted using the DNeasy plant mini kit, Qiagen. Las presence was investigated by real-time PCR and bacterial titer estimated. Las mean concentration was higher in DNA extracted from bark samples rather than those obtained from midribs. The same DNAs were used for analysis of bacterial community composition by 454 pyrosequencing of the 16S rDNA gene amplicons. We determined the composition of bacterial communities in the two plant species and in the different tissues. Proteobacteria dominated the bacterial communities in all but one sample (where Bacilli were dominant). Among these, Alphaproteo-bacteria were the most abundant. Actinobacteria and Acidobacteria were also abundant in all samples. Special attention was devoted to the analysis of the Rhizobiales order to which Las belong to in-vestigate the presence of taxonomically related bacteria that could influence Las detection.HOST-PATHOGEN INTERACTION IN ACTINIDIA-BACTE-RIAL CANKER PATHOSYSTEM: INVESTIGATION ON THE LATENCY PERIOD IN ASYMPTOMATIC PLANTS. P. Mi-nardi1, S. Ardizzi2, A. Bertaccini2. 1Dipartimento di Scienze Medi-che Veterinarie, (DIMEVET), Alma Mater Studiorum, Università di Bologna, Via Tolara di Sopra, 50, 40064 Ozzano Emilia (BO), Italy. 2Dipartimento di Scienze Agrarie (DipSA) Alma Mater Studiorum, Università di Bologna,Viale Fanin 42, 40127 Bologna, Italy. E-mail: paola.minardi@unibo.itBacterial canker of kiwifruit caused by Pseudomonas syringae pv. actinidiae (Psa) still results in serious yield losses in Italy and, despite the studies conducted hitherto to deal with this devastat-ing disease, some epidemiological aspects are still to be clarified. In particular, the available information on life-cycle of Psa is still incomplete on the latency period of Psa within the susceptible host plant. To elucidate this dangerous endophytic latent phase, the survival of a virulent Psa gfp-expressing/Rif-resistant strain (Psa::gfp) within asymptomatic Actinidia spp. plants was studied. The results were obtained both in adult plants of Actinidia chinensis cv. Hort16A four years after inoculation with Psa::gfp at low inocu-lum dose, and in Actinidia deliciosa cv. Hayward plants obtained from micropropagated shoots similarly inoculated more than three years before. Both types of plant were in toto analyzed to re-isolate Psa::gfp on selective media, and to check its ability to induce disease symptoms in host plants and hypersensitivity reaction in tobacco plants. PCR analysis was carried out to confirm the identity of the re-isolate Psa::gfp. On the fourth year following inoculation, the data confirmed that Psa can colonize plants for a long time staying latent at very low concentrations. In the pathosystem Actinidia-Psa the pathogen appears to have achieved a high degree of pathoadap-tation which is witnessed in a pluriannual latency period. The impli-cations of what reported are especially important for its impact on the nursery industry, and control strategies in kiwifruit orchards to prevent the spread of the pathogen present in asymptomatic plants.ISOLATION AND CHARACTERIZATION OF AN ENDO-PHYTE FROM ACTINIDIA SP. SHOWING A STRONG ANTAGONISTIC ACTIVITY AGAINST PSEUDOMONAS SYRINGAE PV. ACTINIDIAE. R. Tontou1, F. Gaggia2, L. Baf-foni2, V. Venturi3, E. Stefani1. 1Dipartimento di Scienze della Vita, Università di Modena & Reggio Emilia, Viale A. Allegri 9, 42121, Reggio Emilia, Italy. 2Dipartimento di Scienze Agrarie, Viale Fanin 44, 40127, Bologna, Italy. 3 Group of Becteriology & Plant Bacteriol-ogy, International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149, Trieste, Italy. E-mail: emilio.stefani@unimore.it The bacterial canker of kiwifruit is the most destructive dis-ease of cultivated Actinidia spp. The causal agent is the Gram JPP 96 (4) supplemento.indb   38 22/12/14   09:33

English

A Xylella fastidiosa strain with unique Biology and phylogeny is associated with severe disease of olive in Southern Apulia

A Xylella fastidiosa strain with unique Biology and phylogeny is associated with severe disease of olive in Southern Apulia

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Archivio istituzionale della ricerca - Università di Bari