Molecular characterization of ‘Candidatus Phytoplasma prunorum’ in Cacopsilla pruni insect vector

Recent investigations on molecular characterization of the ‘Candidatus Phytoplasma prunorum’ (16SrX-B subgroup), causal agent of the European Stone Fruit Yellows (ESFY) syndrome, on the non ribosomal tuf gene resulted in the finding of two groups of isolates, named ‘type a’ and ‘type b’, both with a distinctive geographical distribution in Italian stone fruit growing areas (Ferretti et al., 2007 and 2008). Considering the role of Cacopsylla pruni (Scopoli) in the epidemiological cycle of the disease, the presence of the two groups of isolates has also been investigated in infected psyllid individuals from different Italian areas. Both types have been identified in C. pruni specimens collected on apricot, plum and wild Prunus species, confirming the geographical distribution and the percentages of spread of the two isolates.Keywords: ESFY, phytoplasma, characterization, tuf gene, insect vecto

Detection and distribution of European stone fruit yellows (ESFY) in apricot cv. ‘Bergeron’ and epidemiological studies in the province of Trento (Italy)

The aim was to investigate the performance of ‘Bergeron’ on ‘Wavit’ in 4 experimental fields, in the province of Trento (Italy), where European stone fruit yellows (ESFY) caused by “Candidatus Phytoplasma prunorum” has been constantly spreading since 2000.This included visual inspections for typical symptoms (early bud-break during dormancy and premature leaf-roll) and a highly sensitive Real time-PCR (Rt-PCR) assay. 25 % of the propagation material was checked with this method and found to be healthy, before planting in 2005.The epidemiology of the disease was also studied by focusing on: the presence of the vector Cacopsylla pruni (Scopoli) on conifers, the detection of “Ca. P. prunorum” in psyllid eggs and the transmission efficiency at different stages. This was done by exposing apricot trees in 2 locations, during 2 periods from January to July, to the overlapping presence in the orchards of the re-immigrants and the new generation of C. pruni. The results obtained demonstrated that ‘Bergeron’ seems to be highly susceptible to ESFY: typical bud-break was rarely observed, but up to 20-30% of the plants showed premature leaf-roll, fruit deformation and dieback. C. pruni was caught only once on Picea abies during winter; “Ca. P. prunorum” was found in 4 egg samples from 2 locations and the preliminary results on the exposed trees confirmed that the re-immigrants could be the most efficient vectors at least on apricot.Keywords: Prunus armeniaca, cultivar ‘Bergeron’, Real time-PCR, “Candidatus Phytoplasma prunorum”,epidemiolog

Il giallume europeo delle drupacee.

In Italia ed in Europa, particolarmente nei paesi che si affacciano sul Mediterraneo, sono presenti su varie drupacee coltivate e spontanee diverse sindromi causate dal fitoplasma del giallume europeo delle drupacee; alcune di queste come l\u2019accartocciamento fogliare clorotico dell\u2019albicocco e la leptonecrosi del susino sono note da tempo ed ampiamente diffuse, mentre su altre specie, come il pesco, la gravit\ue0 appare minore, anche negli ultimi anni si \ue8 assistito ad un preoccupante aumento della malattia negli impianti peschicoli del Italia Settentrionale. Altre specie come il susino europeo sono invece tolleranti, anche talvolta alcune cultivar possono evidenziare sintomi lievi. Il patogeno viene trasmesso dalla psilla delle drupacee, Cacopsylla pruni (Scopoli). Si prendono in considerazione le principali sindromi causate dal fitoplasma del giallume europeo delle drupacee nel nostro Paese, indicando anche il comportamento di variet\ue0 e portinnesti nei confronti della malattia. Viene inoltre dedicata una particolare attenzione alle modalit\ue0 di trasmissione, ai metodi diagnostici e alle possibili forme di contenimento della malattia: molto importante risulta la scelta del materiale vivaistico per la costituzione di impianti sani, mentre permangono ancora dubbi circa la capacit\ue0 di limitare la diffusione della malattia con la difesa insetticida in presenza di popolazioni ridotte del vettore

Influenza delle infezioni da virus e fitoplasmi sull'interazione portinnesto/variet\ue0.

Nell'articolo vengono descritte le interazioni fra portinnesti di drupacee e pomacee ed agenti patogeni (virus e fitoplasmi) diffusibili e non diffusibili in natura. In riferimento all' influenza di tali malattie infettive sull'affinit\ue0 vegeto-produttiva degli alberi da frutto, risulta evidente la necessit\ue0 di utilizzare per l'attivit\ue0 vivaistica materiale controllato dal punto di vista sanitario

La moria del pero

Vengono trattate le principali caratteristiche sintomatologiche della moria del pero, che rappresenta oggi uno dei principali problemi sanitari in tutte le aree di coltivazione di questa pomacea. Viene inoltre dedicata particolare attenzione alla suscettibilit\ue0 all'infezione delle principali variet\ue0 e portinnesti, alle modalit\ue0 di trasmissione, alla diagnosi del fitoplasma agente della malattia ed alle modalit\ue0 di lotta

A multiplex Real Time Taqman RT-PCR assay for the detection of grapevine flavescence doree and bois noir phytoplasmas using crude sap extracts.

Flavescence dor\ue9e (FD) and Bois noir (BN) are the most important and spread grapevine yellows diseases in Europe and are caused by phytoplasmas of the 16SrV and 16SrXII-A groups, respectively. Detection of BN and FD phytoplasmas is particularly difficult, as they are generally present in low concentrations and unevenly distributed in the grapevine phloem. Many efforts recently focused on developing of a rapid and sensitive method for phytoplasma detection. In this study a triplex real time TaqMan RT-PCR methodology has been set up to simultaneously, but specifically, amplify a 16SrDNA gene fragment of FD and BN phytoplasmas and a 18SrDNA gene region of the host plant using a crude sap extract as template. The use of RNA as template, instead of DNA, takes advantage from the high ribosomal-RNA copy number present in pathogen cells and provides an evidence of viability and metabolic activity of phytoplasma, which is not provided by DNA-based detection. During our study an efficient and rapid method for GY phytoplasmas detection in different host plants has been obtained. Absence of nucleic acid extraction step allows to greatly decrease both costs and time necessary to perform the assay. Therefore the method presented is a rapid, specific and sensitive alternative to conventional nested-PCR. We successfully applied this technique to the detection of BN and FD phytoplasmas on more than three hundred samples of grapevine, strawberry, tomato, wild host plants and vector insects

Transmission trials of the fig mosaic disease agent.

Transmission trials of the fig mosaic (FM) agent were carried out using a FM-free colony of Aceria ficus. Portions of mite-infested fig leaves were placed onto leaf pieces of a symptomatic diseased periwinkle, obtained in a previous study. Periwinkle leaf pieces, with potentially infected mites, were then transferred to healthy fig seedlings and some (6%) displayed leaf mosaic a month postinoculation. Subsequently, one of these FM-affected plants was employed as inoculum source for further back-inoculations. Among the fig and periwinkle test plants used, those successfully inoculated by A. ficus resulted to be 98.5% and 33.3%, respectively. RT-PCR showed that the FM donor sources of our experiments contained a single infection of FMV. The virus was also detected in A. ficus individuals that fed on a diseased fig plant. Moreover, electron microscopy revealed the presence of FMV particles in symptomatic fig and periwinkle plants. These new data add further support to the suggestion that FMV could be the real FM etiological agent