Direct tissue blot immunoassay for detection of Xylella fastidiosa in olive trees

• Published in: Phytopathologia mediterranea Vol. 53; no. 3; pp. 559 - 564
• Main Authors: DJELOUAH, Khaled, FRASHERI, Dajana, VALENTINI, Franco, D'ONGHIA, Anna Maria, DIGIARO, Michele
• Format: Journal Article
• Language: English
• Published: Florence Mediterranean Phytopathological Union and Firenze University Press 01.12.2014; Firenze University Press Università degli Studi di Firenze; Firenze University Press
• Subjects: Branches; Canopies; DTBIA; Forest canopy; Fruit trees; Immunoassay; Laboratory tests; Olea; Olea europea; Olive quick decline syndrome; Pathogens; PCR; Petioles; Phytopathology; Polymerase chain reaction; SHORT NOTE; Tissue samples; Viruses; Xylella; Xylella fastidiosa
• DOI: 10.14601/Phytopathol_Mediterr-14603
• ISSN: 0031-9465

A direct tissue blot immunoassay (DTBIA) technique has been compared with ELISA and PCR for detection of Xylella fastidiosa in olive trees from Apulia (southern Italy). Fresh cross-sections of young twigs and leaf petioles were printed onto nitrocellulose membranes and analyzed in the laboratory. Analyses of a first group of 61 samples gave similar efficiency for the three diagnostic techniques for detection the bacterium (24 positive and 36 negative samples), except for a single sample which was positive only with DTBIA and PCR. Similar results were obtained by separately analyzing suckers and twigs collected from different sectors of tree canopies of a second group of 20 olive trees (ten symptomatic and ten symptomless). In this second test the three diagnostic techniques confirmed the irregular distribution of the bacterium in the tree canopies and erratic detectability of the pathogen in the young suckers. It is therefore necessary to analyse composite samples per tree which should be prepared with twigs collected from different sides of the canopy. The efficiency comparable to ELISA and PCR, combined with the advantages of easier handling, speed and cost, make DTBIA a valid alternative to ELISA in large-scale surveys for occurrence of X. fastidiosa. Moreover, the printing of membranes directly in the field prevents infections spreading to Xylella-tree areas, through movement of plant material with pathogen vectors for laboratory testing.