Comparison of different diagnostic methods for detection of peach latent mosaic viroid

• Published in: Bulletin OEPP Vol. 29; no. 4; pp. 433 - 438
• Main Authors: Loreti, S., Faggioli, F., Cardoni, M., Mordenti, G., Babini, A. R., Pollini, C. Poggi, Barba, M.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-12-1999
• ISSN: 0250-8052; 1365-2338
• DOI: 10.1111/j.1365-2338.1999.tb01414.x

Latent mosaic is a widely distributed disease of peach caused by peach latent mosaic viroid (PLMVd). Some strains induce mosaic symptoms on leaves, delay in leaf emergence, flowering and maturity, calico and malformation of fruits with cracked sutures and enlarged pits, bud necrosis and, in more severe cases, early decline of the trees. To prevent the use of infected propagating material, international certification schemes provide for the absence of PLMVd from peach mother plants. Until a few years ago, detection of PLMVd was mainly based on cross‐protection tests on GF305 peach seedlings. Recently, improved knowledge of the PLMVd genome and optimization of molecular techniques applied to the diagnosis of plant pathogens have stimulated studies aimed at setting up diagnostic methods that are sensitive, reliable and less time‐consuming. A comparative trial among different Italian institutions has been set up to compare the sensitivity, specificity and reproducibility of the currently available diagnostic techniques that are routinely applied for the detection of PLMVd in peach germplasm. In this paper, we compare the results obtained in the diagnosis of PLMVd performed with biological indicators and molecular techniques (‘spot‐blot’ and ‘tissue‐blot’ hybridization using a non‐radioactive probe and reverse transcriptase‐polymerase chain reaction) starting from different organs (leaves, buds and bark) collected from infected and healthy peach plants and using two total nucleic acid extraction methods. On the basis of the results obtained, we suggest that a tissue‐blot hybridization assay using a PLMVd cRNA digoxigenin‐labelled probe and starting from bud tissue is a reliable diagnostic method for inclusion in quarantine or certification protocols that require the absence of PLMVd from propagating material of peach.