Detection and characterization of phytoplasmas in olive trees from Italy
2002
Poggi Pollini, C. | Bissani, R. | Ragozzino, A. | Faggioli, F. | Pasquini, G. | Barba, M. | Marzachì, C. | Boccardo, G.
Olive trees (51 adult plants and 13 seedlings) showing symptoms of yellowing, shortening of internodes, witches' broom, bud abortion, little leaf, hypertrophied inflorescences, decline and fasciation were tested for the presence of phytoplasmas. DNAs extracted from leaf veins were amplified in reactions using universal or group-specific primers constructed on 16S rRNA phytoplasma sequences and restricted with five different enzymes. Phytoplasmas, identified on the basis of their RFLP patterns as 16Sr-IB, -VA, and -XIIA subgroup members (sensu Lee et al., 1998) were detected in 53 % of the samples. In addition, a IB subgroup member was detected in one symptomless adult tree. A single phytoplasma was detected in 68 % of the samples. Two different organisms (IB and XIIA) were found in 20.5 % and three phytoplasmas were present in about 9 % of the samples. Hence, it appears that phytoplasmas are ubiquitous in the areas surveyed, but a clear correlation between a given syndrome and the presence of one or more phytoplasmas did not emerge. However, subgroup VA phytoplasmas were detected only in samples collected in the north-east (lake Garda) of Italy, whereas subgroup IB was the commonest in samples from central and southern regions. Studies aimed to assess whether phytoplasma detection may be influenced by the tree vegetative cycle did not indicate that this could be the case. Results on alternative detection methods for subgroup XIIA are presented.
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