DETECTION AND IDENTIFICATION OF PHYTOPLASMAS INFECTING CULTIVATED AND WILD PLANTS IN LIGURIA (ITALIAN RIVIERA)

Restriction length polymorphism analysis of PCR-amplified ribosomal DNA was used to detect and characterize phytoplasmas infecting 49 out of 56 symptomatic plants of 16 different botanical species. The survey was conducted on vegetable and ornamental crops as well as shrubs and trees growing outdoors or under protected conditions in a region of Liguria, northern Italy. Different primer pairs were used to drive direct or nested PCR reactions. Seven plants of four botanical species showed typical phytoplasma symptoms but failed to give amplification. Alul, Hhal and Msel restriction profiles of amplified fragments showed that phytoplasmas infecting Brussels' sprouts, cineraria, marguerite, dahlia, French hydrangea, lavender, lettuce, olive, pistachio, primrose, Spanish broom, strawflower and violet were uniform and indistinguishable from the European aster yellows reference strain. Thus, all these isolates could be considered typical members of the 16Sr-IB subgroup. Phytoplasmas with restriction patterns indistinguishable among them and from those of the Serbian pepper stolbur reference strain were identified in samples of jasmine, kiwi, lavender and violet. Some of the diseases examined were already described from Italy, but a phytoplasma different from those previously reported was identified in Spanish broom. Eight plant species (cineraria, dahlia, jasmine, kiwi, lavender, pistachio, strawflower and violet) had not previously been identified as natural hosts of phytoplasmas. With the exception of violet, harbouring the two phytoplasmas, all other hosts were infected by only one kind of phytoplasma. L'analisi del polimorfismo della lunghezza dei frammenti di restrizione del DNA ribosomale amplificato mediante reazione polimerasica a catena è stata impiegata per identificare i fitoplasmi presenti in 49 su 56 campioni prelevati da 16 differenti specie botaniche con sospetti sintomi di infezione da fitoplasma. L'indagine è stata condotta nella piana di Albenga, in Liguria, su specie ortive ed ornamentali coltivate in serra o pieno campo e su piante spontanée. Differenti coppie di iniziatori di reazione sono state impiegate per l'innesco delle reazioni polimerasiche dirette o ripetute, ma in sette campioni di piante con sintomi tipici di fitoplasmosi, appartenenti a quattro diverse specie botaniche, non è stato amplificato in nessun caso DNA riferibile a fitoplasmi. Il confronto dei profili di restrizione ottenuti a seguito di digestione con gli enzimi AluI, Hh