Occurrence in Pseudomonas avellanae strains of gene sequences partly identical to the phaseolotoxin tox gene cluster, present in P-syringae pv. phaseolicola and P-s. pv. actinidiae

Field symptoms of hazelnut Worylus avellana L.) decline include the presence of pale foliage as well as rapid wilting of leaves and twigs. Representative strains of Pseudomonas avellanae, the causal agent of this disease, were assessed for the possible presence of DNA sequences identical to the phaseolotoxin argK-tox gene cluster of R syringae pv. phaseolicola and P.s. pv. actinidiae. Different primers all enabling the detection of PCR products corresponding to different regions of tox or argK genes were used. Cloning and sequencing of PCR products showed that R avellanae strains have in their genomes DNA sequences identical to the tox gene cluster of R s. pv. phaseolicola and R s. pv. actinidiae: a total of about 1,131 bp out of 6,000 bp. Presence of the argK gene was not detected. A possible relationship between presence of the tox gene sequences and the wilting and yellowing symptoms is discussed.