Forty nine Pseudomonas syringae pv. tabaci strains, isolated in 2005 in Central Italy and previously identified by pathogenicity, morphological, biochemical, physiological and nutritional tests, were characterized determining copper sensitivity and capability to produce tabtoxin in vitro, and verifying the presence of the tblA and tabA genes required for tabtoxin production. A further characterization of the strains was carried out by rep-PCR, using the following sets of primers: BOX, ERIC, REP, KRPN2 and KRP. Italian strains were compared with 10 P. syringae pv. tabaci strains: LMG 5192, 5393, 5394, 5526 and 5527; NCPPB 1427 and 1918; ICMP 2835; 113R; 15D41. All strains tested were copper resistant as they grew on nutrient agar added with 0,5% glucose and amended with 200 μg ml-1 of copper sulphate (0.8 mM). Bioassay for tabtoxin production, performed using the strain BL21 Escherichia coli as indicator organism, revealed that among all the strains tested only the NCPPB 1918 and 113R strains produced tabtoxin. These results were confirmed by the amplification of the tblA and tabA genes, except for the strains LMG 5393, NCPPB 1427, ICMP 2835 and 15D41 that, even if they have the tblA and tabA genes, they do not produce tabtoxin. Spontaneous mutations frequently occurring in the gacS and gacA regulator genes, which control the tblA and tabA expression, could explain this discrepancy. Rep-PCR performed with the primers BOX, ERIC and REP showed that the Italian strains generated fingerprints which were identical to each other. By contrast, when KRPN2 and KRP were used, polymorphisms were observed, which were not correlated with geographical provenience of the strains.
Characterization of Pseudomonas syringae pv. tabaci strains collected in Central Italy.
FERRANTE, PATRIZIA;MORETTI, Chiaraluce;BUONAURIO, Roberto
2006
Abstract
Forty nine Pseudomonas syringae pv. tabaci strains, isolated in 2005 in Central Italy and previously identified by pathogenicity, morphological, biochemical, physiological and nutritional tests, were characterized determining copper sensitivity and capability to produce tabtoxin in vitro, and verifying the presence of the tblA and tabA genes required for tabtoxin production. A further characterization of the strains was carried out by rep-PCR, using the following sets of primers: BOX, ERIC, REP, KRPN2 and KRP. Italian strains were compared with 10 P. syringae pv. tabaci strains: LMG 5192, 5393, 5394, 5526 and 5527; NCPPB 1427 and 1918; ICMP 2835; 113R; 15D41. All strains tested were copper resistant as they grew on nutrient agar added with 0,5% glucose and amended with 200 μg ml-1 of copper sulphate (0.8 mM). Bioassay for tabtoxin production, performed using the strain BL21 Escherichia coli as indicator organism, revealed that among all the strains tested only the NCPPB 1918 and 113R strains produced tabtoxin. These results were confirmed by the amplification of the tblA and tabA genes, except for the strains LMG 5393, NCPPB 1427, ICMP 2835 and 15D41 that, even if they have the tblA and tabA genes, they do not produce tabtoxin. Spontaneous mutations frequently occurring in the gacS and gacA regulator genes, which control the tblA and tabA expression, could explain this discrepancy. Rep-PCR performed with the primers BOX, ERIC and REP showed that the Italian strains generated fingerprints which were identical to each other. By contrast, when KRPN2 and KRP were used, polymorphisms were observed, which were not correlated with geographical provenience of the strains.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
