Variability among Isolates of Pseudomonas syringae pv. savastanoi from the Phylloplane of the Olive

Abstract

Leaves of three or four different ages were taken from olive plants quarterly in 1974-1980. One thousand and fifty isolates of Pseudomonas syringae pv. savastanoi from the phylloplane were tested for virulence to the olive and subjected to numerical phenetic analysis using 60 unit characters. The data were analysed using unweighted average linkage (UPGMA) and single linkage clustering on the simple matching ( S S M ) and pattern (S,) coefficients. The isolates obtained from leaves of a given age at a given time of the year shared higher percentage similarity ( S ) values between themselves than with the others. Cluster composition was only marginally affected by different coefficients and methods of clustering. UPGMA analysis on the S,, coefficient recovered 92% of the isolates in 10 major clusters at 75% S. Of the isolates from leaves of the same age collected at the same time of the year, 81-99% fell in the same cluster. Conversely, 91-97% of the isolates in five of the major clusters were from leaves of the same type. Of the isolates in the other major clusters, 95-98% were from two different sources but most of the isolates from leaves of one type segregated into discrete subclusters at 85-90% S. Hypothetical median organisms (HMOs) were constructed to represent all the isolates obtained from the leaves of each type each year. The resulting relationships between the HMOs confirmed those described above for the individual isolates.

Phenotypic and genotypic diversity of fluorescent pseudomonads isolated from field-grown sugar beet

“…savastanoi population of olix e leaves showed that specific phenotypes were found on different sampling occasions, suggesting that long-term survival is dependent upon phenotypic heterogeneity (Ercolani, 1983(Ercolani, , 1985; the extent of genotypic diversity among these isolates was not investigated. We have attempted in this study to examine the degree of phenotypic and genotypic diversity within a selection of closely related isolates sampled from one field during the course of a single season.…”

“…Cert.iin pseudomonads, including Psezldomonas gringae and P. viridzjava, can cause disease (Palleroni, 1984), while othr rs, such as isolates of P. Jzlorescens and P. putida, can promote plant growth (O'Sullivan & O'Gara, 1992). The majority of phyllosphere-inhabiting fluorescent pseudomon:ids have no apparent effect on plant growth, but nevertheless represent important components of the leaf community (Austin e t a /., 1978;Ercolani, 1978; Van Outryve e t d.,…”

Epidemiology and Control of Plant Diseases Caused by Phytopathogenic Bacteria: The Case of Olive Knot Disease Caused by Pseudomonas savastanoi pv. savastanoi

“…In addition, phenotypically distinct Psv isolates from the phyllosphere, succeed each other in time in the olive tree phyllosphere (Ercolani, 1983). This was discovered because Psv isolates obtained by washing leaves of a certain age at a particular time of the year (over eight years) showed more phenotypic similarity with each other, than with isolates obtained by washing leaves www.intechopen.com…”

“…Between 70 and 95% of the maximum variance of some microbiological parameters, such as Psv density in the olive tree phyllosphere, was explained by the influence of seven factors, four of which were related with the weather: summer, summer rainfall, winter rainfall and warm fronts (Ercolani, 1985) and the three remaining factors were cambium activity, leaf age and time of flowering. As described for other epiphytic bacteria and hosts (Kinkel, 1997), Psv population densities varied over several orders of magnitude among leaves sampled concurrently from the same shoot, as assessed by the comparison of leaf printing and isolation experiments (Quesada et al, 2007).…”

“…There are few studies on the epidemiology of olive knot disease and most data of epiphytic Psv populations on the aerial surface of the tree come from studies done in southern Italy (Ercolani, 1971(Ercolani, , 1978(Ercolani, , 1979(Ercolani, , 1983(Ercolani, , 1985(Ercolani, , 1991(Ercolani, , 1993 and southeastern Spain (Quesada et al, 2007;Quesada et al, 2010a;2010b). In the aforementioned studies, epiphytic Psv populations in the phyllosphere of olive trees were estimated by washing, followed by plating serial dilution of the washings.…”