Molecular and phenotypic features of Pseudomonas syringae pv. actinidiae isolated during recent epidemics of bacterial canker on yellow kiwifruit (Actinidia chinensis) in central Italy

Abstract

Pseudomonas syringae pv. actinidiae (Psa) was identified as the causal agent of severe epidemics of bacterial canker on Actinidia chinensis (yellow kiwifruit) in central Italy occurring during 2008-9. A total of 101 strains were obtained from infected leaves, twigs, branches and trunks of cvs Hort16A, Jin Tao and CK3. Outbreaks were also found on A. deliciosa cv. Hayward. A representative set of 21 strains were compared with other Psa strains isolated from previous outbreaks in Japan and Italy as well as with P. s. pv. syringae strains obtained from A. chinensis and with strains of genomospecies 8. Repetitive-sequence PCR (rep-PCR) typing using BOX and ERIC primer sets revealed that all Psa strains obtained during 2008-9 showed the same fingerprinting profile. This profile, however, was different from those of strains previously isolated in Japan and Italy. Multilocus sequence typing (MLST) of gapA, gltA, gyrB and rpoD revealed a higher genetic variability among the strains than rep-PCR, with some of them showing the same sequence pattern although isolated from different areas, cultivars and years. None of the recently obtained strains possessed genes coding for phaseolotoxin or coronatine, and all had an effector protein, namely hopA1, differentiating them from the strains causing past outbreaks in Japan and Italy. All isolates were inhibited in vitro by copper-based compounds, antibiotics, geraniol, citronellol and by a chitin-based organic compound. The recent epidemics found in central Italy on yellow kiwifruit appear to have been caused by a different Psa population than those previously recorded in Japan, South Korea and Italy.

A Review of the Applications of Chitin and Its Derivatives in Agriculture to Modify Plant-Microbial Interactions and Improve Crop Yields

“…While in vitro studies show clear antibiotic activity, there is limited evidence for the antibiotic action of chitosan against major bacterial pathogens in planta. Chitosan toxicity has been shown in the major bacterial plant pathogen Pseudomonas syringae [39], but again, this study was conducted in vitro. Chitin in the form of ground shrimp waste was found to control the pathogen Streptomyces scabies, which causes scab disease on potato tubers [40], minimising the infection of the scab susceptible potato cultivar "Bentje" to 4%, compared to 22% in the control group.…”

First report of Pseudomonas syringae pv. actinidiae causing kiwifruit bacterial canker in New Zealand

“…The epidemic affecting 'Hort16A' in Italy was caused by a strain that appeared to be more virulent than a strain reported in 1994 (Scortichini 1994;Balestra et al 2009;Ferrante and Scortichini 2010). The epidemic in Italy has caused severe vine losses, with removal of entire orchards as a consequence (Balestra et al 2009).…”

“…BLAST analysis of these amplicons showed that the regions were 100% homologous to the respective Psa sequences in GenBank, accessions FN652889 and FN652897 from the 2008 epidemic in Italy (Ferrante and Scortichini 2010) for the gyrB gene, and FN433222 and AB016304 from the type strain (Kw-11, ICMP 9617) for the rpoD gene. Analysis of neighbour joining trees generated in Geneious Pro (ver.…”

Occurrence of a New Type of Pseudomonas syringae pv. actinidiae Strain of Bacterial Canker on Kiwifruit in Korea

“…A recent outbreak of bacterial canker is devastating the Italian kiwifruit industry. The strains isolated from recent outbreaks in Italy are different from those isolated before 2008, or from those isolated from Japan and Korea (Ferrante and Scortichini, 2010;Vanneste et al, 2010).…”

“…In previous works, two different BOX-PCR patterns depending on isolation year were described for P. syringae pv. actinidiae strains (Ferrante and Scortichini, 2010;Vanneste et al, 2011a). It was shown that P. syringae pv.…”