Characterization of Dickeya strains isolated from potato grown under hot‐climate conditions

Abstract

Dickeya strains isolated in Israel in 2006-2010 were characterized by dnaX sequence analysis, pulsed-field gel electrophoresis (PFGE), biochemical assays and pectolytic activity, and found to be homogeneous: most of them could be classified as 'Dickeya solani'. Of the 34 strains isolated from imported seed tubers or potato plants grown from imported seed, 32 were typed as 'D. solani' and only two were characterized as Dickeya dianthicola. Biovar typing indicated that all 'D. solani' strains were biovar 3. 'Dickeya solani' strains were most closely related to Dickeya dadantii subsp. dieffenbachiae according to PFGE and dnaX analyses and both species exhibited high pectolytic activity. Expression levels of two putative virulence genes, pelL (encoding a pectic enzyme) and dspE (encoding a type III effector) were significantly induced in 'D. solani' strains isolated from potato plants or tubers grown in hot climates such as the Negev region in Israel, compared to those isolated from seed tubers imported from the Netherlands, France or Germany. Results of this study support the hypothesis that 'D. solani' strains isolated in Israel are also clonal; however, they appear to be more virulent than strains isolated in Europe.

The effect of temperature on the phenotypic features and the maceration ability of Dickeya solani strains isolated in Finland, Israel and Poland

“…Yet, there is only one comparative study performed on D. solani strains originating from different climate conditions (Tsror (Lahkim) et al 2013). In the present study, we verified the genetic homogeneity of the strains of D. solani isolated in the previous years from infected potato plants under different temperature conditions (in Poland, Finland and Israel) and compared their phenotypic features such as pectinases, cellulases and proteases activities, siderophores production, potato tissue maceration, as well as their motility.…”

“…They also possess features which allow for more effective colonization and faster spread through the plant vascular system than in the case of D. dianthicola (Czajkowski et al 2010). All previously characterized D. solani strains indicated identical rep-PCR and PFGE profiles (Degefu et al 2013;Tsror (Lahkim) et al 2013;van der Wolf et al 2014;Potrykus et al 2016). However, the comparison of genome sequences of several D. solani strains indicated the existence of some differences within the studied strains caused probably by the horizontal gene transfer (Khayi et al 2015).…”

“…Also, the strains of D. solani were isolated from potato plants with blackleg and soft rot symptoms in France, the Netherlands, Poland, Spain and Switzerland (Palacio-Bielsa et al 2006;Helias 2006;Czajkowski et al 2009;Slawiak et al 2009a;Toth et al 2011;Gill et al 2014;Potrykus et al 2016). Besides, Tsror et al (Tsor (Lahkim) et al 2009;Tsror (Lahkim) et al 2013) isolated D. solani strains from blackleg diseased potato plants in Israel. In the recent years, potato losses are caused, apart from the Dickeya strains, also by other pectinolytic bacteria known as tropical and subtropical pathogens, e.g. Pectobacterium wasabiae (Nabhan et al 2012;Waleron et al 2013), and Pectobacterium carotovorum subsp.…”

Cardinal temperature differences, determined in vitro, between closely related species and subspecies of pectinolytic bacteria responsible for blackleg and soft rot on potatoes

“…The broad temperature growth range and high optimal temperature of Dso make the warm South African climate ideal for establishment of this species. Tsror et al (2013) found Dso to be more virulent in the warmer environments of…”

“…Temperature plays an important role in pathogenicity differentiation of soft rot and blackleg pathogens (Pérombelon and Kelman 1980;Pérombelon et al 1987;Pérombelon 1992 (Pérombelon and Kelman 1980;Elphinstone 1987;Pérombelon et al 1987;Pérombelon 1992;Tsror et al 2009Tsror et al , 2013. Each of these blackleg and soft rot bacterial species, however, prefer specific temperatures at which they cause disease.…”