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

Potato blackleg and soft rot cause major losses and are caused by two bacterial genera, Pectobacterium and Dickeya. Species affecting potatoes are Pectobacterium atrosepticum (Pba), Pectobacterium carotovorum subsp. carotovorum (Pcc), Pectobacterium carotovorum subsp. brasiliense (Pcb), Pectobacterium wasabiae (Pwa), Dickeya dadantii (Dda) and Dickeya solani (Dso). Pathogenicity of these species is dependent on temperature, with each species having its own optimal temperature and temperature range for growth, leading to varying degrees of losses. Pectobacterium atrosepticum, a temperature sensitive species, mainly occurs in temperate climates, Pcc in temperate to tropical, and Dickeya spp. in subtropical environments. The aim of this study was to determine the cardinal growth temperatures for the species responsible for blackleg and soft rot in vitro. Bacterial isolates were incubated in a temperature gradient shaking incubator at 30 different temperatures ranging from ±5 °C to ±56 °C, and growth measured at two set time intervals. Results were statistically analysed using the Gaussian function. The optimal temperature of 31 °C and temperature range of 20 °C to 38 °C for Pectobacterium carotovorum subsp. brasiliense, was similar to those recorded for Pcc. Pectobacterium wasabiae grew at an optimal temperature of 29 °C and range of 20 °C to 34 °C. Higher optimal temperatures of 32 °Cand 34 °C,with ranges of 21 °C to 38 °Cand 23 °C to 41 °C were recorded for Dda and Dso, respectively. The minimal variation in optimal temperatures between different species might be an indication that temperature ranges, rather than optimal temperature, play an important role in disease development. Results for Dso, which has not yet been reported in South Africa, are especially important in light of prevailing temperatures in South African potato production regions.Technology and Human Resources in Industry Programme (THRIP) and Potatoes South Africahttp://link.springer.com/journal/106582017-02-20hb201

Isolation, detection and characterization of Pectobacterium and Dickeya species

This chapter outlines isolation, detection and characterization methods for soft rot Pectobacteriaceae (SRP) and finishes with recommendations for diagnostics of SRP and perspectives for improved detection using metagenomic and pan-genomic approaches. For dilution plating and isolation of SRP, crystal violet pectate is still the medium of preference, although it is poorly selective. To improve the diagnostic sensitivity of detection methods, enrichment methods are used in which selective growth of the pathogen is enhanced by incubation in a pectate broth under low oxygen conditions. For molecular characterization, various finger printing techniques are described, but today analysis based on phylogenetic markers are preferred, in particular multi-locus sequence typing of housekeeping genes and comparative genetics using whole-genome sequences. For phenotypic characterization, methods are used based on serological, biochemical and physiological features. Currently the most precise phenotyping method is protein mass fingerprinting using a MALDI-TOF Mass Spectrometry. For detection of the pathogen, DNA-based amplification methods are generally used, including conventional PCR, real time (TaqMan) PCR assays and LAMP assays. They can detect the pathogen at a low density and allow recognition of the pathogens at different taxonomic levels. An inventory has been included of recently developed primer and probe combinations

Delayed recognition of Judah Folkman’s hypothesis on tumor angiogenesis: when a Prince awakens a Sleeping Beauty by self-citation

Judah Folkman is considered the father of angiogenesis research. However, his hypothesis on tumor angiogenesis initially met with considerable skepticism. Scientific resistance has been described in the sociology of science, and leads to delayed recognition of pioneering work. In bibliometrics, delayed recognition is characterized by papers referred to as “sleeping beauties”. Sleeping beauties do not achieve recognition in terms of citations until they are awakened a few years after their original publication. The study of sleeping beauties is necessary to understand scientific knowledge better. The present paper explores the extent to which the phenomenon of delayed recognition affected Folkman’s body of work by analyzing his scientific production and the citation life of his publications. Citation analysis shows that Folkman’s landmark paper published in 1971 is a sleeping beauty. Scientometric analysis was combined with a qualitative analysis of the Folkman case in order to shed light on the reasons behind this delayed recognition, and the awakening of the “Sleeping Beauty” by a “Prince”, thus attracting a lot of attention in terms of citations. Interestingly, the fact that Judah Folkman was one of the co-authors of the Prince paper challenges the practice of excluding self-citations when conducting bibliometric analysis. By continuously citing his own paper after years of sleep, Folkman demonstrated his persistence and belief in the importance of his theory. Constancy and continuity in research are important components in ensuring the acceptance of unpopular hypotheses and the development of new research fields

Diseases Caused by Pectobacterium and Dickeya Species Around the World

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Pectobacterium and Dickeya: Environment to Disease Development

The soft rot Pectobacteriaceae (SRP) infect a wide range of plants worldwide and cause economic damage to crops and ornamentals but can also colonize other plants as part of their natural life cycle. They are found in a variety of environmental niches, including water, soil and insects, where they may spread to susceptible plants and cause disease. In this chapter, we look in detail at the plants colonized and infected by these pathogens and at the diseases and symptoms they cause. We also focus on where in the environment these organisms are found and their ability to survive and thrive there. Finally, we present evidence that SRP may assist the colonization of human enteric pathogens on plants, potentially implicating them in aspects of human/animal as well as plant health