The effect of β-aminobutyric acid (BABA) on root knot nematode and soft rot pathogen disease complexes in Solanum tuberosum plants

The efficacy of three elicitors, DL-β-aminobutyric acid (BABA), Acibenzolar-S-methyl (Bion) and Messenger (Harpin) on potato plants inoculated with Meloidogyne incognita second stage juveniles (J2s) was investigated in this study. The efficacy of each elicitor was evaluated based on galling index, egg numbers, total root knot nematode (RKN) population numbers, number of juveniles and the percentage of females in respective extracted populations per treatment at 28 and 56 dpi. There was a significant decrease in galling indices of all treated compared to untreated control plants. The highest percentage reduction was observed for 20 mM BABA-treated plants (33%) followed by 5mM BABA (23%), 50mg/L Bion (18%), 100mg/L Bion (15%) and Messenger (8%). The number of eggs extracted from plants treated with 20mM BABA was significantly lower (66%) compared to untreated controls. Furthermore, treating plants with 20mM BABA decreased the total RKN population numbers by 55% whilst the decrease observed for Bion and Messenger was between 24-39%. Of the three tested elicitors, 20mM BABA was found to be the most effective elicitor at both 28 and 56 dpi. Hence, it was selected for further testing against RKN and Pectobacterium carotovorum subsp. brasiliense (Pcb) disease complex. Efficacy was tested by comparing the colony forming units (cfu) of Pcb from treated and untreated control plants inoculated with M. incongita and Pcb simultaneously. The concentration of Pcb from untreated plants inoculated with both pathogens was significantly higher (3.3 × 103cfu/ml) compared to their treated counterparts (8.71 × 102cfu/ml). This suggests that BABA has the potential to decrease soft rot bacterial infections in RKN disease complexes by decreasing the rate of RKN infection. This is the first report where BABA is shown to decrease the infection rate of RKN as a primary causal agent in combination with a secondary pathogen.National Research Foundation, South Africa. AM received NRF Innovative and Potatoes South Africa Development Fund bursaries.http://link.springer.com/journal/106582016-05-21hb201

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

Bowel intussusceptions in adults: the role of imaging

Intestinal intussusception in adults is a rare condition, accounting for about 0.003-0.02 % of all hospital admissions. This condition in adults represents only 5 % of all cases of intussusceptions and is different from paediatric intussusception, which is usually idiopathic. In contrast, almost 90 % of cases in adults are secondary to various pathologies that serve as a lead point, such as polyps, Meckel's diverticulum, colonic diverticulum, or malignant or benign neoplasm. The aim of the present study was to assess the capabilities of multislice computed tomography (MSCT) in the diagnosis and correct characterisation of intussusception, especially in distinguishing between intussusceptions with a lead point and those without. Indeed, although the MSCT findings that help to differentiate between lead point and non-lead point intussusceptions have not been well studied, abdominal MSCT remains the most sensitive radiological tool to confirm bowel intussusceptions. Moreover, differentiating intussusceptions with a lead point condition from those without is crucial for directing the patient towards the most appropriate treatment, avoiding surgery when not necessary