Andean potato cultivars (Solanum tuberosum L.) as a source of antioxidant and mineral micronutrients

Potato tubers were evaluated as a source of antioxidants and minerals for the human diet. A genetically diverse sample of Solanum tuberosum L. cultivars native to the Andes of South America was obtained from a collection of nearly 1000 genotypes using microsatellite markers. This size-manageable collection of 74 landraces, representing at best the genetic diversity among potato germplasm, was analyzed for iron, zinc, calcium, total phenolic, total carotenoid, and total vitamin C contents. The hydrophilic antioxidant capacity of each genotype was also measured using the oxygen radical absorbance capacity (ORAC) assay. The iron content ranged from 29.87 to 157.96 microg g-1 of dry weight (DW), the zinc content from 12.6 to 28.83 microg g-1 of DW, and the calcium content from 271.09 to 1092.93 microg g-1 of DW. Total phenolic content varied between 1.12 and 12.37 mg of gallic acid equiv g-1 of DW, total carotenoid content between 2.83 and 36.21 microg g-1 of DW, and total vitamin C content between 217.70 and 689.47 microg g-1 of DW. The range of hydrophilic ORAC values was 28.25-250.67 micromol of Trolox equiv g-1 of DW. The hydrophilic antioxidant capacity and the total phenolic content were highly and positively correlated (r = 0.91). A strong relationship between iron and calcium contents was also found (r = 0.67). Principal component analysis on the studied nutritional contents of the core collection revealed that most potato genotypes were balanced in terms of antioxidant and mineral contents, but some of them could be distinguished by their high level in distinct micronutrients. Correlations between the micronutrient contents observed in the sample and the genetic distances assessed by microsatellites were weakly significant. However, this study demonstrated the wide variability of health-promoting micronutrient levels within the native potato germplasm as well as the significant contribution that distinct potato tubers may impart to the intake in dietary antioxidants, zinc, and iron.     

Identification of the crayfish plague fungus Aphanomyces astaci by polymerase chain reaction and restriction enzyme analysis

To characterise the DNA of the crayfish plague fungus Aphanomyces astaci, Saprolegniales (Oomycetes), primers were developed to amplify a 1050bp segment of the 28S rDNA region. Restriction enzymes were applied to the amplicon obtained, to distinguish A. astaci from 12 fungal species belonging also to the Saprolegniales and five more distantly related fungi. Most of the fungal species included in the study are either known parasites of freshwater crayfish cuticle or can be found in their natural environment. A. astaci DNA was distinguishable from the DNA of other fungal species tested by using the primers developed plus restriction enzymes AluI, HindIII and AvaI.Prior to this study, methods for A. astaci-species determination, e.g. spore production and infection experiments, required a protracted period to yield results; the method described in this study is quicker.