Genetics of dietary fibre in bread wheat

Arabinoxylans (AX) are major components of cell walls in wheat endosperm. The water-extractable part, WEAX, is considered as dietary fibres with health promoting effects. AX exhibit large natural variations in their amount but few studies have been carried out on the genetics of WEAX content and structure in bread wheat. We first carried out a “forward” quantitative genetic approach, using two recombinant populations derived from crosses between WEAX-high and WEAX-low parents and the viscosity of flour extract (WEAX-viscosity) as a predictor of WEAX content. This allowed us to identify two QTL regions, one of them, found on chromosome 6B in both populations, having a major effect with as much as 59% of the phenotypic variation explained by a single QTL. Then, we focused on key enzymes involved in the biosynthetic pathway of arabinoxylans. Out of 34 homoeologous candidate genes studied by sequencing a set of 46 lines, representing a worldwide diversity179 show no polymorphism. In the 16 polymorphic candidate genes, 80 SNP (in 15 genes) and 16 indels (in 4 genes) were detected. Then 27 SNP (in 13 genes) were genotyped in a larger collection of 156 lines (Healthgrain diversity screen). Eight associations were significant at an indicative 5% threshold, but only one, between COMT (Caffeic acid O methyltransferase) on chromosome 7A and A/X in WEAX was significant at a 1% level. The usefulness of these approaches and preliminary results for breeding is discussed.     

Babesia microti-like parasites detected in feral raccoons (Procyon lotor) captured in Hokkaido, Japan

Raccoons (Procyon lotor), which have recently become feral in Japan, were examined for the presence of Babesia microti-like parasites. Out of 372 raccoons captured in the west-central part of Hokkaido, 24 animals with splenomegaly were selected and tested by nested PCR targeting the babesial 18S rRNA gene. B. microti-like parasites were detected in two of the 24 individuals, and their DNA sequences were identical to that of the B. microti-like parasite reported from raccoons in the United States, suggesting that the parasites were probably imported into Japan and that the life cycle of the parasite has already been established in the country. The potential risk of this B. microti-like parasite spreading among dogs and foxes in Japan will need to be carefully monitored, as parasitization by phylogenetically very close parasites has been reported from such animals.