A large nested association mapping population for breeding and quantitative trait locus mapping in Ethiopian durum wheat.

The Ethiopian plateau hosts thousands of durum wheat (Triticum turgidum subsp. durum) farmer varieties (FV) with high adaptability and breeding potential. To harness their unique allelic diversity, we produced a large nested association mapping (NAM) population intercrossing fifty Ethiopian FVs with an international elite durum wheat variety (Asassa). The Ethiopian NAM population (EtNAM) is composed of fifty interconnected bi-parental families, totalling 6280 recombinant inbred lines (RILs) that represent both a powerful quantitative trait loci (QTL) mapping tool, and a large pre-breeding panel. Here, we discuss the molecular and phenotypic diversity of the EtNAM founder lines, then we use an array featuring 13 000 single nucleotide polymorphisms (SNPs) to characterize a subset of 1200 EtNAM RILs from 12 families. Finally, we test the usefulness of the population by mapping phenology traits and plant height using a genome wide association (GWA) approach. EtNAM RILs showed high allelic variation and a genetic makeup combining genetic diversity from Ethiopian FVs with the international durum wheat allele pool. EtNAM SNP data were projected on the fully sequenced AB genome of wild emmer wheat, and were used to estimate pairwise linkage disequilibrium (LD) measures that reported an LD decay distance of 7.4 Mb on average, and balanced founder contributions across EtNAM families. GWA analyses identified 11 genomic loci individually affecting up to 3 days in flowering time and more than 1.6 cm in height. We argue that the EtNAM is a powerful tool to support the production of new durum wheat varieties targeting local and global agriculture.

Determinants of iodine deficiency in school children in different regions of Ethiopia.

OBJECTIVE: To determine the magnitude of goitre in school children and measure indicators of iodine deficiency including the most commonly consumed staple foods. DESIGN: A cross-sectional study. SETTING: Ten villages from four administrative regions of Ethiopia. SUBJECTS: A total of 2485 randomly selected elementary school children were examined for clinical signs of goitre. Indicators of iodine deficiency disorders (IDD) assessed were urinary iodine excretion (UIE) rate, iodine concentration in water, the commonly consumed individual foods of plant origin and milk, and bacterial contamination of drinking water. RESULTS: The gross prevalence (mean of male and female values) among school children was 53.3%. The prevalence was higher in females (56.1%) than in males (50.8%). The highest prevalence (82 and 91%, respectively) were observed in the villages of Lotte and Kodowono and the lowest (31%) in the village of Abossara. Of the urinary measurements, 70% of the samples showed moderate and 30% mild iodine deficiency. Levels of iodine in water and individual food samples were low in general. Breast milk iodine content was similarly low and related to the maternal daily iodine intake which may affect the nutritional status of the nursing infant. The study also provides further evidence that coliforms and E. coli isolated from drinking water contribute to the high incidence of endemic goitre other than iodine deficiency. CONCLUSION: It is difficult to obtain a sufficient iodine intake in the survey villages as the individual foods are very low in the element. However, IDD can be prevented by ensuring normal iodine nutrition through instituting ways that avail iodinated salt to the survey population.