Genomic regions of durum wheat involved in water productivity

Durum wheat is a staple food in the Mediterranean Basin, mostly cultivated under rainfed conditions. As such, the crop is often exposed to moisture stress. Therefore, the identification of genetic factors controlling the capacity of genotypes to convert moisture into grain yield (i.e., water productivity) is quintessential to stabilize production despite climatic variations. A global panel of 384 accessions was tested across 18 Mediterranean environments (in Morocco, Lebanon, and Jordan) representing a vast range of moisture levels. The accessions were assigned to water responsiveness classes, with genotypes 'Responsive to Low Moisture' reaching an average +1.5 kg ha-1 mm-1 yield advantage. Genome wide association studies revealed that six loci explained most of this variation. A second validation panel tested under moisture stress confirmed that carrying the positive allele at three loci on chromosomes 1B, 2A, and 7B generated an average water productivity gain of +2.2 kg ha-1 mm-1. These three loci were tagged by kompetitive allele specific PCR (KASP) markers, and these were used to screen a third independent validation panel composed of elites tested across moisture stressed sites. The three KASP combined predicted up to 10% of the variation for grain yield at 60% accuracy. These loci are now ready for molecular pyramiding and transfer across cultivars to improve the moisture conversion of durum wheat.

Genomic regions involved in the control of 1,000-kernel weight in wild relative-derived populations of durum wheat

Terminal drought is one of the most common and devastating climatic stress factors affecting durum wheat (Triticum durum Desf.) production worldwide. The wild relatives of this crop are deemed a vast potential source of useful alleles to adapt to this stress. A nested association mapping (NAM) panel was generated using as a recurrent parent the Moroccan variety 'Nachit' derived from Triticum dicoccoides and known for its large grain size. This was recombined to three top-performing lines derived from T. dicoccoides, T. araraticum, and Aegilops speltoides, for a total of 426 inbred progenies. This NAM was evaluated across eight environments (Syria, Lebanon, and Morocco) experiencing different degrees of terminal moisture stress over two crop seasons. Our results showed that drought stress caused on average 41% loss in yield and that 1,000-kernel weight (TKW) was the most important trait for adaptation to it. Genotyping with the 25K TraitGenetics array resulted in a consensus map of 1,678 polymorphic SNPs, spanning 1,723 cM aligned to the reference 'Svevo' genome assembly. Kinship distinguished the progenies in three clades matching the parent of origin. A total of 18 stable quantitative trait loci (QTLs) were identified as controlling various traits but independent from flowering time. The most significant genomic regions were named Q.ICD.NAM-04, Q.ICD.NAM-14, and Q.ICD.NAM-16. Allelic investigation in a second germplasm panel confirmed that carrying the positive allele at all three loci produced an average TKW advantage of 25.6% when field-tested under drought conditions. The underlying SNPs were converted to Kompetitive Allele-Specific PCR (KASP) markers and successfully validated in a third germplasm set, where they explained up to 19% of phenotypic variation for TKW under moisture stress. These findings confirm the identification of critical loci for drought adaptation derived from wild relatives that can now be readily exploited via molecular breeding.

Combining QTL Analysis and Genomic Predictions for Four Durum Wheat Populations Under Drought Conditions

Durum wheat is an important crop for the human diet and its consumption is gaining popularity. In order to ensure that durum wheat production maintains the pace with the increase in demand, it is necessary to raise productivity by approximately 1.5% per year. To deliver this level of annual genetic gain the incorporation of molecular strategies has been proposed as a key solution. Here, four RILs populations were used to conduct QTL discovery for grain yield (GY) and 1,000 kernel weight (TKW). A total of 576 individuals were sown at three locations in Morocco and one in Lebanon. These individuals were genotyped by sequencing with 3,202 high-confidence polymorphic markers, to derive a consensus genetic map of 2,705.7 cM, which was used to impute any missing data. Six QTLs were found to be associated with GY and independent from flowering time on chromosomes 2B, 4A, 5B, 7A and 7B, explaining a phenotypic variation (PV) ranging from 4.3 to 13.4%. The same populations were used to train genomic prediction models incorporating the relationship matrix, the genotype by environment interaction, and marker by environment interaction, to reveal significant advantages for models incorporating the marker effect. Using training populations (TP) in full sibs relationships with the validation population (VP) was shown to be the only effective strategy, with accuracies reaching 0.35–0.47 for GY. Reducing the number of markers to 10% of the whole set, and the TP size to 20% resulted in non-significant changes in accuracies. The QTLs identified were also incorporated in the models as fixed effects, showing significant accuracy gain for all four populations. Our results confirm that the prediction accuracy depends considerably on the relatedness between TP and VP, but not on the number of markers and size of TP used. Furthermore, feeding the model with information on markers associated with QTLs increased the overall accuracy.

How to design nutritional intervention trials to slow cognitive decline in apparently healthy populations and apply for efficacy claims: a statement from the International Academy on Nutrition and Aging Task Force

Interventions are crucial as they offer simple and inexpensive public health solutions that will be useful over the long term use. A Task Force on designing trials of nutritional interventions to slow cognitive decline in older adults was held in Toulouse in September 2012. The aim of the Task Force was to bring together leading experts from academia, the food industry and regulatory agencies to determine the best trial designs that would enable us to reach our goal of maintaining or improving cognitive function in apparently healthy aging people. An associated challenge for this Task Force was to determine the type of trials required by the Public Food Agencies for assessing the impact of nutritional compounds in comparison to well established requirements for drug trials. Although the required quality of the study design, rationale and statistical analysis remains the same, the studies designed to show reduction of cognitive decline require a long duration and the objectives of this task force was to determine best design for these trials. Two specific needs were identified to support trials of nutritional interventions: 1- Risk- reduction strategies are needed to tackle the growing burden of cognitive decline that may lead to dementia, 2- Innovative study designs are needed to improve the quality of these studies.

[A descriptive analysis of naratriptan use among migraineurs in ambulatory medicine]

The objective of this study was to provide an epidemiological description of naratriptan use in ambulatory medicine. 1695 patients were recruited by 384 primary care physicians and 111 neurologists, and followed for 12 weeks. Physicians had to document the migraine history, and to report symptoms and health care in a structured case report form. Patients were to document each episode of migraine (EM) in a diary. At baseline, 45 p.cent of the patients reported their migraine treatment as unsatisfactory. Ninety-eight percent of included patients were migraineurs according to criteria of the International Headache Society (IHS), including migrainous disorders. Ninety-two percent of naratriptan prescriptions were established in the second intention in patients with migraine, according to the IHS classification, including migrainous disorders. A total of 79 p.cent of patients had complied with the good practices for all EMs. More appropriate health education strategies should target the small group of patients who over-use naratriptan, and patients with aura. However, this study shows that naratriptan tends to be correctly prescribed by physicians, and used by patients with acute migraine.

There are some benefits for eradicating Helicobacter pylori in patients with non-ulcer dyspepsia

BACKGROUND

The relationship between Helicobacter pylori infection and non-ulcer dyspepsia is not established.

AIM

To determine whether eradication of H. pylori might be of benefit in non-ulcer dyspepsia patients.

METHODS

We randomly assigned 129 H. pylori infected patients with severe epigastric pain, without gastro-oesophageal reflux symptoms, to receive twice daily treatment with 300 mg of ranitidine, 1000 mg of amoxicillin, and 500 mg of clarithromycin for 7 days and 124 such patients to receive identical-appearing placebos.

RESULTS

Treatment was successful (decrease of symptoms at 12 months) in 62% of patients in the active-treatment group and in 60% of the placebo group (N.S.). At 12 months, the rate of eradication of H. pylori was 69% in the active-treatment group and 18% in the placebo group (P < 0.001). Complete relief of symptoms occurred significantly more frequently in patients on the active treatment (43%) than in placebo-treated patients (31%, P=0.048). Within the active-treatment group, therapeutic success was significantly more frequent in the non-infected patients (84% vs. 64%, P=0.04).

CONCLUSIONS

Although eradicating H. pylori is not likely to relieve symptoms in the majority of patients with non-ulcer dyspepsia, a small proportion of H. pylori-infected patients may benefit from eradication treatment.

[Acid suppression therapy is not required after one-week anti-Helicobacter pylori triple therapy for duodenal ulcer healing]

AIM

To compare healing of Helicobacter pylori-related non complicated duodenal ulcer after one-week eradication triple therapy alone and after triple therapy with further 3-weeks antisecretory treatment with ranitidine.

METHODS

Three hundred and forty three patients with symptomatic H. pylori positive duodenal ulcer were included in this randomized double-blind placebo controlled study. H. pylori infection was established by rapid urease test and histopathology of antral biopsies. All patients were treated for one week with ranitidine 300 mg b.i.d., amoxicillin 1 g b.i.d., clarithromycin 500 mg b.i.d., and then randomly treated for the following 3 weeks either with ranitidine 300 mg once daily (triple therapy + ranitidine, n =180) or placebo (triple therapy alone, n =163). Ulcer healing was assessed by endoscopy 4 weeks after inclusion. H. pylori eradication was established by (13) C-urea breath testing 5 weeks after the end of triple therapy.

RESULTS

In intention to treat, duodenal ulcer healed at 4 weeks in 86 % of patients treated with triple therapy + ranitidine and in 83 % of patients treated with triple therapy alone (equivalence: 90 % CI [-3. 8 %; 9.2 %]). The H. pylori eradication rates were 67 % and 69 % respectively. Ulcer healed in 88 % of patients in whom H. pylori eradication was achieved and in 77 % of patients in whom eradication failed.

CONCLUSION

These results demonstrate that one-week triple therapy alone is highly effective in healing non complicated H. pylori associated duodenal ulcer without additional antisecretory treatment.