Genetic and Environmental Variation in Starch Content, Starch Granule Distribution and Starch Polymer Molecular Characteristics of French Bread Wheat.

This study investigates genetic and environmental variation in starch content and characteristics of 14 French bread cultivars. Understanding the impact of these factors on wheat quality is important for processors and especially bakers to maintain and meet the requirements of industrial specifications. Different traits were evaluated: starch content, distribution of starch granules, percentage of amylose and amylopectin and their molecular characteristics (weight-average molar mass, number-average molar mass, polydispersity and gyration radius). Genetic, environment and their interaction had significant effects on all parameters. The relative magnitude of variance attributed to growth conditions, for most traits, was substantially higher (21% to 95%) than that attributed to either genotype (2% to 73%) or G × E interaction (2% to 17%). The largest environmental contribution (95%) to total variance was found for starch dispersity. The highest genetic influence was found for the percentage of A-type starch granules. G × E interaction had relatively little influence (≈7%) on total phenotypic variance. All molecular characteristics were much more influenced by environment than the respective percentages of amylose and amylopectin were. This huge difference in variance between factors obviously revealed the importance of the effect of growing conditions on characteristics of cultivars.

Efficient models for predicting durum wheat grain Cd conformity using soil variables and cultivars.

Contamination of durum wheat grain by cadmium (Cd) threatens food safety and is of increasing concern because regulations concerning Cd are becoming stricter due to its toxicity. This work aimed at using soil variables and cultivar types to build models to predict whether durum wheat grain Cd will conform with current and possibly lower regulatory thresholds. We combined multiple Gaussian and logistic regressions and the random forest algorithm to take advantage of their strength. Models tested using cross-validation produced excellent performances including for the lowest regulatory threshold of 0.1 mg Cd/kg, half of the current one: 79-85% of the non-conformity cases were detected and the reliability of predictions was 69-82%. The models enabled identification of a x1.4 variability in grain Cd content between cultivars that do not have the low Cd accumulation allele of the Cdu1 gene. The models confirmed that for the grain Cd content, the between-cultivar variability had much less influence than the phytoavailability of Cd in soil, the critical contexts of which were characterized by the models. For farmers, these models are valuable tools to predict whether durum wheat production will conform with existing and future Cd regulation in foodstuffs.

Fusarium species and enniatin mycotoxins in wheat, durum wheat, triticale and barley harvested in France.

Contamination with enniatins A, A1, B and B1 was investigated in 1240 samples of small grain cereals (470 wheat, 260 durum wheat, 282 spring barley, 172 triticale and 56 winter barley) from the French harvests of 2012 to 2014. Associations with Fusarium avenaceum, F. tricinctum and F. poae were assessed, with the identification of Fusarium species by real-time PCR and mycotoxin quantification by LC-MS/MS. Enniatins were common in the fields sampled. Enniatin concentrations varied between years but were consistently highest on spring barley (mean values of 199 to 1316 µg/kg) and triticale (mean values from 131 to 1218 µg/kg), and lower on wheat (mean values from 47 to 142 µg/kg) and durum wheat (mean values from 55 to 596 µg/kg). The concentrations of the various enniatins were strongly correlated with each other (Pearson's correlation coefficient of 0.61 to 0.98). Enniatin B was the most frequent (68% of the total enniatin content), followed by enniatin B1 (22%), enniatin A1 (7%) and enniatin A (3%). Fusarium species were quantified by calculating arithmetic mean total DNA levels. F. tricinctum was the most abundant (0.177 pg/ng total DNA), followed by F. avenaceum (0.141 pg/ng total DNA) and F. poae (0.091 pg/ng total DNA). Total DNA levels for each species, and the predominant species varied between years and crops. Small grain cereal species (p value < 0.001), harvest year (p value = < 0.001) and the presence of F. avenaceum (p value < 0.001), F. tricinctum (p value < 0.001) or F. poae (p value = 0.017) affected enniatin content. F. tricinctum was the leading enniatin producer on durum wheat (29% to 45%) and spring barley (23 to 37%). F. avenaceum produced large amounts of enniatins on durum wheat (13% to 17%) and wheat (1% to 18%) and was the leading producer on triticale (30% to 55%). F. poae made a minor contribution on all crops, never accounting for more than 2% of total enniatin content. Enniatins are, thus, highly prevalent in French small grain cereals and are mostly produced by F. avenaceum and F. tricinctum.