GWAS for Starch-Related Parameters in Japonica Rice (Oryza sativa L.).

Rice quality is mainly related to the following two starch components, apparent amylose content (AAC) and resistant starch (RS). The former affects grain cooking properties, while RS acts as a prebiotic. In the present study, a Genome Wide Association Scan (GWAS) was performed using 115 rice japonica accessions, including tropical and temperate genotypes, with the purpose of expanding the knowledge of the genetic bases affecting RS and AAC. High phenotypic variation was recorded for the two traits, which positively correlated. Moreover, both the parameters correlated with seed length (positive correlation) and seed width (negative correlation). A correlational selection according to human preferences has been hypothesized for the two starch traits and grain size. In addition, human selection has been proposed as the causal agent even for the different phenotypes related to starch and grain size showed by the tropical and temperate japonica accessions utilized in this study. The present GWAS led to the identification of 11 associations for RS on seven chromosomes and five associations for AAC on chromosome 6. Candidate genes and co-positional relationships with quantitative trait loci (QTLs) previously identified as affecting RS and AAC were identified for 6 associations. The candidate genes and the new RS- and/or AAC-associated regions detected provide valuable sources for future functional characterizations and for breeding programs aimed at improving rice grain quality.

Hydrothermal grain pre-processing and ultra-fine milling for the production of durum wheat flour fractions with high nutritional value.

This work describes a process for producing durum wheat flour fractions with high potential nutritional value using grain pre-milling hydrothermal treatment and ultra-fine grinding (micronization), coupled with air classification. The difference of bioactive value of the flour fractions in relation to dietary fibre and phenolic compounds was monitored on four durum wheat cultivars by analysing total arabinoxylans, water extractable arabinoxylans and 5- n-alkylresorcinols. The extractability of the analysed compounds was most significantly affected by hydrothermal treatment. On average, the hydrothermally treated kernels compared with the untreated ones presented a marked increase of water extractable arabinoxylans and alkylresorcinols (about 25 and 48%, respectively), whereas slightly lower total arabinoxylans content (about 9%) was detected. The air classification applied on micronized kernels produced two flour fractions, coarse and fine, with the last showing, irrespective of the hydrothermal treatment, an increment of alkylresorcinols (24 and 22% in untreated and treated samples) and of total arabinoxylans (13 and 20% in untreated and treated samples) in comparison with the coarse one. The fine fraction (particles ≤ 120 µm), resulting richer in bioactive compounds, provides an interesting raw material to enrich traditional semolina in which, due to the removal of the external layers, the losses of total arabinoxylans and of alkylresorcinols were more than 60 and 90% alkylresorcinols, respectively, if compared with whole wheat grain.

Effect of 5-n-alkylresorcinol extracts from durum wheat whole grain on the growth of fusarium head blight (FHB) causal agents.

In an approach toward the identification of ecofriendly compounds for fusarium head blight biocontrol, the in vitro antifungal activity of 5-n-alkylresorcinol (AR) extracts, obtained from durum wheat intact kernels, was tested. In comparison with ethyl acetate and acetone extracts containing AR, total inhibition of Fusarium graminearum spore germination was observed with cyclohexane extract, which also exhibited a significant fungistatic activity against F. graminearum, Fusarium culmorum, Fusarium avenaceum, and Fusarium poae. Additionally, the study of the influence of such variables as predrying of seeds and durum wheat genotype on AR cyclohexane extract properties allowed the association of its highest antifungal activity with the AR homologue composition and, in particular, with the presence of a higher C21:0/C23:0 ratio. The interesting finding of this study suggests a potential application of the AR homologues in crop protection systems and could be an important step toward the development of commercial formulations suitable to the prevention of fungal diseases.

Qualitative and quantitative determination of peptides related to celiac disease in mixtures derived from different methods of simulated gastrointestinal digestion of wheat products.

During wheat digestion, gluten-derived proteolytic resistant peptides are generated, some of them involved in celiac disease. In vitro digestion models able to mimic the peptides generated in the human gastrointestinal tract are extremely useful to assess the pathogenicity of wheat-derived products. In this paper, samples belonging to three different durum wheat varieties were taken at six different steps of the pasta production chain and two different digestion models present in the literature were assessed on the different samples: a more complex one using artificial fluids simulating the exact composition of digestive juices, and a simplified method based on a peptic-tryptic/chymotryptic treatment of wheat ethanolic extract. An extensive characterization of the peptides generated using two in vitro digestion models was performed through LC-MS/MS techniques and the two methods were compared in order to evaluate qualitative and quantitative differences and their possible implications for varietal screening. Strong differences in the type of peptides produced with the two methods were detected, indicating that the simplified method can still be used for a varietal screening but is not representative of the peptides really generated after physiological human digestion. Results indicate a clear necessity of physiologically accurate models for simulating human gastrointestinal digestion of wheat products.

Variations in content and extractability of durum wheat (Triticum turgidum L. var durum) Arabinoxylans associated with genetic and environmental factors.

Arabinoxylans (AX) represent the most abundant components of non-starch polysaccharides in wheat, constituting about 70% of cell wall polysaccharides. An important property of AX is their ability to form highly viscous water solutions; this peculiarity has a significant impact on the technological characteristics of wheat and determines the physiologically positive influence in consumption. Durum wheat (Triticum turgidum L. var durum), the raw material for pasta production, is one of the most important crops in Italy. As part of a large project aimed at improving durum wheat quality, the characterization of the nutritional and technological aspects of whole grains was considered. Particular attention was addressed to identify the best suited genotypes for the production of innovative types of pasta with enhanced functional and organoleptic properties. The objective of the present study was to investigate the genetic variability of AX by examining a group of durum wheat genotypes collected at two localities in Italy for two consecutive years. The environmental influence on AX content and extractability was also evaluated. Variability in the AX fraction contents was observed; the results indicated that AX fractions of durum wheat grain can be affected by the genotype and environment characteristics and the different contribution of genotype and environment to total variation was evidenced. The genotype × environment (G × E) interaction was significant for all examined traits, the variations due to G × E being lower than that of genotype or environment. The data and the statistical analysis allowed identification of the Italian durum wheat varieties that were consistently higher in total arabinoxilans; in addition, principal component analysis biplots illustrated that for arabinoxylan fractions some varieties responded differently in various environment climatic conditions.

Use of near infrared reflectance and transmittance coupled to robust calibration for the evaluation of nutritional value in naked oats.

A rapid accurate and precise method for simultaneous determination of ß-glucan and protein content in naked oat samples, based on the coupling of near-infrared spectroscopy and chemometrics, is presented. In particular, three different spectroscopic approaches [near infrared reflectance (NIR) and transmittance (NIT) on flour and NIT on whole grains] and various spectral pretreatments were considered. To account for the possibility of outlying samples, a robust version of the PLS algorithm (namely partial robust M-regression) was used. All the models resulted as accurate as the reference methods, reflectance spectroscopy being the technique providing the best outcomes. Variable reduction by inclusion of the most relevant predictors only (as evaluated by VIP scores) resulted in simpler and, in one case, more parsimonious models, without loss in accuracy.