Domestication and breeding have influenced the genetic structure of plant populations due to selection for adaptation from natural habitats to agro-ecosystems. Here, we investigate the effects of selection on the contents of 51 primary kernel metabolites and their relationships in three Triticum turgidum L. subspecies (i.e., wild emmer, emmer, durum wheat) that represent the major steps of tetraploid wheat domestication. We present a methodological pipeline to identify the signature of selection for molecular phenotypic traits (e.g., metabolites and transcripts). Following the approach, we show that a reduction in unsaturated fatty acids was associated with selection during domestication of emmer (primary domestication). We also show that changes in the amino acid content due to selection mark the domestication of durum wheat (secondary domestication). These effects were found to be partially independent of the associations that unsaturated fatty acids and amino acids have with other domestication-related kernel traits. Changes in contents of metabolites were also highlighted by alterations in the metabolic correlation networks, indicating wide metabolic restructuring due to domestication. Finally, evidence is provided that wild and exotic germplasm can have a relevant role for improvement of wheat quality and nutritional traits.

Abstract:Fermented foods and beverages are a heterogeneous class of products with a relevant worldwide significance for human economy, nutrition and health for millennia. A huge diversity of microorganisms is associated with the enormous variety in terms of raw materials, fermentative behavior and obtained products. In this wide microbiodiversity it is possible that the presence of microbial pathogens and toxic by-products of microbial origin, including mycotoxins, ethyl carbamate and biogenic amines, are aspects liable to reduce the safety of the consumed product. Together with other approaches (e.g., use of preservatives, respect of specific physico-chemical parameters), starter cultures technology has been conceived to successfully dominate indigenous microflora and to drive fermentation to foresee the desired attributes of the matrix, assuring quality and safety. Recent trends indicate a general return to spontaneous food fermentation. In this review, we point out the potential risks for human health associated with uncontrolled (uninoculated) food fermentation and we discuss biotechnological approaches susceptible to conciliate fermented food safety, with instances of an enhanced contribution of microbes associated to spontaneous fermentation.Keywords: fermented food; fermentation; beverage; safety; risks; spontaneous fermentation; starter cultures; spoilage microbes; pathogens; contaminant Fermented Foods and Beverages: Scientific Dimension, Social Relevance, and Economic SignificanceA large basket of food and beverages is obtained from a microbial-based transformation of food raw materials. Different classes of microorganisms can be involved, mainly yeasts and bacteria, with a certain role of molds. The obtained fermented foods and beverages have ben staple foods for millennia, with a considerable importance in the human diet for reasons of generally enhanced shelf-life, palatability, safety and nutritional quality [1]. In fact, the desired fermentation process consists of protechnological microbial development in the given matrix, with direct and indirect effects of primary and secondary microbial metabolism. Protechnological microorganisms, in order to obtain energy and to sustain their anabolic processes, reduce the content of carbohydrates and other macromolecules available in the raw matrix, accumulating catabolic products (e.g., lactic acid, ethanol). These biological dynamics, together with the possible release of antimicrobial compounds [2], reduce the risks of undesired microbial developments (thus increasing product shelf-life and safety level). On the other hand, both primary and secondary metabolites strongly influence palatability

Domestication has induced major genetic changes in crop plants to satisfy human needs and as a consequence of adaptation to agroecosystems. This adaptation might have affected root exudate composition, which can influence the interactions in the rhizosphere. Here, using two different soil types (sand, soil), we provide an original example of the impact of domestication and crop evolution on root exudate composition through metabolite profiling of root exudates for a panel of 10 wheat genotypes that correspond to the key steps in domestication of tetraploid wheat (wild emmer, emmer, durum wheat). Our data show that soil type can dramatically affect the composition of root exudates in the rhizosphere. Moreover, the composition of the rhizosphere metabolites is associated with differences among the genotypes of the wheat domestication groups, as seen by the high heritability of some of the metabolites. Overall, we show that domestication and breeding have had major effects on root exudates in the rhizosphere, which suggests the adaptive nature of these changes.

The process of domestication has led to dramatic morphological and physiological changes in crop species due to adaptation to cultivation and to the needs of farmers. To investigate the phenotypic architecture of shoot- and root-related traits and quantify the impact of primary and secondary domestication, we examined a collection of 36 wheat genotypes under optimal and nitrogen-starvation conditions. These represented three taxa that correspond to key steps in the recent evolution of tetraploid wheat (i.e. wild emmer, emmer, and durum wheat). Overall, nitrogen starvation reduced the shoot growth of all genotypes, while it induced the opposite effect on root traits, quantified using the automated phenotyping platform GROWSCREEN-Rhizo. We observed an overall increase in all of the shoot and root growth traits from wild emmer to durum wheat, while emmer was generally very similar to wild emmer but intermediate between these two subspecies. While the differences in phenotypic diversity due to the effects of primary domestication were not significant, the secondary domestication transition from emmer to durum wheat was marked by a large and significant decrease in the coefficient of additive genetic variation. In particular, this reduction was very strong under the optimal condition and less intense under nitrogen starvation. Moreover, although under the optimal condition both root and shoot traits showed significantly reduced diversity due to secondary domestication, under nitrogen starvation the reduced diversity was significant only for shoot traits. Overall, a considerable amount of phenotypic variation was observed in wild emmer and emmer, which could be exploited for the development of pre-breeding strategies.

The objectives of this study were to determine the pattern of dry matter (DM) accumulation and the evolution of phenolic compounds in the rhizosphere soil from tillering to the ripe seed stages of wild oat (Avena fatua L.), a widespread annual grassy weed. Plants were grown under controlled conditions and harvested 13 times during the growing season. At each harvest, shoot and root DM and phenolic compounds in the rhizosphere soil were determined. The maximum DM production (12.6 g/plant) was recorded at 122 days after sowing (DAS; kernel hard stage). The increase in total aerial DM with age coincided with reductions in the leaf/stem and source/sink ratios, and an increase in the shoot/root ratio. HPLC analysis shows production of seven phenolic compounds in the rhizosphere soil of wild oat, in order of their decreasing levels: syringic acid, vanillin, 4-hydroxybenzoic acid, syringaldehyde, ferulic acid, p-cumaric acid and vanillic acid. The seasonal distribution for the total phenolic compounds showed two peaks of maximum concentrations, at the stem elongation stage (0.71 μg/kg; 82 DAS) and at the heading stage (0.70 μg/kg; 98 DAS). Thus, wild oat roots exude allelopathic compounds, and the levels of these phenolics in the rhizosphere soil vary according to plant maturity.

Climate change threatens food systems, with huge repercussions on food security and on the safety and quality of final products. We reviewed the potential of food microbiology as a source of biotechnological solutions to design climate-smart food systems, using wine as a model productive sector. Climate change entails considerable problems for the sustainability of oenology in several geographical regions, also placing at risk the wine typicity. The main weaknesses identified are: (i) The increased undesired microbial proliferation; (ii) the improved sugars and, consequently, ethanol content; (iii) the reduced acidity and increased pH; (iv) the imbalanced perceived sensory properties (e.g., colour, flavour); and (v) the intensified safety issues (e.g., mycotoxins, biogenic amines). In this paper, we offer an overview of the potential microbial-based strategies suitable to cope with the five challenges listed above. In terms of microbial diversity, our principal focus was on microorganisms isolated from grapes/musts/wines and on microbes belonging to the main categories with a recognized positive role in oenological processes, namely Saccharomyces spp. (e.g., Saccharomyces cerevisiae), non-Saccharomyces yeasts (e.g., Metschnikowia pulcherrima, Torulaspora delbrueckii, Lachancea thermotolerans, and Starmerella bacillaris), and malolactic bacteria (e.g., Oenococcus oeni, Lactobacillus plantarum).

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Durum wheat (Triticum turgidum (L.) subsp. turgidum (L.) convar. durum (Desf.)) is momentous for human nutrition, and environmental stresses can strongly limit the expression of yield potential and affect the qualitative characteristics of the grain. The aim of this study was to determine how heat stress (five days at 37 °C) applied five days after flowering affects the nutritional composition, antioxidant capacity and metabolic profile of the grain of two durum wheat genotypes: “Primadur”, an elite cultivar with high yellow index, and “T1303”, an anthocyanin-rich purple cultivar. Qualitative traits and metabolite evaluation (by gas chromatography linked to mass spectrometry) were carried out on immature (14 days after flowering) and mature seeds. The effects of heat stress were genotype-dependent. Although some metabolites (e.g., sucrose, glycerol) increased in response to heat stress in both genotypes, clear differences were observed. Following the heat stress, there was a general increase in most of the analyzed metabolites in “Primadur”, with a general decrease in “T1303”. Heat shock applied early during seed development produced changes that were observed in immature seeds and also long-term effects that changed the qualitative and quantitative parameters of the mature grain. Therefore, short heat-stress treatments can affect the nutritional value of grain of different genotypes of durum wheat in different ways.