Infrared Thermography Monitoring of Durum and Common Wheat for Adaptability Assessing and Yield Performance Prediction

Wheat is one of the most cultivated cereals thanks to both its nutritional value and its versatility to technological transformation. Nevertheless, the growth and yield of wheat, as well as of the other food crops, can be strongly limited by many abiotic and biotic stress factors. To face this need, new methodological approaches are required to optimize wheat cultivation from both a qualitative and quantitative point of view. In this context, crop analysis based on imaging techniques has become an important tool in agriculture. Thermography is an appealing method that represents an outstanding approach in crop monitoring, as it is well suited to the emerging needs of the precision agriculture management strategies. In this work, we performed an on-field infrared monitoring of several durum and common wheat varieties to evaluate their adaptability to the internal Mediterranean area chosen for cultivation. Two new indices based on the thermal data useful to estimate the agronomical response of wheat subjected to natural stress conditions during different phenological stages of growth have been introduced. The comparison with some productive parameters collected at harvest highlighted the correlation of the indices with the wheat yield (ranging between p < 0.001 and p < 0.05), providing interesting information for their early prediction.

A conditional mutation in a wheat (Triticum aestivum L.) gene regulating root morphology

KEY MESSAGE

Characterisation and genetic mapping of a key gene defining root morphology in bread wheat. Root morphology is central to plants for the efficient uptake up of soil water and mineral nutrients. Here we describe a conditional mutant of hexaploid wheat (Triticum aestivum L.) that when grown in soil with high Ca2+ develops a larger rhizosheath accompanied with shorter roots than the wild type. In wheat, rhizosheath size is a reliable surrogate for root hair length and this was verified in the mutant which possessed longer root hairs than the wild type when grown in high Ca2+ soil. We named the mutant Stumpy and showed it to be due to a single semi-dominant mutation. The short root phenotype at high Ca2+ was due to reduced cellular elongation which might also explain the long root hair phenotype. Analysis of root cell walls showed that the polysaccharide composition of Stumpy roots is remodelled when grown at non-permissive (high) Ca2+ concentrations. The mutation mapped to chromosome 7B and sequencing of the 7B chromosomes in both wild type and Stumpy identified a candidate gene underlying the Stumpy mutation. As part of the process to determine whether the candidate gene was causative, we identified wheat lines in a Cadenza TILLING population with large rhizosheaths but accompanied with normal root length. This finding illustrates the potential of manipulating the gene to disconnect root length from root hair length as a means of developing wheat lines with improved efficiency of nutrient and water uptake. The Stumpy mutant will be valuable for understanding the mechanisms that regulate root morphology in wheat.

Environment-oriented selection criteria to overcome controversies in breeding for drought resistance in wheat

Wheat is one of the most important cereal crops, representing a fundamental source of calories and protein for the global human population. Drought stress (DS) is a widespread phenomenon, already affecting large wheat-growing areas worldwide, and a major threat for cereal productivity, resulting in consistent losses in average grain yield (GY). Climate change is projected to exacerbate DS incidence and severity by increasing temperatures and changing rainfall patterns. Estimating that wheat production has to substantially increase to guarantee food security to a demographically expanding human population, the need for breeding programs focused on improving wheat drought resistance is manifest. Drought occurrence, in terms of time of appearance, duration, frequency, and severity, along the plant's life cycle varies significantly among different environments and different agricultural years, making it difficult to identify reliable phenological, morphological, and functional traits to be used as effective breeding tools. The situation is further complicated by the presence of confounding factors, e.g., other concomitant abiotic stresses, in an open-field context. Consequently, the relationship between morpho-functional traits and GY under water deficit is often contradictory; moreover, controversies have emerged not only on which traits are to be preferred, but also on how one specific trait should be desired. In this review, we attempt to identify the possible causes of these disputes and propose the most suitable selection criteria in different target environments and, thus, the best trait combinations for breeders in different drought contexts. In fact, an environment-oriented approach could be a valuable solution to overcome controversies in identifying the proper selection criteria for improving wheat drought resistance.

Wheat Germ and Lipid Oxidation: An Open Issue

Wheat germ (WG)’s shelf life after the milling process is incredibly short because of the presence of enzymes that aggravate the oxidation process; thus, stabilization is required in order to exploit the nutrients and bioactive compounds within WG. The critical point for the oxidation process is the mechanical treatment used to separate WG from the kernel, which exposes the lipid fraction to the air. Showing the connection between the quality of durum wheat, considering its storage management, and wheat germ oil (WGO), extracted with a cold press, solvent and supercritical CO₂, is the aim of the study. The acidity and peroxide values were analyzed to evaluate lipid oxidation, while fatty acids, tocols, sterols and policosanols were evaluated for WGO characterization. The first fundamental step to control lipid oxidation is raw material management. Subsequently, the tempering phase of durum wheat, which is applied before the degermination process, is the most critical point for oxidation to develop because of the increase in moisture in the caryopsis and the activation of lipase and lipoxygenase. This represents a paradox: in order to stabilize the germ with degermination, first it seems inevitable to carry out a process that destabilizes it. To retains its highest quality, this will lead to a better use of the whole grain by reducing WG and by-product waste.

Assessment of the efficacy of slow-release formulations of the tribenuron-methyl herbicide in field-grown spring wheat

The efficacy of slow-release formulations of tribenuron-methyl (TBM) embedded in the matrix of degradable poly(3-hydroxybutyrate) blended with birch wood flour [polymer/wood flour/herbicide 50/30/20 wt.%] was compared with the efficacy of TBM as the active ingredient of the Mortira commercial formulation, which was applied as post-emergence spray to treat spring wheat cv. Novosibirskaya 15. The study was conducted in Central Siberia (in the environs of the city of Krasnoyarsk, Russia) from May to August 2020. The biological efficacy of the embedded TBM was 92.3%, which was considerably higher than the biological efficacy of the Mortira formulation used as the post-emergence spray (15.4%). The embedding of TBM into degradable blended matrix enabled long-duration functioning of this unstable herbicide in soil. The sensitivity of weed plants to TBM differed depending on the species. TBM was more effective against A. retroflexus and A. blitoides, which were killed at an earlier stage, than against C. album and G. aparine, whose percentage increased in the earlier stage and which were controlled by the herbicide less effectively and at later stages. On the plot treated with the embedded herbicide, the parameters of the wheat yield structure were the best, and the total yield was the highest: 3360 ± 40 kg/ha versus 3250 ± 50 kg/ha in the group of plants sprayed with the Mortira formulation. The grain produced in all groups was of high quality and was classified as Grade 1 food grain. The highest quality parameters (grain hectoliter mass, gluten, and protein contents) were obtained in the group of plants treated with the embedded herbicide. The study of the embedded TBM confirmed the high efficacy of the experimental formulation.

Processing contaminants in wheat-based foods - a systematic review, meta-analysis and bibliometric analysis

Wheat is one of the main cereals grown around the world and is the basis for several foods such as bread, cakes and pasta. The consumption of these foods raises a concern with food safety, as toxic substances such as acrylamide, 5-hydroxymethylfurfural and polycyclic aromatic hydrocarbons are formed during their processing. To assess the occurrence of processing contaminants in wheat-based foods, a systematic search was carried out in four databases: PubMed, Embase, Web of Science and Scopus. Of the 1479 results, 28 were included for a meta-analysis. Most studies (69.7%) evaluated acrylamide in bread, cookies, and pasta, while PAHs (26.2%) were determined mainly in wheat grains and pasta. HMF was the least determined contaminant (4.1%), with only four studies on cookies included in the meta-analysis. The highest concentration was for acrylamide (136.29 µg·kg-1) followed by HMF (70.59 µg·kg-1) and PAHs (0.11 µg·kg-1). Acrylamide is the main processing contaminant researched, and no studies on the subject have been found in commercial samples in some regions of the world. This result shows a gap in the dates available about process contaminants in wheat-based foods and how the levels can change depending on the process parameters and the ingredients used.

Carotenoid Extraction from Locally and Organically Produced Cereals Using Saponification Method

Carotenoids are important phytochemicals contributing nutritional health benefits in the human diet, with a significant contribution from cereals as one of the major food component around the world. Different methods have been described and adopted for the extraction and isolation of carotenoid compounds. Saponification can be seen as an option for carotenoid extraction from cereals as it converts retinol esters to retinol and removes other abundant compounds such as triglycerides. Extraction of carotenoids content of locally adapted and organic cereals have been limitedly investigated and was, therefore, evaluated in the present study, with a specific aim to understand genotypic and local cultivation effects and interactions. Therefore, 17 diverse cereal genotypes of local origin were grown organically in four localities and evaluated for carotenoid content and composition by HPLC. The results showed a large variation in content and composition of carotenoids in locally adapted and organically grown cereal genotypes, with lutein as the dominating type in wheat and rye, while zeaxanthin was the dominating type in barley. High-level genotypes showed values (9.9 mg/kg of total carotenoids) similar to the highest values previously reported in specific types of wheat. The barley genotypes showed relatively high stability in carotenoids content within and between cultivation locations, while large interactions were found with the cultivation location for the rest of the genotypes, indicating their local adaptation. The local adaptation of the cereal genotypes evaluated contributes large opportunities for local production of high value, highly nutritious food products, while the direct value of these genotypes for conventional plant breeding for varieties performing similar over broad environmental ranges, are more limited.

Comparative Study on Kernel Quality and Chemical Composition of Ancient and Modern Wheat Species: Einkorn, Emmer, Spelt and Hard Red Spring Wheat

Hulled wheat species are often used as whole grains in processing, and have been attracting attention in the last 20 years in the food industry. Whole wheat flour of hulled wheat can be used in the food industry for value addition. This study was conducted to evaluate the kernel quality and chemical composition of the whole grain flour of hulled wheats as a preliminary approach to use these species for value addition. The experimental design was separate, randomized complete block designs for einkorn, emmer, and spelt, with four field replicates. According to the results, significant differences (p < 0.05) were observed in kernel quality traits, such as test weight, 1000 kernel weight, and kernel hardness, compared to hard red spring wheat. The results of the chemical composition revealed that hulled wheats were characterized by significantly lower (p < 0.05) protein and higher (p < 0.05) crude fat contents compared to whole wheat flour of hard red spring wheat. Among hulled wheats, total dietary fiber content was highest in emmer, followed by einkorn and spelt. In conclusion, the whole wheat flour of einkorn, emmer, and spelt used in this study differ from hard red spring wheat in their kernel quality and chemical composition.

Locally Adapted and Organically Grown Landrace and Ancient Spring Cereals-A Unique Source of Minerals in the Human Diet

Consumer interest in local and organic produce, sustainability along the production chain and food products contributing to health, are laying the foundation for local and organic-based diets using nutrient-dense food. Here, we evaluated 25 locally adapted landrace and ancient spring cereal genotypes per location over four locations and three years, for mineral content, nutritional yield and nutrient density. The results showed a large variation in minerals content and composition in the genotypes, but also over cultivation locations, cultivation years and for genotype groups. Highest minerals content was found in oats, while highest content of Zn and Fe was found in ancient wheats. The wheat Diamant brun, the wheat landrace Öland and naked barley showed high mineral values and high content of Zn and Fe when grown in Alnarp. Nutritional yield, of the cereals evaluated here, was high related to values reported internationally but lower than those found in a comparable winter wheat material. The nutrient density was generally high; less than 350 g was needed if any of the evaluated genotype groups were to be used in the daily diet to reach the recommended value of Zn and Fe, while if the suggested Novel Nordic Diet mix was used, only 250 g were needed. A transfer from currently consumed cereals to those in the present study, along the New Nordic Diet path, showed their potential to contribute as sustainable and nutrient-rich sources in the human diet.

Food Security and the Dynamics of Wheat and Maize Value Chains in Africa and Asia

There is an ongoing debate about how best to feed the growing world population in the long run and associated implications for research and development. Some call for a new Green Revolution to secure the supply of staple foods, whereas others emphasize the importance of diversifying and improving people's diets. We aim to contribute to this debate by reviewing the case of wheat and maize value chains and their contribution to food security in Africa and Asia. We first identify drivers transforming food systems. We then apply these to the cereal value chains and disentangle their effects on food security. We thereby add to the three strands in the literature around production, consumption, and food system transformation and point to different research needs and recommendations for the future. The review highlights: (1) Wheat and maize production will be increasingly impaired by ecological drivers such as land degradation, water scarcity and climate change. (2) There are promising innovations to increase and maintain productivity, but constraints in adopting these innovations have to be overcome (i.e., access to seeds, finance, and education/training). (3) The drivers affect all four dimensions of food security, but first and foremost they determine the availability and stability of maize and wheat. This indirectly also influences the economic and physical access of people to maize and wheat. (4) Research tends to focus on improving the productivity and sustainability of wheat and maize farming which is largely interlinked with the availability dimension of food security. (5) The stability and utilization dimension of food security merits continued yet increased support. First, to address climate change and implications for biotic and abiotic stresses. Second, to promote healthier diets and enable the equitable transformation of food systems.

Pantoea ananatis, A New Bacterial Pathogen Affecting Wheat Plants (Triticum L.) in Poland

Wheat (Triticum aestivum) is one of the most economically important crops in the world. During the routine monitoring of wheat pest, the cereal leaf beetle (CLB, Oulema melanopus, Coleoptera, Chrysomelidae), in the Greater Poland region, it was observed that some leaves wounded by CLB also displayed brownish lesions with clear margins and yellow halo, disease symptoms resembling a bacterial infection. The aim of this study was therefore to investigate those symptoms to establish a causal agent of the disease. The identification based on the results of the Biolog’s Gen III system, 16S rRNA, and gyrB genes sequencing, revealed the presence of eight strains of Pantoea ananatis bacteria. Four strains were derived from wheat leaves (Ta024, Ta027, Ta030, Ta046), and four from the CLB’s oral secretion (OUC1, OUD2, OUF2, and OUG1). They shared the nucleotide identity ranging from 99 to 100% to P. ananatis strains deposited in the GenBank database. Additionally, the multi-locus sequence analysis (MLSA) of concatenated sequences of partial atpD, fusA, gyrB, rplB, and rpoB genes was performed. All P. ananatis strains isolated in Poland, grouped into one cluster supported with high bootstrap value. Pathogenicity tests performed on four varieties of wheat plants have identified P. ananatis strains as a causal agent of wheat disease. To our knowledge, this is the first report of P. ananatis affecting wheat plants.

Microbial Inoculants Differentially Influence Plant Growth and Biomass Allocation in Wheat Attacked by Gall-Inducing Hessian Fly (Diptera: Cecidomyiidae)

Beneficial root microbes may mitigate negative effects of crop pests by enhancing plant tolerance or resistance. We used a greenhouse experiment to investigate impacts of commercially available microbial root inoculants on growth and biomass allocation of wheat (Triticum aestivum L. [Cyperales: Poaceae]) and on survival and growth of the gall-inducing wheat pest Hessian fly, Mayetiola destructor (Say). A factorial design was used, with two near-isogenic wheat lines (one susceptible to Hessian fly, the other resistant), two levels of insect infestation (present, absent), and four inoculants containing: 1) Azospirillum brasilense  Tarrand et al. (Rhodospirillales: Azospirillaceae), a plant growth-promoting bacterium, 2) Rhizophagus intraradices (N.C. Schenck & G.S. Sm.) (Glomerales: Glomeraceae), an arbuscular mycorrhizal fungus, 3) A. brasilense + R. intraradices, and 4) control, no inoculant. Larval feeding stunted susceptible wheat shoots and roots. Plants had heavier roots and allocated a greater proportion of biomass to roots when plants received the inoculant with R. intraradices, regardless of wheat genotype or insect infestation. Plants receiving the inoculant containing A. brasilense (alone or with R. intraradices) had comparable numbers of tillers between infested and noninsect-infested plants and, if plants were susceptible, a greater proportion of aboveground biomass was allocated to tillers. However, inoculants did not impact density or performance of Hessian fly immatures or metrics associated with adult fitness. Larvae survived and grew normally on susceptible plants and mortality was 100% on resistant plants irrespective of inoculants. This initial study suggests that by influencing plant biomass allocation, microbial inoculants may offset negative impacts of Hessian flies, with inoculant identity impacting whether tolerance is related to root or tiller growth.

The potential of hybrid breeding to enhance leaf rust and stripe rust resistance in wheat

KEY MESSAGE

Hybrid wheat breeding is a promising strategy to improve the level of leaf rust and stripe rust resistance in wheat. Leaf rust and stripe rust belong to the most important fungal diseases in wheat production. Due to a dynamic development of new virulent races, epidemics appear in high frequency and causes significant losses in grain yield and quality. Therefore, research is needed to develop strategies to breed wheat varieties carrying highly efficient resistances. Stacking of dominant resistance genes through hybrid breeding is such an approach. Within this study, we investigated the genetic architecture of leaf rust and stripe rust resistance of 1750 wheat hybrids and their 230 parental lines using a genome-wide association study. We observed on average a lower rust susceptibility for hybrids in comparison to their parental inbred lines and some hybrids outperformed their better parent with up to 56%. Marker-trait associations were identified on chromosome 3D and 4A for leaf rust and on chromosome 2A, 2B, and 6A for stripe rust resistance by using a genome-wide association study with a Bonferroni-corrected threshold of P < 0.10. Detected loci on chromosomes 4A and 2A were located within previously reported genomic regions affecting leaf rust and stripe rust resistance, respectively. The degree of dominance was for most associations favorable in the direction of improved resistance. Thus, resistance can be increased in hybrid wheat breeding by fixing complementary leaf rust and stripe rust resistance genes with desired dominance effects in opposite parental pools.

Novel sources of variation in grain Zinc (Zn) concentration in bread wheat germplasm derived from Watkins landraces

A diverse panel of 245 wheat genotypes, derived from crosses between landraces from the Watkins collection representing global diversity in the early 20th century and the modern wheat cultivar Paragon, was grown at two field sites in the UK in 2015-16 and the concentrations of zinc and iron determined in wholegrain using inductively coupled plasma-mass spectrometry (ICP-MS). Zinc concentrations in wholegrain varied from 24-49 mg kg-1 and were correlated with iron concentration (r = 0.64) and grain protein content (r = 0.14). However, the correlation with yield was low (r = -0.16) indicating little yield dilution. A sub-set of 24 wheat lines were selected from 245 wheat genotypes and characterised for Zn and Fe concentrations in wholegrain and white flour over two sites and years. White flours from 24 selected lines contained 8-15 mg kg-1 of zinc, which was positively correlated with the wholegrain Zn concentration (r = 0.79, averaged across sites and years). This demonstrates the potential to exploit the diversity in landraces to increase the concentration of Zn in wholegrain and flour of modern high yielding bread wheat cultivars.

Using intervarietal substitution lines for the identification of wheat chromosomes involved in early responses to water-deficit stress

Water deficit induces reactive oxygen species (ROS) overproduction, which in turn inhibits plant growth and development. High concentrations of ROS disrupt the osmotic balance in plant cells and alter membrane integrity. Chromosomes carrying structural or regulatory genes must be detected to better understand plant response mechanisms to stress. The aim of our study was to identify Triticum aestivum L. chromosomes involved in early responses to short-term water-deficit stress (1, 3 and 6 h). In the present study, intervarietal substitution lines of drought-tolerant 'Saratovskaya 29' and sensitive 'Janetzkis Probat' wheat cultivars were examined. We studied the biochemical plant response system and conducted an analysis of catalase, ascorbate peroxidase and guaiacol peroxidase activities, levels of lipid peroxidation and changes in relative water content. Our results determined that the first reaction was a significant increase in guaiacol peroxidase (GPX) activity. However, the strongest impact on plant responses was found for catalase (CAT), which caused a significant decrease in lipid peroxidation (LPO) levels. Our findings indicate that chromosomes 5A, 4B, 6B and 7D are associated with early responses to short-term osmotic stress in wheat.

Metabolic response to drought in six winter wheat genotypes

Wheat is one of the most important cereals, whose growth and development is strongly limited by drought. This study investigated the physiological and metabolic response of six winter wheat cultivars to drought with the emphasis on the induction of dominant metabolites affected by the treatment and genotypes or both. The plants were exposed to a moderate (non-lethal) drought stress, which was induced by withholding watering for six days under controlled greenhouse conditions. A decline in CO2 assimilation (Pn) and transpiration rate, stomata closure, a decrease in relative water content (RWC) and increase of malondialdehyde content were observed in drought-treated plants of all cultivars. These changes were most pronounced in Ellvis, while Soissons was able to retain the higher RWC and Pn. Among the studied metabolites, sugars (sucrose, glucose, fructose, several disaccharides), organic acids (malic acid, oxalic acids), amino acids (proline, threonine, gamma-aminobutyric acid (GABA), glutamine) and sugar alcohols such as myo-inositol accumulated to higher levels in the plants exposed to drought stress in comparison with the control. The accumulation of several metabolites in response to drought differed between the genotypes. Drought induced the production of sucrose, malic acid and oxalic acid, unknown organic acid 1, unknown disaccharide 1, 2 and 3, GABA, L-threonine, glutamic acid in four (Soissons, Žitarka, Antonija or Toborzó) out of six genotypes. In addition, Soissons, which was the most drought tolerant genotype, accumulated the highest amount of unknown disaccharide 5, galactonic and phosphoric acids. The two most drought sensitive cultivars, Srpanjka and Ellvis, demonstrated different metabolic adjustment in response to the stress treatment. Srpanjka responded to drought by increasing the amount of glucose and fructose originated from hydrolyses of sucrose and accumulating unidentified sugar alcohols 1 and 2. In Ellvis, drought caused inhibition of photosynthetic carbon metabolism, as evidence by the decreased Pn, gs, RWC and accumulation levels of sugar metabolites (sucrose, glucose and fructose). The results revealed the differences in metabolic response to drought among the genotypes, which drew attention on metabolites related with general response and on those metabolites which are part of specific response that may play an important role in drought tolerance.

Mutations and functional analysis of 14-3-3 stress response protein from Triticum aestivum: An evolutionary analysis through in silico structural biochemistry approach

Wheat (Triticum aestivum), having high nutritional values is one of the staple food of most of the countries in the world. The productivity of the crop decreases drastically when it encounters various abiotic stresses, most common of which are heat, drought, flood and salinity. There is a crucial role of stress response proteins for the survival of the crops in stress conditions. So the study of wheat stress response proteins is of great importance to raise wheat production in different stress conditions. In this study, we analysed 14-3-3 protein, a stress response protein that is expressed in three major stresses, for example heat, drought and salinity and helps the plants to survive in those conditions. Effect of mutations in the 14-3-3 sequence was predicted using its domain, secondary structure and multiple sequence alignment of amino acid sequences from wheat and its related species. The functional diversity of the protein in different species was correlated with mutations, change in secondary structure and the evolutionary relatedness of the protein in different species. This is the first novel work for analysing the mutational effect on the structure and function of a stress response protein (14-3-3) from Triticum aestivum and its related species.

Nutritional Combined Greenhouse Gas Life Cycle Analysis for Incorporating Canadian Yellow Pea into Cereal-Based Food Products

Incorporating low cost pulses, such as yellow peas, that are rich in nutrients and low in fertilizer requirements, into daily food items, can improve the nutritional and sustainability profile of national diets. This paper systematically characterized the effect of using Canadian grown whole yellow pea and refined wheat flours on nutritional density and carbon footprint in cereal-based food products. Canada-specific production data and the levels of 27 macro- and micronutrients were used to calculate the carbon footprint and nutrient balance score (NBS), respectively, for traditional and reformulated pan bread, breakfast cereal, and pasta. Results showed that partial replacement of refined wheat flour with yellow pea flour increased the NBS of pan bread, breakfast cereal, and pasta by 11%, 70%, and 18%, and decreased the life cycle carbon footprint (kg CO₂ eq/kg) by 4%, 11%, and 13%, respectively. The cultivation stage of wheat and yellow peas, and the electricity used during the manufacturing stage of food production, were the hotspots in the life cycle. The nutritional and greenhouse gas (GHG) data were combined as the nutrition carbon footprint score (NCFS) (NBS/g CO₂ per serving), a novel indicator that reflects product-level nutritional quality per unit environmental impact. Results showed that yellow pea flour increased the NCFS by 15% for pan bread, 90% for breakfast cereal, and 35% for pasta. The results and framework of this study are relevant for food industry, consumers, as well as global and national policy-makers evaluating the effect of dietary change and food reformulation on nutritional and climate change targets.