Stress-induced changes in wheat grain composition and quality

Analysis of widely targeted metabolites of quinoa sprouts (Chenopodium quinoa Willd.) under saline-alkali stress provides new insights into nutritional value

Quinoa sprouts are a green vegetable rich in bioactive chemicals, which have multiple health benefits. However, there is limited information on the overall metabolic profiles of quinoa sprouts and the metabolite changes caused by saline-alkali stress. Here, a UHPLC-MS/MS-based widely targeted metabolomics technique was performed to comprehensively evaluate the metabolic profiles of quinoa sprouts and characterize its metabolic response to saline-alkali stress. A total of 930 metabolites were identified of which 232 showed significant response to saline-alkali stress. The contents of lipids and amino acids were significantly increased, while the contents of flavonoids and phenolic acids were significantly reduced under saline-alkali stress. Moreover, the antioxidant activities of quinoa sprouts were significantly affected by saline-alkali stress. The enrichment analysis of the differentially accumulated metabolites revealed that flavonoid, amino acid and carbohydrate biosynthesis/metabolism pathways responded to saline-alkali stress. This study provided an important theoretical basis for evaluating the nutritional value of quinoa sprouts and the changes in metabolites in response to saline-alkali stress.

CRISPR-Cas9-mediated editing of GmARM improves resistance to multiple stresses in soybean

The growth and development of soybean plants can be affected by both abiotic and biotic stressors, such as saline-alkali stress and Phytophthora root rot. In this study, we identified a stress-related gene-GmARM-whose promoter contained several hormone-response and stress-regulatory elements, including ABRE, TCA element, STRE, and MBS. qRT-PCR analysis showed that the expression of GmARM was the highest in seeds at 55 days after flowering. Furthermore, this gene was upregulated after exposure to saline-alkali stress and Phytophthora root rot infection at the seedling stage. Thus, we generated GmARM mutants using the CRISPR-Cas9 system to understand the role of this gene in stress response. T3 plants showed significantly improved salt tolerance, alkali resistance, and disease resistance, with a significantly higher survival rate than the wildtype plants. Moreover, mutations in GmARM affected the expression of related stress-resistance genes, indicating that GmARM mutants achieved multiple stress tolerance. Therefore, this study provides a foundation for further exploration of the genes involved in resistance to multiple stresses in soybean that can be used for breeding multiple stress-resistance soybean varieties.

Aeluropus littoralis stress-associated protein promotes water deficit resilience in engineered durum wheat

Global climate change-related water deficit negatively affect the growth, development and yield performance of multiple cereal crops, including durum wheat. Therefore, the improvement of water-deficit stress tolerance in durum wheat varieties in arid and semiarid areas has become imperative for food security. Herein, we evaluated the water deficiency resilience potential of two marker-free transgenic durum wheat lines (AlSAP-lines: K9.3 and K21.3) under well-watered and water-deficit stress conditions at both physiological and agronomic levels. These two lines overexpressed the AlSAP gene, isolated from the halophyte grass Aeluropus littoralis, encoding a stress-associated zinc finger protein containing the A20/AN1 domains. Under well-watered conditions, the wild-type (WT) and both AlSAP-lines displayed comparable performance concerning all the evaluated parameters. Ectopic transgene expression exerted no adverse effects on growth and yield performance of the durum wheat plants. Under water-deficit conditions, no significant differences in the plant height, leaf number, spike length, and spikelet number were observed between AlSAP-lines and WT plants. However, compared to WT, the AlSAP-lines exhibited greater dry matter production, greater flag leaf area, improved net photosynthetic rate, stomatal conductance, and water use efficiency. Notably, the AlSAP-lines displayed 25 % higher grain yield (GY) than the WT plants under water-deficit conditions. The RT-qPCR-based selected stress-related gene (TdDREB1, TdLEA, TdAPX1, and TdBlt101-2) expression analyses indicated stress-related genes enhancement in AlSAP-durum wheat plants under both well-watered and water-deficit conditions, potentially related to the water-deficit resilience. Collectively, our findings support that the ectopic AlSAP expression in durum wheat lines enhances water-deficit resilience ability, thereby potentially compensate for the GY loss in arid and semi-arid regions.

The SPL transcription factor TaSPL6 negatively regulates drought stress response in wheat

Environmental stresses, such as heat and drought, severely affect plant growth and development, and reduce wheat yield and quality globally. Squamosa promoter binding protein-like (SPL) proteins are plant-specific transcription factors that play a critical role in regulating plant responses to diverse stresses. In this study, we cloned and characterized TaSPL6, a wheat orthologous gene of rice OsSPL6. Three TaSPL6 homoeologs are located on the long arms of chromosomes 4A, 5B, and 5D, respectively, and share more than 98% sequence identity with each other. The TaSPL6 genes were preferentially expressed in roots, and their expression levels were downregulated in wheat seedlings subjected to heat, dehydration, and abscisic acid treatments. Subcellular localization experiments showed that TaSPL6 was localized in the nucleus. Overexpression of TaSPL6-A in wheat resulted in enhanced sensitivity to drought stress. The transgenic lines exhibited higher leaf water loss, malondialdehyde and reactive oxygen species (ROS) content, and lower antioxidant enzyme activities after drought treatment than wild-type plants. Gene silencing of TaSPL6 enhanced the drought tolerance of wheat, as reflected by better growth status. Additionally, RNA-seq and qRT-PCR analyses revealed that TaSPL6-A functions by decreasing the expression of a number of genes involved in stress responses. These findings suggest that TaSPL6 acts as a negative regulator of drought stress responses in plants, which may have major implications for understanding and enhancing crop tolerance to environmental stresses.

Impact of climate change on wheat grain composition and quality

Wheat grain quality, an important determinant for human nutrition, is often overlooked when improving crop production for stressed environments. Climate change makes this task more difficult by imposing combined stresses. The scenarios relevant to climate change include elevated CO₂ concentrations (eCO₂ ) and extreme climatic events such as drought, heat waves, and salinity stresses. However, data on wheat quality in terms of climate change are limited, with no concerted efforts at the global level to provide an equitable and consistent climate risk assessment for wheat grain quality. Climate change induces changes in the quality and composition of wheat grain, a premier staple food crop globally. Climate-change events, such as eCO₂ , heat, drought, salinity stress stresses, heat + drought, eCO₂  + drought, and eCO₂  + heat stresses, alter wheat grain quality in terms of grain weight, nutrient, anti-nutrient, fiber, and protein content and composition, starch granules, and free amino acid composition. Interestingly, in comparison with other stresses, heat stress and drought stress increase phytate content, which restricts the bioavailability of essential mineral elements. All climatic events, except for eCO₂  + heat stress, increase grain gliadin content in different wheat varieties. However, grain quality components depend more on inter-varietal difference, stress type, and exposure time and intensity. The climatic events show differential regulation of protein and starch accumulation, and mineral metabolism in wheat grains. Rapid climate shifting impairs wheat productivity and causes grain quality to deteriorate by interrupting the allocation of essential nutrients and photoassimilates. © 2022 Society of Chemical Industry.

The Influence of Biostimulants Used in Sustainable Agriculture for Antifungal Protection on the Chemical Composition of Winter Wheat Grain

Field studies were conducted from 2016 to 2019 (south-eastern Poland; 49°58'40.6″ N 22°33'11.3″ E) with the aim to identify the chemical composition of winter wheat grain upon foliar application of biostimulants, of which PlanTonic BIO (containing nettle and willow extracts) showed antifungal activity. The main chemical compositions and their spatial distribution in wheat grain were characterized by Raman spectroscopy technique. It was established that applied biostimulants and hydro-thermal conditions changed the chemical composition of the grain during all the studied years. A similar chemical composition of the grain was achieved in plants treated with synthetic preparations, including both intensive and extensive variants. The second group, in terms of an increase in fatty acid content, consists of grains of plants treated with biostimulants PlanTonic BIO, PlanTonic BIO + Natural Crop and PlanTonic BIO + Biofol Plex. The future of using biostimulants in crop production, including those containing salicylic acid and nettle extracts, appears to be a promising alternative to synthetic crop protection products.

Genome-Wide Analysis of the RAV Gene Family in Wheat and Functional Identification of TaRAV1 in Salt Stress

RAV transcription factors (TFs) are unique to higher plants and contain both B3 and APETALA2 (AP2) DNA binding domains. Although sets of RAV genes have been identified from several species, little is known about this family in wheat. In this study, 26 RAV genes were identified in the wheat genome. These wheat RAV TFs were phylogenetically clustered into three classes based on their amino acid sequences. A TaRAV gene located on chromosome 1D was cloned and named TaRAV1. TaRAV1 was expressed in roots, stems, leaves, and inflorescences, and its expression was up-regulated by heat while down-regulated by salt, ABA, and GA. Subcellular localization analysis revealed that the TaRAV1 protein was localized in the nucleus. The TaRAV1 protein showed DNA binding activity in the EMSA assay and transcriptional activation activity in yeast cells. Overexpressing TaRAV1 enhanced the salt tolerance of Arabidopsis and upregulated the expression of SOS genes and other stress response genes. Collectively, our data suggest that TaRAV1 functions as a transcription factor and is involved in the salt stress response by regulating gene expression in the SOS pathway.

The E3 Ligase GmPUB21 Negatively Regulates Drought and Salinity Stress Response in Soybean

E3-ubiquitin ligases are known to confer abiotic stress responses in plants. In the present study, GmPUB21, a novel U-box E3-ubiquitin ligase-encoding gene, was isolated from soybean and functionally characterized. The expression of GmPUB21, which possesses E3-ubiquitin ligase activity, was found to be significantly up-regulated by drought, salinity, and ABA treatments. The fusion protein GmPUB21-GFP was localized in the cytoplasm, nucleus, and plasma membrane. Transgenic lines of the Nicotiana benthamiana over-expressing GmPUB21 showed more sensitive to osmotic, salinity stress and ABA in seed germination and inhibited mannitol/NaCl-mediated stomatal closure. Moreover, higher reactive oxygen species accumulation was observed in GmPUB21 overexpressing plants after drought and salinity treatment than in wild-type (WT) plants. Contrarily, silencing of GmPUB21 in soybean plants significantly enhanced the tolerance to drought and salinity stresses. Collectively, our results revealed that GmPUB21 negatively regulates the drought and salinity tolerance by increasing the stomatal density and aperture via the ABA signaling pathway. These findings improved our understanding of the role of GmPUB21 under drought and salinity stresses in soybean.

Evaluation of the Heterogeneity of Wheat Kernels as a Traditional Model Object in Connection with the Asymmetry of Development

Wheat is one of the most important crops in the world, providing food for most of the world’s population. Wheat seeds are a popular model object for many experiments to evaluate various factors that improve germination or protect against various adverse stressful effects. Based on the high significance of increasing the productivity of this cereal crop and the applicability of this object, a detailed statistical evaluation of wheat grain (kernel) morphometry was carried out to assess the asymmetry of parameters of this ideal model. Depending on the location of the kernels in the spikelet of a wheat spike, there was a significant asymmetry between the right and left cheeks of the kernels located closer or further from the center of the spikelet. The expressiveness of asymmetry, and consequently, the kernel deformation was higher in the lower kernels of the spikelet. The degree of symmetry; that is, the similarity of the two halves (cheeks) and the kernel as a whole, was higher in kernels located higher in the spikelet. It seems that the reason for this phenomenon lies in the mechanical nature of kernel deformation. The ultrastructure of A-type and B-type starch grains in the central part of the kernel had significant differences between the upper and lower kernels, which indicated in favor of a high probability of differences by the composition and quality of kernels of the same variety when assessed separately. Uniform development of kernels and smaller differences between them may reveal more valuable genotypes in the future, provided their steady reproduction under adverse conditions of a changing climate.

Exploration of the Genetic Diversity of Solina Wheat and Its Implication for Grain Quality

Different Solina wheat accessions (n = 24) collected in the Abruzzo region (Italy) were studied using 45,000 SNP markers generated from the DarTseq platform. The structure of genetic data was analyzed by Principal Component Analysis and Hierarchical Cluster analysis that revealed the existence of two main clusters (Clu1 and Clu2) characterized by samples with different geographical origin. The Solina genetic dataset was further merged and analyzed with a public genetic one provided by CIMMYT containing 25,963 genotypes from all over the world. The Solina accessions occupied a vast space, thus confirming a high heterogeneity of this landrace that, nevertheless, is considerably unique and placed quite far from other clusters. Clu1 and Clu2 divergence were clearly visible. Solina clusters were genetically closer to landraces from Turkey and the central fertile crescent than to the Italian genotypes present in the dataset. Selected commercial quality traits of accessions of the two Solina clusters were analyzed (yield, thousand kernel weight, test weight, and protein content), and significant differences were found between clusters. The results of this investigation did not highlight any relationships of Solina with Italian genotypes, and confirmed its wide genetic diversity by permitting to identify two genetic groups with distinct origin and quality traits.

Comparison of photosynthetic activity and heat tolerance between near isogenic lines of wheat with different photosynthetic rates

Wheat (Triticum aestivum L.) is one of the most important crops in the world, but the yield and quality of wheat are highly susceptible to heat stress, especially during the grain-filling stage. Therefore, it is crucial to select high-yield and high-temperature-resistant varieties for food cultivation. There is a positive correlation between the yield and photosynthetic rate of wheat during the entire grain-filling stage, but few studies have shown that lines with high photosynthetic rates can maintain higher thermotolerance at the same time. In this study, two pairs of wheat near isogenic lines (NILs) with different photosynthetic rates were used for all experiments. Our results indicated that under heat stress, lines with a high photosynthetic rate could maintain the activities of photosystem II (PSII) and key Calvin cycle enzymes in addition to their higher photosynthetic rates. The protein levels of D1 and HSP70 were significantly increased in the highly photosynthetic lines, which contributed to maintaining high photosynthetic rates and ensuring the stability of the Calvin cycle under heat stress. Furthermore, we found that lines with a high photosynthetic rate could maintain high antioxidant enzyme activity to scavenge reactive oxygen species (ROS) and reduce ROS accumulation better than lines with a low photosynthetic rate under high-temperature stress. These findings suggest that lines with high photosynthetic rates can maintain a higher photosynthetic rate despite heat stress and are more thermotolerant than lines with low photosynthetic rates.

Gene Expression and Proteomics Studies Suggest an Involvement of Multiple Pathways Under Day and Day-Night Combined Heat Stresses During Grain Filling in Wheat

Recent weather fluctuations imposing heat stress at the time of wheat grain filling cause frequent losses in grain yield and quality. Field-based studies for understanding the effect of terminal heat stress on wheat are complicated by the effect of multiple confounding variables. In the present study, the effect of day and day-night combined heat stresses during the grain-filling stage was studied using gene expression and proteomics approaches. The gene expression analysis was performed by using real-time quantitative PCR (RT-qPCR). The expression of genes related to the starch biosynthetic pathway, starch transporters, transcription factors, and stress-responsive and storage proteins, at four different grain developmental stages, indicated the involvement of multiple pathways. Under the controlled conditions, their expression was observed until 28 days after anthesis (DAA). However, under the day stress and day-night stress, the expression of genes was initiated earlier and was observed until 14 DAA and 7 DAA, respectively. The protein profiles generated using two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF MS/MS) showed a differential expression of the proteins belonging to multiple pathways that included the upregulation of proteins related to the translation, gliadins, and low-molecular-weight (LMW) glutenins and the downregulation of proteins related to the glycolysis, photosynthesis, defense, and high-molecular-weight (HMW) glutenins. Overall, the defense response to the day heat stress caused early gene expression and day-night heat stress caused suppression of gene expression by activating multiple pathways, which ultimately led to the reduction in grain-filling duration, grain weight, yield, and processing quality.

EMS Derived Wheat Mutant BIG8-1 (Triticum aestivum L.)-A New Drought Tolerant Mutant Wheat Line

Drought response in wheat is considered a highly complex process, since it is a multigenic trait; nevertheless, breeding programs are continuously searching for new wheat varieties with characteristics for drought tolerance. In a previous study, we demonstrated the effectiveness of a mutant known as RYNO3936 that could survive 14 days without water. In this study, we reveal another mutant known as BIG8-1 that can endure severe water deficit stress (21 days without water) with superior drought response characteristics. Phenotypically, the mutant plants had broader leaves, including a densely packed fibrous root architecture that was not visible in the WT parent plants. During mild (day 7) drought stress, the mutant could maintain its relative water content, chlorophyll content, maximum quantum yield of PSII (Fv/Fm) and stomatal conductance, with no phenotypic symptoms such as wilting or senescence despite a decrease in soil moisture content. It was only during moderate (day 14) and severe (day 21) water deficit stress that a decline in those variables was evident. Furthermore, the mutant plants also displayed a unique preservation of metabolic activity, which was confirmed by assessing the accumulation of free amino acids and increase of antioxidative enzymes (peroxidases and glutathione S-transferase). Proteome reshuffling was also observed, allowing slow degradation of essential proteins such as RuBisCO during water deficit stress. The LC-MS/MS data revealed a high abundance of proteins involved in energy and photosynthesis under well-watered conditions, particularly Serpin-Z2A and Z2B, SGT1 and Calnexin-like protein. However, after 21 days of water stress, the mutants expressed ABC transporter permeases and xylanase inhibitor protein, which are involved in the transport of amino acids and protecting cells, respectively. This study characterizes a new mutant BIG8-1 with drought-tolerant characteristics suited for breeding programs.

Integrative Analysis of Transcriptome and Metabolome Reveals Salt Stress Orchestrating the Accumulation of Specialized Metabolites in Lycium barbarum L. Fruit

Salt stress seriously affects yield and quality of crops. The fruit of Lycium barbarum (LBF) is extensively used as functional food due to its rich nutrient components. It remains unclear how salt stress influences the quality of LBF. In this study, we identified 71 differentially accumulated metabolites (DAMs) and 1396 differentially expressed genes (DEGs) among ripe LBF with and without 300 mM of NaCl treatment. Pearson correlation analysis indicated that the metabolomic changes caused by salt stress were strongly related to oxidoreductases; hydrolases; and modifying enzymes, in particular, acyltransferases, methyltransferases and glycosyltransferases. Further analysis revealed that salt stress facilitated flavonoid glycosylation and carotenoid esterification by boosting the expression of structural genes in the biosynthetic pathways. These results suggested that salt stress prompts the modification of flavonoids and carotenoids to alleviate ROS damage, which in turn improves the quality of LBF. Our results lay a solid foundation for uncovering the underlying molecular mechanism of salt stress orchestrating LBF quality, and the candidate genes identified will be a valuable gene resource for genetic improvement of L. barbarum.

Use of Meat Industry Waste in the Form of Meat-and-Bone Meal in Fertilising Maize (Zea mays L.) for Grain

The processing of meat industry waste into meat-and-bone meal (MBM) provides the opportunity to use it as fertiliser in the cultivation of agricultural crops. This study was conducted in the years 2014–2017 at the Experimental Station in Tomaszkowo, Poland to assess MBM effects on yield and quality of maize cultivated for grain. An example of the effective use of nutrients contained in MBM applied at doses of 2.0 and 3.0 t ha is the cultivation of maize in 2016, which was affected by favourable weather conditions. The effect of the accumulation of MBM doses and, consequently, the provision of a greater amount of nutrients ensure sufficient amounts to obtain yields, greater than those provided by mineral fertilisation only. The macronutrient concentration in the maize grains following the application of MBM was similar to the composition of the grains of maize fertilised with mineral N, P and K fertilisers. With the MBM, micronutrients are introduced in amounts that are able to satisfy plants with these components, yet this study failed to demonstrate any effect of increased MBM doses on the concentration of the analysed elements in the maize grains.

Differentiate responses of tetraploid and hexaploid wheat (Triticum aestivum L.) to moderate and severe drought stress: a cue of wheat domestication

Differentiate mechanism of wheat species in response to contrasting drought stress gradients implies a cue of its long-term domestication. In the present study, three water regimes including well-watered control (WW, 80% field water capacity (FC)), moderate drought stress (MS, 50% FC,) and severe drought stress (SS, 30% FC) were designed to reveal different responses of eight wheat species (four tetraploid and four hexaploid) representing different breeding decades and genetic origins to drought stresses. The data indicated that 50% FC and 30% FC fell into the soil moisture threshold range of non-hydraulic and hydraulic root signal occurrence, respectively. In general, grain yield, grain number/spike weight per plant, aboveground biomass, harvest index (HI) and water use efficiency (WUE) were significantly higher in hexaploid species than those of tetraploid species under drought stress (P < .05). Particularly, non-hydraulic root signal was triggered and continuously operated under 50% FC, while hydraulic root signal was observed under 30% FC, respectively. Under 80% FC, the allometric exponent (ɑ) of M_aboveground vs M_root decreased from tetraploid to hexaploid (both were of <1), indicating that during the domestication, the hexaploid species allocated less biomass to root system. For the relationship of M_ear vs M_vegetative, the ɑ value was significantly greater in the hexaploid species, showing that hexaploid wheat distributed more biomass to ear than tetraploid to improve yield. Under 50% FC, this trend was enhanced. However, under 30% FC, there was no significant difference in the ɑ value between two species. Additionally, correlation analyses on yield formation affirmed the above results. Therefore, drought tolerance tended to be enhanced in hexaploid species under the pressure of artificial selection than that of tetraploid species. When drought stress exceeded a certain threshold, both species would be negatively seriously affected and followed a similar mechanism for better survival.

Impacts of Nitrogen Deficiency on Wheat (Triticum aestivum L.) Grain During the Medium Filling Stage: Transcriptomic and Metabolomic Comparisons

Nitrogen (N) supplementation is essential to the yield and quality of bread wheat (Triticum aestivum L.). The impact of N-deficiency on wheat at the seedling stage has been previously reported, but the impact of distinct N regimes applied at the seedling stage with continuous application on filling and maturing wheat grains is lesser known, despite the filling stage being critical for final grain yield and flour quality. Here, we compared phenotype characteristics such as grain yield, grain protein and sugar quality, plant growth, leaf photosynthesis of wheat under N-deficient and N-sufficient conditions imposed prior to sowing (120 kg/hm²) and in the jointing stage (120 kg/hm²), and then evaluated the effects of this continued stress through RNA-seq and GC-MS metabolomics profiling of grain at the mid-filling stage. The results showed that except for an increase in grain size and weight, and in the content of total sugar, starch, and fiber in bran fraction and white flour, the other metrics were all decreased under N-deficiency conditions. A total of 761 differentially expressed genes (DEGs) and 77 differentially accumulated metabolites (DAMs) were identified. Under N-deficiency, 51 down-regulated DEGs were involved in the process of impeding chlorophyll synthesis, chloroplast development, light harvesting, and electron transfer functions of photosystem, which resulted in the SPAD and Pn value decreased by 32 and 15.2% compared with N-sufficiency, inhibited photosynthesis. Twenty-four DEGs implicated the inhibition of amino acids synthesis and protein transport, in agreement with a 17-42% reduction in ornithine, cysteine, aspartate, and tyrosine from metabolome, and an 18.6% reduction in grain protein content. However, 14 DEGs were implicated in promoting sugar accumulation in the cell wall and another six DEGs also enhanced cell wall synthesis, which significantly increased fiber content in the endosperm and likely contributed to increasing the thousands-grain weight (TGW). Moreover, RNA-seq profiling suggested that wheat grain can improve the capacity of DNA repair, iron uptake, disease and abiotic stress resistance, and oxidative stress scavenging through increasing the content levels of anthocyanin, flavonoid, GABA, galactose, and glucose under N-deficiency condition. This study identified candidate genes and metabolites related to low N adaption and tolerance that may provide new insights into a comprehensive understanding of the genotype-specific differences in performance under N-deficiency conditions.

Advances and Challenges in the Breeding of Salt-Tolerant Rice

Soil salinization and a degraded ecological environment are challenging agricultural productivity and food security. Rice (Oryza sativa), the staple food of much of the world’s population, is categorized as a salt-susceptible crop. Improving the salt tolerance of rice would increase the potential of saline-alkali land and ensure food security. Salt tolerance is a complex quantitative trait. Biotechnological efforts to improve the salt tolerance of rice hinge on a detailed understanding of the molecular mechanisms underlying salt stress tolerance. In this review, we summarize progress in the breeding of salt-tolerant rice and in the mapping and cloning of genes and quantitative trait loci (QTLs) associated with salt tolerance in rice. Furthermore, we describe biotechnological tools that can be used to cultivate salt-tolerant rice, providing a reference for efforts aimed at rapidly and precisely cultivating salt-tolerance rice varieties.

Stability analysis of wheat lines with increased level of arabinoxylan

Plant breeders have long sought to develop lines that combine outstanding performance with high and stable quality in different environments. The high-arabinoxylan (AX) Chinese variety Yumai-34 was crossed with three Central European wheat varieties (Lupus, Mv-Mambo, Ukrainka) and 31 selected high-AX lines were compared for physical (hectolitre weight, thousand grain weight, flour yield), compositional (protein content, gluten content, pentosan) and processing quality traits (gluten index, Zeleny sedimentation, Farinograph parameters) in a three-year experiment (2013–2015) in the F₇-F₉ generations. The stability and heritability of different traits, including the relative effects of the genotype (G) and environment (E), were determined focusing on grain composition. The contents of total and water-soluble pentosans were significantly affected by G, E and G × E interactions, but the heritability of total (TOT)-pentosan was significantly lower (0.341) than that of water-extractable (WE)-pentosan (0.825). The main component of the pentosans, the amount and composition (arabinose:xylose ratio) of the arabinoxylan (AX), was primarily determined by the environment and, accordingly, the broader heritability of these parameters were 0.516 and 0.772. However, genotype significantly affected the amount of water-soluble arabinoxylan and its composition and thus the heritability of these traits was also significant (0.840 and 0.721). The genotypes exhibiting higher stability of content of TOT-pentosan also showed more stable contents of WE-pentosan. There was a positive correlation between the stability of contents of WE-pentosan and WE-AX, while the stability of the WE-AX content and AX composition were also strongly correlated. Water absorption was strongly genetically determined with a heritability of 0.829 with the genotype determining 38.67% of the total variance. Many lines were grouped in the GGE biplot, indicating that they did not significantly differ stability.

Responses of an old and a modern Indian wheat cultivar to future O3 level: Physiological, yield and grain quality parameters

A field study was conducted to understand the physiological responses, yield and grain quality of an old (HUW234) and a modern (HD3118) wheat cultivar exposed to elevated ozone (O₃). The cultivars were grown under ambient O₃ (NF) and ambient +20 ppb O₃ (NF+) conditions using open-top chambers (OTCs). The comparative study of an old and a modern cultivar showed variable physiological responses under elevated O₃ exposure. Elevated O₃ in old cultivar caused high reductions in Rubisco activity (Vc_max) and electron transport rate (J) compared to modern cultivar with simultaneous reductions in the rate of photosynthesis and chlorophyll fluorescence. In modern cultivar, high stomatal density and conductance caused higher O₃ uptake thereby triggering more damage to the adjacent stomatal cells and photosynthetic pigments coupled with reductions in photosynthetic rate and photosynthetic nitrogen use efficiency (PNUE). Modern cultivar also showed relatively high reduction in grain yield compared to old one under NF + treatment. Furthermore, grain quality traits (such as starch, protein and amino acids) of modern cultivar were better than old cultivar under ambient O₃, but showed more deterioration under NF + treatment. Results thus indicated that modern cultivar is relatively more susceptible to O₃ and showed more negative impacts on plant performance, yield and quality of grains compared to old cultivar.

Salt stress induces physiochemical alterations in rice grain composition and quality

Salinity has drastic effects on plant growth and productivity and is one of the major factors responsible for crop yield losses throughout the agricultural soils of the world. The mechanisms of salinity tolerance in plants are regulated by a set of inherent multigenes and prevalent environmental factors, which bring about a myriad of metabolic changes in each plant part. The stress-induced metabolic changes in the rice plant have been intensively studied, but extensively in plant parts such as stem, leaf, and root. However, little information exists in the literature about such stress-induced architectural and physiological changes in rice grain, a premier staple food of a large proportion of human population. Thus, the current review comprehensively describes the effects of salinity stress on rice grain composition including changes in carbohydrate, protein, fat, and mineral contents. Elucidation of salinity induced changes in rice grain composition would help to understand whether or not a nutritious and healthy staple food is available to human population from rice grown under saline environments.

Adverse Reactions to Wheat or Wheat Components

Wheat is an important staple food globally, providing a significant contribution to daily energy, fiber, and micronutrient intake. Observational evidence for health impacts of consuming more whole grains, among which wheat is a major contributor, points to significant risk reduction for diabetes, cardiovascular disease, and colon cancer. However, specific wheat components may also elicit adverse physical reactions in susceptible individuals such as celiac disease (CD) and wheat allergy (WA). Recently, broad coverage in the popular and social media has suggested that wheat consumption leads to a wide range of adverse health effects. This has motivated many consumers to avoid or reduce their consumption of foods that contain wheat/gluten, despite the absence of diagnosed CD or WA, raising questions about underlying mechanisms and possible nocebo effects. However, recent studies did show that some individuals may suffer from adverse reactions in absence of CD and WA. This condition is called non-celiac gluten sensitivity (NCGS) or non-celiac wheat sensitivity (NCWS). In addition to gluten, wheat and derived products contain many other components which may trigger symptoms, including inhibitors of α-amylase and trypsin (ATIs), lectins, and rapidly fermentable carbohydrates (FODMAPs). Furthermore, the way in which foods are being processed, such as the use of yeast or sourdough fermentation, fermentation time and baking conditions, may also affect the presence and bioactivity of these components. The present review systematically describes the characteristics of wheat-related intolerances, including their etiology, prevalence, the components responsible, diagnosis, and strategies to reduce adverse reactions.

Exploring the traits for lodging tolerance in wheat genotypes: a review

The rising population entails enhancement in wheat productivity to ensure substantial food supply which often get hindered by various biotic and abiotic stresses. Lodging, due to rain and high velocity wind causes significant economic and yield losses in cereals. Hence, lodging is emerging as a major hurdle to achieve the required yield targets. Various morphological, biochemical, anatomical and genetic traits contribute to produce a plant competent enough to bear lodging stress. Hence, in this review, we intend to elaborate the cause and impact relationship of lodging and tried to link lodging tolerance traits to field practices to minimize the losses. Because of the complex nature of lodging phenomenon, it is still obscure to identify best correlated traits to screen genotype in breeding programmes. However, the genotypes with best correlated traits like plant height, culm wall thickness should be introduced/selected in breeding programmes to inculcate lodging tolerance in a high yielding variety as in recent era lodging tolerance is a key factor to enhance productivity and farmer's income as well.

Drought stress affects the protein and dietary fiber content of wholemeal wheat flour in wheat/Aegilops addition lines

Wild relatives of wheat, such as Aegilops spp. are potential sources of genes conferring tolerance to drought stress. As drought stress affects seed composition, the main goal of the present study was to determine the effects of drought stress on the content and composition of the grain storage protein (gliadin (Gli), glutenin (Glu), unextractable polymeric proteins (UPP%) and dietary fiber (arabinoxylan, β-glucan) components of hexaploid bread wheat (T. aestivum) lines containing added chromosomes from Ae. biuncialis or Ae. geniculata. Both Aegilops parents have higher contents of protein and β-glucan and higher proportions of water-soluble arabinoxylans (determined as pentosans) than wheat when grown under both well-watered and drought stress conditions. In general, drought stress resulted in increased contents of protein and total pentosans in the addition lines, while the β-glucan content decreased in many of the addition lines. The differences found between the wheat/Aegilops addition lines and wheat parents under well-watered conditions were also manifested under drought stress conditions: Namely, elevated β-glucan content was found in addition lines containing chromosomes 5U^g, 7U^g and 7M^b, while chromosomes 1U^b and 1M^g affected the proportion of polymeric proteins (determined as Glu/Gli and UPP%, respectively) under both well-watered and drought stress conditions. Furthermore, the addition of chromosome 6M^g decreased the WE-pentosan content under both conditions. The grain composition of the Aegilops accessions was more stable under drought stress than that of wheat, and wheat lines with the added Aegilops chromosomes 2M^g and 5M^g also had more stable grain protein and pentosan contents. The negative effects of drought stress on both the physical and compositional properties of wheat were also reduced by the addition of these. These results suggest that the stability of the grain composition could be improved under drought stress conditions by the intraspecific hybridization of wheat with its wild relatives.

Genome-wide identification and analysis of the ALTERNATIVE OXIDASE gene family in diploid and hexaploid wheat

A comprehensive understanding of wheat responses to environmental stress will contribute to the long-term goal of feeding the planet. ALERNATIVE OXIDASE (AOX) genes encode proteins involved in a bypass of the electron transport chain and are also known to be involved in stress tolerance in multiple species. Here, we report the identification and characterization of the AOX gene family in diploid and hexaploid wheat. Four genes each were found in the diploid ancestors Triticum urartu, and Aegilops tauschii, and three in Aegilops speltoides. In hexaploid wheat (Triticum aestivum), 20 genes were identified, some with multiple splice variants, corresponding to a total of 24 proteins for those with observed transcription and translation. These proteins were classified as AOX1a, AOX1c, AOX1e or AOX1d via phylogenetic analysis. Proteins lacking most or all signature AOX motifs were assigned to putative regulatory roles. Analysis of protein-targeting sequences suggests mixed localization to the mitochondria and other organelles. In comparison to the most studied AOX from Trypanosoma brucei, there were amino acid substitutions at critical functional domains indicating possible role divergence in wheat or grasses in general. In hexaploid wheat, AOX genes were expressed at specific developmental stages as well as in response to both biotic and abiotic stresses such as fungal pathogens, heat and drought. These AOX expression patterns suggest a highly regulated and diverse transcription and expression system. The insights gained provide a framework for the continued and expanded study of AOX genes in wheat for stress tolerance through breeding new varieties, as well as resistance to AOX-targeted herbicides, all of which can ultimately be used synergistically to improve crop yield.

Identification of Genomic Regions Contributing to Protein Accumulation in Wheat under Well-Watered and Water Deficit Growth Conditions

Sustaining wheat production under low-input conditions through development and identifying genotypes with enhanced nutritional quality are two current concerns of wheat breeders. Wheat grain total protein content, to no small extent, determines the economic and nutritive value of wheat. Therefore, the objectives of this study are to identify accessions with high and low grain protein content (GPC) under well-watered and water-deficit growth conditions and to locate genomic regions that contribute to GPC accumulation. Spring wheat grains obtained from 2111 accessions that were grown under well-watered and water-deficit conditions were assessed for GPC using near-infrared spectroscopy (NIR). Results indicated significant influences of moisture, genotype, and genotype × environment interaction on the GPC accumulation. Furthermore, genotypes exhibited a wide range of variation for GPC, indicating the presence of high levels of genetic variability among the studied accessions. Around 366 (166 with high GPC and 200 with low GPC) wheat genotypes performed relatively the same across environments, which implies that GPC accumulation in these genotypes was less responsive to water deficit. Genome-wide association mapping results indicated that seven single nucleotide polymorphism (SNPs) were linked with GPC under well-watered growth conditions, while another six SNPs were linked with GPC under water-deficit conditions only. Moreover, 10 SNPs were linked with GPC under both well-watered and water-deficit conditions. These results emphasize the importance of using diverse, worldwide germplasm to dissect the genetic architecture of GPC in wheat and identify accessions that might be potential parents for high GPC in wheat breeding programs.

Genetic diversity of bread wheat genotypes in Iran for some nutritional value and baking quality traits

Genetic variation among 78 irrigated bread wheat genotypes was studied for their nutritional value and baking quality traits as well as some agronomic traits. The experiment was conducted in a randomized complete block design with three replicates under normal and terminal drought stress conditions in Kermanshah, Iran during 2012-2013 cropping season. The results of combined ANOVA indicated highly significant genotypic differences for all traits. All studied traits except grain yield, hectoliter weight and grain fiber content were significantly affected by genotype × environment interaction. Drought stress reduced grain yield, thousand kernel weight, gluten index, grain starch content and hectoliter weight and slightly promoted grain protein and fiber contents, falling number, total gluten and ratio of wet gluten to grain protein content. Grain yield by 31.66% and falling number by 9.20% attained the highest decrease and increase due to drought stress. There were negative and significant correlations among grain yield with grain protein and fiber contents under both conditions. Results of cluster analysis showed that newer genotypes had more grain yield and gluten index than older ones, but instead, they had the lower grain protein and fiber contents. It is thought that wheat breeders have bred cultivars with high grain yield, low protein content, and improved bread-making attributes during last seven decades. While older genotypes indicated significantly higher protein contents, and some of them had higher gluten index. We concluded from this study that it is imperative for breeders to pay more attention to improve qualitative traits coordinated to grain yield.

Microscopic and Proteomic Analysis of Dissected Developing Barley Endosperm Layers Reveals the Starchy Endosperm as Prominent Storage Tissue for ER-Derived Hordeins Alongside the Accumulation of Barley Protein Disulfide Isomerase (HvPDIL1-1)

Barley (Hordeum vulgare) is one of the major food sources for humans and forage sources for animal livestock. The average grain protein content (GPC) of barley ranges between 8 and 12%. Barley hordeins (i.e., prolamins) account for more than 50% of GPC in mature seeds and are important for both grain and flour quality. Barley endosperm is structured into three distinct cell layers: the starchy endosperm, which acts essentially as storage tissue for starch; the subaleurone, which is characterized by a high accumulation of seed storage proteins (SSPs); and the aleurone, which has a prominent role during seed germination. Prolamins accumulate in distinct, ER-derived protein bodies (PBs) and their trafficking route is spatio-temporally regulated. The protein disulfide isomerase (PDI) has been shown to be involved in PB formation. Here, we unravel the spatio-temporal proteome regulation in barley aleurone, subaleurone, and starchy endosperm for the optimization of end-product quality in barley. We used laser microdissection (LMD) for subsequent nanoLC-MS/MS proteomic analyses in two experiments: in Experiment One, we investigated the proteomes of dissected barley endosperm layers at 12 and at ≥20 days after pollination (DAP). We found a set of 10 proteins that were present in all tissues at both time points. Among these proteins, the relative protein abundance of D-hordein, B3-hordein and HvPDIL1-1 significantly increased in starchy endosperm between 12 and ≥20 DAP, identifying the starchy endosperm as putative major storage tissue. In Experiment Two, we specifically compared the starchy endosperm proteome at 6, 12, and ≥20 DAP. Whereas the relative protein abundance of D-hordein and B3-hordein increased between 6 and ≥20 DAP, HvPDIL1-1 increased between 6 and 12 DAP, but remained constant at ≥20 DAP. Microscopic observations showed that these relative protein abundance alterations were accompanied by additional localization of hordeins at the periphery of starch granules and a partial re-localization of HvPDIL1-1 from PBs to the periphery of starch granules. Our data indicate a spatio-temporal regulation of hordeins and HvPDIL1-1. These results are discussed in relation to the putative role of HvPDIL1-1 in end-product quality in barley.

Effects of water stress on the composition and immunoreactive properties of gliadins from two wheat cultivars: Nawra and Tonacja

BACKGROUND

Water shortage during wheat vegetation causes changes in the composition of gliadins in grains, which can lead to changes in their immunoreactive properties.

RESULTS

The investigated wheat cultivars exposed to water stress accumulated significantly lower amounts (P < 0.05) of gliadins and glutenins in grains. The composition of proteins accumulated in grains was also modified. Water shortage results in a decreased share of αβ and γ fractions in total gliadins. Grains of wheat cultivated under water stress contain significantly higher (P < 0.05) levels of ω-gliadins by 4.5% and 43.3% for Nawra and Tonacja cultivars, respectively. Water stress promotes an increase in the share of P and Q/E residues in gliadins. In protein samples R5 antibodies recognized increased amounts of gliadins matching the QQPFP sequence. Wheat proteins also reacted with IgE antibodies isolated from subjects allergic to gluten.

CONCLUSION

Cultivation of wheat under conditions of water stress results in the qualitative and quantitative changes of gliadins by increasing their immunoreactivity. © 2016 Society of Chemical Industry.

Role of Proteomics in Crop Stress Tolerance

Plants often experience various biotic and abiotic stresses during their life cycle. The abiotic stresses include mainly drought, salt, temperature (low/high), flooding and nutritional deficiency/excess which hamper crop growth and yield to a great extent. In view of a projection 50% of the crop loss is attributable to abiotic stresses. However, abiotic stresses cause a myriad of changes in physiological, molecular and biochemical processes operating in plants. It is now widely reported that several proteins respond to these stresses at pre- and post-transcriptional and translational levels. By knowing the role of these stress inducible proteins, it would be easy to comprehensively expound the processes of stress tolerance in plants. The proteomics study offers a new approach to discover proteins and pathways associated with crop physiological and stress responses. Thus, studying the plants at proteomic levels could help understand the pathways involved in stress tolerance. Furthermore, improving the understanding of the identified key metabolic proteins involved in tolerance can be implemented into biotechnological applications, regarding recombinant/transgenic formation. Additionally, the investigation of identified metabolic processes ultimately supports the development of antistress strategies. In this review, we discussed the role of proteomics in crop stress tolerance. We also discussed different abiotic stresses and their effects on plants, particularly with reference to stress-induced expression of proteins, and how proteomics could act as vital biotechnological tools for improving stress tolerance in plants.

Mechanisms of waterlogging tolerance in wheat--a review of root and shoot physiology

We review the detrimental effects of waterlogging on physiology, growth and yield of wheat. We highlight traits contributing to waterlogging tolerance and genetic diversity in wheat. Death of seminal roots and restriction of adventitious root length due to O2 deficiency result in low root:shoot ratio. Genotypes differ in seminal root anoxia tolerance, but mechanisms remain to be established; ethanol production rates do not explain anoxia tolerance. Root tip survival is short-term, and thereafter, seminal root re-growth upon re-aeration is limited. Genotypes differ in adventitious root numbers and in aerenchyma formation within these roots, resulting in varying waterlogging tolerances. Root extension is restricted by capacity for internal O2 movement to the apex. Sub-optimal O2 restricts root N uptake and translocation to the shoots, with N deficiency causing reduced shoot growth and grain yield. Although photosynthesis declines, sugars typically accumulate in shoots of waterlogged plants. Mn or Fe toxicity might occur in shoots of wheat on strongly acidic soils, but probably not more widely. Future breeding for waterlogging tolerance should focus on root internal aeration and better N-use efficiency; exploiting the genetic diversity in wheat for these and other traits should enable improvement of waterlogging tolerance.

Transcriptome dynamics of a susceptible wheat upon Fusarium head blight reveals that molecular responses to Fusarium graminearum infection fit over the grain development processes

In many plant/pathogen interactions, host susceptibility factors are key determinants of disease development promoting pathogen growth and spreading in plant tissues. In the Fusarium head blight (FHB) disease, the molecular basis of wheat susceptibility is still poorly understood while it could provide new insights into the understanding of the wheat/Fusarium graminearum (Fg) interaction and guide future breeding programs to produce cultivars with sustainable resistance. To identify the wheat grain candidate genes, a genome-wide gene expression profiling was performed in the French susceptible wheat cultivar, Recital. Gene-specific two-way ANOVA of about 40 K transcripts at five grain developmental stages identified 1309 differentially expressed genes. Out of these, 536 were impacted by the Fg effect alone. Most of these Fg-responsive genes belonged to biological and molecular functions related to biotic and abiotic stresses indicating the activation of common stress pathways during susceptibility response of wheat grain to FHB. This analysis revealed also 773 other genes displaying either specific Fg-responsive profiles along with grain development stages or synergistic adjustments with the grain development effect. These genes were involved in various molecular pathways including primary metabolism, cell death, and gene expression reprogramming. An increasingly complex host response was revealed, as was the impact of both Fg infection and grain ontogeny on the transcription of wheat genes. This analysis provides a wealth of candidate genes and pathways involved in susceptibility responses to FHB and depicts new clues to the understanding of the susceptibility determinism in plant/pathogen interactions.

Quinoa for Marginal Environments: Toward Future Food and Nutritional Security in MENA and Central Asia Regions

Quinoa is recognized as a crop of great value in terms of tolerance to abiotic stresses and there is growing interest to introduce it in marginal agricultural production systems worldwide. Also, quinoa is one of the most nutritious food crops currently known and the nutritive properties of the crop are seen as a mean to fight malnutrition globally. Various quinoa cultivars have been screened for tolerance to salinity, water-use efficiency and nutritional quality and the positive attributes found in them have created even wider global interest in its cultivation. This paper summarizes 15 years of studies on assessing the potential for introducing the crop in a few countries of the Middle East and North Africa (MENA) and Central Asia regions and describes the key constraints for scaling-up the production under marginal growing conditions in the newly introduced countries.