Mitigating drought stress in wheat plants (Triticum Aestivum L.) through grain priming in aqueous extract of spirulina platensis.

BACKGROUND: The study focuses on the global challenge of drought stress, which significantly impedes wheat production, a cornerstone of global food security. Drought stress disrupts cellular and physiological processes in wheat, leading to substantial yield losses, especially in arid and semi-arid regions. The research investigates the use of Spirulina platensis aqueous extract (SPAE) as a biostimulant to enhance the drought resistance of two Egyptian wheat cultivars, Sakha 95 (drought-tolerant) and Shandawel 1 (drought-sensitive). Each cultivar's grains were divided into four treatments: Cont, DS, SPAE-Cont, and SPAE + DS. Cont and DS grains were presoaked in distilled water for 18 h while SPAE-Cont and SPAE + DS were presoaked in 10% SPAE, and then all treatments were cultivated for 96 days in a semi-field experiment. During the heading stage (45 days: 66 days), two drought treatments, DS and SPAE + DS, were not irrigated. In contrast, the Cont and SPAE-Cont treatments were irrigated during the entire experiment period. At the end of the heading stage, agronomy, pigment fractions, gas exchange, and carbohydrate content parameters of the flag leaf were assessed. Also, at the harvest stage, yield attributes and biochemical aspects of yielded grains (total carbohydrates and proteins) were evaluated. RESULTS: The study demonstrated that SPAE treatments significantly enhanced the growth vigor, photosynthetic rate, and yield components of both wheat cultivars under standard and drought conditions. Specifically, SPAE treatments increased photosynthetic rate by up to 53.4%, number of spikes by 76.5%, and economic yield by 190% for the control and 153% for the drought-stressed cultivars pre-soaked in SPAE. Leaf agronomy, pigment fractions, gas exchange parameters, and carbohydrate content were positively influenced by SPAE treatments, suggesting their effectiveness in mitigating drought adverse effects, and improving wheat crop performance. CONCLUSION: The application of S. platensis aqueous extract appears to ameliorate the adverse effects of drought stress on wheat, enhancing the growth vigor, metabolism, and productivity of the cultivars studied. This indicates the potential of SPAE as an eco-friendly biostimulant for improving crop resilience, nutrition, and yield under various environmental challenges, thus contributing to global food security.

An SNP based genotyping assay for genes associated with drought tolerance in bread wheat.

BACKGROUND: SnRK2 plays vital role in responding to adverse abiotic stimuli. The applicability of TaSnRK2.4 and TaSnRK2.9 was investigated to leverage the potential of these genes in indigenous wheat breeding programs. METHODS: Genetic diversity was assessed using pre-existing markers for TaSnRK2.4 and TaSnRK2.9. Furthermore, new markers were also developed to enhance their broader applicability. KASP markers were designed for TaSnRK2.4, while CAPS-based markers were tailored for TaSnRK2.9. RESULTS: Analysis revealed lack of polymorphism in TaSnRK2.4 among Pakistani wheat germplasm under study. To validate this finding, available gel-based markers for TaSnRK2.4 were employed, producing consistent results and offering limited potential for application in marker-assisted wheat breeding with Pakistani wheat material. For TaSnRK2.9-5A, CAPS2.9-5A-1 and CAPS2.9-5A-2 markers were designed to target SNP positions at 308 nt and 1700 nt revealing four distinct haplotypes. Association analysis highlighted the significance of Hap-5A-1 of TaSnRK2.9-5A, which exhibited association with an increased number of productive tillers (NPT), grains per spike (GPS), and reduced plant height (PH) under well-watered (WW) conditions. Moreover, it showed positive influence on NPT under WW conditions, GPS under water-limited (WL) conditions, and PH under both WW and WL conditions. High selection intensity observed for Hap-5A-1 underscores the valuable role it has played in Pakistani wheat breeding programs. Gene expression studies of TaSnRK2.9-5A revealed the involvement of this gene in response to PEG, NaCl, low temperature and ABA treatments. CONCLUSION: These findings propose that TaSnRK2.9 can be effectively employed for improving wheat through marker-assisted selection in wheat breeding efforts.

Elucidating the modulatory effect of melatonin on enzyme activity and oxidative stress in wheat: a global meta-analysis.

In our comprehensive meta-analysis, we initially collected 177 publications focusing on the impact of melatonin on wheat. After meticulous screening, 40 published studies were selected, encompassing 558 observations for antioxidant enzymes, 312 for reactive oxygen species (ROS), and 92 for soluble biomolecules (soluble sugar and protein). This analysis revealed significant heterogeneity across studies (I2 > 99% for enzymes, ROS, and soluble biomolecules) and notable publication bias, indicating the complexity and variability in the research field. Melatonin application generally increased antioxidant enzyme activities [superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX)] in wheat, particularly under stress conditions, such as high temperature and heavy-metal exposure. Compared to control, melatonin application increased SOD, POD, CAT, and APX activities by 29.5, 16.96, 35.98, and 171.64%, respectively. Moreover, oxidative stress markers like hydrogen peroxide (H2O2), superoxide anion (O2), and malondialdehyde (MDA) decreased with melatonin by 23.73, 13.64, and 21.91%, respectively, suggesting a reduction in oxidative stress. The analysis also highlighted melatonin's role in improving carbohydrate metabolism and antioxidant defenses. Melatonin showed an overall increase of 12.77% in soluble sugar content, and 22.76% in glutathione peroxidase (GPX) activity compared to the control. However, the effects varied across different wheat varieties, environmental conditions, and application methods. Our study also uncovered complex relationships between antioxidant enzyme activities and H2O2 levels, indicating a nuanced regulatory role of melatonin in oxidative stress responses. Our meta-analysis demonstrates the significant role of melatonin in increasing wheat resilience to abiotic stressors, potentially through its regulatory impact on antioxidant defense systems and stress response.

Inhibitory effects of Pseudomonas sp. W112 on cadmium accumulation in wheat grains: Reduced the bioavailability in soil and enhanced the interception by plant organs.

Microorganisms play an important role in heavy metal bioremediation and soil fertility. The effects of soil inoculation with Pseudomonas sp. W112 on Cd accumulation in wheat were investigated by analyzing the transport, subcellular distribution and speciation of Cd in the soil and plants. Pseudomonas sp. W112 application significantly decreased Cd content in the roots, internode and grains by 10.2%, 29.5% and 33.0%, respectively, and decreased Cd transfer from the basal nodes to internodes by 63.5%. Treatment with strain W112 decreased the inorganic and water-soluble Cd content in the roots and increased the proportion of residual Cd in both the roots and basal nodes. At the subcellular level, the Cd content in the root cell wall and basal node cytosol increased by 19.6% and 61.8%, respectively, indicating that strain W112 improved the ability of the root cell wall and basal node cytosol to fix Cd. In the rhizosphere soil, strain W112 effectively colonized and significantly decreased the exchangeable Cd, carbonate-bound Cd and iron-manganese oxide-bound Cd content by 43.5%, 27.3% and 17.6%, respectively, while it increased the proportion of residual Cd by up to 65.2%. Moreover, a 3.1% and 23.5% increase in the pH and inorganic nitrogen content in the rhizosphere soil, respectively, was recorded. Similarly, soil bacterial community sequencing revealed that inoculating with strain W112 increased the abundance of Pseudomonas, Thauera and Azoarcus, which are associated with inorganic nitrogen metabolism, and decreased that of Acidobacteria, which is indicative of soil alkalinization. Hence, root application of Pseudomonas sp. W112 improved soil nitrogen availability and inhibited Cd accumulation in the wheat grains in a two-stage process: by reducing the Cd availability in the rhizosphere soil and by improving Cd interception and fixation in the wheat roots and basal nodes. Pseudomonas sp. W112 may be a suitable bioremediation agent for restoring Cd-contaminated wheat fields.

Genome-Wide Identification and Analysis of APC E3 Ubiquitin Ligase Genes Family in Triticum aestivum.

E3 ubiquitin ligases play a pivotal role in ubiquitination, a crucial post-translational modification process. Anaphase-promoting complex (APC), a large cullin-RING E3 ubiquitin ligase, regulates the unidirectional progression of the cell cycle by ubiquitinating specific target proteins and triggering plant immune responses. Several E3 ubiquitin ligases have been identified owing to advancements in sequencing and annotation of the wheat genome. However, the types and functions of APC E3 ubiquitin ligases in wheat have not been reported. This study identified 14 members of the APC gene family in the wheat genome and divided them into three subgroups (CCS52B, CCS52A, and CDC20) to better understand their functions. Promoter sequence analysis revealed the presence of several cis-acting elements related to hormone and stress responses in the APC E3 ubiquitin ligases in wheat. All identified APC E3 ubiquitin ligase family members were highly expressed in the leaves, and the expression of most genes was induced by the application of methyl jasmonate (MeJA). In addition, the APC gene family in wheat may play a role in plant defense mechanisms. This study comprehensively analyzes APC genes in wheat, laying the groundwork for future research on the function of APC genes in response to viral infections and expanding our understanding of wheat immunity mechanisms.

Genome-Wide Identification, Characterization, and Expression Analysis of Four Subgroup Members of the GH13 Family in Wheat (Triticum aestivum L.).

The glycoside hydrolase 13 (GH13) family is crucial for catalyzing α-glucoside linkages, and plays a key role in plant growth, development, and stress responses. Despite its significance, its role in plants remains understudied. This study targeted four GH13 subgroups in wheat, identifying 66 GH13 members from the latest wheat database (IWGSC RefSeq v2.1), including 36 α-amylase (AMY) members, 18 1,4-α-glucan-branching enzyme (SBE) members, 9 isoamylase (ISA) members, and 3 pullulanase (PU) members. Chromosomal distribution reveals a concentration of wheat group 7 chromosomes. Phylogenetic analysis underscores significant evolutionary distance variations among the subgroups, with distinct molecular structures. Replication events shaped subgroup evolution, particularly in regard to AMY members. Subcellular localization indicates AMY member predominance in extracellular and chloroplast regions, while others localize solely in chloroplasts, confirmed by the heterologous expression of TaSEB16 and TaAMY1 in tobacco. Moreover, 3D structural analysis shows the consistency of GH13 across species. Promoter cis-acting elements are suggested to be involved in growth, stress tolerance, and starch metabolism signaling. The RNA-seq data revealed TaGH13 expression changes under drought and submergence stress, and significant expression variation was observed between strong and weak gluten varieties during seed germination using quantitative real-time PCR (qRT-PCR), correlating with seed starch content. These findings demonstrate the pivotal role of GH13 family gene expression in wheat germination, concerning variety preference and environmental stress. Overall, this study advances the understanding of wheat GH13 subgroups, laying the groundwork for further functional studies.

Biochemical and molecular responses of the ascorbate-glutathione cycle in wheat seedlings exposed to different forms of selenium.

Biofortification aims to increase selenium (Se) concentration and bioavailability in edible parts of crops such as wheat (Triticum aestivum L.), resulting in increased concentration of Se in plants and/or soil. Higher Se concentrations can disturb protein structure and consequently influence glutathione (GSH) metabolism in plants which can affect antioxidative and other detoxification pathways. The aim of this study was to elucidate the impact of five different concentrations of selenate and selenite (0.4, 4, 20, 40 and 400 mg kg-1) on the ascorbate-glutathione cycle in wheat shoots and roots and to determine biochemical and molecular tissue-specific responses. Content of investigated metabolites, activities of detoxification enzymes and expression of their genes depended both on the chemical form and concentration of the applied Se, as well as on the type of plant tissue. The most pronounced changes in the expression level of genes involved in GSH metabolism were visible in wheat shoots at the highest concentrations of both forms of Se. Obtained results can serve as a basis for further research on Se toxicity and detoxification mechanisms in wheat. New insights into the Se impact on GSH metabolism could contribute to the further development of biofortification strategies.

Comparative uptake, translocation and metabolism of phenamacril in crops under hydroponic and soil cultivation conditions.

Many studies investigate the plant uptake and metabolism of xenobiotics by hydroponic experiments, however, plants grown in different conditions (hydroponic vs. soil) may result in different behaviors. To explore the potential differences, a comparative study on the uptake, translocation and metabolism of the fungicide phenamacril in crops (wheat/rice) under hydroponic and soil cultivation conditions was conducted. During 7-14 days of exposure, the translocation factors (TFs) of phenamacril were greatly overestimated in hydroponic-wheat (3.6-5.2) than those in soil-wheat systems (1.1-2.0), with up to 3.3 times of difference between the two cultivation systems, implying it should be cautious to extrapolate the results obtained from hydroponic to field conditions. M-144 was formed in soil pore water (19.1-29.9 µg/L) in soil-wheat systems but not in the hydroponic solution in hydroponics; M-232 was only formed in wheat shoots (89.7-103.0 µg/kg) under soil cultivation conditions, however, it was detected in hydroponic solution (20.1-21.2 µg/L), wheat roots (146.8-166.0 µg/kg), and shoots (239.2-348.1 µg/kg) under hydroponic conditions. The root concentration factors (RCFs) and TFs of phenamacril in rice were up to 2.4 and 3.6 times higher than that in wheat for 28 days of the hydroponic exposure, respectively. These results highlighted that cultivation conditions and plant species could influence the fate of pesticides in crops, which should be considered to better assess the potential accumulation and transformation of pesticides in crops.

Wheat BREVIS RADIX (BRX) regulates organ size, stomatal density and enhances drought tolerance in Arabidopsis.

BREVIS RADIX (BRX) is a small plant-specific and evolutionary conserved gene family with divergent yet partially redundant biological functions including root and shoot growth, stomatal development and tiller angle in plants. We characterized a BRX family gene from wheat (Triticum aestivum) by gain-of-function in Arabidopsis. Overexpression of TaBRXL2A resulted in longer primary roots with increased root meristem size and higher root growth under control and exogenous hormone treatments as compared to wild type (Col-0) plants. Overexpression lines also exhibited significant differences with the wild type such as increased rosette size, higher leaf number and leaf size. At reproductive stage, overexpression lines exhibited wider siliques and higher grain weight per plant. Under drought stress, overexpression lines exhibited enhanced drought tolerance in terms of higher chlorophyll retention and lower oxidative stress, thereby leading to significant recovery from drought stress. The analysis suggests that the inherent lower stomatal density in the leaves of overexpression lines and higher stomatal closure in response to ABA might contribute to lower water loss from the overexpression lines. Furthermore, TaBRXL2A protein showed membrane localization, presence of conserved residues at N-terminal for palmitoylation, and phosphosites in the linker region which are prescribed for its potential role in protophloem differentiation and stomatal lineage. Thus, we identified a TaBRX family gene which is involved in developmental pathways essential for plant growth, and also enhances drought tolerance in Arabidopsis.

Metabolism of Tembotrione, a Triketone Herbicide, confers Differential Sensitivity in Winter Wheat (Triticum aestivum).

Tembotrione is a triketone herbicide widely used for broad-spectrum weed control in corn but not registered for use in wheat. A wide collection of spring, winter, and EMS-derived mutant lines of wheat was evaluated for their response to tembotrione treatment. Two winter wheat (WW) genotypes (WW-1 and WW-2) were found to be least sensitive to this herbicide, surviving >6 times the field recommended dose (92 g ai ha-1) compared to the most sensitive genotype (WW-24). Further, HPLC analysis using [14C] tembotrione suggested that both WW-1 and WW-2 metabolized tembotrione rapidly to nontoxic metabolites. Pretreatment with a P450 inhibitor (malathion) followed by tembotrione application increased the sensitivity of WW-1 and WW-2 genotypes to this herbicide, suggesting likely involvement of P450 enzymes in metabolizing tembotrione similar to corn. Overall, our results suggest that the genotypes WW-1 and WW-2 can potentially be used to develop tembotrione-resistant wheat varieties.

Antifungal Activity and Mechanism of 4-Propylphenol Against Fusarium graminearum, Agent of Wheat Scab, and Its Potential Application.

Fusarium head blight (FHB), caused by Fusarium graminearum, is a predominant disease of wheat. Due to the lack of disease-resistant germplasm, chemical control is an important means to control wheat scab. Volatile substances produced in near-isogenic wheat lines were detected after inoculation with F. graminearum, and 4-propylphenol, which appears in FHB-resistant lines, was identified. In vitro and in vivo antifungal activity tests demonstrate that 4-propylphenol effectively inhibits the mycelial growth of F. graminearum. Metabolomics analysis showed changes in glutathione metabolism, indicating that 4-propylphenol triggered reactive oxygen species (ROS) stress. This was consistent with the increasing ROS levels in Fusarium cells treated with 4-propylphenol. Further results demonstrated that excessive accumulation of ROS induced DNA and cell membrane damage in the mycelium. Moreover, 4-propylphenol showed different degrees of inhibition against other soil-borne pathogens (fungi and oomycetes). These findings illustrated that 4-propylphenol has broad spectrum and high antifungal activity and should be considered for use as an ecological fungicide.

Novel insights into the mechanism of laccase-driven rhizosphere humification for alleviating wheat 17ß-estradiol contamination.

Global-scale crop contamination with environmental estrogens has posed a huge risk to agri-food safety and human health. Laccase is regarded as an unexceptionable biocatalyst for regulating pollution and expediting humification, but the knowledge of estrogen bioremediation and C storage strengthened by laccase-driven rhizosphere humification (LDRH) remains largely unknown. Herein, a greenhouse microcosm was performed to explore the migration and fate of 17ß-estradiol (E2) in water-wheat (Triticum aestivum L.) matrices by LDRH. Compared to the non-added laccase, the pseudo-first-order decay rate constants of E2 in the rhizosphere solution after 10 and 50 µM exposures by LDRH increased from 0.03 and 0.02 h-1 to 0.36 and 0.09 h-1, respectively. Furthermore, LDRH conferred higher yield, polymerizability, O-containing groups, and functional-C signals in the humified precipitates, because it accelerated the formation of highly complex precipitates by radical-controlled continuous polymerization. In particular, not only did LDRH mitigate the phytotoxicity of E2, but it also diminished the metabolic load of E2 in wheat tissues. This was attributed to the rapid attenuation of E2 in the rhizosphere solution during LDRH, which limited E2 uptake and accumulation in each subcellular fraction of the wheat roots and shoots. Although several typical intermediate products such as estrone, estriol, and E2 oligomers were detected in roots, only small-molecule species were found in shoots, evidencing that the polymeric products of E2 were unable to be translocated acropetally due to the vast hydrophobicity and biounavailability. For the first time, our study highlights a novel, eco-friendly, and sustainable candidate for increasing the low-C treatment of organics in rhizosphere microenvironments and alleviating the potential risks of estrogenic contaminants in agroenvironments.

Genome-wide analysis of MADS-box transcription factor gene family in wild emmer wheat (Triticum turgidum subsp. dicoccoides).

The members of MADS-box gene family have important roles in regulating the growth and development of plants. MADS-box genes are highly regarded for their potential to enhance grain yield and quality under shifting global conditions. Wild emmer wheat (Triticum turgidum subsp. dicoccoides) is a progenitor of common wheat and harbors valuable traits for wheat improvement. Here, a total of 117 MADS-box genes were identified in the wild emmer wheat genome and classified to 90 MIKCC, 3 MIKC*, and 24 M-type. Furthermore, a phylogenetic analysis and expression profiling of the emmer wheat MADS-box gene family was presented. Although some MADS-box genes belonging to SOC1, SEP1, AGL17, and FLC groups have been expanded in wild emmer wheat, the number of MIKC-type MADS-box genes per subgenome is similar to that of rice and Arabidopsis. On the other hand, M-type genes of wild emmer wheat is less frequent than that of Arabidopsis. Gene expression patterns over different tissues and developmental stages agreed with the subfamily classification of MADS-box genes and was similar to common wheat and rice, indicating their conserved functionality. Some TdMADS-box genes are also differentially expressed under drought stress. The promoter region of each of the TdMADS-box genes harbored 6 to 48 responsive elements, mainly related to light, however hormone, drought, and low-temperature related cis-acting elements were also present. In conclusion, the results provide detailed information about the MADS-box genes of wild emmer wheat. The present work could be useful in the functional genomics efforts toward breeding for agronomically important traits in T. dicoccoides.

TaMAPK3 phosphorylates TaCBF and TaICE and plays a negative role in wheat freezing tolerance.

Freezing temperature during overwintering often kills plants; plants have thus, developed a defense mechanism called 'cold acclimation', in which a number of genes are involved in increasing cell protection and gene expression. Mitogen-activated protein kinase (MAPK) controls proteins' activities by phosphorylation and is involved in numerous metabolic pathways. In this study, we identified the protein interaction between TaMAPK3 and the proteins in the cold response pathway, ICE41, ICE87, and CBFIVd-D9. The subcellular localization and bimolecular fluorescence complement (BiFC) assays revealed that these proteins interact in the nucleus or in the plasma membrane. Furthermore, MAPK3-mediated phosphorylation of ICE41, ICE87, and CBFIVd-D9 was verified using an in vitro phosphorylation assay. TaMAPK3-overexpressing transgenic Brachypodium showed a lower survival rate upon freezing stress and lower proline content during cold acclimation, compared to wild-type plants. Furthermore, cold response gene expression analysis revealed that the expression of these genes was suppressed in the transgenic lines under cold treatment. It was further elucidated that MAPK3 mediates the degradation of ICE and CBF proteins, which implies the negative impact of MAPK3 on the freezing tolerance of plants. This study will help to elucidate the molecular mechanisms of cold tolerance and the activity of MAPK3 in wheat.

High- or Low-Yielding F2 Progeny of Wheat Is Result of Specific TaCKX Gene Coexpression Patterns in Association with Grain Yield in Paternal Parent.

Members of the TaCKX gene family (GFM) encode oxidase/dehydrogenase cytokinin degrading enzymes (CKX), which play an important role in the homeostasis of phytohormones, affecting wheat development and productivity. Therefore, the objective of this investigation was to test how the expression patterns of the yield-related TaCKX genes and TaNAC2-5A (NAC2) measured in 7 days after pollination (DAP) spikes and the seedling roots of parents are inherited to apply this knowledge in the breeding process. The expression patterns of these genes were compared between parents and their F2 progeny in crosses of one mother with different paterns of awnless cultivars and reciprocal crosses of awned and awnless lines. We showed that most of the genes tested in the 7 DAP spikes and seedling roots of the F2 progeny showed paternal expression patterns in crosses of awnless cultivars as well as reciprocal crosses of awned and awnless lines. Consequently, the values of grain yield in the F2 progeny were similar to the pater; however, the values of seedling root mass were similar to the mother or both parents. The correlation analysis of TaCKX GFMs and NAC2 in spikes and spikes per seedling roots reveals that the genes correlate with each other specifically with the pater and the F2 progeny or the mother and the F2 progeny, which shape phenotypic traits. The numbers of spikes and semi-empty spikes are mainly correlated with the specific coexpression of the TaCKX and NAC2 genes expressed in spikes or spikes per roots of the pater and F2 progeny. Variable regression analysis of grain yield and root mass with TaCKX GFMs and NAC2 expressed in the tested tissues of five crosses revealed a significant dependency of these parameters on the mother and F2 and/or the pater and F2 progeny. We showed that the inheritance of yield-related traits depends on the specific cooperative expression of some TaCKX GFMs, in some crosses coupled with NAC2, and is strongly dependent on the genotypes used for the crosses. Indications for parental selection in the breeding of high-yielding lines are discussed.

Topless-related 2 conferred cadmium accumulation in wheat.

Wheat is a vital food crop that faces threats from various abiotic and biotic stresses. Understanding the molecular mechanism of cadmium (Cd) resistance can provide valuable insights into the tolerance of wheat. Plant proteins known as Topless/Topless-Related (TPL/TPR) play a role in growth, development, defense regulation, and stress response. In this study, we identified TaTPR2 as being induced by Cd stress treatment. Upon Cd treatment, wheat plants overexpressing TaTPR2 exhibited better growth compared to wild-type (WT) plants. Moreover, the transgenic lines showed reduced accumulation of reactive oxygen species (ROS), along with significantly higher activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) compared to WT plants. Additionally, the transgenic lines exhibited lower levels of malondialdehyde (MDA) and electrolyte leakage compared to WT plants. Further analysis revealed that TabHLH41 directly binds to the E-box motif of the TaTPR2 promoter and positively regulates its expression. Overall, the overexpression of TaTPR2 in transgenic wheat resulted in reduced accumulation of Cd and ROS. These findings highlight the significance of the TabHLH41-TaTPR2 pathway as a crucial response to Cd stress in wheat.

Effects of frying on the surface oil absorption of wheat, potato, and pea starches.

The effects of structural changes on surface oil absorption characteristics of wheat starch, pea starch and potato starch during frying under different water content (20%, 30%, 40%, 50%) were studied. Fried potato starch with a 40% water content exhibited the highest surface oil content. When the initial moisture content reached 30%, the scattering intensity of the crystal layer structure decreased for wheat and pea starches, while the scattering peak for potato starch completely disappeared. At 40% moisture content, the amorphous phase ratio values for fried potato, wheat and pea starches were 13.50%, 11.78% and 11.24%, respectively, and the nitrogen adsorption capacity of fried starch decreased in turn. These findings that the structure of potato starch was more susceptible to degradation compared to pea starch and wheat starch, resulting in higher surface oil absorbed by potato starch during frying process.

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.

Active oxygen generation induced by the glucose sensor TaHXK7-1A decreased the drought resistance of transgenic Arabidopsis and wheat (Triticum aestivum L.).

Improving wheat drought resistance is of great significance for grain production and food security. Hexokinases (HXKs) play a role in sugar signal transduction and are involved in abiotic stress responses in wheat. To clarify the relationship between HXKs and drought stress in wheat, we used the rice active oxygen induction gene OsHXK1 as a reference sequence and the homologously cloned wheat TaHXK7-1A gene. TaHXK7-1A was localized in the nucleus and cell membrane. Under drought stress, over-expression of TaHXK7-1A increased the contents of O2·ï¼ and malondialdehyde (MDA) and significantly up-regulated the respiratory burst oxidative homologue (RBOHs) genes in transgenic Arabidopsis. In addition, the over-expression of TaHXK7-1A inhibited the growth of Arabidopsis seedlings and increased ROS accumulation under 6 % exogenous glucose treatment. Gene silencing of TaHXK7-1 decreased the contents of O2·ï¼ and MDA in wheat leaves under drought stress, and the RBOHs was significantly down-regulated, which improved the drought resistance of wheat. The results of yeast one-hybrid, EMSA, and dual-luciferase assays showed that TabHLH148-5A bound to the E-box motif of the TaHXK7-1A promoter and inhibited the expression of TaHXK7-1A. In addition, yeast two-hybrid and luciferase complementation imaging assays showed that TaHXK7-1A interacted with TaGRF3-4A. These results indicate that the glucose sensor TaHXK7-1A was negatively regulated by TabHLH148-5A, interacted with TaGRF3-4A, and negatively regulated wheat drought resistance by regulating RBOHs expression and inducing ROS production, thus providing a theoretical basis for revealing the molecular mechanism of wheat drought resistance.

Assessment of the oxidative stress intensity and the integrity of cell membranes under the manganese nanoparticles toxicity in wheat seedlings.

A response to manganese nanoparticles was studied in seedlings of two wheat cultivars and a model system of plant cell membranes. Nanoparticles at concentrations of 125 and 250 mg/ml were applied foliar. The application of NPs enhanced the content of Mn in plant cells, indicating its penetration through the leaf surface. The stressful effect in the plant cells was estimated based on changes in the activity of antioxidant enzymes, content of chlorophylls and starch. MnNPs evoked no significant changes in the leaf morphology, however, an increase in enzyme activity, starch accumulation, and a decrease in chlorophyll synthesis indicated the stress occurrence. Moreover, a rise in the electrokinetic potential of the chloroplast membrane surface and the reconstruction of their hydrophobic parts toward an increase in fatty acid saturation was found.