Update on the Basic Understanding of Fusarium graminearum Virulence Factors in Common Wheat Research.

Wheat is one of the most important food crops, both in China and worldwide. Wheat production is facing extreme stresses posed by different diseases, including Fusarium head blight (FHB), which has recently become an increasingly serious concerns. FHB is one of the most significant and destructive diseases affecting wheat crops all over the world. Recent advancements in genomic tools provide a new avenue for the study of virulence factors in relation to the host plants. The current review focuses on recent progress in the study of different strains of Fusarium infection. The presence of genome-wide repeat-induced point (RIP) mutations causes genomic mutations, eventually leading to host plant susceptibility against Fusarium invasion. Furthermore, effector proteins disrupt the host plant resistance mechanism. In this study, we proposed systematic modification of the host genome using modern biological tools to facilitate plant resistance against foreign invasion. We also suggested a number of scientific strategies, such as gene cloning, developing more powerful functional markers, and using haplotype marker-assisted selection, to further improve FHB resistance and associated breeding methods.

Appropriate reduction of importin-α gene expression enhances yellow dwarf disease resistance in common wheat.

Barley yellow dwarf viruses (BYDVs) cause widespread damage to global cereal crops. Here we report a novel strategy for elevating resistance to BYDV infection. The 17K protein, a potent virulence factor conserved in BYDVs, interacted with barley IMP-α1 and -α2 proteins that are nuclear transport receptors. Consistently, a nuclear localization signal was predicted in 17K, which was found essential for 17K to be transported into the nucleus and to interact with IMP-α1 and -α2. Reducing HvIMP-α1 and -α2 expression by gene silencing attenuated BYDV-elicited dwarfism, accompanied by a lowered nuclear accumulation of 17K. Among the eight common wheat CRISPR mutants with two to four TaIMP-α1 and -α2 genes mutated, the triple mutant α1aaBBDD /α2AAbbdd and the tetra-mutant α1aabbdd /α2AAbbDD displayed strong BYDV resistance without negative effects on plant growth under field conditions. The BYDV resistance exhibited by α1aaBBDD /α2AAbbdd and α1aabbdd /α2AAbbDD was correlated with decreased nuclear accumulation of 17K and lowered viral proliferation in infected plants. Our work uncovers the function of host IMP-α proteins in BYDV pathogenesis and generates the germplasm valuable for breeding BYDV-resistant wheat. Appropriate reduction of IMP-α gene expression may be broadly useful for enhancing antiviral resistance in agricultural crops and other economically important organisms.

Blue light receptor CRY1 regulates HSFA1d nuclear localization to promote plant thermotolerance.

Temperature increases as light intensity rises, but whether light signals can be directly linked to high temperature response in plants is unclear. Here, we find that light pre-treatment enables plants to survive better under high temperature, designated as light-induced thermotolerance (LIT). With short-term light treatment, plants induce light-signaling pathway genes and heat shock genes. Blue light photoreceptor cryptochrome 1 (CRY1) is required for LIT. We also find that CRY1 physically interacts with the heat shock transcription factor A1d (HsfA1d) and that HsfA1d is involved in thermotolerance under light treatment. Furthermore, CRY1 promotes HsfA1d nuclear localization through importin alpha 1 (IMPα1). Consistent with this, CRY1 shares more than half of the chromatin binding sites with HsfA1d. Mutation of CRY1 (cry1-304) diminishes a large number of HsfA1d binding sites that are shared with CRY1. We present a model where, by coupling light sensing to high-temperature stress, CRY1 confers thermotolerance in plants via HsfA1d.

Wheat PHT1;9 acts as one candidate arsenate absorption transporter for phytoremediation.

Arsenate (AsV) is one of the most common forms of arsenic (As) in environment and plant high-affinity phosphate transporters (PHT1s) are the primary plant AsV transporters. However, few PHT1s involved in AsV absorption have been identified in crops. In our previous study, TaPHT1;3, TaPHT1;6 and TaPHT1;9 were identified to function in phosphate absorption. Here, their AsV absorption capacities were evaluated using several experiments. Ectopic expression in yeast mutants indicated that TaPHT1;9 had the highest AsV absorption rates, followed by TaPHT1;6, while not for TaPHT1;3. Under AsV stress, further, BSMV-VIGS-mediated TaPHT1;9-silencing wheat plants exhibited higher AsV tolerance and lower As concentrations than TaPHT1;6-silenced plants, whereas TaPHT1;3-silencing plants had similar phenotype and AsV concentrations to control. These suggested that TaPHT1;9 and TaPHT1;6 possessed AsV absorption capacity with the former showing higher activities. Under hydroponic condition, furthermore, CRISPR-edited TaPHT1;9 wheat mutants showed the enhanced tolerance to AsV with decreased As distributions and concentrations, whereas TaPHT1;9 ectopic expression transgenic rice plants had the opposite results. Also, under AsV-contaminated soil condition, TaPHT1;9 transgenic rice plants exhibited depressed AsV tolerance with increased As concentrations in roots, straws and grains. Moreover, Pi addition alleviated the AsV toxicity. These suggested that TaPHT1;9 should be a candidate target gene for AsV phytoremediation.

Abscisic acid alleviates mercury toxicity in wheat (Triticum aestivum L.) by promoting cell wall formation.

Mercury (Hg) is a heavy metal (HM) that affects crop growth and productivity. In a previous study, we found that application of exogenous abscisic acid (ABA) alleviated growth inhibition in Hg-stressed wheat seedlings. However, the physiological and molecular mechanisms underlying ABA-mediated Hg detoxification remained unclear. In this study, Hg exposure reduced the plant fresh and dry weights and root numbers. Exogenous ABA treatment significantly resumed the plant growth, increased the plant height and weight, and enriched the roots numbers and biomass. The application of ABA enhanced Hg absorption and raised the Hg levels in the roots. In addition, exogenous ABA decreased Hg-induced oxidative damage and significantly brought down the activities of antioxidant enzymes, such as SOD, POD and CAT. Global gene expression patterns in the roots and leaves exposed to HgCl2 and ABA treatments were examined via RNA-Seq. The data showed that genes related to ABA-mediated Hg detoxification were enriched in functions related to cell wall formation. Weighted gene co-expression network analysis (WGCNA) further indicated that the genes implicated in Hg detoxification were related to cell wall synthesis. Under Hg stress, ABA significantly induced expression of the genes encoding cell wall synthesis enzymes, regulated the activity of hydrolase, and increased the concentrations of cellulose and hemicellulose, hence promoting cell wall synthesis. Taken together, these results suggest that exogenous ABA could alleviate Hg toxicity in wheat by promoting cell wall formation and suppressing translocation of Hg from roots to shoots.

Genome-Wide Identification and Analysis of FKBP Gene Family in Wheat (Triticum asetivum).

FK506-binding protein (FKBP) genes have been found to play vital roles in plant development and abiotic stress responses. However, limited information is available about this gene family in wheat (Triticum aestivum L.). In this study, a total of 64 FKBP genes were identified in wheat via a genome-wide analysis involving a homologous search of the latest wheat genome data, which was unevenly distributed in 21 chromosomes, encoded 152 to 649 amino acids with molecular weights ranging from 16 kDa to 72 kDa, and was localized in the chloroplast, cytoplasm, nucleus, mitochondria, peroxisome and endoplasmic reticulum. Based on sequence alignment and phylogenetic analysis, 64 TaFKBPs were divided into four different groups or subfamilies, providing evidence of an evolutionary relationship with Aegilops tauschii, Brachypodium distachyon, Triticum dicoccoides, Arabidopsis thaliana and Oryza sativa. Hormone-related, abiotic stress-related and development-related cis-elements were preferentially presented in promoters of TaFKBPs. The expression levels of TaFKBP genes were investigated using transcriptome data from the WheatExp database, which exhibited tissue-specific expression patterns. Moreover, TaFKBPs responded to drought and heat stress, and nine of them were randomly selected for validation by qRT-PCR. Yeast cells expressing TaFKBP19-2B-2 or TaFKBP18-6B showed increased influence on drought stress, indicating their negative roles in drought tolerance. Collectively, our results provide valuable information about the FKBP gene family in wheat and contribute to further characterization of FKBPs during plant development and abiotic stress responses, especially in drought stress.

WRKY74 regulates cadmium tolerance through glutathione-dependent pathway in wheat.

Cadmium (Cd) is a toxic heavy metal to plants and human health. Ascorbate (ASA)-glutathione (GSH) synthesis pathway plays key roles in Cd detoxification, while its molecular regulatory mechanism remains largely unknown, especially in wheat. Here, we found a WRKY transcription factor-TaWRKY74, and its function in wheat Cd stress is not clear in previous studies. The expression levels of TaWRKY74 were significantly induced by Cd stress. Compared to control, the activities of GST, GR, or APX were significantly increased by 1.55-, 1.43-, or 1.75-fold and 1.63-, 2.65-, or 2.30-fold in shoots and roots of transiently TaWRKY74-silenced wheat plants under Cd stress. Similarly, the contents of hydrogen peroxide (H2O2), malondialdehyde (MDA), GSH, or Cd were also significantly increased by 2.39- or 1.25-fold, 1.54- or 1.20-fold, and 1.34- or 5.94-fold in shoots or roots in transiently TaWRKY74-silenced wheat plants, while ASA content was decreased by 47.4 or 43.3% in shoots, 10.7 or 6.5% in roots in these silenced wheat plants, respectively. Moreover, the expression levels of GSH, GPX, GR, DHAR, MDHAR, and APX genes, which are involved in ASA-GSH synthesis, were separately induced by 2.42-, 2.16-, 3.28-, 2.08-, 1.92-, and 2.23-fold in shoots, or by 10.69-, 3.33-, 3.26-, 1.81-, 16.53-, and 3.57-fold in roots of the BSMV-VIGS-TaWRKY74-inoculated wheat plants, respectively. However, the expression levels of TaNramp1, TaNramp5, TaHMA2, TaHMA3, TaLCT1, and TaIRT1 metal transporters genes were decreased by 21.2-76.3% (56.6%, 59.2%, 76.3%, 53.6%, 35.8%, and 21.2%) in roots of the BSMV-VIGS-TaWRKY74-inoculated wheat plants. Taken together, our results suggested that TaWRKY74 alleviated Cd toxicity in wheat by affecting the expression of ASA-GSH synthesis genes and suppressing the expression of Cd transporter genes, and further affecting Cd uptake and translocation in wheat plants.

Mercury stress tolerance in wheat and maize is achieved by lignin accumulation controlled by nitric oxide.

Nitric oxide (NO) is an important phytohormone for plant adaptation to mercury (Hg) stress. The effect of Hg on lignin synthesis, NO production in leaf, sheath and root and their relationship were investigated in two members of the grass family - wheat and maize. Hg stress decreased growth and lignin contents, significantly affected phenylpropanoid and monolignol pathways (PAL, phenylalanine ammonia-lyase; 4-coumarate: CoA ligase, 4CL; cinnamyl alcohol dehydrogenase, CAD), with maize identified to be more sensitive to Hg stress than wheat. Among the tissue types, sheath encountered severe damage compared to leaves and roots. Hg translocation in maize was about twice that in wheat. Interestingly, total NO produced under Hg stress was significantly decreased compared to control, with maximum reduction of 43.4% and 42.9% in wheat and maize sheath, respectively. Regression analysis between lignin and NO contents or the activities of three enzymes including CAD, 4CL and PAL displayed the importance of NO contents, CAD, 4CL and PAL for lignin synthesis. Further, the gene expression profiles encoding CAD, 4CL and PAL provided support for the damaging effect of Hg on wheat sheath, and maize shoot. To validate NO potential to mitigate Hg toxicity in maize and wheat, NO donor and NO synthase inhibitor were supplemented along with Hg. The resulting phenotype, histochemical analysis and lignin contents showed that NO mitigated Hg toxicity by improving growth and lignin synthesis and accumulation. In summary, Hg sensitivity was higher in maize seedlings compared to wheat, which was associated with the lower lignin contents and reduced NO contents. External supplementation of NO is proposed as a sustainable approach to mitigate Hg toxicity in maize and wheat.

Exogenous melatonin mitigates cadmium toxicity through ascorbic acid and glutathione pathway in wheat.

Cadmium (Cd) is a dispensable element that can be absorbed by crops, posing a threat to human health through the food chains. Melatonin (MT), as a plant growth regulator, has been used to alleviate Cd toxicity in many plant species; however, the underlying molecular mechanisms responsible for Cd toxicity in wheat are still poorly understood. In this study, the suitable exogenous MT concentration (50 µM) was screened to mitigate Cd toxicity of wheat plants by increasing the plant height, root length, fresh or dry weight and chlorophyll content, or decreasing the malondialdehyde (MDA) content. In addition, MT application significantly increased ascorbic acid (ASA) and glutathione (GSH) content by reducing ROS production, especially in roots, further decreasing Cd content in fraction of organelles. Moreover, the expression levels of ASA-GSH synthesis genes, APX, GR, and GST were significantly increased by 171.5%, 465.2%, and 256.8% in roots, respectively, whereas GSH, DHAR, or MDHAR were significantly decreased by 48.5%, 54.3%, or 60.0% in roots under MT + Cd stress. However, the expression levels of Cd-induced metal transporter genes TaNramp1, TaNramp5, TaHMA2, TaHMA3, and TaLCT1 were significantly decreased by 53.7%, 50.1%, 86.5%, 87.2%, and 94.5% in roots under MT + Cd stress compared with alone Cd treatment, respectively. In conclusion, our results suggesting that MT alleviate Cd toxicity in wheat by enhancing ASA-GSH metabolism, suppressing Cd transporter gene expression, and regulating Cd uptake and translocation in wheat plants.

Genome-wide analysis and functional characterization of CHYR gene family associated with abiotic stress tolerance in bread wheat (Triticum aestivum L.).

BACKGROUND: CHY zinc-finger and RING finger (CHYR) proteins have been functionally characterized in plant growth, development and various stress responses. However, the genome-wide analysis was not performed in wheat. RESULTS: In this study, a total of 18 TaCHYR genes were identified in wheat and classified into three groups. All TaCHYR genes contained CHY-zinc finger, C3H2C3-type RING finger and zinc ribbon domains, and group III members included 1-3 hemerythrin domains in the N-terminus regions. TaCHYR genes in each group shared similar conserved domains distribution. Chromosomal location, synteny and cis-elements analysis of TaCHYRs were also analyzed. Real-time PCR results indicated that most of selected 9 TaCHYR genes exhibited higher expression levels in leaves during wheat seedling stage. All these TaCHYR genes were up-regulated after PEG treatment, and these TaCHYRs exhibited differential expression patterns in response to salt, cold and heat stress in seedling leaves. The growth of yeast cells expressing TaCHYR2.1, TaCHYR9.2 and TaCHYR11.1 were inhibited under salt and dehydration stress. Moreover, gene ontology (GO) annotation, protein interaction and miRNA regulatory network of TaCHYR genes were analyzed. CONCLUSIONS: These results increase our understanding of CHYR genes and provide robust candidate genes for further functional investigations aimed at crop improvement.

TaWRKY74 participates copper tolerance through regulation of TaGST1 expression and GSH content in wheat.

Glutathione S-transferase (GST) is the key enzyme in glutathione (GSH) synthesis, and plays a crucial role in copper (Cu) detoxification. Nonetheless, its regulatory mechanisms remain largely unclear. In this study, we identified a Cu-induced glutathione S-transferase 1 (TaGST1) gene in wheat. Yeast one-hybrid (Y1H) screened out TaWRKY74, which was one member from the WRKY transcription factor family. The bindings between TaGST1 promoter and TaWRKY74 were further verified by using another Y1H and luciferase assays. Expression of TaWRKY74 was induced more than 30-folds by Cu stress. Functions of TaWRKY74 were tested by using transiently silence methods. In transiently TaWRKY74-silenced wheat plants, TaWRKY74 and TaGST1 expression, GST activity, and GSH content was significantly inhibited by 25.68%, 19.88%, 27.66%, and 12.68% in shoots, and 53.81%, 52.11%, 23.47%, and 17.11% in roots, respectively. However, contents of hydrogen peroxide, malondialdehyde, or Cu were significantly increased by 2.58%, 12.45%, or 37.74% in shoots, and 25.24%, 53.84%, and 103.99% in roots, respectively. Notably, exogenous application of GSH reversed the adverse effects of transiently TaWRKY74-silenced wheat plants during Cu stress. Taken together, our results suggesting that TaWRKY74 regulated TaGST1 expression and affected GSH accumulation under Cu stress, and could be useful to ameliorate Cu toxicity for crop food safety.

TaPHT1;9-4B and its transcriptional regulator TaMYB4-7D contribute to phosphate uptake and plant growth in bread wheat.

Efficient phosphate (Pi) uptake and utilisation are essential for promoting crop yield. However, the underlying molecular mechanism is still poorly understood in complex crop species such as hexaploid wheat. Here we report that TaPHT1;9-4B and its transcriptional regulator TaMYB4-7D function in Pi acquisition, translocation and plant growth in bread wheat. TaPHT1;9-4B, a high-affinity Pi transporter highly upregulated in roots by Pi deficiency, was identified using quantitative proteomics. Disruption of TaPHT1;9-4B function by BSMV-VIGS or CRISPR editing impaired wheat tolerance to Pi deprivation, whereas transgenic expression of TaPHT1;9-4B in rice improved Pi uptake and plant growth. Using yeast-one-hybrid assay, we isolated TaMYB4-7D, a R2R3 MYB transcription factor that could activate TaPHT1;9-4B expression by binding to its promoter. Silencing TaMYB4-7D decreased TaPHT1;9-4B expression, Pi uptake and plant growth. Four promoter haplotypes were identified for TaPHT1;9-4B, with Hap3 showing significant positive associations with TaPHT1;9-4B transcript level, growth performance and phosphorus (P) content in wheat plants. A functional marker was therefore developed for tagging Hap3. Collectively, our data shed new light on the molecular mechanism controlling Pi acquisition and utilisation in bread wheat. TaPHT1;9-4B and TaMYB4-7D may aid further research towards the development of P efficient crop cultivars.

Exogenous Glutathione Alleviates Cadmium Toxicity in Wheat by Influencing the Absorption and Translocation of Cadmium.

Cadmium (Cd), a toxic heavy metal, is harmful to plants and human health. Glutathione (GSH) could alleviate Cd toxicity of plant species, whereas its mechanism responsible for wheat remains poorly understood. Here, we found that exogenous GSH application significantly increased the fresh and dry weight, root elongation, chlorophyll contents, while decreased the contents of malondialdehyde (MDA) and GSH, and translocation factor of Cd compared with Cd treatment. Moreover, GSH application significantly increased activities of antioxidant enzymes and expression of related genes, which involved in GSH synthesis, especially in roots. In addition, we found that GSH application suppressed Cd-induced expression of metal transporter genes TaNramp1, TaNramp5, TaHMA2, TaHMA3, TaLCT1 and TaIRT2 in roots. Taken together, our results suggested that GSH could alleviate Cd toxicity in wheat by increasing GSH synthesis gene expression or suppressing Cd transporter genes expression, and further affecting Cd uptake and translocation in wheat plants.

Melatonin promotes potassium deficiency tolerance by regulating HAK1 transporter and its upstream transcription factor NAC71 in wheat.

Melatonin (MT) is involved in various physiological processes and stress responses in animals and plants. However, little is known about the molecular mechanisms by which MT regulates potassium deficiency (DK) tolerance in crops. In this study, an appropriate concentration (50 µmol/L) was found to enhance the tolerance of wheat plants against DK. RNA-seq analysis showed that a total of 6253 and 5873 differentially expressed genes (DEGs) were separately identified in root and leaf tissues of the DK + MT-treated wheat plants. They functionally involved biological processes of secondary metabolite, signal transduction, and transport or catabolism. Of these, an upregulated high-affinity K transporter 1 (TaHAK1) gene was next characterized. TaHAK1 overexpression markedly enhanced the K absorption, while its transient silencing exhibited the opposite effect, suggesting its important role in MT-mediated DK tolerance. Moreover, yeast one-hybrid (Y1H) was used to screen the upstream regulators of TaHAK1 gene and the transcription factor TaNAC71 was identified. The binding between TaNAC71 and TaHAK1 promoter was evidenced by using Y1H, LUC, and EMSA assays. Transient overexpression of TaNAC71 in wheat protoplasts activated the TaHAK1 expression, whereas its transient silencing inhibited the TaHAK1 expression and aggravated the sensitivity to DK. Exogenous MT application greatly upregulated the expression of TaHAK1 in both transient overexpression and silencing systems. Our findings revealed some molecular mechanisms underlying MT-mediated DK tolerance and helped broaden its practical application in agriculture.

Tillage and irrigation increase wheat root systems at deep soil layer and grain yields in lime concretion black soil.

In lime concretion black soil, a two-factor (tillage and irrigation) split block experiment from 2015 to 2017 was conducted to identify whether their combination is suitable for the improvement of winter wheat yield and water use efficiency. The main treatments were subsoiling (SS) and rotary tillage (RT), with secondary treatments of three irrigation regimes: no irrigation during the whole growth period (W0), irrigation at jointing stage (W1), and irrigation at both jointing and anthesis stages (W2). In combination with a soil column experiment, the contribution of the root system in different soil layers to yield was clarified. The results indicated that both tillage and irrigation significantly influenced the spatiotemporal distributions of the root systems and yield components, while tillage produced the strongest effect. Compared with RT, SS significantly promoted the root penetration and delayed root senescence in deep soil layers. With increasing soil depth, each root configuration parameter (dry root weight density, DRWD; root length density, RLD; root surface area per unit area, RSA; root volume per unit area, RV) gradually decreased, and the peak appearance times of each root parameter in RT and three parameters (RLD, RSA and RV) in SS were postponed from heading to anthesis and from anthesis to filling stage, respectively. The average post-peak attenuation values at soil layers from 60 to 100 cm in W1 were less than those in W0 and W2. SSW1 generated the highest grain yields, with an average increase of 31.88% compared with the yield in RTW0. Root systems at three soil layers (0-40 cm, 40-80 cm and below 80 cm) differentially contributed to grain yields with 78.32%, 12.09% and 9.59%, respectively. The growth peak of the deep root system in SSW1 was postponed to the filling stage, and the post-peak attenuation declining rates were also slowed. Therefore, SSW1 is an effective cultivation method improving grain yields and water use efficiency in lime concretion black soil.

Successive biochar amendment affected crop yield by regulating soil nitrogen functional microbes in wheat-maize rotation farmland.

Biochar has attracted increased attention because of its potential benefits for carbon sequestration, soil fertility, and contaminant immobilization. However, mechanism of long-term successive biochar amendment affected crop yield by regulating soil properties and nitrogen (N) functional microbes is still unclear by now. A field fixed experiment was carried out from 2011 to 2018 that aimed to study the effects of successive biochar on soil properties, soil nitrogen functional microbial genes, and grain yield in wheat and maize rotation farmland in Northern China. Four straw biochar treatments were tested in this study: 0 (BC0, CK), 2.25 (BC2.25), 6.75 (BC6.75), and 11.25 (BC11.25) Mg ha-1. The results showed that, after seven wheat-maize rotations, the total organic carbon (TOC), total N (TN), NO3-, available potassium (AK), and the C/N ratio in 0-20 cm topsoil were increased significantly following biochar application; however, there were no obvious differences in available phosphorus (AP) and NH4+ among biochar treatments. Biochar also resulted in a significant increase in crop yield and NO3- accumulation in 0-200 cm soil layer, with the highest yield in BC6.75. Furthermore, a marked increase was found in the amoA gene abundance in topsoil; however, it decreased significantly with excessive biochar application (BC11.25). At wheat maturity, the nirS gene abundance consistently decreased following biochar application, whereas the nosZ gene abundance initially increased and then decreased (peaking in BC6.75); however, no obvious changes in the nirK gene were observed. At maize maturity, biochar significantly increased the nirS and nosZ gene abundance in topsoil, especially in BC6.75. In addition, redundancy analysis indicated that the soil moisture content, AP, AK, TN, TOC, NO3-, NH4+, pH, and C/N ratio had markedly effects on the abundance of the amoA, nirK, nirS, and nosZ genes. In general, biochar-induced alterations of soil properties resulted in changes of gene abundance of soil nitrifying and denitrifying bacteria, and eventually affecting crop yields.

Functional characterization and regulatory mechanism of wheat CPK34 kinase in response to drought stress.

BACKGROUND: Drought is one of the most adverse environmental factors limiting crop productions and it is important to identify key genetic determinants for food safety. Calcium-dependent protein kinases (CPKs) are known to be involved in plant growth, development, and environmental stresses. However, biological functions and regulatory mechanisms of many plant CPKs have not been explored. In our previous study, abundance of the wheat CPK34 (TaCPK34) protein was remarkably upregulated in wheat plants suffering from drought stress, inferring that it could be involved in this stress. Therefore, here we further detected its function and mechanism in response to drought stress. RESULTS: Transcripts of the TaCPK34 gene were significantly induced after PEG-stimulated water deficiency (20% PEG6000) or 100 µM abscisic acid (ABA) treatments. The TaCPK34 gene was transiently silenced in wheat genome by using barley stripe mosaic virus-induced silencing (BSMV-VIGS) method. After 14 days of drought stress, the transiently TaCPK34-silenced wheat seedlings showed more sensitivity compared with control, and the plant biomasses and relative water contents significantly decreased, whereas soluble sugar and MDA contents increased. The iTRAQ-based quantitative proteomics was employed to measure the protein expression profiles in leaves of the transiently TaCPK34-silenced wheat plants after drought stress. There were 6103 proteins identified, of these, 51 proteins exhibited significantly altered abundance, they were involved in diverse function. And sequence analysis on the promoters of genes, which encoded the above identified proteins, indicated that some promoters harbored some ABA-responsive elements. We determined the interactions between TaCPK34 and three identified proteins by using bimolecular fluorescent complementation (BiFC) method and our data indicated that TaCPK34directly interacted with the glutathione S-transferase 1 and prx113, respectively. CONCLUSIONS: Our study suggested that the TaCPK34 gene played positive roles in wheat response to drought stress through directly or indirectly regulating the expression of ABA-dependent manner genes, which were encoding identified proteins from iTRAQ-based quantitative proteomics. And it could be used as one potential gene to develop crop cultivars with improved drought tolerance.

Bacterial Community Structure and Predicted Function in Wheat Soil From the North China Plain Are Closely Linked With Soil and Plant Characteristics After Seven Years of Irrigation and Nitrogen Application.

The influence of water and nitrogen (N) management on wheat have been investigated, but studies on the impact of long-term interactive water and N management on microbial structure and function are limited. Soil chemical properties and plants determine the soil microbial communities whose functions involved in nutrient cycling may affect plant productivity. There is an urgent need to elucidate the underlying mechanisms to optimize these microbial communities for agricultural sustainability in the winter wheat production area of the North China Plain. We performed high-throughput sequencing and quantitative PCR of the 16S rRNA gene on soil from a 7-year-old stationary field experiment to investigate the response of bacterial communities and function to water and N management. It was observed that water and N management significantly influenced wheat growth, soil properties and bacterial diversity. N application caused a significant decrease in the number of operational taxonomic units (OTUs), and both Richness and Shannon diversity indices, in the absence of irrigation. Irrigation led to an increase in the relative abundance of Planctomycetes, Latescibacteria, Anaerolineae, and Chloroflexia. In addition, most bacterial taxa were correlated with soil and plant properties. Some functions related to carbohydrate transport, transcription, inorganic ion transport and lipid transport were enriched in irrigation treatment, while N enriched predicted functions related to amino acid transport and metabolism, signal transduction, and cell wall/membrane/envelope biogenesis. Understanding the impact of N application and irrigation on the structure and function of soil bacteria is important for developing strategies for sustainable wheat production. Therefore, concurrent irrigation and N application may improve wheat yield and help to maintain those ecosystem functions that are driven by the soil microbial community.

PDIL1-2 can indirectly and negatively regulate expression of the AGPL1 gene in bread wheat.

BACKGROUND: ADP-glucose pyrophosphorylase (AGPase), the key enzyme in plant starch biosynthesis, is a heterotetramer composed of two identical large subunits and two identical small subunits. AGPase has plastidial and cytosolic isoforms in higher plants, whereas it is mainly detected in the cytosol of grain endosperms in cereal crops. Our previous results have shown that the expression of the TaAGPL1 gene, encoding the cytosolic large subunit of wheat AGPase, temporally coincides with the rate of starch accumulation and that its overexpression dramatically increases wheat AGPase activity and the rate of starch accumulation, suggesting an important role. METHODS: In this study, we performed yeast one-hybrid screening using the promoter of the TaAGPL1 gene as bait and a wheat grain cDNA library as prey to screen out the upstream regulators of TaAGPL1 gene. And the barley stripe mosaic virus-induced gene-silencing (BSMV-VIGS) method was used to verify the functional characterization of the identified regulators in starch biosynthesis. RESULTS: Disulfide isomerase 1-2 protein (TaPDIL1-2) was screened out, and its binding to the TaAGPL1-1D promoter was further verified using another yeast one-hybrid screen. Transiently silenced wheat plants of the TaPDIL1-2 gene were obtained by using BSMV-VIGS method under field conditions. In grains of BSMV-VIGS-TaPDIL1-2-silenced wheat plants, the TaAGPL1 gene transcription levels, grain starch contents, and 1000-kernel weight also significantly increased. CONCLUSIONS: As important chaperones involved in oxidative protein folding, PDIL proteins have been reported to form hetero-dimers with some transcription factors, and thus, our results suggested that TaPDIL1-2 protein could indirectly and negatively regulate the expression of the TaAGPL1 gene and function in starch biosynthesis.

Effects of cultivation management on the winter wheat grain yield and water utilization efficiency.

The growth of winter wheat consumes a substantial amounts of water, and precipitation in most years cannot meet the water demand for the normal growth of winter wheat. The unsuitable irrigation strategies waste a large number of water resource, and the low water use efficiency has become the main factor limiting wheat yields. This research explored the effects of different cultivation managements on water consumption characteristics, water utilization efficiency, and grain yields of winter wheat. A field experiment, in which 4 cultivation managements including traditional cultivation management (T1), optimized cultivation management compared with T1 (T2), super high-yield cultivation management (T3) and optimized cultivation management compared with T3 (T4), was conducted during 2008-2010 to measure the above parameters. The results showed that different cultivation managements had significant effects on the total water consumption amounts and water source compositions. Total water consumption amounts in T1 and T3 managements were significantly higher than that in T2 and T4 managements, possibly from irrigation water. T2 and T4 managements remarkably increased the uptake and utilization of soil storage water and precipitation amounts. T3 and T1 managements increased and decreased water consumption in upper (0-40 cm) and lower (60-100 cm) soil layers, respectively, while effectively increased the consumption of storage water in middle and lower soil layers (60-100 cm) and yield water use efficiency (WUEY), precipitation water use efficiency (WUEP), soil water use efficiency (WUES), irrigation water use efficiency (WUEI), and irrigation efficiency (IE) in T4 and T2 managements were higher than those in T3 and T1, respectively. Total water consumption amounts markedly raised in T1 and T3 managements, whereas their soil storage water amounts utilization declined. T2 and T4 managements reduced irrigation water amounts and optimized the water and fertilizer supplies, resulting in significant increase in WUES and WUEI. Collectively, our results suggest that synergetic improving the water uptake and utilization of irrigation water and soil storage water can be the primary means to increase the grain yields and WUE.