Estimation of wheat protein content and wet gluten content based on fusion of hyperspectral and RGB sensors using machine learning algorithms.

The protein content (PC) and wet gluten content (WGC) are crucial indicators determining the quality of wheat, playing a pivotal role in evaluating processing and baking performance. Original reflectance (OR), wavelet feature (WF), and color index (CI) were extracted from hyperspectral and RGB sensors. Combining Pearson-competitive adaptive reweighted sampling (CARs)-variance inflation factor (VIF) with four machine learning (ML) algorithms were used to model accuracy of PC and WGC. As a result, three CIs, six ORs, and twelve WFs were selected for PC and WGC datasets. For single-modal data, the back-propagation neural network exhibited superior accuracy, with estimation accuracies (WF > OR > CI). For multi-modal data, the random forest regression paired with OR + WF + CI showed the highest validation accuracy. Utilizing the Gini impurity, WF outweighed OR and CI in the PC and WGC models. The amalgamation of MLs with multimodal data harnessed the synergies among various remote sensing sources, substantially augmenting model precision and stability.

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.

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.

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.

Comparing methods for estimating leaf area index by multi-angular remote sensing in winter wheat.

The reflectance of wheat's canopy exhibits angular sensitivity, which can influence the accuracy of different methods for its leaf area index (LAI) estimation through multi-angular remote sensing. The primary objective of this study was to assess and compare the ability of various methods for LAI estimation from 13 view zenith angles (VZAs). The four methods included: (1) common hyper-spectral vegetation indices (VIs), (2) optimal two-band combination VIs (i.e., VIs: normalized difference index, simple ratio index, and difference vegetation index), (3) back-propagation neural network (BPNN), and (4) partial least squares regression (PLSR). Our results demonstrated that the red-edge plays a key role in estimating LAI, in that the traditional VIs, optimal two-band VIs, and PLSR including the red-edge band all showed satisfactory performance, with coefficient of determination (R2) > 0.72 in the nadir direction. However, the estimation accuracy of LAI was not positively related with band number, and BPNN gave unsatisfactory results under a larger viewing angle, with R2 ≤ 0.60 for extreme angles. The predictive ability of all four methods declined with an increasing VZA, with reliable LAI estimation near the nadir direction. Importantly, by comparing the four methods, PLSR emerged as superior in both its estimation accuracy and angular insensitivity, with R2 = 0.83 in the nadir direction and ≥ 0.65 for extreme angles. For this reason, we highly recommend it be used with multi-angular remote sensing data, especially in agricultural applications.

Coordination of carbon and nitrogen accumulation and translocation of winter wheat plant to improve grain yield and processing quality.

The objective of this work was to characterize the accumulation of carbon (C) and nitrogen (N), and the translocation of wheat (Triticum aestivum L.) cultivars to achieve both high-quality and high-yield. Twenty-four wheat cultivars, including 12 cultivars containing high-quality gluten subunit 5 + 10 at Glu-D1, and 12 cultivars with no Glu-D1 5 + 10, were planted at Yuanyang and Xuchang in Henan Province, during 2016-2017, and 2017-2018 cropping seasons. Wheat cultivars containing Glu-D1 5 + 10 had an advantage in grain quality traits. Significant difference (P < 0.05) was observed for grain protein concentration (GPC) between 5 + 10 group and no 5 + 10 group. Grain yield (GY) was significantly correlated with kernel number (KN) (r = 0.778, P < 0.01), thousand-kernel weight (TKW) (r = 0.559, P < 0.01), dry matter accumulation at post-anthesis (r = 0.443, P < 0.05), and stem water-soluble carbohydrate (WSC) accumulation (r = 0.487, P < 0.05) and translocation amount (r = 0.490, P < 0.05). GPC, dough stability time (DST) and nitrogen agronomic efficiency (NAE) were significantly correlated with nitrogen accumulation (NAA) at maturity stage (r = 0.524, = 0.404, = 0.418, P < 0.01, < 0.05, < 0.05, respectively), and nitrogen translocation amount (r = 0.512, = 0.471, = 0.405, P < 0.05, < 0.05, < 0.05, respectively). These results suggest that good-quality, high-yield, and high-efficiency could achieve through the selection of high-quality wheat cultivars and coordination of C and N accumulation and translocation. High-quality gluten subunit gene Glu-D1 5 + 10 and stem WSC could be used as a selection index for breeding and production of high-quality and high-yield wheat.

Root and nitrate-N distribution and optimization of N input in winter wheat.

Scientific management of nitrogen (N) fertilizer has a significant effect on yield while also reducing the environmental risks. In this study, we conducted field experiments over three years at two different sites (Zhengzhou and Shangshui) in Henan Province, China, using different N application rates (0, 90,180, 270, and 360 kg ha-1) to determine the relationships between soil N supply and N demand in winter wheat (Triticum aestivum L.). Optimal N input was then determined. Both sites showed the same trend. Namely, aboveground N uptake and soil nitrate N (NO3--N) increased with increasing N, while NO3--N decreased with increasing soil depth, gradually moving downwards with growth. A significant correlation (p < 0.001) between increasing aboveground N uptake and increasing NO3--N was also observed under N application, with the best relationships occurring in the 20-60 cm layer during jointing-anthesis (R2 = 0.402-0.431) and the 20-80 cm layer at maturity (R2 = 0.474). Root weight density showed the same spatial-temporal characteristics as NO3--N, following a unimodal trend with increasing N, and peaking at 90 kg ha-1. The root weight density was mainly distributed in the 0-60 cm layer (above 80%), with the 20-60 cm layer accounting for 30% of the total root system. In this layer, the root weight density was also significantly positively correlated with aboveground N uptake. Wheat yield reached saturation under high N (>270 kg ha-1), with a sharp decrease in N use efficiency (NUE) and linear increase in residual NO3--N. To balance yield and the risk of environmental pollution in the experimental area, an N application rate of 180-270 kg ha-1 is recommended under sufficient irrigation, thereby supporting a well-developed root system while ensuring balance between N supply and demand.

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.

The Highly Conserved Barley Powdery Mildew Effector BEC1019 Confers Susceptibility to Biotrophic and Necrotrophic Pathogens in Wheat.

Effector proteins secreted by plant pathogens play important roles in promoting colonization. Blumeria effector candidate (BEC) 1019, a highly conserved metalloprotease of Blumeria graminis f. sp. hordei (Bgh), is essential for fungal haustorium formation, and silencing BEC1019 significantly reduces Bgh virulence. In this study, we found that BEC1019 homologs in B. graminis f. sp. tritici (Bgt) and Gaeumannomyces graminis var. tritici (Ggt) have complete sequence identity with those in Bgh, prompting us to investigate their functions. Transcript levels of BEC1019 were abundantly induced concomitant with haustorium formation in Bgt and necrosis development in Ggt-infected plants. BEC1019 overexpression considerably increased wheat susceptibility to Bgt and Ggt, whereas silencing this gene using host-induced gene silencing significantly enhanced wheat resistance to Bgt and Ggt, which was associated with hydrogen peroxide accumulation, cell death, and pathogenesis-related gene expression. Additionally, we found that the full and partial sequences of BEC1019 can trigger cell death in Nicotiana benthamiana leaves. These results indicate that Bgt and Ggt can utilize BEC1019 as a virulence effector to promote plant colonization, and thus these genes represent promising new targets in breeding wheat cultivars with broad-spectrum resistance.

Integrative Analysis of the Wheat PHT1 Gene Family Reveals A Novel Member Involved in Arbuscular Mycorrhizal Phosphate Transport and Immunity.

Phosphorus (P) deficiency is one of the main growth-limiting factors for plants. However, arbuscular mycorrhizal (AM) symbiosis can significantly promote P uptake. Generally, PHT1 transporters play key roles in plants' P uptake, and thus, PHT1 genes have been investigated in some plants, but the regulation and functions of these genes in wheat (TaPHT1) during AM symbiosis have not been studied in depth. Therefore, a comprehensive analysis of TaPHT1 genes was performed, including sequence, phylogeny, cis-elements, expression, subcellular localization and functions, to elucidate their roles in AM-associated phosphate transport and immunity. In total, 35 TaPHT1s were identified in the latest high-quality bread wheat genome, 34 of which were unevenly distributed on 13 chromosomes, and divided into five groups. Sequence analysis indicated that there are 11 types of motif architectures and five types of exon-intron structures in the TaPHT1 family. Duplication mode analysis indicated that the TaPHT1 family has expanded mainly through segmental and tandem duplication events, and that all duplicated gene pairs have been under purifying selection. Transcription analysis of the 35 TaPHT1s revealed that not only known the mycorrhizal-specific genes TaPht-myc, TaPT15-4B (TaPT11) and TaPT19-4D (TaPT10), but also four novel mycorrhizal-specific/inducible genes (TaPT3-2D, TaPT11-4A, TaPT29-6A, and TaPT31-7A) are highly up-regulated in AM wheat roots. Furthermore, the mycorrhizal-specific/inducible genes are significantly induced in wheat roots at different stages of infection by colonizing fungi. Transient Agrobacterium tumefaciens-mediated transformation expression in onion epidermal cells showed that TaPT29-6A is a membrane-localized protein. In contrast to other AM-specific/inducible PHT1 genes, TaPT29-6A is apparently required for the symbiotic and direct Pi pathway. TaPT29-6A-silenced lines exhibited reduced levels of AM fungal colonization and arbuscules, but increased susceptibility to biotrophic, hemi-biotrophic and necrotrophic pathogens. In conclusion, TaPT29-6A was not only essential for the AM symbiosis, but also played vital roles in immunity.

Approach to Higher Wheat Yield in the Huang-Huai Plain: Improving Post-anthesis Productivity to Increase Harvest Index.

Both increased harvest index (HI) and increased dry matter (DM) are beneficial to yield; however, little is known about the priority of each under different yield levels. This paper aims to determine whether HI or DM is more important and identify the physiological attributes that act as indicators of increased yield. Two field experiments involving different cultivation patterns and water-nitrogen modes, respectively, were carried out from 2013 to 2016 in Huang-Huai Plain, China. Plant DM, leaf area index (LAI), and radiation interception (RI) were measured. Increased yield under low yield levels <7500 kg ha-1 was attributed to an increase in both total DM and HI, while increases under higher yield levels >7500 kg ha-1 were largely dependent on an increase in HI. Under high yield levels, HI showed a significant negative correlation with total DM and a parabolic relationship with net accumulation of DM during filling. Higher net accumulation of DM during filling helped slow down the decrease in HI, thereby maintaining a high value. Moreover, net DM accumulation during filling was positively correlated with yield, while post-anthesis accumulation showed a significant linear relationship with leaf area potential (LAP, R 2 = 0.404-0.526) and radiation interception potential (RIP, R 2 = 0.452-0.576) during grain filling. These findings suggest that the increase in LAP and RIP caused an increase in net DM accumulation after anthesis. Under DM levels >13,000 kg ha-1 at anthesis, maintaining higher LAI and RI in lower layers during grain formation contributed to higher yield. Furthermore, the ratio of upper- to lower-layer RI showed a second-order curve with yield during filling, with an increase in the optimal range with grain development. Pre-anthesis translocation amount, translocation ratios and contribution ratios also showed second-order curves under high yield levels, with optimal values of 3000-4500 kg ha-1, 25-35, and 30-50%, respectively. These results confirm the importance of HI in improving the yield, thereby providing a theoretical basis for wheat production in the Huang-Huai Plain.

Quantitative analysis of the grain amyloplast proteome reveals differences in metabolism between two wheat cultivars at two stages of grain development.

BACKGROUND: Wheat (Triticum aestivum L.) is one of the world's most important grain crops. The amyloplast, a specialized organelle, is the major site for starch synthesis and storage in wheat grain. Understanding the metabolism in amyloplast during grain development in wheat cultivars with different quality traits will provide useful information for potential yield and quality improvement. RESULTS: Two wheat cultivars, ZM366 and YM49-198 that differ in kernel hardness and starch characteristics, were used to examine the metabolic changes in amyloplasts at 10 and 15 days after anthesis (DAA) using label-free-based proteome analysis. We identified 523 differentially expressed proteins (DEPs) between 10 DAA and 15 DAA, and 229 DEPs between ZM366 and YM49-198. These DEPs mainly participate in eight biochemical processes: carbohydrate metabolism, nitrogen metabolism, stress/defense, transport, energetics-related, signal transduction, protein synthesis/assembly/degradation, and nucleic acid-related processes. Among these proteins, the DEPs showing higher expression levels at 10 DAA are mainly involved in carbohydrate metabolism, stress/defense, and nucleic acid related processes, whereas DEPs with higher expression levels at 15 DAA are mainly carbohydrate metabolism, energetics-related, and transport-related proteins. Among the DEPs between the two cultivars, ZM366 had more up-regulated proteins than YM49-198, and these are mainly involved in carbohydrate metabolism, nucleic acid-related processes, and transport. CONCLUSIONS: The results of our study indicate that wheat grain amyloplast has the broad metabolic capability. The DEPs involved in carbohydrate metabolism, nucleic acids, stress/defense, and transport processes, with grain development and cultivar differences, are possibly responsible for different grain characteristics, especially with respect to yield and quality-related traits.

Grain number responses to pre-anthesis dry matter and nitrogen in improving wheat yield in the Huang-Huai Plain.

Wheat yield components vary between different ecological regions and yield levels. Grain number responses to pre-anthesis dry matter (DM) and nitrogen (N) in increasing yield were always investigated in spike organs, neglecting the effect of non-spike organ nutrition or overall distribution. This paper determined the relationships between grain number and pre-anthesis DM and N in spike and non-spike organs under different yield levels, with using two sorts of field experiments (different water-nitrogen modes and cultivation management patterns) from 2012-2015 in Huang-Huai plain. The results indicated that improving yield under yield of <7500 kg ha-1 depends on increasing grain number per spike (GNs) or spike number (SN) or both, increased yield under higher yield of >7500 kg ha-1 mainly depends on GNs. GNs showed significant positive relationships with above-ground DM accumulation from jointing to anthesis under high or low yield levels. Rapid DM growth in spring achieves higher GNs. Spike and non-spike DM and N contents both demonstrated strong positive relationships with GNs, spike DM distribution also shows a positive correlation, but spike N distribution ratio show negatively correlation with GNs. Improved N distribution in non-spike organs and DM partition in spike organs conduce to increasing GNs.

Large-scale Proteomics Combined with Transgenic Experiments Demonstrates An Important Role of Jasmonic Acid in Potassium Deficiency Response in Wheat and Rice.

Potassium (K+) is the most abundant inorganic cation in plants, and molecular dissection of K+ deficiency has received considerable interest in order to minimize K+ fertilizer input and develop high quality K+-efficient crops. However, the molecular mechanism of plant responses to K+ deficiency is still poorly understood. In this study, 2-week-old bread wheat seedlings grown hydroponically in Hoagland solution were transferred to K+-free conditions for 8 d, and their root and leaf proteome profiles were assessed using the iTRAQ proteome method. Over 4000 unique proteins were identified, and 818 K+-responsive protein species showed significant differences in abundance. The differentially expressed protein species were associated with diverse functions and exhibited organ-specific differences. Most of the differentially expressed protein species related to hormone synthesis were involved in jasmonic acid (JA) synthesis and the upregulated abundance of JA synthesis-related enzymes could result in the increased JA concentrations. Abundance of allene oxide synthase (AOS), one key JA synthesis-related enzyme, was significantly increased in K+-deficient wheat seedlings, and its overexpression markedly increased concentrations of K+ and JA, altered the transcription levels of some genes encoding K+-responsive protein species, as well as enhanced the tolerance of rice plants to low K+ or K+ deficiency. Moreover, rice AOS mutant (osaos) exhibited more sensitivity to low K+ or K+ deficiency. Our findings could highlight the importance of JA in K+ deficiency, and imply a network of molecular processes underlying plant responses to K+ deficiency.

Physiological Responses and Yield of Wheat Plants in Zinc-Mediated Alleviation of Drought Stress.

To evaluate the physiological responses of wheat to zinc (Zn) fertilizer application under drought stress, pot, and field experiments were conducted on wheat plants grown under different soil moistures and treated with soil and foliar Zn applications. Photosynthetic characteristics, antioxidant content, Zn element concentration, and the transcription level of genes involved in antioxidant biosynthesis were analyzed. Zn application increased SPAD and Fv/Fm of wheat flag leaves, while decreased lipid peroxidation levels and H2O2 content. Zn application increased the antioxidant content (ascorbate, reduced glutathione, total phenolic, and total flavonoid) of wheat flag leaves, and enhanced the relative expression levels of two antioxidant enzyme genes, four ascorbate-glutathione cycle genes, and two flavonoid biosynthesis pathway genes under drought stress. Soil Zn application increased grain yield and Zn concentration by 10.5 and 15.8%, 22.6 and 9.7%, and 28.2 and 32.8% under adequate water supply, moderate drought, and severe drought, respectively. Furthermore, foliar application of Zn in the field increased grain yield and grain Zn concentration under both adequate water supply and rain-fed conditions. Zn plays a role in alleviating wheat plant drought stress by Zn-mediated increase in photosynthesis pigment and active oxygen scavenging substances, and reduction in lipid peroxidation. Furthermore, Zn fertilizer could regulate multiple antioxidant defense systems at the transcriptional level in response to drought.

Effect of irrigation and nitrogen application on grain amino acid composition and protein quality in winter wheat.

Water management and nitrogen application are critical factors in wheat grain yield and protein quality. This study aimed to evaluate the effect of irrigation and nitrogen application on the grain yield, protein content and amino acid composition of winter wheat. Field experiments were conducted in a split-plot design with three replications in high-yielding land on the North China Plain in 2012/2013, 2013/2014 and 2014/2015. Three irrigation treatments were examined in main plots: no irrigation, irrigation at jointing, and irrigation at jointing plus anthesis, while subplots were assigned to nitrogen treatment at four different rates: 0, 180, 240, 300 kg N ha-1, respectively. The results indicated that irrigation at jointing and at jointing plus anthesis improved grain yield by an average of 12.79 and 18.65% across three cropping seasons, respectively, compared with no irrigation. However, different irrigation treatments had no significant effect on grain protein content in any cropping season. Compared with no N treatment, 180, 240, and 300 kg N ha-1 N application significantly increased grain yield, by 58.66, 61.26 and 63.42% respectively, averaged over three cropping seasons. Grain protein and the total, essential and non-essential amino acid content significantly increased with increasing nitrogen application. Irrigation significantly improved the essential amino acid index (EAAI) and protein-digestibility-corrected amino acid score (PDCAAS) compared with no irrigation; however, N application decreased them by an average of 7.68 and 11.18% across three cropping seasons, respectively. EAAI and PDCAAS were positively correlated, however, they were highly negatively correlated with yield and grain protein content.

Functional Analysis of a Wheat AGPase Plastidial Small Subunit with a Truncated Transit Peptide.

ADP-glucose pyrophosphorylase (AGPase), the key enzyme in starch synthesis, consists of two small subunits and two large subunits with cytosolic and plastidial isoforms. In our previous study, a cDNA sequence encoding the plastidial small subunit (TaAGPS1b) of AGPase in grains of bread wheat (Triticum aestivum L.) was isolated and the protein subunit encoded by this gene was characterized as a truncated transit peptide (about 50% shorter than those of other plant AGPS1bs). In the present study, TaAGPS1b was fused with green fluorescent protein (GFP) in rice protoplast cells, and confocal fluorescence microscopy observations revealed that like other AGPS1b containing the normal transit peptide, TaAGPS1b-GFP was localized in chloroplasts. TaAGPS1b was further overexpressed in a Chinese bread wheat cultivar, and the transgenic wheat lines exhibited a significant increase in endosperm AGPase activities, starch contents, and grain weights. These suggested that TaAGPS1b subunit was targeted into plastids by its truncated transit peptide and it could play an important role in starch synthesis in bread wheat grains.