Protein Accumulation In Grain Research Articles

POTENTIAL IMPACT OF NITROGEN ON POPULATION FLUCTUATION OF APHID AND YIELD PARAMETERS IN BARLEY

The present study was carried out on the farmer field under the supervision of the Department of Plant Protection and Quality Control of Pesticides during 2020 and 2021. Barley cultivar ‘Haider-93’ was sown in a randomized complete block design (RCBD) with three replications to examine the effect of two levels ofnitrogen fertilizer, 50 and 100 kg/ha along with control (no fertilizer), on population fluctuation of aphid and on barley yield components like grain protein (%), 1000-grain weight and the barley grain yield. Aphid incidence was recorded throughout the cropping season. The results revealed that peak infestation of aphids per tiller were recorded in the 3rd week of February in successive year. The study indicated a significant relationship between nitrogen fertilizer and aphid population density per tiller. The mean aphid population per tiller was recorded a significantly higher (34.12 ± 0.81 and 28.65 ± 0.17 for the years 2020 and 2021, respectively) at 100 kg/ha of nitrogen level while lowest infestation (14.51 ± 0.20 and 12.30 ± 0.10 aphids per tiller for the year 2020 and 2021, respectively) was recorded at 0 kg/ha of nitrogen fertilizer. Nitrogen fertilizer level at 100 kg/ha gave significantly higher grain protein (12.80 ± 0.17 and 13.70 ± 0.26% for the years 2020 and 2021, respectively) and grain yield (2758.75 ± 60.82 and 2673.79 ± 61.88 kg/ha produce for the year 2020 and 2021, respectively) of the barley crop. However, treatment differences for 1000-grain weight (g) were recorded as non-significant. These findings suggest that the nitrogen fertilizer at 100 kg/ha level produced significantly higher grain protein (%) and grain yield at the same time, also supported the higher infestation of aphids per tiller. Still, this aphid density did not affect the accumulation of grain protein (%) and grain yield of the barley crop. The results of this study might be used for decision-making to apply nitrogen fertilizer for better grain yield of barley crop but at the same time considering the colonizing aphid population.

Marker assisted selection (MAS) of spring bread wheat to improve productivity, grain quality, resistance to diseases and drought in the conditions of Western Siberia

The challenges at the modern consumer market, climate change, an increase in the number of epiphytotic and arid years dictate the necessity to accelerate wheat breeding for a whole range of traits and, above all, those associated with an improvement of productivity, grain quality, resistance to diseases and drought. Marker assisted selection (MAS) allows reducing time for developing varieties with specified parameters in the conditions of a particular region. The purpose of the current work was to identify KASP-markers associated with genes of valuable traits in the collection and breeding material of wheat and effective SNP-loci for marker assisted selection (MAS) in Western Siberia. Identification of genes that control economically valuable traits using 64 KASP-markers in 2020 was performed in the LGC-Genomics laboratory (Great Britain). It was found that the platforms for genotyping SNP-loci of a large number of current varieties had a significant similarity, despite the geographical separation of varieties, which indicated the vulnerability of grain production during large-scale epiphytoties and drought. There have been found differences in the identified SNP-loci and their frequency of occurrence between current varieties, ancient wheat varieties, and breeding material based on synthetic wheat. According to the results of phenotyping of the studied samples in the field seasons of 2020–2021 there has been shown a significant effect of the root system’s parameters (genes TraesCS2D01G395500.1 and TraesCS4D01G341800.1 in chromosomes 2D and 4D) on grain size and productivity improvement. The drought resistant gene TaDreb-B1 has affected on an increase of grain content of a head and productivity. The genes GPC-B1 and TraesCS2D01G316300.1, which are responsible for nitrogen remobilization, protein and dry biomass accumulation in grain, significantly contributed to the improvement of nutritional grain value and accumulation of protein in grain. Due to marker-controlled selection in the CVT, there have been identified the varieties that significantly exceeded productivity standards, with a complex of genes that have positive effects on grain quality, resistance to diseases and drought.

The Influence of Flag Leaf Removal and Its Characteristics on Main Yield Components and Yield Quality Indices on Wheat

The flag leaf can be an important vehicle for high grain yield due to its position and photosynthetic characteristics. To identify the most adaptive and stable yielding genotype, three winter wheat genotypes were studied during two experimental years under field conditions to quantify the influence of flag leaf removal in different phenological stages on the grain yield and grain quality. To quantify the influence of the flag leaf on the main yield components, the flag leaf was removed every 7 days, starting from the booting stage to ripening. Chlorophyll a, chlorophyll b, and carotenoids were determined from the removed leaves. As a complex trait, the number of grains/spikes and the weight of the grains/spikes were highly influenced by the flag leaf removal during the early generative stages, causing a yield loss from 9% to more than 40%, depending on the variety. It was established that the photosynthetic pigments were highly influenced by the plant phenology stages and the environmental conditions, especially carotenoids, which act as photoprotective and antioxidant agents under stress conditions. Regarding grain quality, flag leaf removal had a significant influence on the accumulation of grain protein and the wet gluten content, the variability of these quantitative traits being also influenced by the climatic conditions.

Dissecting of the Deterioration in Eating Quality for Erect Panicle (Ep) Type High Yield Japonica Super Rice in Northest China

Ep type is an important morphological improvement (following dwarf breeding and ideal plant type) that has contributed to breeding super-high yielding, and shows a pleiotropic effect in increasing grain yield and also nitrogen-use efficiency (NUE) in rice. Nevertheless, it remains unclear whether Ep has adverse effects on eating quality and how it affects nitrogen uptake and assimilation. In this study, we developed a pair of near-isogenic lines (NILs) for panicle type (NIL-Ep, NIL-non Ep) in the Liaogeng 5 (LG5) and Akihikari (AKI) backgrounds. Rice plants of the NIL-Ep had higher grain numbers per panicle in the middle to bottom spike positions than plants of the NIL-non Ep. The increased grain number is not only is the key factor leading to increased yield but also is the reason for reduced the eating quality. The content of prolamin and glutelin was significantly higher in NIL-Ep, which resulted in higher hardness and worse viscosity of rice after cooking. In addition, the activity of several essential enzymes catalyzing nitrogen metabolism was higher in the NIL-Ep line grains than in the NIL-non Ep, especially from the mid to late grain filling stage. Based on these results, we conclude that Ep positively regulates grain protein accumulation, primarily through enhancing the activity of enzymes involved in nitrogen assimilation and redistribution during the mid to late grain-filling stage, resulting in excessive accumulation of grain protein and decreased eating quality.

Effects of Nitrogen Fertilizer on Quality Characteristics of Wheat with the Absence of Different Individual High-Molecular-Weight Glutenin Subunits (HMW-GSs).

High-molecular-weight glutenin subunits (HMW-GSs) are important components of gluten, which determine the grain quality of wheat. In this study, we investigated the effects of nitrogen (N) fertilizer application on the synthesis and accumulation of grain protein and gluten quality in wheat lines with different HMW-GSs absent. The results showed that the absence of the HMW-GS in the wheat variety Ningmai 9 significantly decreased the contents of gluten, glutenin macropolymer (GMP), protein compositions, HMW-GS and HMW-GS/LMW-GS. The reduction in glutenins was compensated to some extent by an increase of gliadins. The absence of x-type HMW-GSs (1, 7 and 2 subunits) had a greater effect on gluten and GMP properties than y-type HMW-GSs (8 and 12 subunits). The content of protein compositions, gluten and GMP increased with an increase of N level; however, the increment in wheat lines with the absence of HMW-GS, especially in Ax1a, Bx7a and Dx2a, was lower than that in the wild type under various N levels. The expression level of genes encoding HMW-GSs, and activities of nitrate reductase (NR) and glutamine synthetase (GS), differed significantly among the investigated wheat lines. The reduction in gene expression and activities in Ax1a and Dx2a may account for the reductions in gluten, GMP, protein compositions, HMW-GS and HMW-GS/LMW-GS.

Evaluation of consumer properties of grain of spring soft wheat selection lines

The article presents the results of studying 10 numbers of competitive variety testing in the Ryazan region in order to identify new breeding lines of spring soft wheat with high technological and baking indicators. The assessment carried out in 2017-2019 revealed that according to the yield the breeding lines 1036-09Н21 and 898-09Н125 exceeded the Agata standard variety (4.47 t/ha) by 0.61 t/ha and 0.48 t ha, respectively (LSD05 = 0.34 t/ha). Over the years of the research, the variety samples formed a glassy well-made grain with the nature of 770-817 g/l, with the protein content in the grain of 14.1-16.0 % and the mass fraction of raw gluten in the flour of 29-41 % of high quality (IDK 45-75 units). The greatest potential for protein accumulation in grain was possessed by the varieties Agata, RIMA, lines 539-10H163, 543-13H163 – 16.8-19.3 %. On the average, the falling number was relatively high 264-331 s, corresponding for wheat of the first and second classes. Lines 543-13H163, 539-10H163 and 898-09H125 exceeded the standard in terms of sedimentation value by 15-17 ml or 35-40 %. The specific work of the dough deformation in the samples varied from 305 a.u. up to 421 a.u., corresponding to the standards of strong or valuable wheat. It has been established that the volumetric yield of bread for lines 509-13Н148, 539-10Н163 and 543-13Н163 was 1633-1647 cm3, higher than the Agat standard variety by 16-17 %. Valuable material 539-10N163 and 898-09N125 that meets the requirements of flour-grinding and bakery enterprises has been developed. It has the following varietal characteristics: grain nature is more than 800 g/l, protein content in grain is 15-16 %, gluten in flour is 33-34 %, with the sedimentation indicator of 58-60 ml, the deformation energy of the dough of 389-421 a.u, the volumetric bread yield of 1523-1647 cm3.

Physiological features of the accumulation and distribution of whole protein in the organs of plants of soybean varieties of the Northern ecotype

Soybean is a valuable protein crop. Promotion of its production in the northwestern direction became possible by the creation of varieties of the Northern ecotype. The physiological mechanisms of the adaptive potential of these varieties and, in particular, the features of protein accumulation in grain under contrasting weather conditions are insufficiently studied. Physiological factors that determine the level of whole protein accumulation in vegetative organs and in plant grain were studied on 7 varieties and 2 lines of breeding of the FRC of LGC. Effective assimilation activity of leaves; adaptive changes in the pigment complex, consisting in an increase in the number of carotenoids in adverse conditions; active nitrogen fixation of nodule bacteria lead to increased accumulation of nitrogen in the plant, followed by its remobilization into generative organs. The intensity of nitrogen accumulation and reutilization processes in soybean varieties of the Northern ecotype is especially high in unfavorable conditions of high humidity and lack of heat. In adverse weather conditions, correlations were established between the protein content in leaves and grains and elements of the pigment and symbiotic systems.

ОЦЕНКА СОРТОВ ЯЧМЕНЯ, ВОЗДЕЛЫВАЕМЫХ В ТАТАРСТАНЕ, НА УРОЖАЙНОСТЬ И КАЧЕСВА ЗЕРНА

The estimation of Raushan variety of barley and the new Kamazhevsky variety, which was regionalized in Tatarstan in 2017, is given. The experiment revealed the influence of weather conditions and varieties during the years of research (2015-2017), on the formation of grain productivity, the content of total nitrogen in the aboveground mass of plants, the accumulation of protein in grain and gross harvest of protein per hectare. It is noted that the productivity for different years are different, the highest yields of grain of Raushan and Kamashevsky varieties were obtained in 2017 - 4.62 and 5.21 tons per hectare, respectively, when the hydrothermal coefficient was 1.3 units. In comparison with 2015 the productivity of Raushan variety was higher to 1.89 tons per hectare and to 1.69 tons per hectare in 2016. The same pattern was also found in Kamashevsky variety, 1.64 and 1.52 tons per hectare, respectively. The average productivity of Raushan variety for 3 years was 3.43 tons per hectare, less to 0.73 tons per hectare than Kamashevsky. The highest nitrogen content (close to the optimum 4.7-5.1%) in the aboveground mass was found in 2016 in plants of Raushan variety of 4.3%, Kamashevsky variety 4.0%, whereas in 2017 - 2.89% and 3.32%, respectively. The nitrogen content in dry years is higher in the aboveground mass of the Raushan variety, beginning with the tillering phase - 4.3%, Kamashevsky variety - 4.0%. It was revealed that the maximum content of protein in grain grade Kamashevsky accumulate in arid 2015-2016 years - 13.84%, more by 0.95% than the Raushan variety. In 2017 the protein content in the grain was formed at the same level Raushan 11.77%, Kamashevsky 11.07%. Evaluation of varieties on the gross harvest of protein per hectare, shows that the Kamashevsky variety forms on average 5.37 tons per hectare of protein over 3 years, more than Raushan grade by 1.08 tons per hectare.

Effects of short-term post-anthesis high-temperature stress on dynamic process of accumulation of grain protein and its composition in rice (Oryza sativa L.)

Extremely high temperature decreases grain yield and grain quality in rice (Oryza sativa L.). To investigate the effects of short-term post-anthesis high-temperature stress on accumulation of grain protein and protein compositions in rice, 2-year experiments were carried out in phytotron with two different cultivars, Nanjing 41 (NJ41, heat-sensitive) and Wuxiangjing 14 (WJ14, heat-tolerant), under different conditions of high-temperature levels and durations during anthesis and grain-filling stages. The results showed that grain protein content and its components (albumin, globulin, and glutelin) increased with rising temperature levels and durations, while prolamin content decreased. The contents of total protein, storage protein, albumin, globulin, and prolamin in NJ41 were more sensitive to different temperature levels than those in WJ14. Moreover, the contents of albumin and prolamin in NJ41 changed greater under temperature durations than those in WJ14. The effects of high-temperature stress on accumulation of grain protein and composition were more sensitive to high-temperature levels and durations during anthesis stage than those during grain-filling stage. The results could help us further understand the physiochemical processes governing rice yield and quality under high-temperature conditions during rice anthesis and grain-filling stages.

The effect and molecular mechanism of powdery mildew on wheat grain prolamins

SUMMARYA field experiment was conducted to investigate the effects of powdery mildew (Blumeria graminis f. sp. Tritici, Bgt) on wheat grain at varying levels of disease severity and at different growth stages. Methods used to determine these effects included Kjeldahl determination, unidimensional polyacrylamide gel electrophoresis, dielectrophoresis combined with mass spectrometric analysis. The specific influences explored were those on prolamins and protein composition at the molecular level. Concentrations of both grain protein and prolamin in wheat increased as disease indices (DIs) of powdery mildew rose from 20 days after anthesis (DAA) to maturity. Globulin concentrations changed dynamically and significantly, especially at 25 DAA when DI was the highest. This was verified by proteomic analysis which showed globulins (such as globulin 3, globulin 3B, globulin 3C, gliadin/avenin-like protein and triticin) being up-regulated significantly under powdery mildew stress. It was proposed that powdery mildew might indirectly affect protein accumulation in grain by influencing the regulative enzymes (including peptidylprolyl isomerase, cyclophilin A-2 and GTPase ObgE) and metabolic processes. It was speculated that the indirect increase caused by yield reduction was not the only factor causing the increase in prolamin concentration. Another factor may be the rise of expression level of molecular chaperones and enzymes relating to protein synthesis, which led to the rise in protein synthesis.

Effect of source–sink manipulation on accumulation of micronutrients and protein in wheat grains

AbstractThe effect of source and sink manipulation on accumulation of micronutrients (Fe, Zn, Mn, Cu) and protein in wheat grains was studied in a field experiment and ear culture. The source and sink manipulation was obtained by reducing assimilate source (through defoliation and spike shading) or sink (through 50% spikelets removal) after anthesis in the field and by changing sucrose or NH4NO3 levels of the culture media in ear culture. In the field experiment, reducing source and sink generally increased Fe, Zn, Mn, Cu, and protein concentrations except defoliation which decreased Mn concentration. Grain yield as well as micronutrient and protein contents in grains were all reduced by reducing source and sink sizes, suggesting that the accumulation of micronutrients and protein in grains was restricted by source supply and sink capacity. In ear culture, the supply of 20 to 80 g L–1 sucrose increased grain weight and yield, but decreased grain Fe, Zn, Mn, Cu, and protein concentrations. The supply of 0.57 to 2.28 g L–1 NH4NO3 increased grain yield and the concentrations and contents of micronutrients and protein. All these results show that micronutrient and protein accumulation in grains can be affected by the source–sink relationship of carbohydrate and nitrogen. Adequate N supply can simultaneously increase grain yield and the accumulation of Fe, Zn, Mn, Cu, and protein.

Starch Characteristics of Transgenic Wheat (Triticum aestivum L.) Overexpressing the Dx5 High Molecular Weight Glutenin Subunit are Substantially Equivalent to Those in Nonmodified Wheat

The effects of engineering higher levels of the High Molecular Weight Glutenin Dx5 subunit on starch characteristics in transgenic wheat (Triticum aestivum L.) grain were evaluated. This is important because of the interrelationship between starch and protein accumulation in grain, the strong biotechnological interest in modulating Dx5 levels and the increasing likelihood that transgenic wheat will be commercialized in the U.S. Unintended effects of Dx5 overexpression on starch could affect wheat marketability and therefore should be examined. Two controls with native levels of Dx5 were used: (i) the nontransformed Bobwhite cultivar, and (ii) a transgenic line (Bar-D) expressing a herbicide resistant (bar) gene, and they were compared with 2 transgenic lines (Dx5G and Dx5J) containing bar and additional copies of Dx5. There were few changes between Bar-D and Dx5G compared to Bobwhite. However, Dx5J, the line with the highest Dx5 protein (×3.5) accumulated 140% more hexose, 25% less starch and the starch had a higher frequency of longer amylopectin chains. These differences were not of sufficient magnitude to influence starch functionality, because granule morphology, crystallinity, amylose-to-amylopectin ratio, and the enthalpy of starch gelatinization and the amylose-lipid complex melting were similar to the control (P > 0.05). This overall similarity was borne out by Partial Least Squares-Discriminant Function Analysis, which could not distinguish among genotypes. Collectively our data imply that higher Dx5 can affect starch accumulation and some aspects of starch molecular structure but that the starches of the Dx5 transgenic wheat lines are substantially equivalent to the controls. Transgenic manipulation of biochemical pathways is an effective way to enhance food sensory quality, but it can also lead to unintended effects. These spurious changes are a concern to Government Regulatory Agencies and to those Industries that market the product. In this study we examined if making "specific" changes to the composition of gluten proteins in wheat seeds would simultaneously alter starch, as their synthesis is interrelated and the molecular structure of both determine flour functionality. This information may be used to address issues of "substantial equivalence" and to inform Industrial End-Users of possible changes in product performance.

Relationship of Endogenous ABA and IAA to Accumulation of Grain Protein and Starch in Two Winter Wheat Cultivars under Post-anthesis Water Deficit

Accumulation of protein and starch in grain is a key process determining grain yield and quality in wheat. Under drought endogenous plant hormone levels will change and may have an impact on the yield and quality of wheat. In a greenhouse experiment, two winter wheat (Triticum aestivum L.) varieties differing in post anthesis drought resistance, tolerant (cv. Zagros) and sensitive (cv. Marvdasht), were subjected to either well-watered (WW) or water-stressed (WS) from anthesis to maturity. On the 7, 15 (grain enlargement stage) and 31 (grain filling stage) days after anthesis (DAA), endogenous abscisic acid (ABA) and indole-3-acetic acid (IAA) were determined in grain of wheat plants by enzyme linked immunosorbent assay (ELISA). The patterns of hormonal changes were similar in two varieties. The ABA levels were much higher under water deficit than well water treatment. In comparison grain ABA levels in all sampling stages was more in Marvdasht than Zagros. The endogenous grains IAA content display a marked reduction by the time and the water stress aggravated this reduction in both cultivars, however, the depresstion was more in drought-sensitive than drought-tolerant. The relationship between yields and contents of starch and protein in grains and levels of two hormones in sink organ indicated that the changes in yield and content of grain starch and protein under water withholding were associated with the reduced IAA and elevated ABA level in grains. It was proposed that the changed levels of endogenous hormones under drought post-anthesis might indirectly affect protein and starch accumulation in grains by influencing the regulatory enzymes and processes.

Spatial distribution pattern analysis of Dof1 transcription factor in different tissues of three Eleusine coracana genotypes differing in their grain colour, yield and photosynthetic efficiency

In the present study Dof1 gene of finger millet was cloned and sequenced. In silico analysis reveals 61% identity with the Sorghum bicolor and 57% identity with the Oryza sativa Dof1 sequence. A comparative analysis of gene sequences from different crops and three finger millet genotypes {Brown (PRM-1), Golden (PRM-701) and White (PRM-801)} differing in grain colour, yield and photosynthetic efficiency showed a high degree of sequence identity of Dof1 sequence gene ranging from 22 to 70% as evident from distance matrix of the built phylogenetic tree showing two major clusters. A total of five conserved motifs were observed in Dof1 sequences of different cereals. Motif 1 with multilevel consensus sequence CKNCRRYWTKGGAMRNVPVG contains zinc finger Dof domain. Motif 3 and motif 5 contains protein kinase phosphorylation site. Motif 2 contains Dof domain and zinc finger N-glycosylation site while motif 4 is involved in Zinc finger type profiling. Further, we studied the spatial distribution of Dof1 gene in three vegetative tissues (root, stem and flag leaf) as well as four stages of developing spikes (S1, S2, S3 and S4) of the three finger millet genotypes using qualitative and quantitative PCR based approaches. Physiological parameters (plant height, leaf area, chlorophyll content, SPAD value and photosynthetic efficiency) at the time of flowering was found to be highest in white (PRM-801) genotype followed by golden (PRM-701) and brown (PRM-1) genotype. Semi-quantitative RT-PCR and quantitative real-time PCR analysis revealed that the expression of Dof1 is highest in leaves and lowest in roots, which suggests its role in regulation of photosynthesis-related genes and carbon skeleton synthesis. Also at grain maturity stage, expression of Dof1 was higher in white (PRM-801) genotype followed by golden (PRM-701) and brown (PRM-1) genotype. The result is suggestive of Dof1 role in the accumulation of grain protein and yield attribute through regulation of key enzymes involved in source to sink relationship during grain filling stage.

Manipulating corn germplasm to increase recombinant protein accumulation

Using plants as biofactories for industrial enzymes is a developing technology. The application of this technology to plant biomass conversion for biofuels and biobased products has potential for significantly lowering the cost of these products because of lower enzyme production costs. However, the concentration of the enzymes in plant tissue must be high to realize this goal. We describe the enhancement of the accumulation of cellulases in transgenic maize seed as a part of the process to lower the cost of these dominant enzymes for the bioconversion process. We have used breeding to move these genes into elite and high oil germplasm to enhance protein accumulation in grain. We have also explored processing of the grain to isolate the germ, which preferentially contains the enzymes, to further enhance recovery of enzyme on a dry weight basis of raw materials. The enzymes are active on microcrystalline cellulose to release glucose and cellobiose.

Yield Response of Uniculm Wheat (Triticum aestivum L.) to Early and Late Application of Nitrogen: Flag Leaf Development and Senescence

Nitrogen (N) supply increased flag leaf area by increasing cell number. N promoted initiation and development of floret primordia. N availability upto ear emergence affected fertile floret number more than spikelet number and increased the number of grains. Late application of nitrogen at 5 days after anthesis increased percentage nitrogen in grains, grain weight and grain number due to its effect on ability of floret to set grain. Larger number of florets and grains provided sink not only for carbon but also for nitrogen accumulation with high nitrogen availability. The accumulation of grain protein depended on the accumulation and partitioning of reduced N accumulated during the vegetative stage of growth and the relative contributions of nitrate assimilation and N redistribution during grain development in low as well as high nitrogen supply. Flag leaf of ‘Gigas’ wheat retained the ability to synthesize RuBPCO on induction of nitrate reductase by substrate supply at post anthesis stage. The reductions in proteolytic enzymes were coincident with loss of Chl, total soluble protein and nitrate reductase activity from the flag leaves.

Protein Accumulation in Grains of Wheat Cultivars Differing in Drought Tol-erance and Its Regulation by Nitrogen Application Amount under Irrigated and Dryland Conditions

The protein accumulation in wheat (Triticum aestivum L.) grains is seldom studied under dryland condition although it has been widely tested under irrigated conditions. For understanding the protein accumulation characteristics of wheat cultivars differing in drought tolerance and the effects of water and nitrogen, a drought-tolerant cultivar, Jinmai 47, and a drought-sensitive cultivar, Nongda 189, were planted under both irrigated and dryland conditions with three nitrogen application rates. From the 5th day after anthesis, spikelets and flag leaves were sampled at a 5 days interval for measuring the contents of protein and its com-ponents in grains and the enzymes activities in grains and flag leaves. The results indicated that the contents of albumin, gliadin, glutenin, total protein, and the ratio of glutenin to gliadin in dryland cropping were higher than those in irrigated cropping, but the globulin content was lower than that in irrigated cropping. For Nongda 189, the contents of protein and its components and the ratio of glutenin to gliadin in grains were affected significently by drought, whereas for Jinmai 47, the variations on contents of globulin, gliadin, total protein, and ratio of glutenin to gliadin were slightly. The activities of glutamine synthetase (GS), glutamate synthase (GOGAT), glutamic acid-pyruvate transaminase (GPT) in grains and the activities of GS and GOGAT in flag leaves were reduced in dryland cropping compared with those in irrigated cropping. Simultaneously, the trend of GPT activity in grains was also affected by dryland cropping. The effect of drought on activities of these enzymes that involved in protein accumulation was greater in Nongda 189 than in Jinmai 47. Nitrogen application promoted the contents of protein and its components in grains, and higher rate of nitrogen application resulted in greater positive effect. Jinmai 47 presented greater effect of nitrogen application on protein content in grains than Nongda 189. Under both growing conditions, the activities of GS, GOGAT, and GPT in grains and the activity of GOGAT in flag leaves in all nitrogen treatments significantly correlated with the protein yield rather than the pro-tein content in grains. The correlation between GS activity in flag leaves and protein yield in grains was different in the two cultivars. The above results suggest that the drought-tolerant cultivar is less affected by water condition compared with the drought-sensitive cultivar; application of nitrogen could promote the protein content in grains, and the effect is greater in the drought-tolerant cultivar than in the drought-sensitive cultivar.

Effects of High Temperature on Key Enzymes Involved in Starch and Protein Formation in Grains of Two Wheat Cultivars

AbstractHigh temperature is a major determinant of grain growth and yield formation in wheat. The present study was undertaken to investigate the effects of high temperature regimes on the activities of key regulatory enzymes involved in starch and protein accumulation in grains of two winter wheat (Triticum aestivum L.) cultivars Yangmai 9 and Xuzhou 26 with different protein contents. Four day/night temperature regimes of 34 °C/22 °C, 32 °C/24 °C, 26 °C/14 °C and 24 °C/16 °C were established after anthesis, resulting in two daily temperature levels of 28 °C and 20 °C and two diurnal temperature differences of 12 °C and 8 °C. The activities of glutamine synthase (GS) in flag leaves and glutamate pyruvic aminotransferase (GPT), sucrose synthase (SS), soluble starch synthase (SSS) and granule‐bound starch synthase (GBSS) in grains were measured during the periods of grain filling. High temperature reduced both content and yield of starch in grains, while enhanced protein content and reduced protein yield in grains. High temperature significantly enhanced the activities of SS and GBSS on 14 days after anthesis (DAA). High temperature affected SSS slightly in Yangmai 9, but reduced SSS activity markedly in Xuzhou 26 on 14 DAA. However, at the middle and late stages of grain filling, high temperature reduced the activities of SS, GBSS and SSS significantly in the two wheat cultivars. High temperature reduced GPT activity in grains in the two wheat cultivars, but reduced GS activity in flag leaves of Yangmai 9 and enhanced GS activity of Xuzhou 26 on 14 DAA. In addition, under the same high temperature level, SS activity was higher at 34 °C/22 °C, whereas the activities of SSS and GBSS were higher at 32 °C/24 °C. Also, diurnal temperature differences affected GPT and GS activities differently between the two cultivars. Under optimum temperature level, the activities of key enzymes for starch and protein synthesis were higher at 26 °C/14 °C. The activities of SS, SSS and GBSS significantly correlated with starch accumulation in grains, except for GBSS activity to starch content on 14 DAA. GPT activity was positively correlated with protein yield, and GS activity was negatively correlated with protein yield on 14 DAA, while the activities of both GPT and GS were negatively related to protein content in grains.

Effects of exogenous ABA and cytokinin on leaf photosynthesis and grain protein accumulation in wheat ears cultured in vitro

A detached culture system and steady-state 15N labeling technique were used to study the effects of exogenous ABA and ZR on photosynthetic characteristics, nitrogen remobilization and the activities of key enzymes for nitrogen metabolism in detached wheat parts during grain protein accumulation. The differences in net photosynthetic rate, chlorophyll content (SPAD value) and soluble protein content in the flag leaves of detached culture system between the treatments of ABA and ZR showed that ABA facilitates the post-anthesis senescence course compared to the ZR treatment. The differences in the changes of 15N amount in different organs in the detached culture system between the ABA and ZR treatments showed that nitrogen remobilization from vegetative organs to the grain is accelerated by the ABA treatment but is delayed by ZR. The activities of GS and GPT in grains treated with ABA were significantly higher than those with the control treatment at 5 DAC, but reduced significantly compared with control at 11 DAC. The two enzyme activities in grains were reduced significantly by ZR at 5 DAC and increased significantly at 11 DAC, compared with those treated with ABA. The above changes of enzyme activity showed that the ABA treatment hastens amino acid conversion into grains and protein accumulation in grains, whereas the ZR treatment delays these processes. A significant reduction in grain weight with ABA treatment is associated with the reduction of net photosynthesis, chlorophyll content, and soluble protein content in flag leaves. Compared with the control and ZR treatments, a significant increase in grain protein content with the ABA treatment may result from the accelerating effects of ABA on N remobilization, amino acid conversion into grains and protein accumulation in grains.

Relationships of endogenous plant hormones to accumulation of grain protein and starch in winter wheat under different post-anthesis soil water statusses

Accumulation of protein and starch in grain is a key process determining grain yield and quality in wheat. Under drought or waterlogging, endogenous plant hormone levels will change and may have an impact on the yield and quality of wheat. In a greenhouse experiment, four winter wheat (Triticum aestivum L.) varieties differing in grain protein content, Heimai 76, Wanmai 38, Yangmai 10 and Yangmai 9, were subjected to drought (SRWC = 45∼50%, DR), waterlogging (WL) and moderate water supply (SRWC = 75∼80%, CK), beginning from 4 days post-anthesis (DPA) to maturity. On the 10 (grain enlargement stage) and 20 (grain filling stage) DPA, endogenous abscisic acid (ABA), gibberellins (GA1+3), indole-3-acetic acid (IAA) and zeatin riboside (ZR) were determined in sink and source organs of wheat plants by enzyme linked immunosorbent assay (ELISA). The patterns of hormonal changes were similar in four varieties. The ABA levels were much higher under DR and WL than under CK. Compared with CK, GA1+3 levels in whole-plant under DR and WL changed a little at 10 DPA, but markedly decreased under DR and WL at 20 DPA. Changes of endogenous IAA level under DR and WL exhibited a complicated pattern, depending on organs and growth stages. Particularly at the 20 DPA, the mean levels of IAA in roots, leaves and grains decreased significantly under DR and WL. In comparison with CK, ZR levels in all organs significantly decreased under DR and WL at both stages. The correlation analyses between yields and contents of starch and protein in grains and levels and ratios of four hormones in source and sink organs indicated that the changes in yield and content of grain starch and protein under DR and WL were associated with the reduced IAA, ZR and GA1+3 levels and elevated ABA level in plants, especially in grains. It was proposed that the changed levels of endogenous hormones under post-anthesis DR and WL might indirectly affect protein and starch accumulation in grains by influencing the regulatory enzymes and processes.