Selection and application of four QTLs for grain protein content in modern wheat cultivars

The grain protein content(GPC)is the key parameter for wheat grain nutritional quality.This study conducted a resampling GWAS analysis using 406 wheat accessions across eight environments,and identified four previously reported GPC QTLs.An analysis of 87 landraces and 259 modern cultivars revealed the loss of superior GPC haplotypes,especially in Chinese cultivars.These haplotypes were preferentially adopted in different agroecological zones and had broad effects on wheat yield and agronomic traits.Most GPC QTLs did not significantly reduce yield,suggesting that high GPC can be achieved without a yield penalty.The results of this study provide a reference for future GPC breeding in wheat using the four identified QTLs.

Effects of Sulfur Fertilizer Application Methods on Grain Protein Content During Filling Stage of Winter Wheat

[ Objective] The experiment aimed to provide a theoretical base of optimal cultivation management for the high yield and good quality and high efficiency of winter wheat. [ Method] The effects of two sulfur fertilizer application methods on dynamic changes of grain protein content and glutenin content of Yumai 49 and Yumai 66 during wheat grain filling stage were studied under the field conditions. [Result] Both the grain protein and glutenin content of two cultivars were increased by sulfur fertilizer, particularly, the effects on Yumai 49 were more significant.[ Conclusion] The grain content and glutenin content of different wheat cultivars could be increased by taking different sulfur fertilizer application methods.

Analysis of the Conditional Correlations from Different Genetic Systems Between the Protein Content and the Appearance Quality Traits of Indica Rice

A factorial mating design in two environments was conducted using 7 cytoplasmic male sterile lines （A） and 5 restorer lines （R） along with their F1 （A × R） and F2 populations. The unconditional and conditional analyses of genetic models and the corresponding statistic methods, including endospermic, cytoplasmic, and maternal plant genetic systems, were used to analyze the genetic relationships between protein content （PC） and the appearance quality traits of indica rice （Oryza sativa L.）. The results from unconditional analysis indicated that PC was significantly correlated with the appearance quality traits of rice, except for the brown rice thickness （BRT）. Only the genetic covariance between PC and the brown rice width （BRW） was positively correlative, whereas all the other pairwise traits were negatively correlative. The results from conditional analysis revealed that the weight of brown rice （WBR） or the amylose content （AC） could significantly affect the relationships between PC and the appearance quality traits of indica rice. The conditional analysis showed that WBR might negatively affect the relationships between PC and the brown rice length （BRL）, BRW, or BRT through the geuotype x environmental （GE） interaction effects, but positively affected the relationships between PC and the ratio of brown rice length to width （RLW） or the ratio of brown rice length to thickness （RLT）. The amylase content could positively affect the relationships between PC and BRL, RLW, RLT through the cytoplasmic effects and maternal additive effects, but negatively affected the relationships between PC and BRW.

Variation of Protein Content in Tartary Buckwheat Seeds

[Objective]The aim was to select tartary buckwheat materials with high protein content.[Method]Used 35 kinds of tartary buckwheat as experimental material,and the protein content of seeds had been determined.[Result]The protein content of 35 kinds of tartary buckwheat will change in the range of 23.65-193.28 mg/g with an average of 111.85 mg/g.There was difference among different origins of tartary buckwheat.The seeds from Hezhang in Guizhou and Sichuan had highest protein content,while the seeds from Nayong had lowest protein content.[Conclusion]The study had provided theoretical basis for the further study on the genetic and variation law of protein content in different tartary buckwheat resources.

Comparison of Protein Content among Non-diapause Pupae,Diapause Pupae and Eclosion-adult from Diapause Pupae of Papilio memnon

[ Objective] The experiment aimed to explore the diapause mechanism of Papilio memnon L. further. [ Method] The colorimetry method was used to detect protein content of non-diapause pupae, diapause pupae and eclosion-adult from diapause pupae at different developmental stages. [Result] It was showed that the protein content of non-diapause pupae was from 111.768 to 115.030 7 mg/g and the change of protein content during whole pupal stage, while diapause pupae were from 81.218 to 131.623 7 mg/g and the change of protein content was not big from last ten-day period of October to last ten-day pariod of November, however, the content increased from the last ten-day period of November. The protein content of emerging adult was 296.969 3 mg/g. [Conclusion] The change of protein content was related to Papilio memnon at different development stage.

Variations in Phytic Acid Content and Their Relationship with Protein Content and Kernel Morphological Characters of Chinese Winter Wheat Cultivars

[Objective] The aim of this study was to determine the variation of phytic acid content （PAC） and its frequency distribution, as well as the relationship between PAC and protein content, kernel characteristics in 161 Chinese winter wheat cultivars from four regions. [Method] One hundred and sixty-one winter wheat varieties from China Wheat Zones I, II, III and IV （Table 1） were grown in a randomized block de- sign, in the 2009-2011 cropping season; and then the indexes for describing the grain morphological characteristics such as the thousand kernel weight （TKW）, kernel length （KL）, kernel width （KW） and kernel thickness （KT） were measured; the phytic acid content （PAC）, protein content and sedimentation value were also determined; finally, the relationship between PAC and protein content, kernel characteristics were analyzed. [Result] The PAC in the cultivars tested ranged from 0.92% to 1.95% with a mean value of 1.41%. Protein content ranged from 12.60% to 19.20%, with a mean of 15.24%. Most （53.4%） of the wheat genotypes had a PAC value in the range of 1.25% to 1.55%. No significant correlation was found between PAC and protein content, sedimentation value, while protein content and SDS sedimentation value was significant correlated, which suggested the possibility of breeding wheat cultivars that have a low PAC but a high protein content and good gluten quality. There was a high correlation between TKW and KW （,.=0.79）, KL （r=0.50） and KT （r=0.64）. PAC was found having no significant correlation with TKW, KW, KL and KT. [Conclusion] The result suggests the possibility of breeding wheat cultivars that have a low PAC but high kernel weight.

Predicting Grain Yield and Protein Content in Winter Wheat at Different N Supply Levels Using Canopy Reflectance Spectra

A field experiment using a split-plot randomized complete block design with three replications was carried out to determine relationships between spectral indices and wheat grain yield （GY）, to compare the performance of four vegetation indices （VIs） for GY prediction, and to study the feasibility of VI to estimate grain protein content （GPC） in winter wheat. Two typical winter wheat （Triticum aestivum L.） cultivars ＇Xuzhou 26＇ （high protein content） and ＇Huaimai 18＇ （low protein content） were used as the main plot treatments and four N rates, i.e., 0, 120, 210, and 300 kg N ha^-1, as the sub-plot treatments. Increasing soil N supply significantly increased GY and GPC （P ≤ 0.05）. For the two cultivars combined, significant and positive correlations were found between four VIs and GY, with the strongest relationship observed when using the green ratio vegetation index （GRVI） at mid-filling. Cumulative VI estimates improved yield predictions substantially, with the best interval being heading to maturity stage. Similar results were found between VI and grain protein yield. However, when using cumulative VI, GPC showed no significant improvement. The strong relationship between leaf N status and GPC （R2 =0.9144 for ＇Xuzhou 26＇ and R2 = 0.8285 for ＇Huaimai 18＇） indicated that canopy spectra could be used to predict GPC. The strong fit between estimated and observed GPC （R2 = 0.7939） indicated that remote sensing techniques were potentially useful predictors of grain protein content and quality in wheat.

Protein Content and Amino Acid Composition in Grains of Wheat-Related Species

The protein content and amino acid composition for 17 wheat-related species （WRS） and three common wheats （control） were determined and analyzed, and the essential amino acids （EAAs） in WRS were evaluated according to FAO/WHO amino acid recommendations. The results showed that the mean protein content for WRS was 16.67%, which was 23.21% higher than that for the control. The mean contents （g 100 g^-1 protein） of most amino acids for WRS were lysine 2.74%, threonine 2.83%, phenylalanine 4.17%, isoleucine 3.42%, valine 3.90%, histidine 2.81%, glutamic acid 29.96%, proline 9.12%, glycine 3.59%, alanine 3.37%, and cysteine 1.57%, which were higher than those for the control. The contents of the other 6 amino acids for WRS were lower than those for the control. The materials （Triticum monococcum L., Triticum carthlicum Nevski, and Triticum turgidum L.） contained relatively high concentration of the most deficient EAAs （lysine, threonine, and methionine）. Comparing with FAO/WHO amino acid recommendations, the amino acid scores （AAS） of lysine （49.8%）, threonine （70.7%）, and sulfur-containing amino acids （74.8%） were the lowest, which were considered as the main limiting amino acids in WRS. It was observed that the materials with Triticum urartu Turn. （AA） and Aegilops speltoides Tausch. （SS） genomes had relatively high contents of protein and EAA. The contents of protein （16.91%）, phenylalanine （4.78%）, isoleucine （3.53%）, leucine （6.16%）, and valine （4.09%） for the diploid materials were higher than those for the other materials. These results will provide some information for selecting parents in breeding about nutrient quality and utilization of fine gene in wheat.

Effects of Different Nitrogen Fertilizer Levels and Native Soil Properties on Rice Grain Fe, Zn and Protein Contents

Deposition of protein and metal ions （Fe, Zn） in rice grains is a complex polygenic trait showing considerable environmental effect. To analyze the effect of nitrogen application levels and native soil properties on rice grain protein, iron （Fe） and zinc （Zn） contents, 32 rice genotypes were grown at three different locations each under 80 and 120 kg/hm2 nitrogen fertilizer applications. In treatments with nitrogen fertilizer application, the brown rice grain protein content （GPC） increased significantly （1.1% to 7.0%） under higher nitrogen fertilizer application （120 kg/hm2） whereas grain Fe/Zn contents showed non-significant effect of nitrogen application level, thus suggesting that the rate of uptake and translocation of macro-elements does not influence the uptake and translocation of micro-elements. The pH, organic matter content and inherent Fe/Zn levels of native soil showed significant effects on grain Fe and Zn contents of all the rice genotypes. Grain Zn content of almost all the tested rice genotypes was found to increase at Location III having loamy soil texture, neutral pH value （pH 6.83） and higher organic matter content than the other two locations （Locations I and II）, indicating significant influence of native soil properties on brown rice grain Zn content while grain Fe content showed significant genotype × environment interaction effect. Genotypic difference was found to be the most significant factor to affect grain Fe/Zn contents in all the tested rice genotypes, indicating that although native soil properties influence phyto-availability of micronutrients and consequently influencing absorption, translocation and grain deposition of Fe/Zn ions, yet genetic makeup of a plant determines its response to varied soil conditions and other external factors. Two indica rice genotypes R-RF-31 （27.62 μg/g grain Zn content and 7.80% GPC） and R1033-968-2-1 （30.05 μg/g grain Zn content and 8.47% GPC） were identified as high grain Zn and moderate GPC rice genotypes. These results indicate that soil property and organic matter content increase the availability of Fe and Zn in rhizosphere, which in turn enhances the uptake, translocation and redistribution of Fe/Zn into rice grains.

Estimating Wheat Grain Protein Content Using Multi-Temporal Remote Sensing Data Based on Partial Least Squares Regression

Estimating wheat grain protein content by remote sensing is important for assessing wheat quality at maturity and making grains harvest and purchase policies. However, spatial variability of soil condition, temperature, and precipitation will affect grain protein contents and these factors usually cannot be monitored accurately by remote sensing data from single image. In this research, the relationships between wheat protein content at maturity and wheat agronomic parameters at different growing stages were analyzed and multi-temporal images of Landsat TM were used to estimate grain protein content by partial least squares regression. Experiment data were acquired in the suburb of Beijing during a 2-yr experiment in the period from 2003 to 2004. Determination coefficient, average deviation of self-modeling, and deviation of cross- validation were employed to assess the estimation accuracy of wheat grain protein content. Their values were 0.88, 1.30%, 3.81% and 0.72, 5.22%, 12.36% for 2003 and 2004, respectively. The research laid an agronomic foundation for GPC （grain protein content） estimation by multi-temporal remote sensing. The results showed that it is feasible to estimate GPC of wheat from multi-temporal remote sensing data in large area.

Effects of Powdery Mildew on 1 000-Kernel Weight, Crude Protein Content and Yield of Winter Wheat in Three Consecutive Growing Seasons

In order to clarify the impact posed by wheat powdery mildew （Blumeria graminis f. sp. tritici） on the yield and yield components in different epidemic seasons, field trials were conducted in three growing seasons, 2009-2010, 2010-2011 and 2011-2012, in Langfang City, Hebei Province, China. The relationships between 1000-kernel weight, crude protein content of grain and yield and disease index （DI）, as well as area under disease progress curve （AUDPC） were studied. The models of the percentage of loss of 1000-kernel weight, crude protein content and yield were constructed using DI at critical point （CP） of growth stages （GS） and AUDPC in the three growing seasons, respectively. The CPs for estimating 1 000-kernel weight, crude protein content of grain and yield of wheat caused by powdery mildew were GS 11.1, GS 10.5.3 and GS l 0.5.3, respectively. Models based on DI at CP to estimate the percentage of loss of 1000-kernel weight, crude protein content of grain and yield were better than models based on AUDPC. And models of the percentage of loss of 1000-kernel weight, crude protein content and yield for 2011-2012 season were significant different from these for 2009-2010 and 2010-2011 seasons. These results indicated that besides powdery mildew, weather conditions also had influence on 1 000-kernel weight, crude protein content of grain and yield loss of wheat when powdery mildew occurred.

Effects of Waterlogging in Different Growth Stages on the Photosynthesis,Growth,Yield,and Protein Content of Three Wheat Cultivars in Jianghan Plain

To maintain high wheat grain yield in areas where frequent and periodic waterlogging occurs,the effects of waterlogging on the photosynthesis,growth,yield,and protein content of three wheat cultivars,namely Xiangmai55(X55),Jingmai102(J102),and Zhengmai9023(Z9023),in four different growth stages were investigated.Experiments were conducted in specially designed experimental tanks in the middle and lower reaches of the Yangtze River during the 2012-2013 and 2013-2014 wheat growing seasons in China.Results showed that X55 was the most susceptible to waterlogging,followed by J102 and Z9023.Chlorophyll content reduction and leaf senescence,which resulted in decreased green-to-total leaf number ratio,were induced to the greatest extents by waterlogging in booting and flowering stages,followed by milky stage.Meanwhile,chlorophyll content in flag leaf,plant height were significantly decreased by waterlogging in jointing stage but effectively recovered after waterlogging withdrawal,and recovery ability varied among the cultivars.Plant biomass and grain yield were most significantly decreased by waterlogging in booting and flowering stages,followed by milky and jointing stages.Grain protein content was also considerably affected by waterlogging depending on growth stage and cultivars.The decreased grain yield caused by waterlogging was mostly due to the sharp decline in 1 000-grain mass.Waterlogging led to reduced protein yield in all growth stages in three wheat cultivars.Above all,in this experiment,waterlogging decreased grain yield significantly,and waterlogging at booting stage and flowering stage was most serious.Comparing the three cultivars,X55 was most sensitive to waterlogging.

Effects and Mechanisms of P and K Nutrients on Yield and Protein Content of Fodder Rice

Effects and mechanisms of P and K nutrients on yield and protein content of Weiyou 56, a fodder hybrid rice combination,were studied through pot experiment and biochemical analysis. The results showed that the increase of P and K nutrients enhanced the activities of PEP carboxylase (PEPC), glutamine synthase (GS) and sucrose phosphate synthase (SPS) in leaves, sucrose synthase (SS), ADP glucose pyrophosphorylase (ADPGP) and GS in grains, and the chlorophyll content in leaves, soluble sugar and starch content in grains, protein N and total N content in leaves and grains. Howerer, they decreased soluble sugar content in leaves and led to an increase of protein content in brown rice, biomass, grain yield and harvest index. Excessive P nutrients slightly reduced SPS and ADPG activity in leaves and grains respectively.

Amino acid permease 6 regulates grain protein content in maize

Grain protein content(GPC)is an indicator of cereal nutritional quality.Identification of genes involved in the regulation of GPC provides targets for molecular breeding for crop protein quality.We characterized a maize gene encoding the putative amino acid transporter ZmAAP6,a gene expressed mainly in immature seeds,especially in the basal endosperm transfer layer.Total protein and zein contents were decreased in ZmAAP6 null mutants and increased in ZmAAP6 overexpression(OE)lines,consistent with their changed in the size of protein bodies.Metabolic and transcriptomic analysis supported the regulatory role of ZmAAP6 in amino acid transportation.These results suggest that ZmAAP6 functions as a positive regulator of GPC in maize,shedding new light on the genetic basis of GPC regulation.

Genetic Analysis and Improvement Strategies of Protein Content in Rice Seeds

Enhancing the nutritional quality of food crops is a way to improve human nutrition and health. Grain protein content （ GPC ） is an important nutritional quality trait for rice and many other crops. Therefore, it will be very significant to increase GPC and improve rice quality. This paper mainly reviewed the genetic studies GPC in rice, mapping and cloning of QTLs and genes associated with GPC. However, little is known about the molecular mechanism and gene function related to GPC in rice. Thus, here we put forward the genetic strategy by gene pyramiding or molecular marker assisted selection to improve GPC and nutritional quality in rice. This review could provide important information for genetic improvement of grain nutritional quality of rice.

Evaluation of Total Seed Protein Content in Eleven Arkansas Cowpea (Vigna unguiculata (L.) Walp.) Lines

Cowpea is cultivated on more than 11 million hectares with a worldwide production of 5.4 million tons of dried seeds. Cowpea is an affordable source of protein, which is used as an alternative to soybean for people who are allergic to soybean protein. The aim of this research was to assess the variability of the total seed protein content in cowpea. Eleven Arkansas breeding lines were used in this study. Field experiment design was a randomized complete block design (RCBD) with 2 blocks, and conducted in three different locations within Arkansas State (Fayetteville, Alma, and Hope) in 2015. A standard chemical protocol was performed involving an analysis of the total nitrogen by combustion using an Elementar Rapid N III instrument to estimate the protein content. The average protein content was 25.4%, and ranged from 23.7% to 27.4% with a standard deviation of 1.9%. The significant effects of genotype, environment (location), and genotype by environment were observed for the total seed protein content in cowpea. The broad sense heritability (H2) for cowpea seed protein was estimated to be 57.8% based on the eleven cowpea genotypes studied. The cowpea lines, “Early Scarlet” and 09-204 had the highest seed protein content with 27.4% and 26.9% dried seed weight, respectively. This study provides valuable information on cowpea protein content for breeders to select and utilize those breeding lines with high seed protein content to develop new high protein cowpea cultivars.

Rapid and Non-destructive Prediction of Protein Content in Peanut Varieties Using Near-infrared Hyperspectral Imaging Method

This study was undertaken to investigate the feasibility of near-infrared(NIR) hyperspectral imaging(1 000–2 500 nm) for non-destructive and quantitative prediction of protein content in peanut kernels. Partial least squares regression(PLSR) calibration model was established between the spectral data extracted from the hyperspectral images and the reference measured protein content values, with the coefficient of determination of prediction(R_P^2) of 0.885 and root mean square error of prediction(RMSEP) of 0.465%.Regression coefficients(RC) from PLSR analysis were used to identify the most essential wavelengths that had the greatest influence on changes in the protein content. Eight optimal wavelengths were selected by RC and its corresponding simplified RC-PLSR prediction model was also obtained, showing better performance with a higher R_P^2 of 0.870 and a lower RMSEP of 0.494%. The results indicate that hyperspectral imaging with PLSR analysis can be used as a rapid and non-destructive method for predicting protein content in peanut.

Influence of Wheat Protein Contents and Fractions on Dough RheologicalProperties as Determined by Using a Reconstitution Method

A strong gluten wheat cultivar Shannong 12 and a medium-strength wheat cultivar Shannong 11 were used to investigate the effects of wheat protein contents and protein fractions on dough rheological properties using a reconstitution method. The results indicated that the peak height, peak width, peak integral, resistance to extension and area under the curve were increased when protein content increased to 120, 140, and 160% （w/w） of the protein content in the base flours for doughs made from each wheat cultivar. All protein fractions were added to each of the base flours at three levels （0.25, 0.50 and 1.00%, w/w） based upon the protein content. The mixograph dough development time, peak width, and resistance to extension increased when the glutenin, insoluble glutenin, soluble glutenin, and glutenin macropolymer were added and increased systematically with increasing levels of these fractions. Peak integral increased by adding and increasing protein content, however, albumin-globulin had no obvious effects. Extensibility at rupture decreased when the glutenin, insoluble glutenin, soluble glutenin, and glutenin macropolymer were added, and decreased systematically with increasing levels of these fractions. However, extensibility at rupture increased when the monomeric protein, albumin-globulin, and gliadin were added, and increased systematically with increasing levels of these fractions.

Wheat Grain Yield and Protein Content as Influenced by Sodium Bisulfite

Two wheat varieties with similar yield and significantly different protein content were chosen to study the effect of foliage spraying sodium bisulfite (NaHSO3) at low concentration to wheat plants receiving different levels of nitrogen on nitrate reduction along with yield and protein content of grain, so as to discuss the relationship between carbon metabolism and nitrogen metabolism, and find out the intrinsic mechanism of grain yield and protein content formation. The results showed that spraying NaHSO3 at grain-filing stage increased the yield of grain, but declined the capacity of nitrate reduction, which might result in decrease of protein content in the end. Whether receiving NaHSO, or not, the variety with high protein content had higher final protein level and nitrate reduction capacity than that with low protein content.

Effects of Grain Protein Content Selection on Protein Content and Key Enzyme Activity Involved in Nitrogen Metabolism in Progenies Derived from a Rice Cross

Two japonica rice parents （Tong 769 and Xixuan 1） and their progenies, significantly different in protein content of grains, were investigated to reveal the activities of proteinase in leaves and glutamine synthetase in grains, as well as the dynamic changes of soluble protein content in grains during rice grain filling. The results showed that the parents were very similar in protein content, however, advanced lines with different protein contents in grains and varied activities of proteinase and glutamine synthetase were acquired by consecutively directional selection of the grain protein content in their progenies. Moreover, the enzyme activity and the protein content in grains exceeded their parents during grain filling. The protein content in grains was positively related with the proteinase activity, and the soluble protein content was negatively related with the glutamine synthetase activity in grains to some extent.