In rice(Oryza sativa), amylose content(AC) is the major factor that determines eating and cooking quality(ECQ). The diversity in AC is largely attributed to natural allelic variation at the Waxy(Wx)locus. Here we iden...In rice(Oryza sativa), amylose content(AC) is the major factor that determines eating and cooking quality(ECQ). The diversity in AC is largely attributed to natural allelic variation at the Waxy(Wx)locus. Here we identified a rare Wx allele, Wx^(mw) ,which combines a favorable AC, improved ECQ and grain transparency. Based on a phylogenetic analysis of Wx genomic sequences from 370 rice accessions, we speculated that Wx^(mw) may have derived from recombination between two important natural Wx alleles, Wx^(in) and Wx^(b). We validated the effects of Wx^(mw) on rice grain quality using both transgenic lines and near-isogenic lines(NILs). When introgressed into the japonica Nipponbare(NIP) background, Wx^(mw) resulted in a moderate AC that was intermediate between that of NILs carrying the Wx^(b)allele and NILs with the Wx^(mp) allele. Notably, mature grains of NILs fixed for Wx^(mw) had an improved transparent endosperm relative to soft rice. Further, we introduced Wx^(mw) into a high-yielding japonica cultivar via molecular marker-assisted selection: the introgressed lines exhibited clear improvements in ECQ and endosperm transparency. Our results suggest that Wx^(mw) is a promising allele to improve grain quality, especially ECQ and grain transparency of high-yielding japonica cultivars, in rice breeding programs.展开更多
Cooking and nutrition qualities of grain are two of the most important aspects of rice quality. To understand the difference in cooking and nutrition qualities among the grains at different positions within a rice pan...Cooking and nutrition qualities of grain are two of the most important aspects of rice quality. To understand the difference in cooking and nutrition qualities among the grains at different positions within a rice panicle, the distributions of gel consistency （GC）, amylose content （AC） and crude protein content （CPC） of grains in a panicle in association with different nitrogen levels （0, 120 and 240 k c/ha） were investigated by using two rice varieties, Yangdao 6 （indica） and Wuyujing 3 （japonica）. In general, the grains at the basal part of a panicle had lower GC and higher AC than those at the upper or middle part of a panicle. The 1^st grain on the secondary branch with earlier flowering exhibited the highest GC, whereas the 2nd grain on the primary branch with later flowering showed the highest AC. For Yangdao 6, CPC in the grains on the primary branches was lower at the middle part of a panicle than at the upper or basal part of a panicle. For Wuyujing 3, there were no significant differences in CPCs in the grains among the upper, middle and basal parts of a panicle. GC in the grains was increased, whereas AC was reduced from zero nitrogen application （ON） to low amount of nitrogen application （LN）, and the result was reversed from LN to medium amount of nitrogen application （MN）. CPC was increased with the increase in the amount of nitrogen application.展开更多
Amylose content(AC),which is regulated by the Waxy(Wx)gene,is a major indicator of eating and cooking quality(ECQ)in rice(Oryza sativa).Thus far,only a limited number of mutations in the N-terminal domain of Wx were f...Amylose content(AC),which is regulated by the Waxy(Wx)gene,is a major indicator of eating and cooking quality(ECQ)in rice(Oryza sativa).Thus far,only a limited number of mutations in the N-terminal domain of Wx were found to have a major impact on the AC of rice grains and no mutations with such effects were reported for other regions of the Wx protein.Here,nucleotide substitutions in the middle region of Wx were generated by adenine and cytosine base editors.The nucleotide substitutions led to changes in 15 amino acid residues of Wx,and a series of novel Wx alleles with ACs of 0.3%-29.43%(wild type with AC of 19.87%)were obtained.Importantly,the waxy~(abe2)allele showed a"soft rice"AC,improved ECQ,favorable appearance,and no undesirable agronomic traits.The transgenes were removed from the waxy~(abe2)progeny,generating a promising breeding material for improving rice grain quality.展开更多
Four japonica rice varieties differed in cooking and eating qualities were used in a pot experiment to study the relationship between the activities of glutamine synthetase during grain filling and rice quality. The a...Four japonica rice varieties differed in cooking and eating qualities were used in a pot experiment to study the relationship between the activities of glutamine synthetase during grain filling and rice quality. The activities of glutamine synthetase gradually increased and then declined as a single peak curve in the course of grain filling. The 15th day after heading was a turning point, before which the enzymatic activities in the inferior rice varieties with high protein content were higher than those in the superior rice varietie with low protein content, and after which it was converse. The activity of glutamine synthetase in grain was correlated with the taste meter value, peak viscosity and breakdown negatively at the early stage of grain filling whereas positively at the middle and late stages. Moreover, it was correlated with the protein content of rice grain and setback positively at the early stage and negatively at the middle and late stages. The correlation degree varied with the course of grain filling. From 15 days to 20 days after heading was a critical stage, in which the direction of correlation between the activity of glutamine synthetase and taste meter value and RVA properties of rice changed.展开更多
Four japonica rice varieties with significant differences in quality of eating and cooking were used in the experiment. The varieties showed differences in amylose and amylopectin contents at different grain filling s...Four japonica rice varieties with significant differences in quality of eating and cooking were used in the experiment. The varieties showed differences in amylose and amylopectin contents at different grain filling stages, which were attributed to the accumulative speed of starch at different grain filling stages. During grain filling period, the varieties had no difference in the time when the activities of ADPglocose pyrophosphorylase （AGPP） and soluble starch synthesis （SSS） reached a maximum, but had difference in the time when the activity of starch branching enzyme （SBE） reached a maximum, in which the inferior quality varieties were earlier than the high quality ones, and high quality varieties still kept high enzyme activities at the late stage of grain filling. The correlation and correlative degree between AGPP, SSS, SBE and amylose content, amylopectin content, taste meter value, and RVA properties varied with the different stages of grain filling. The correlation between SSS activity and taste meter value was not significant during the whole period of grain filling, but the activities of AGPP and SBE had significant or highly significant correlation with taste meter value. It was helpful for improving quality of eating and cooking of japonica rice to use the materials with low enzyme activity at the early stage of grain filling or high enzyme activity at the late stage as parents.展开更多
Rice eating and cooking quality(ECQ)is a major concern of breeders and consumers,determining market competitiveness worldwide.Rice grain protein content(GPC)is negatively related to ECQ,making it possible to improve E...Rice eating and cooking quality(ECQ)is a major concern of breeders and consumers,determining market competitiveness worldwide.Rice grain protein content(GPC)is negatively related to ECQ,making it possible to improve ECQ by manipulating GPC.However,GPC is genetically complex and sensitive to environmental conditions;therefore,little progress has been made in traditional breeding for ECQ.Here,we report that CRISPR/Cas9-mediated knockout of genes encoding the grain storage protein glutelin rapidly produced lines with downregulated GPC and improved ECQ.Our finding provides a new strategy for improving rice ECQ.展开更多
With 10 rice cultivars (lines) as materials, the changes in activities of adenosine diphosphoglucose pyrophosphorylase(ADPGPase), starch synthase (SSase) and starch branching enzyme (Q-enzyme) in the grains during gra...With 10 rice cultivars (lines) as materials, the changes in activities of adenosine diphosphoglucose pyrophosphorylase(ADPGPase), starch synthase (SSase) and starch branching enzyme (Q-enzyme) in the grains during grain filling, and theirrelationships with the filling rate, gel consistency (GC), alkali spreading value (ASV) and amylose content (AC) werestudied. The results showed that changes in activities of ADPGPase, SSase and Q-enzyme exhibited a single peak duringgrain filling, and the time of the activity peaks for the former two enzymes was earlier than that of the maximum grain-fillingrate (Tmax), and the time reaching the peak for Q-enzyme was synchronous with Tmax. The activities at early grain fillingstage, and the mean and maximum activities of each enzyme during grain filling period were positively and significantly orvery significantly correlated with the mean and maximum grain filling rate and starch content (mg grain-1) in the grains.Activities of ADPGPase at all grain filling stages and those of Q-enzyme at the early and mid filling stages were notsignificantly correlated the cooking quality (GC, ASV and AC). SSase activities at the early filling stage were significantlyand negatively correlated with GC and ASV, and positively correlated with AC. Activities of SSase at mid and late grainfilling stages and Q-enzyme at the late filling stage were significantly and positively correlated with GC and ASV, andnegatively correlated with AC. Spraying zeatin or abscisic acid at early grain filling stage could obviously regulate theactivities of ADPGPase, SSase and Q-enzyme in the grains.展开更多
A new phenomenological and empirically-based constitutive model was proposed to modify the term in the original Johnson−Cook constitutive model.The new model can be used to describe and predict the flow stress of AA10...A new phenomenological and empirically-based constitutive model was proposed to modify the term in the original Johnson−Cook constitutive model.The new model can be used to describe and predict the flow stress of AA1070 aluminum with different initial grain sizes in the hot working process.This developed model considers thermal softening,strain-rate hardening,strain hardening,initial grain size,and interactions with each other and can correctly model the behavior of AA1070 at elevated temperature with different strains,strain rates,and initial grain sizes.The hot flow behavior of AA1070 was investigated through compression tests over wide ranges of temperature from 623 to 773 K,strain rate from 0.005 to 0.5 s−1 and initial grain size from 50 to 450μm.Results show that the initial grain size has a significant effect on the flow behavior of AA1070.Then,correlation coefficient(R),average absolute relative error(AARE),and relative error were examined for comparative predictability of the model.Results show that flow stresses for different initial grain sizes calculated by the new proposed model perfectly correlate with experimental ones,with a mean relative error of 1.19%,which confirms that the new modified Johnson−Cook relation can give a precise estimation of the hot flow stress of AA1070 aluminum by considering the initial grain size.展开更多
Three japonica rice varieties with different cooking and eating quality were grown at high temperature in the greenhouse and natural field. Effects of temperature at the grain filling stage on these varieties were inv...Three japonica rice varieties with different cooking and eating quality were grown at high temperature in the greenhouse and natural field. Effects of temperature at the grain filling stage on these varieties were investigated in terms of the activities of key enzymes related to starch synthesis and cooking and eating quality of rice grain. The high temperature at the grain filling stage increased protein content, and decreased amylose content and taste meter value of rice; inferior grain quality varieties showed a greater magnitude of the increase or decrease than the superior ones. Reaction of rapid visco analyser profiles to the temperature varied with rice varieties. The activities of adenosine diphosphoglucose pyrophosphoryiase （AGPP）, soluble starch synthase （SSS） and starch branching enzyme （SBE） gradually increased to a peak value, and thereafter declined as grain filling progressed. Enzyme activities in different varieties differed in a same filling stage, and also in the time when the enzyme activity reached a maximum. AGPP and SSS were insensitive to the environmental temperature, but SBE was comparatively sensitive to the temperature, and its activity declined when temperature was too high or too low.展开更多
基金This work was supported by the Ministry of Science and Technology of China(2016YFD0100501)National Natural Science Foundation of China(31825019,31901517,and U19A2032)the Programs from Jiangsu Province Government(BE2018357,19KJA560006 and PAPD)。
文摘In rice(Oryza sativa), amylose content(AC) is the major factor that determines eating and cooking quality(ECQ). The diversity in AC is largely attributed to natural allelic variation at the Waxy(Wx)locus. Here we identified a rare Wx allele, Wx^(mw) ,which combines a favorable AC, improved ECQ and grain transparency. Based on a phylogenetic analysis of Wx genomic sequences from 370 rice accessions, we speculated that Wx^(mw) may have derived from recombination between two important natural Wx alleles, Wx^(in) and Wx^(b). We validated the effects of Wx^(mw) on rice grain quality using both transgenic lines and near-isogenic lines(NILs). When introgressed into the japonica Nipponbare(NIP) background, Wx^(mw) resulted in a moderate AC that was intermediate between that of NILs carrying the Wx^(b)allele and NILs with the Wx^(mp) allele. Notably, mature grains of NILs fixed for Wx^(mw) had an improved transparent endosperm relative to soft rice. Further, we introduced Wx^(mw) into a high-yielding japonica cultivar via molecular marker-assisted selection: the introgressed lines exhibited clear improvements in ECQ and endosperm transparency. Our results suggest that Wx^(mw) is a promising allele to improve grain quality, especially ECQ and grain transparency of high-yielding japonica cultivars, in rice breeding programs.
文摘Cooking and nutrition qualities of grain are two of the most important aspects of rice quality. To understand the difference in cooking and nutrition qualities among the grains at different positions within a rice panicle, the distributions of gel consistency （GC）, amylose content （AC） and crude protein content （CPC） of grains in a panicle in association with different nitrogen levels （0, 120 and 240 k c/ha） were investigated by using two rice varieties, Yangdao 6 （indica） and Wuyujing 3 （japonica）. In general, the grains at the basal part of a panicle had lower GC and higher AC than those at the upper or middle part of a panicle. The 1^st grain on the secondary branch with earlier flowering exhibited the highest GC, whereas the 2nd grain on the primary branch with later flowering showed the highest AC. For Yangdao 6, CPC in the grains on the primary branches was lower at the middle part of a panicle than at the upper or basal part of a panicle. For Wuyujing 3, there were no significant differences in CPCs in the grains among the upper, middle and basal parts of a panicle. GC in the grains was increased, whereas AC was reduced from zero nitrogen application （ON） to low amount of nitrogen application （LN）, and the result was reversed from LN to medium amount of nitrogen application （MN）. CPC was increased with the increase in the amount of nitrogen application.
基金supported by funding from the National Natural Science Foundation of China(31801016)the Agricultural Variety Improvement Project of Shandong Province(2019LZGC015)。
文摘Amylose content(AC),which is regulated by the Waxy(Wx)gene,is a major indicator of eating and cooking quality(ECQ)in rice(Oryza sativa).Thus far,only a limited number of mutations in the N-terminal domain of Wx were found to have a major impact on the AC of rice grains and no mutations with such effects were reported for other regions of the Wx protein.Here,nucleotide substitutions in the middle region of Wx were generated by adenine and cytosine base editors.The nucleotide substitutions led to changes in 15 amino acid residues of Wx,and a series of novel Wx alleles with ACs of 0.3%-29.43%(wild type with AC of 19.87%)were obtained.Importantly,the waxy~(abe2)allele showed a"soft rice"AC,improved ECQ,favorable appearance,and no undesirable agronomic traits.The transgenes were removed from the waxy~(abe2)progeny,generating a promising breeding material for improving rice grain quality.
文摘Four japonica rice varieties differed in cooking and eating qualities were used in a pot experiment to study the relationship between the activities of glutamine synthetase during grain filling and rice quality. The activities of glutamine synthetase gradually increased and then declined as a single peak curve in the course of grain filling. The 15th day after heading was a turning point, before which the enzymatic activities in the inferior rice varieties with high protein content were higher than those in the superior rice varietie with low protein content, and after which it was converse. The activity of glutamine synthetase in grain was correlated with the taste meter value, peak viscosity and breakdown negatively at the early stage of grain filling whereas positively at the middle and late stages. Moreover, it was correlated with the protein content of rice grain and setback positively at the early stage and negatively at the middle and late stages. The correlation degree varied with the course of grain filling. From 15 days to 20 days after heading was a critical stage, in which the direction of correlation between the activity of glutamine synthetase and taste meter value and RVA properties of rice changed.
文摘Four japonica rice varieties with significant differences in quality of eating and cooking were used in the experiment. The varieties showed differences in amylose and amylopectin contents at different grain filling stages, which were attributed to the accumulative speed of starch at different grain filling stages. During grain filling period, the varieties had no difference in the time when the activities of ADPglocose pyrophosphorylase （AGPP） and soluble starch synthesis （SSS） reached a maximum, but had difference in the time when the activity of starch branching enzyme （SBE） reached a maximum, in which the inferior quality varieties were earlier than the high quality ones, and high quality varieties still kept high enzyme activities at the late stage of grain filling. The correlation and correlative degree between AGPP, SSS, SBE and amylose content, amylopectin content, taste meter value, and RVA properties varied with the different stages of grain filling. The correlation between SSS activity and taste meter value was not significant during the whole period of grain filling, but the activities of AGPP and SBE had significant or highly significant correlation with taste meter value. It was helpful for improving quality of eating and cooking of japonica rice to use the materials with low enzyme activity at the early stage of grain filling or high enzyme activity at the late stage as parents.
基金funded by the National Natural Science Foundation of China(31871241,31970519)the programs from Jiangsu Province Government(BK20210798,JBGS[2021]001,BE2022335,BE2021334-1,BE2022365-2)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAP).
文摘Rice eating and cooking quality(ECQ)is a major concern of breeders and consumers,determining market competitiveness worldwide.Rice grain protein content(GPC)is negatively related to ECQ,making it possible to improve ECQ by manipulating GPC.However,GPC is genetically complex and sensitive to environmental conditions;therefore,little progress has been made in traditional breeding for ECQ.Here,we report that CRISPR/Cas9-mediated knockout of genes encoding the grain storage protein glutelin rapidly produced lines with downregulated GPC and improved ECQ.Our finding provides a new strategy for improving rice ECQ.
基金supported by the National Natural Science Foundation of China(30370828)the Natural Science Foundation of Jiangsu Province,China(BK2003041)
文摘With 10 rice cultivars (lines) as materials, the changes in activities of adenosine diphosphoglucose pyrophosphorylase(ADPGPase), starch synthase (SSase) and starch branching enzyme (Q-enzyme) in the grains during grain filling, and theirrelationships with the filling rate, gel consistency (GC), alkali spreading value (ASV) and amylose content (AC) werestudied. The results showed that changes in activities of ADPGPase, SSase and Q-enzyme exhibited a single peak duringgrain filling, and the time of the activity peaks for the former two enzymes was earlier than that of the maximum grain-fillingrate (Tmax), and the time reaching the peak for Q-enzyme was synchronous with Tmax. The activities at early grain fillingstage, and the mean and maximum activities of each enzyme during grain filling period were positively and significantly orvery significantly correlated with the mean and maximum grain filling rate and starch content (mg grain-1) in the grains.Activities of ADPGPase at all grain filling stages and those of Q-enzyme at the early and mid filling stages were notsignificantly correlated the cooking quality (GC, ASV and AC). SSase activities at the early filling stage were significantlyand negatively correlated with GC and ASV, and positively correlated with AC. Activities of SSase at mid and late grainfilling stages and Q-enzyme at the late filling stage were significantly and positively correlated with GC and ASV, andnegatively correlated with AC. Spraying zeatin or abscisic acid at early grain filling stage could obviously regulate theactivities of ADPGPase, SSase and Q-enzyme in the grains.
文摘A new phenomenological and empirically-based constitutive model was proposed to modify the term in the original Johnson−Cook constitutive model.The new model can be used to describe and predict the flow stress of AA1070 aluminum with different initial grain sizes in the hot working process.This developed model considers thermal softening,strain-rate hardening,strain hardening,initial grain size,and interactions with each other and can correctly model the behavior of AA1070 at elevated temperature with different strains,strain rates,and initial grain sizes.The hot flow behavior of AA1070 was investigated through compression tests over wide ranges of temperature from 623 to 773 K,strain rate from 0.005 to 0.5 s−1 and initial grain size from 50 to 450μm.Results show that the initial grain size has a significant effect on the flow behavior of AA1070.Then,correlation coefficient(R),average absolute relative error(AARE),and relative error were examined for comparative predictability of the model.Results show that flow stresses for different initial grain sizes calculated by the new proposed model perfectly correlate with experimental ones,with a mean relative error of 1.19%,which confirms that the new modified Johnson−Cook relation can give a precise estimation of the hot flow stress of AA1070 aluminum by considering the initial grain size.
基金the Key Research Proiect of the Department of Education of Heilongjiang Province,China(10S11Z002)the Natural Science Foundation of Heilongjiang Province,China(C01-10) the Rice Science Foundation Project of China(0003219)
文摘Three japonica rice varieties with different cooking and eating quality were grown at high temperature in the greenhouse and natural field. Effects of temperature at the grain filling stage on these varieties were investigated in terms of the activities of key enzymes related to starch synthesis and cooking and eating quality of rice grain. The high temperature at the grain filling stage increased protein content, and decreased amylose content and taste meter value of rice; inferior grain quality varieties showed a greater magnitude of the increase or decrease than the superior ones. Reaction of rapid visco analyser profiles to the temperature varied with rice varieties. The activities of adenosine diphosphoglucose pyrophosphoryiase （AGPP）, soluble starch synthase （SSS） and starch branching enzyme （SBE） gradually increased to a peak value, and thereafter declined as grain filling progressed. Enzyme activities in different varieties differed in a same filling stage, and also in the time when the enzyme activity reached a maximum. AGPP and SSS were insensitive to the environmental temperature, but SBE was comparatively sensitive to the temperature, and its activity declined when temperature was too high or too low.
