Seedlings of the gymnosperm, Pinus edulis Engelm., have a distinctive pattern of starch accumulation following germination; however, the enzymes involved in starch synthesis have not been studied in gymnosperm sp...Seedlings of the gymnosperm, Pinus edulis Engelm., have a distinctive pattern of starch accumulation following germination; however, the enzymes involved in starch synthesis have not been studied in gymnosperm species. In this study, enzymes and starch were extracted from P. edulis seedlings germinated in the dark at room temperature. Granule_bound proteins of 58 kD and 91 kD were recognized by a pea SS Ⅱ antiserum. The 58 kD granule_bound protein was purified and identified as granule_bound starch synthase Ⅰ by alignment of the N_terminal sequence with that of granule_bound starch synthase Ⅰ from several angiosperms. Elution of soluble starch synthase activity from a DEAE_Sepharose column showed two starch synthase activity peaks, indicating at least two isoforms of soluble starch synthases. Primer affinities of soluble starch synthases were investigated. Glycogen from rabbit was the best primer for soluble starch synthase. The enzymological properties of Pinus starch synthases appear to be similar to those reported for angiosperms.展开更多
The purpose of this study is to reveal the genetic mechanism of the variation of amylose content among different semi waxy or glutinous japonica rice in the background of Wxmp gene.Sixty-four semi waxy lines derived f...The purpose of this study is to reveal the genetic mechanism of the variation of amylose content among different semi waxy or glutinous japonica rice in the background of Wxmp gene.Sixty-four semi waxy lines derived from the hybrid progenies of Wujing 13 and Milky Princess(Kantou 194)with polymorphism in soluble starch synthase gene SSIIa(SSII-3)and SSIIIa(SSIII-2)but no polymorphism in other starch synthase related genes were used as test materials.The genotypes of SSIIa and SSIIIa allele were identified by molecular markers,and the allelic effects of SSIIa and SSIIIa gene on amylose content(AC),gel consistency(GC),gelatinization temperature(GT)and rapid visco analyzer(RVA)profile characteristics were analyzed.The significant effects of SSIIa and SSIIIa alleles and the interactive effects between two genes on AC,GT,GC and RVA profile characteristics were found.The SSIIa and SSIIIa alleles from Wujing13 shown positive effects on AC with an average increase of 1.87 and 1.23%in 2 years respectively.There was no significant effect on GT for SSIIa or SSIIIa allele but remarkable influence on GT when the co-existence of the two genes.The genotype SSIIa^(mp)SSIIIa^(mp) shown 1.34℃higher GT than genotype SSIIawjSSIIIawj(mp and wj indicated that the gene was derived from Milky Princess and Wujing 13 respectively,the same as in the below).Different genes and alleles resulted in significant different GC.The genetic effect of SSIIawj and SSIIIamp on GC was 8.74 and 9.62mm respectively.The GC of SSIIa^(wj)SSIIIa^(mp) was 10.64 and 16.95mm higher than that of SSIIa^(mp)SSIIIa^(wj) and SSIIawjSSIIIawj,respectively.The allele SSIIa^(wj) could increase the peak viscosity(PKV),hot paste viscosity(HPV),cool paste viscosity(CPV)and breakdown viscosity(BDV),while decrease the consistency viscosity(CSV)and setback viscosity(SBV).However for the allele SSIIIa^(wj) the opposite was true.The genotype SSIIa^(wj)SSIIIa^(mp) had the largest PKV,HPV and CPV,the genotype SSIIa^(wj)SSIIIa^(wj) had the largest BDV and CSV,but the genotype SSIIa^(wj)SSIIIa^(mp) had the least SBV.According to the comprehensive effect of each trait,the genotype SSIIawjSSIIIamp was the best.The allelic variation and interaction effect of SSIIa and SSIIIa genes have important reference value for improving cooking and eating quality of semi waxy japonica rice.展开更多
Starch biosynthesis is a complex process that relies on the coordinated action of multiple enzymes.Resistant starch is not digested in the small intestine,thus preventing a rapid rise in the glycemic index.Starch synt...Starch biosynthesis is a complex process that relies on the coordinated action of multiple enzymes.Resistant starch is not digested in the small intestine,thus preventing a rapid rise in the glycemic index.Starch synthase 2a(SS2a)is a key enzyme in amylopectin biosynthesis that has significant effects on starch structure and properties.In this study,we identified an ss2a null mutant(M3-1413)with a single base mutation from an ethyl methane sulfonate(EMS)-mutagenized population of barley.The mutation was located at the 3'end of the first intron of the RNA splicing receptor(AG)site,and resulted in abnormal RNA splicing and two abnormal transcripts of ss2a,which caused the inactivation of the SS2a gene.The starch structure and properties were significantly altered in the mutant,with M3-1413 containing lower total starch and higher amylose and resistant starch levels.This study sheds light on the effect of barley ss2a null mutations on starch properties and will help to guide new applications of barley starch in the development of nutritious food products.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
Dynamic changes of starch, amylose, sucrose contents and the activities of starch synthesis enzymes under shading treatments alter flowering were studied using two rice varieties IR72 （indica） and Nipponbare （japon...Dynamic changes of starch, amylose, sucrose contents and the activities of starch synthesis enzymes under shading treatments alter flowering were studied using two rice varieties IR72 （indica） and Nipponbare （japonica） as materials. Under shading treatments, the starch, amylose and sucrose contents decreased, while ADP-glucose pyrophosphorylase （ADPGPPase） activity only changed a little, soluble starch synthase activity and granule bound starch synthase activity decreased, soluble starch branching enzyme （SSBE, Q-enzyme） activity and granule bound starch branching enzyme （GBSBE, Q-enzyme） activity increased, and starch debranching enzyme （DBE, R-enzyme） activity varied with varieties. Correlation analyses showed that the changes of starch content were positively and significantly correlated with the changes of sucrose content in the weak light. Both ADPGPPase activity and SSBE activity were positively and significantly correlated with starch accumulation rate. It was implied that the decline of starch synthase activities was related to the decrease of starch content and the increase of the activity of starch branching enzyme played an important role in the decrease of the ratio of amylose to the total starch under the weak light.展开更多
Waxy maize with its pure amylopectin starch is the staple food of many ethnic minorities in hilly regions of Southeast Asia （SEA）. A combination of waxy and quality protein maize （QPM） traits would improve the qua...Waxy maize with its pure amylopectin starch is the staple food of many ethnic minorities in hilly regions of Southeast Asia （SEA）. A combination of waxy and quality protein maize （QPM） traits would improve the quality of protein of waxy maize for human consumption. Double recessive waxy-QPM （wx-o2） genotypes had been generated from Southern Chinese material by haploid induction of crosses heterozygous for the two quality traits with an absolutely conserved waxy type and an improved amino acid profile. The vitreous kernel trait （due to the additional modifier genes present in QPM） was lost in the wx-o2 plant material; this may be due to the waxy mutation, this is anyhow desirable for acceptance as waxy maize is preferred due to its soft grains. The content of the quality limiting amino acid lysine was greatly increased in double recessive wx-o2 genotypes compared to standard waxy maize, but still with a high variation among genotypes for future improvement. Conclusively, it was indeed possible to combine two grain quality mutations successfully within one genotype and prototypes of double quality wx-o2 are available now to contribute to meet human requirements in essential amino acids and thus reduce malnutrition in various regions of Asia.展开更多
Six rice varieties, PR120, PR116, Feng Ai Zan, PR115, PAU201 and Punjab Mehak 1 were raised under aerobic and transplanting conditions to assess the effects of planting conditions on sucrose metabolising enzymes in re...Six rice varieties, PR120, PR116, Feng Ai Zan, PR115, PAU201 and Punjab Mehak 1 were raised under aerobic and transplanting conditions to assess the effects of planting conditions on sucrose metabolising enzymes in relation to the transformation of free sugars to starch and protein in flag leaves and grains. Activities of sucrose synthase, sucrose phosphate synthase and acid invertase increased till flowering stage in leaves and mid-milky stage（14 d after flowering） in grains and thereafter declined in concomitant with the contents of reducing sugar. Under aerobic conditions, the activities of acid invertase and sucrose synthase（cleavage） significantly decreased in conjunction with the decrease in non-reducing sugars and starch content in all the varieties. Disruption of starch biosynthesis under the influence of aerobic conditions in both leaves and grains and the higher build up of sugars possibly resulted in their favoured utilization in nitrogen metabolism. Feng Ai Zan, PR115 and PR120 maintained higher levels of sucrose synthase enzymes in grains and leaves and contents of metabolites（amino acid, protein and non-reducing sugar） under aerobic conditions, while PR116, Punjab Mehak 1 and PAU201 performed better under transplanting conditions, thus showing their adaptation to environmental stress. Yield gap between aerobic and transplanting rice is attributed primarily to the difference in sink activity and strength. Overall, it appear that up-regulation of sucrose synthase（synthesis） and sucrose phosphate synthase under aerobic conditions might be responsible in enhancing growth and productivity of rice varieties.展开更多
[ Objective ] The study aimed to establish an efficient method to extract RNA from cassava, and clone the core sequence d SSS II gene. [ Method ] The cassava RNA was obtained using the modified CTAB method, which was ...[ Objective ] The study aimed to establish an efficient method to extract RNA from cassava, and clone the core sequence d SSS II gene. [ Method ] The cassava RNA was obtained using the modified CTAB method, which was then reversely transefiptod into eDNA. Degenerate primers were designed based on the ho- mology property of known SSS II sequences in other plant species. A fragment was amplified with the previously mentioned eDNA as template and the degenerate primers through Polymerase Chain Reaction （PCR）. [Result] After online blasting in NCBI, the sequence was identified as the core fragment of cassava SSS I1 gene. [ Conclusion] Our research would lay the original basis for the cloning of the cassava SSS II full length cDNA sequence and construction of its anti - sense vector, which could further provide proper candidate genes for the development of starch metah）lic en^necring.展开更多
Transitory starch in rice leaves is critical for temporary carbon storage,plant growth,and subsequent grain filling,yet the regulatory mechanisms underlying its biosynthesis remain poorly understood.Here,we found that...Transitory starch in rice leaves is critical for temporary carbon storage,plant growth,and subsequent grain filling,yet the regulatory mechanisms underlying its biosynthesis remain poorly understood.Here,we found that Leaf Starch Deficiency 3(LSD3),a rice glutamyl–tRNA reductase(GluTR),interacts with GluTR-binding protein(GluTRBP),which in turn associates with granule-bound starch synthase Ⅱ(GBSSⅡ),the key enzyme responsible for amylose synthesis in leaves.The LSD3–GluTRBP module maintains both the protein stability and enzymatic activity of GBSSⅡ.The lsd3 and glutrbp mutants exhibited markedly reduced GBSSⅡ activity,resulting in significant decreases in leaf starch accumulation.Moreover,these mutants displayed severe defects in carbon-source transport from leaves to developing grains,accompanied by strong downregulation of genes associated with carbon-source allocation.Consequently,the lsd3 and glutrbp mutants showed reduced endosperm-storage starch content and severely compromised grain quality and yield.Notably,overexpression of GBSSⅡ partially rescued defective phenotypes in both leaves and grains of the mutants.In summary,our findings establish that the LSD3–GluTRBP module acts upstream of GBSSⅡ and plays a central role in transitory starch biosynthesis as well as in determining grain quality and yield in rice.These findings provide new molecular targets for simultaneously improving both grain yield and quality in rice.展开更多
The dynamic changes of the activities of enzymes involving in starch biosynthesis,including ADP-glucose pyrophosphorylase(AGPase),soluble starch synthases(SSS),starch branching enzyme(SBE)and starch debranching enzyme...The dynamic changes of the activities of enzymes involving in starch biosynthesis,including ADP-glucose pyrophosphorylase(AGPase),soluble starch synthases(SSS),starch branching enzyme(SBE)and starch debranching enzymes(DBE)were studied,and changes of fine structure of amy-lopectin were characterized by isoamylase treatment during rice grain development,using trans anti-waxy gene rice plants.The relationships between the activities of those key enzymes were also analyzed.The amylose synthesis was significantly inhibited in transgenic Wanjing 9522,but the total starch content and final grain weight were less affected as compared with those of non-transgenic Wanjing 9522 rice cultivar.Analyses on the changes of activities of enzymes involving in starch bio-synthesis showed that different enzyme activities were expressed differently during rice endosperm development.Soluble starch synthase is relatively highly expressed in earlier stage of endosperm de-velopment,whilst maximal expression of granule-bound starch synthase(GBSS)occurred in mid-stage of endosperm development.No obvious differences in changes of the activities of AGPase and SBE between two rice cultivars investigated,except the DBEs.Distribution patterns of branches of amy-lopectin changed continually during the development of rice grains and varied between two rice culti-vars.It was suggested that amylopectin synthesis be prior to the synthesis of amylose and different enzymes have different roles in controlling syntheses of branches of amylopectin.展开更多
Starch,a semi-crystalline energy storage form primarily found in plant plastids plays a crucial role in various food or no-food applications.Despite the starch biosynthetic pathway’s main enzymes have been characteri...Starch,a semi-crystalline energy storage form primarily found in plant plastids plays a crucial role in various food or no-food applications.Despite the starch biosynthetic pathway’s main enzymes have been characterized,their origin and evolution remained a subject of debate.In this study,we conducted the comprehensive phylogenetic and structural analysis of three types of starch biosynthetic enzymes:starch synthase(SS),starch branching enzyme(SBE)and isoamylase-type debranching enzyme(ISA)from 51,151 annotated genomes.Our findings provide valuable insights into the possible scenario for the origin and evolution of the starch biosynthetic pathway.Initially,the ancestor of SBE can be traced back to an unidentified bacterium that existed before the formation of the last eukaryotic common ancestor(LECA)via horizontal gene transfer(HGT).This transfer event likely provided the eukaryote ancestor with the ability to synthesize glycogen.Furthermore,during the emergence of Archaeplastida,one clade of SS was transferred from Deltaproteobacteria by HGT,while ISA and the other clade of SS originated from Chlamydiae through endosymbiosis gene transfer(EGT).Both these transfer events collectively contributed to the establishment of the original starch biosynthetic pathway.Subsequently,after the divergence of Viridiplantae from Rhodophyta,all three enzymes underwent multiple duplications and N-terminus extension domain modifications,resulting in the formation of functionally specialized isoforms and ultimately leading to the complete starch biosynthetic pathway.By shedding light on the evolutionary origins of key enzymes involved in the starch biosynthetic pathway,this study provides important insights into the evolutionary events of plants.展开更多
The present study investigated whether an irrigation system could be established to save water and increase grain yield to enhance water productivity by proper water management at the field level in irrigated lowland ...The present study investigated whether an irrigation system could be established to save water and increase grain yield to enhance water productivity by proper water management at the field level in irrigated lowland rice （Oryza sativa L.）. Using two field-grown rice cultivars, two irrigation systems; conventional irrigation and water-saving irrigation, were conducted. In the water-saving irrigation system, limiting values of soil water potential related to specific growth stages were proposed as irrigation indices. Compared with conventional irrigation where drainage was in mid-season and flooded at other times, the water-saving irrigation increased grain yield by 7.4% to 11.3%, reduced irrigation water by 24.5% to 29.2%, and increased water productivity （grain yield per cubic meter of irrigation water） by 43.1% to 50.3%. The water-saving irrigation significantly increased harvest index, improved milling and appearance qualities, elevated zeatin-I-zeaUn riboside concentrations in root bleedings and enhanced activities of sucrose synthase, adenosine diphosphate glucose pyrophosphorylase, starch synthase and starch branching enzyme in grains. Our results indicate that water-saving irrigation by controlling limiting values of soil water potential related to specific growth stages can enhance physiological activities of roots and grains, reduce water input, and increase grain yield.展开更多
Gelatinization temperature (GT) is an important parameter for evaluating the cooking and eating quality of rice besides amylose content (AC). The inheritance of the genes affecting GT has been widely studied and is co...Gelatinization temperature (GT) is an important parameter for evaluating the cooking and eating quality of rice besides amylose content (AC). The inheritance of the genes affecting GT has been widely studied and is considered to be controlled by a major gene. Here, we report the map-based cloning of rice ALK that encodes the soluble starch synthase II (SSSII). Comparison between the DNA sequences from different rice varieties, together with the results obtained with digestion of the rice seeds in alkali solution, indicates that the base substitutions in coding se-quence of ALK may cause the alteration in GT.展开更多
文摘Seedlings of the gymnosperm, Pinus edulis Engelm., have a distinctive pattern of starch accumulation following germination; however, the enzymes involved in starch synthesis have not been studied in gymnosperm species. In this study, enzymes and starch were extracted from P. edulis seedlings germinated in the dark at room temperature. Granule_bound proteins of 58 kD and 91 kD were recognized by a pea SS Ⅱ antiserum. The 58 kD granule_bound protein was purified and identified as granule_bound starch synthase Ⅰ by alignment of the N_terminal sequence with that of granule_bound starch synthase Ⅰ from several angiosperms. Elution of soluble starch synthase activity from a DEAE_Sepharose column showed two starch synthase activity peaks, indicating at least two isoforms of soluble starch synthases. Primer affinities of soluble starch synthases were investigated. Glycogen from rabbit was the best primer for soluble starch synthase. The enzymological properties of Pinus starch synthases appear to be similar to those reported for angiosperms.
基金supported by Jiangsu Natural Science Foundation(No.BK20180302)Jiangsu agricultural science and Technology Innovation Fund(No.CX[18]1001)+3 种基金Jiangsu Key Research and development program(No.BE2018357)Jiangsu major new varieties creation project(No.PZCZ201703)the earmarked fund for China Agriculture Research System(No.CARS-1-62)the open project of key Laboratory of Jiangsu crop genomics and molecular Breeding(No.PL201902).
文摘The purpose of this study is to reveal the genetic mechanism of the variation of amylose content among different semi waxy or glutinous japonica rice in the background of Wxmp gene.Sixty-four semi waxy lines derived from the hybrid progenies of Wujing 13 and Milky Princess(Kantou 194)with polymorphism in soluble starch synthase gene SSIIa(SSII-3)and SSIIIa(SSIII-2)but no polymorphism in other starch synthase related genes were used as test materials.The genotypes of SSIIa and SSIIIa allele were identified by molecular markers,and the allelic effects of SSIIa and SSIIIa gene on amylose content(AC),gel consistency(GC),gelatinization temperature(GT)and rapid visco analyzer(RVA)profile characteristics were analyzed.The significant effects of SSIIa and SSIIIa alleles and the interactive effects between two genes on AC,GT,GC and RVA profile characteristics were found.The SSIIa and SSIIIa alleles from Wujing13 shown positive effects on AC with an average increase of 1.87 and 1.23%in 2 years respectively.There was no significant effect on GT for SSIIa or SSIIIa allele but remarkable influence on GT when the co-existence of the two genes.The genotype SSIIa^(mp)SSIIIa^(mp) shown 1.34℃higher GT than genotype SSIIawjSSIIIawj(mp and wj indicated that the gene was derived from Milky Princess and Wujing 13 respectively,the same as in the below).Different genes and alleles resulted in significant different GC.The genetic effect of SSIIawj and SSIIIamp on GC was 8.74 and 9.62mm respectively.The GC of SSIIa^(wj)SSIIIa^(mp) was 10.64 and 16.95mm higher than that of SSIIa^(mp)SSIIIa^(wj) and SSIIawjSSIIIawj,respectively.The allele SSIIa^(wj) could increase the peak viscosity(PKV),hot paste viscosity(HPV),cool paste viscosity(CPV)and breakdown viscosity(BDV),while decrease the consistency viscosity(CSV)and setback viscosity(SBV).However for the allele SSIIIa^(wj) the opposite was true.The genotype SSIIa^(wj)SSIIIa^(mp) had the largest PKV,HPV and CPV,the genotype SSIIa^(wj)SSIIIa^(wj) had the largest BDV and CSV,but the genotype SSIIa^(wj)SSIIIa^(mp) had the least SBV.According to the comprehensive effect of each trait,the genotype SSIIawjSSIIIamp was the best.The allelic variation and interaction effect of SSIIa and SSIIIa genes have important reference value for improving cooking and eating quality of semi waxy japonica rice.
基金supported by the Major Program of National Agricultural Science and Technology of China(NK20220607)the Sichuan Science and Technology Program,China(2023YFH0041)。
文摘Starch biosynthesis is a complex process that relies on the coordinated action of multiple enzymes.Resistant starch is not digested in the small intestine,thus preventing a rapid rise in the glycemic index.Starch synthase 2a(SS2a)is a key enzyme in amylopectin biosynthesis that has significant effects on starch structure and properties.In this study,we identified an ss2a null mutant(M3-1413)with a single base mutation from an ethyl methane sulfonate(EMS)-mutagenized population of barley.The mutation was located at the 3'end of the first intron of the RNA splicing receptor(AG)site,and resulted in abnormal RNA splicing and two abnormal transcripts of ss2a,which caused the inactivation of the SS2a gene.The starch structure and properties were significantly altered in the mutant,with M3-1413 containing lower total starch and higher amylose and resistant starch levels.This study sheds light on the effect of barley ss2a null mutations on starch properties and will help to guide new applications of barley starch in the development of nutritious food products.
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Dynamic changes of starch, amylose, sucrose contents and the activities of starch synthesis enzymes under shading treatments alter flowering were studied using two rice varieties IR72 （indica） and Nipponbare （japonica） as materials. Under shading treatments, the starch, amylose and sucrose contents decreased, while ADP-glucose pyrophosphorylase （ADPGPPase） activity only changed a little, soluble starch synthase activity and granule bound starch synthase activity decreased, soluble starch branching enzyme （SSBE, Q-enzyme） activity and granule bound starch branching enzyme （GBSBE, Q-enzyme） activity increased, and starch debranching enzyme （DBE, R-enzyme） activity varied with varieties. Correlation analyses showed that the changes of starch content were positively and significantly correlated with the changes of sucrose content in the weak light. Both ADPGPPase activity and SSBE activity were positively and significantly correlated with starch accumulation rate. It was implied that the decline of starch synthase activities was related to the decrease of starch content and the increase of the activity of starch branching enzyme played an important role in the decrease of the ratio of amylose to the total starch under the weak light.
文摘Waxy maize with its pure amylopectin starch is the staple food of many ethnic minorities in hilly regions of Southeast Asia （SEA）. A combination of waxy and quality protein maize （QPM） traits would improve the quality of protein of waxy maize for human consumption. Double recessive waxy-QPM （wx-o2） genotypes had been generated from Southern Chinese material by haploid induction of crosses heterozygous for the two quality traits with an absolutely conserved waxy type and an improved amino acid profile. The vitreous kernel trait （due to the additional modifier genes present in QPM） was lost in the wx-o2 plant material; this may be due to the waxy mutation, this is anyhow desirable for acceptance as waxy maize is preferred due to its soft grains. The content of the quality limiting amino acid lysine was greatly increased in double recessive wx-o2 genotypes compared to standard waxy maize, but still with a high variation among genotypes for future improvement. Conclusively, it was indeed possible to combine two grain quality mutations successfully within one genotype and prototypes of double quality wx-o2 are available now to contribute to meet human requirements in essential amino acids and thus reduce malnutrition in various regions of Asia.
文摘Six rice varieties, PR120, PR116, Feng Ai Zan, PR115, PAU201 and Punjab Mehak 1 were raised under aerobic and transplanting conditions to assess the effects of planting conditions on sucrose metabolising enzymes in relation to the transformation of free sugars to starch and protein in flag leaves and grains. Activities of sucrose synthase, sucrose phosphate synthase and acid invertase increased till flowering stage in leaves and mid-milky stage（14 d after flowering） in grains and thereafter declined in concomitant with the contents of reducing sugar. Under aerobic conditions, the activities of acid invertase and sucrose synthase（cleavage） significantly decreased in conjunction with the decrease in non-reducing sugars and starch content in all the varieties. Disruption of starch biosynthesis under the influence of aerobic conditions in both leaves and grains and the higher build up of sugars possibly resulted in their favoured utilization in nitrogen metabolism. Feng Ai Zan, PR115 and PR120 maintained higher levels of sucrose synthase enzymes in grains and leaves and contents of metabolites（amino acid, protein and non-reducing sugar） under aerobic conditions, while PR116, Punjab Mehak 1 and PAU201 performed better under transplanting conditions, thus showing their adaptation to environmental stress. Yield gap between aerobic and transplanting rice is attributed primarily to the difference in sink activity and strength. Overall, it appear that up-regulation of sucrose synthase（synthesis） and sucrose phosphate synthase under aerobic conditions might be responsible in enhancing growth and productivity of rice varieties.
基金Supported by Special Fund for Agricultural Comprehensive Development of Ministry of Agriculture(Agricultural Reclamation[2010]No.23)
文摘[ Objective ] The study aimed to establish an efficient method to extract RNA from cassava, and clone the core sequence d SSS II gene. [ Method ] The cassava RNA was obtained using the modified CTAB method, which was then reversely transefiptod into eDNA. Degenerate primers were designed based on the ho- mology property of known SSS II sequences in other plant species. A fragment was amplified with the previously mentioned eDNA as template and the degenerate primers through Polymerase Chain Reaction （PCR）. [Result] After online blasting in NCBI, the sequence was identified as the core fragment of cassava SSS I1 gene. [ Conclusion] Our research would lay the original basis for the cloning of the cassava SSS II full length cDNA sequence and construction of its anti - sense vector, which could further provide proper candidate genes for the development of starch metah）lic en^necring.
基金supported by the National Key Research and Development Program of China(2023YFF1000500)the Innovation Program of the Chinese Academy of Agricultural Sciences(CAAS-CSCB-202402)+2 种基金the National Natural Science Foundation of China(32372099 and 32172080)the Zhejiang Provincial Natural Science Foundation of China(LZ25C130011)the Central Public-Interest Scientific Institution Basal Research Fund(Y2025YC97).
文摘Transitory starch in rice leaves is critical for temporary carbon storage,plant growth,and subsequent grain filling,yet the regulatory mechanisms underlying its biosynthesis remain poorly understood.Here,we found that Leaf Starch Deficiency 3(LSD3),a rice glutamyl–tRNA reductase(GluTR),interacts with GluTR-binding protein(GluTRBP),which in turn associates with granule-bound starch synthase Ⅱ(GBSSⅡ),the key enzyme responsible for amylose synthesis in leaves.The LSD3–GluTRBP module maintains both the protein stability and enzymatic activity of GBSSⅡ.The lsd3 and glutrbp mutants exhibited markedly reduced GBSSⅡ activity,resulting in significant decreases in leaf starch accumulation.Moreover,these mutants displayed severe defects in carbon-source transport from leaves to developing grains,accompanied by strong downregulation of genes associated with carbon-source allocation.Consequently,the lsd3 and glutrbp mutants showed reduced endosperm-storage starch content and severely compromised grain quality and yield.Notably,overexpression of GBSSⅡ partially rescued defective phenotypes in both leaves and grains of the mutants.In summary,our findings establish that the LSD3–GluTRBP module acts upstream of GBSSⅡ and plays a central role in transitory starch biosynthesis as well as in determining grain quality and yield in rice.These findings provide new molecular targets for simultaneously improving both grain yield and quality in rice.
基金the National Key Research and Development Program of China(GrantNo.G199810100)
文摘The dynamic changes of the activities of enzymes involving in starch biosynthesis,including ADP-glucose pyrophosphorylase(AGPase),soluble starch synthases(SSS),starch branching enzyme(SBE)and starch debranching enzymes(DBE)were studied,and changes of fine structure of amy-lopectin were characterized by isoamylase treatment during rice grain development,using trans anti-waxy gene rice plants.The relationships between the activities of those key enzymes were also analyzed.The amylose synthesis was significantly inhibited in transgenic Wanjing 9522,but the total starch content and final grain weight were less affected as compared with those of non-transgenic Wanjing 9522 rice cultivar.Analyses on the changes of activities of enzymes involving in starch bio-synthesis showed that different enzyme activities were expressed differently during rice endosperm development.Soluble starch synthase is relatively highly expressed in earlier stage of endosperm de-velopment,whilst maximal expression of granule-bound starch synthase(GBSS)occurred in mid-stage of endosperm development.No obvious differences in changes of the activities of AGPase and SBE between two rice cultivars investigated,except the DBEs.Distribution patterns of branches of amy-lopectin changed continually during the development of rice grains and varied between two rice culti-vars.It was suggested that amylopectin synthesis be prior to the synthesis of amylose and different enzymes have different roles in controlling syntheses of branches of amylopectin.
基金the National Key R&D Program of China(No.2021YFC2103500)the Tianjin Synthetic Biotechnology Innovation Capacity Improvement Project(No.TSBICIP-KJGG-009-02 and No.TSBICIP-CXRC-003).
文摘Starch,a semi-crystalline energy storage form primarily found in plant plastids plays a crucial role in various food or no-food applications.Despite the starch biosynthetic pathway’s main enzymes have been characterized,their origin and evolution remained a subject of debate.In this study,we conducted the comprehensive phylogenetic and structural analysis of three types of starch biosynthetic enzymes:starch synthase(SS),starch branching enzyme(SBE)and isoamylase-type debranching enzyme(ISA)from 51,151 annotated genomes.Our findings provide valuable insights into the possible scenario for the origin and evolution of the starch biosynthetic pathway.Initially,the ancestor of SBE can be traced back to an unidentified bacterium that existed before the formation of the last eukaryotic common ancestor(LECA)via horizontal gene transfer(HGT).This transfer event likely provided the eukaryote ancestor with the ability to synthesize glycogen.Furthermore,during the emergence of Archaeplastida,one clade of SS was transferred from Deltaproteobacteria by HGT,while ISA and the other clade of SS originated from Chlamydiae through endosymbiosis gene transfer(EGT).Both these transfer events collectively contributed to the establishment of the original starch biosynthetic pathway.Subsequently,after the divergence of Viridiplantae from Rhodophyta,all three enzymes underwent multiple duplications and N-terminus extension domain modifications,resulting in the formation of functionally specialized isoforms and ultimately leading to the complete starch biosynthetic pathway.By shedding light on the evolutionary origins of key enzymes involved in the starch biosynthetic pathway,this study provides important insights into the evolutionary events of plants.
基金Supported by the National Natural Science Foundation of China(30671225)the State Key Project(2004-BA520A12-5)+1 种基金the Natural Science Foundation of Jiangsu Province(BK2006069)Hong Kong Research Grants Council(Project HKBU 2465/05M).
文摘The present study investigated whether an irrigation system could be established to save water and increase grain yield to enhance water productivity by proper water management at the field level in irrigated lowland rice （Oryza sativa L.）. Using two field-grown rice cultivars, two irrigation systems; conventional irrigation and water-saving irrigation, were conducted. In the water-saving irrigation system, limiting values of soil water potential related to specific growth stages were proposed as irrigation indices. Compared with conventional irrigation where drainage was in mid-season and flooded at other times, the water-saving irrigation increased grain yield by 7.4% to 11.3%, reduced irrigation water by 24.5% to 29.2%, and increased water productivity （grain yield per cubic meter of irrigation water） by 43.1% to 50.3%. The water-saving irrigation significantly increased harvest index, improved milling and appearance qualities, elevated zeatin-I-zeaUn riboside concentrations in root bleedings and enhanced activities of sucrose synthase, adenosine diphosphate glucose pyrophosphorylase, starch synthase and starch branching enzyme in grains. Our results indicate that water-saving irrigation by controlling limiting values of soil water potential related to specific growth stages can enhance physiological activities of roots and grains, reduce water input, and increase grain yield.
基金supported by the National Special Program for Research and Transgenic Plants(Grant No.JY03-A-07-01)Natural Science Foundation,Zhejiang Province.
文摘Gelatinization temperature (GT) is an important parameter for evaluating the cooking and eating quality of rice besides amylose content (AC). The inheritance of the genes affecting GT has been widely studied and is considered to be controlled by a major gene. Here, we report the map-based cloning of rice ALK that encodes the soluble starch synthase II (SSSII). Comparison between the DNA sequences from different rice varieties, together with the results obtained with digestion of the rice seeds in alkali solution, indicates that the base substitutions in coding se-quence of ALK may cause the alteration in GT.
