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
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
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...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
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.
文摘以马铃薯普通栽培种"甘农薯2号"块茎为材料,利用RNA提取试剂盒提取总RNA,通过RT-PCR技术和DNA序列测定分析,证实获得了马铃薯颗粒结合淀粉合成酶(GBSS I)基因的cDNA序列。该cDNA全长1824bp,包括607个氨基酸和1个终止密码子序列,且与原序列(accession number X58453)同源性为99.78%,但与其他科植物GBSS基因的同源性较低,注册该基因到GenBank中,注册号为EU403426。利用生物信息学相关软件分析预测GBSS I基因cDNA序列编码的蛋白质功能和结构,结果发现,该蛋白与其他15种植物GBSS蛋白一样,具有3个完全保守区域,并具许多重要功能位点,且与农杆菌淀粉合成酶具有相似三级结构模型,表明该蛋白具淀粉合成功能。
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.
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.
文摘颗粒结合型淀粉合成酶(granule-bound starch synthase, GBSS)是一种能够决定直链淀粉生物合成的关键性酶。根据已发表的多种淀粉粒结合淀粉合成酶(GBSS)基因序列的对比分析,设计一对简并引物,采用同源克隆法和5’/3’RACE (Rapid amplification of c DNA ends)的方法,获得芭蕉芋GBSS全长的cDNA,从芭蕉芋中获得GBSSⅠ基因的cDNA全长片段,并对其核酸序列及其推导的氨基酸序列进行了生物信息学分析,结果表明:芭蕉芋块茎GBSSⅠ基因ORF全长1 851 bp,编码616个氨基酸且蛋白质为一个稳定的蛋白;生物进化分析结果显示芭蕉芋与同姜目下巴西蕉、天宝蕉和马六甲小果野蕉亚种亲缘关系最为接近,芭蕉芋GBSSⅠ的克隆在分子生物学基础上对芭蕉芋块根直链淀粉生物合成及表达途径与调控的研究奠定重要的理论基础。
