[Objective] The aim was to study characters of pollen grains of tetraploid lines and diploid control line of Chrysanthemum cinerariifolium (Trev.) Vis.,morphological characters,fertility of pollen grain and germinatio...[Objective] The aim was to study characters of pollen grains of tetraploid lines and diploid control line of Chrysanthemum cinerariifolium (Trev.) Vis.,morphological characters,fertility of pollen grain and germination percentage of seeds. [Method] Pollen grains were prepared by sulphuric acid-acetyl oxide decomposition method. The lengths of polar axis and equatorial axis of pollen grains were determined with general optical microscope. The morphology of pollen grains was observed with SEM (scanning electron microscope) and the typical visual fields of 2 500× (or 2 000×),7 000× were taken pictures. [Result] Comparing with the diploid control line,the pollen grains of five tetraploid lines which were tested were different from the diploid line in morphology,sculpture,etc.. 4 of the 5 tested samples were significant larger than the diploid line in size and one was similar to the diploid line. [Conclusion] This research provided references for breeding tetraploid improved varieties of Chrysanthemum cinerariifolium (Trev.) Vis. with good fertility and high germination percentage.展开更多
Gamma-aminobutyric acid is a versatile and non-protein amino acid that plays a significant role in medicine,food,and cosmetics.The synthesis of gamma-aminobutyric acid is restricted by complex metabolic mechanisms and...Gamma-aminobutyric acid is a versatile and non-protein amino acid that plays a significant role in medicine,food,and cosmetics.The synthesis of gamma-aminobutyric acid is restricted by complex metabolic mechanisms and suboptimal fermentation conditions.Previously,we had constructed the Corynebacterium glutamicum strain CGY-PG-304 which could efficiently produce gamma-aminobutyric acid.In this study,we promoted gamma-aminobutyric acid production in CGY-PG-304 by enhancing the carbon flow in the TCA cycle,streamlining the mycolic acid layer of the cell wall,and optimizing the fermentation conditions.First,the genes sucCD encoding succinyl coenzyme A synthase,the gene cmrA encoding the ketoacyl reductase,and the gene treY encoding maltooligosaccharyl trehalose synthase were deleted in CGY-PG-304 individually or in combination.The yield of gamma-aminobutyric acid was increased in all the resulting strains among which CGW003 was the best.Next,the gene acnA encoding cis-aconitase or the gltS encoding sodium-coupled glutamate secondary uptake system were overexpressed in CGW003 using plasmid,and the former produced more gamma-aminobutyric acid than the latter.Therefore,the promoter of the chromosomal gene acnA in CGW003 was replaced by the strong promoter PtacM,resulting in the final strain CGW005.CGW005 could produce 112.03 g/L of gamma-aminobutyric acid with a yield of 0.34 g/g of glucose by fed-batch fermentation.展开更多
基金Supported by the Fundamental Research Funds for the Central Universities (SWJTU09BR221)~~
文摘[Objective] The aim was to study characters of pollen grains of tetraploid lines and diploid control line of Chrysanthemum cinerariifolium (Trev.) Vis.,morphological characters,fertility of pollen grain and germination percentage of seeds. [Method] Pollen grains were prepared by sulphuric acid-acetyl oxide decomposition method. The lengths of polar axis and equatorial axis of pollen grains were determined with general optical microscope. The morphology of pollen grains was observed with SEM (scanning electron microscope) and the typical visual fields of 2 500× (or 2 000×),7 000× were taken pictures. [Result] Comparing with the diploid control line,the pollen grains of five tetraploid lines which were tested were different from the diploid line in morphology,sculpture,etc.. 4 of the 5 tested samples were significant larger than the diploid line in size and one was similar to the diploid line. [Conclusion] This research provided references for breeding tetraploid improved varieties of Chrysanthemum cinerariifolium (Trev.) Vis. with good fertility and high germination percentage.
基金supported by the National Key Research and Development Program of China(2021YFC2100900).
文摘Gamma-aminobutyric acid is a versatile and non-protein amino acid that plays a significant role in medicine,food,and cosmetics.The synthesis of gamma-aminobutyric acid is restricted by complex metabolic mechanisms and suboptimal fermentation conditions.Previously,we had constructed the Corynebacterium glutamicum strain CGY-PG-304 which could efficiently produce gamma-aminobutyric acid.In this study,we promoted gamma-aminobutyric acid production in CGY-PG-304 by enhancing the carbon flow in the TCA cycle,streamlining the mycolic acid layer of the cell wall,and optimizing the fermentation conditions.First,the genes sucCD encoding succinyl coenzyme A synthase,the gene cmrA encoding the ketoacyl reductase,and the gene treY encoding maltooligosaccharyl trehalose synthase were deleted in CGY-PG-304 individually or in combination.The yield of gamma-aminobutyric acid was increased in all the resulting strains among which CGW003 was the best.Next,the gene acnA encoding cis-aconitase or the gltS encoding sodium-coupled glutamate secondary uptake system were overexpressed in CGW003 using plasmid,and the former produced more gamma-aminobutyric acid than the latter.Therefore,the promoter of the chromosomal gene acnA in CGW003 was replaced by the strong promoter PtacM,resulting in the final strain CGW005.CGW005 could produce 112.03 g/L of gamma-aminobutyric acid with a yield of 0.34 g/g of glucose by fed-batch fermentation.
