| Glycogen is a branched macromolecular polysaccharide composed of glucoses,which is widely stored in human,animal,fungi,bacteria,and plant tissues.Loss of glycogen in the heart and skeletal muscles from human body results in cardiomyopathy and muscle weakness.Glycogen from animal is mainly responsible for controlling blood glucose homeostasis.Glycogen as a basic energy exists mainly in fungi and bacteria,it can be released quickly when needed,which can be recoveried rapidly when not needed.Phytoglycogen is a soluble a-D-glucan and the most important storage polysaccharide in plant isoamylase deletion mutant(sul mutants),It is the basic material that constitutes the carbon skeleton of all plants organs.Glycogen biosynthesis is a complex biochemical reaction process,a series of enzymes are involved,Such as glycogen synthase(GN),glycogen synthase(GS),glycogen branching enzyme(GBE)and Glycogen phosphorylase(GP).GN is the first rate-limiting enzyme that initiates glycogen synthesis.Based on transcriptomics analysis,this study analysis GN family expression characteristics,cloned high expression in banana fruits MaGN12 and its promoter sequences,through gene expression analysis,promoter response element analysis and over-express in tomato,initially reveals the function of banana MaGN12,lays a theoretical foundation for further understanding the role of glycogen in plant growth and development.The main results of this study are as follows:(1)Glycogen existed in different development periods and tissues in bananas.The glycogen content in the fruit is higher than that in the roots,stems,leaves,and flowers.(2)14 GN gene family members were obtained from banana fruit through transcriptome analyses.Expression analysis show that the GN family members exhibit tissue-specific expression,MaGN12 has the highest expression in banana fruit.(3)Based on banana A genome,MaGN12 was cloned and analyzed by bi oinformation.The ORF of MaGN12 was 1407 bp.Bioinformatics analysis sho wed that the gene is located on 5 chromosomes,included 49 endonuclease enz yme loci and encoded 468 a mino acids.Its molecular weight was 117.96 kDa,isoelectric point was 4.99,and the chemical formula was C4272H7139N140701807S338.It contains a signal peptide and 3U2X|B functional domain.Its protei n secondary structure contains 221 alpha helixes,66 stretches and 181 random curly structures,serine and threonine and tyrosine phosphorylated a mino acid,and 8 across the membrane structure,and three conserved motifs:Galactinol sy nthase,Alpha-mannosyltransferase,Nucleotide-diphospho-sugar transferases.(4)The full length of MaGN12 promoter was 1497 bp and contained TATA-box,GC-box,and CAAT box core elements.In addition,there are 55 cis-acting elements such as ABA,GA,ethylene,and drought-induced activation.It is speculated that the gene is regulated by various hormones.(5)In vitro induction showed that the promoter responded to ethylene signals.The results showed that exogenous ethylene treatment inhibition GN gene expression,reduce GN enzyme activity and reduce glycogen content.The results showed that ethylene negatively regulates the banana MaGN12 expression.(6)MaGN12 was over-expressed in tomato,obtained transgenic plants.The results showed that the MaGN12 is the highest express in fruit,follow leaves and flowers.With the development of tomato fruit,the glycogen content,GN enzyme activity,and MaGN12 gene expression in the fruit were significant increase compared to the control.Meanwhile,in transgenic tomato fruits,the content of fructose and glucose increased... |
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