Study On Gene Expression Involving In Starch Metabolism And Starch Quality In Potato

Starch biosynthesis pathway involves the participation of various enzymes. Though the metabolic pathway of starch biosynthesis is clear, the methods to improve the temporary starch by regulating the expression of genes in starch biosynthesis are limited. The experimental material is the high starch potatoes obtained by previous experiment. This study measures and analyzes the relationship between the expression of gene related to starch biosynthesis and phenotype, and lay the foundation for increasing the starch quality.Analysis of the transcripts data showed that, there are 22951 common genes and 2966 differential genes in the high starch potatoes and control plants, occupying 11% of the total genes, and among them, there are 1766 special genes expressed in high starch stains, and 1200 special genes in control. It is found that the gene expressive quantity of 12 genes in high starch strains are higher than control by screening out 22 related genes to biological synthesis and degradation and comparing the RPKM of encoding genes.The RPKM of one small subunit and 2 in 3 large subunit encoding genes in AGPase,2 in 6 SSS encoding genes, glycoside membrane transport protein encoding genes,5 SP encoding genes, one in 3 BA encoding gens are higher in high starch stains than control.qRT-PCR results were as follows, the mRNA relatively expressions of one small subunit in AGPase, and SBE in high starch strains are higher than control,but the mRNA relatively expressions of GBSS in high starch strains are lower than control. The result is the same as the comparison of RPKM by transcriptome analysis.These results suggested that increased expressions of AGPase and ADP-glucose synthesis, resulting in phosphorylating of temporary starch, and increasing the transport speed of glucoside transmembrane transport.Thereby, increasing the storage starch synthesis; suppressing GBSSI, and inducing expression of SBE and SSS,increasing starch synthesis of amylopectin, following by increasing ADP-glucose synthesis.It has showed that, under the condition of the experiment, transparency, swelling power, dynamic viscosity and the freeze-thaw resistance of potato starch paste in high starch strains are higher than control,and dynamic viscosity of potato starch paste in high starch strains is higher than control by 37%, but retrogradation property and solubility of potato starch paste in high starch strains are lower than control.High starch viscosity means high content of amylopectin starch. Amylopectin starch is insoluble in water, resulting in high starch strains, the solubility was lower than control, transmittance and dilation are higher than control; Suffocating the formation of intermolecular hydrogen bonding because of high amylopectin starch, starch retrogradation is lower than that of control; amylopectin starch holds more separated water in high starch strains, the freeze-thaw stability is higher than control.Previous studies have showed that, increasing amylopectin synthesis by inducing GBSSI gene, increasing the expression of AGPase gene can increase the amount of starch synthesis; the results of this study has shown that, increasing the expression of AGPase gene can not only increasing the starch synthesis, but also can induce the increase straight starch synthesis, and increase the synthesis of amylopectin starch.