Effects Of High Temperature Stress On Starch Synthesis And Related Gene Expression In Wheat

Objective: High temperatures have plagued wheat production in recent years.Therefore,this experiment studied the grain starch formation,related enzyme activities and gene expression of synthetase genes by simulating high temperature environment,and provided the theoretical basis for breeding and response of wheat high temperature resistant varieties.Methods: The experimental material was Xinchun No.11,which was potted and planted in the greenhouse in Shihezi Experimental Field.Some of the materials were transplanted into controlled incubators at temperature of 35°C for 5 to 8 days after flowering.Detection of high temperature induced starch content,related enzyme activities and gene expression differences in wheat grains at specific time.Results:(1)The accumulation rate of total starch and amylopectin showed a single peak curve,while the accumulation process of amylose changed rapidly after falling first and then falling again.Early post-anthesis high temperature significantly reduced the content of total starch,amylose and amylopectin at different stages of grain,and the accumulative rate decreased.Adverse stress reduced the total starch content by 2.14%-15.31% compared with the control,and the amylose content was comparable.The control decreased by 0.6% to 3.78%,and the amylopectin content decreased by 1.54% to 9.74% compared to the control.(2)In the early post-anthesis high temperature treatment,SS activity,SSS activity,GBSS activity,and SBE activity at each stage of wheat grain were significantly decreased compared with the control.ADPGase activity was not significant compared with the control in each period.Sexual differences.According to correlation analysis,the correlation between SS,SSS,SBE activity,total starch content and amylopectin content in the middle and late stages of filling was extremely significant.(3)Eight starch synthesis-related enzyme genes(agp I,gbssI,ssII,ssIIa,sbe IIa,sbe IIb,agpII,gbssII)were all expressed in wheat endosperm during the seed filling process,and the changes were basically similar.They were slowly uplifted initially.The unimodal curve that reaches the top and then falls quickly or the pattern that rises quickly and then rises rapidly until the peak straight down.Although early adversity stress reduced the expression levels of starch synthesis-related enzyme genes at all stages of agpI and agpII,there was no significant difference between them.At the same time,the expression levels of the two genes in the 8 genes were lower,and they guessed that they had a role in starch synthesis.The influence was small,and the temperature did not affect their expression levels.Early post-anthesis stress increased the expression level of SSS isozyme gene in the early stage of filling,suggesting that abiotic stress might be the expression of SSS isoenzyme gene.In the early stage of filling,there was a certain promoting effect,while the expression of sbeIIa was significantly increased in the whole stage of grain starch accumulation.For sbeIIb gene,the expression level of sbeIIb gene was the highest at 10 days after anthesis,while it was less than the control at other stages,and the difference was significant and significantly decreased.The stress peak of gbss I was advanced by abiotic stress,and the expression of gbssI was higher than that of the control at 10 days after anthesis.The other phases were significantly smaller than the control,and there was no significant difference.The gbssII treatment was higher than the control at 15 days after anthesis.All other phases were lower than the control,and the difference was not significant.Conclusion: Due to the high temperature stress,the accumulative rate of each component of starch was significantly reduced,and the accumulation amount was significantly reduced;the expression of related genes was significantly different from the control,and the change was significant.The correlation analysis also clarified that the accumulation rate of starch at each stage of grain was significantly correlated with ADGPase,GBSS,SSS,SBE activity and related gene expression.It can be seen that the decrease of starch content in wheat grains is the combined effect of various enzymatic reactions and the expression of related genes.At the same time,this study also showed that the temperature stress had some effect on the expression of some genes in the early stage of filling,but did not affect the starch content.