Factors Regulating Protein Expression In Wheat Grains Under Heat Stress

Wheat is a fixed organism and likes cool.It often encounters dry and hot wind in the middle and late stages of wheat filling,which leads to a decline in wheat yield.Studying the mechanism of wheat's response to heat and cultivating heat-resistant varieties are essential for ensuring food security.Using the methods of transcriptome and proteome,this study conducted transcriptome and proteomic analysis on two kinds of short-term heat stress wheat grains.The influencing factors of differentially expressed proteins were studied under different degrees of thermal environment.Studies have shown that wheat grains have different response measures to different degrees of heat stress,and post-transcriptional regulation plays an important role in regulating protein expression to adapt to changing temperatures.The main findings are as follows:(1)By analyzing the transcriptome of wheat grains under 30 ? and 40 ? thermal conditions,the expression of genes in response to heat stress at the transcriptional level under1 hour of heat stress was studied.Under mild heat stress,wheat grain mobilized about 4% of the transcripts in response to heat stress,while under severe heat stress,about 12% of the transcripts changed significantly.By enriching the GO and KEGG of 1,800 and 5551 differentially expressed transcripts of two degrees of heat stress,the functions of the two different degrees of heat stress response genes were clarified.The transcripts that respond to two different degrees of heat stress are enriched in pathways such as transcriptional regulation,protein folding,thermal response,redox process,endoplasmic reticulum,metal ion binding,ATPase activity,and spliceosome.These functions are important for plants to respond to heat.Transcripts that only respond to mild stress perform functions in the pathways of amino acid synthesis,ribosome,and sugar metabolism.Transcripts that only respond to severe heat stress are also involved in transport,signal transduction,enzyme activity,hormone regulation,and various other metabolic pathways.Heat stress also leads to changes in the transcription level of transcription factors.Among them,HSF,ERF and MYB are the three types with the largest number of transcription factors that change significantly under heat stress.Heat stress also has a significant impact on photosynthesis,chlorophyll and amino acid metabolism on the transcriptional level.(2)Through proteomics,the expression changes of two different degrees of heat stress wheat grain protein were analyzed.Under mild heat stress,about 8% of the protein is differentially expressed in response to heat,and 12% of the protein changes significantly under severe heat stress.Differentially expressed proteins in mild heat stress have the functions of translation,ribosome and RNA binding,among which RNA binding is significantly enriched only in mild stress.In severe heat stress,in addition to containing the same functions as mild stress,it also involves protein Metabolism,carbon metabolism,protein transport,protein folding,redox and enzyme activity and other metabolic pathways.The functions of proteins that only respond to mild stress and both moderate and severe stresses are mainly concentrated in the ribosomal pathway.Proteins that only respond to severe stress mainly involve some metabolic pathways and protein folding in the endoplasmic reticulum.Heat stress damages photosynthesis,and rapid synthesis of new proteins is essential.Short-term heat stress has already affected amino acid biosynthesis,aminoacyl-t RNA and protein export pathways at the protein level.(3)Under the same temperature stress,there is little overlap between genes encoding differentially expressed transcripts and proteins.This phenomenon can be observed in both mild and severe stress.Only 11 transcripts may be involved in the expression of protein under30 ? heat stress and there are 36 genes involved in regulating protein expression at 40 ?.The functions of these proteins mainly involve molecular chaperones,heat shock proteins and enzymes.Except for protein folding,the response to heat and the processing of proteins on the endoplasmic reticulum,there was a significant response at both the transcriptional level and the protein level,and the other enrichment results did not overlap.In addition to the above,the functions of DETs at the transcriptional level are mainly focused on transcriptional regulation,signal transduction,transport and flavonoid biosynthesis;at the protein level,besides protein folding,they are also involved in ribosomal and three major metabolisms.By analyzing the expression of genes encoding ribosomes at the transcriptional and protein levels,approximately 14-20% of ribosomal genes are involved in the translation of heat-responsive transcripts and the up-regulation of ribosomal protein may not be related to transcription changes.(4)Through systematic analysis of the transcriptome and proteome of wheat grains under different degrees of heat stress,the related factors that affect the rapid changes of grain protein expression under short-term high temperature stress were studied.Transcription,codon usage,and amino acid frequency are the main driving factors for protein expression changes under heat stress.Their combined contributions explain 58.2% and 66.4% of protein variation at30 ? and 40 ?(20 ? as a control),respectively.Compared with 30 ?(6%),transcription at 40 ?(31%)contributes more to the change in protein content.In addition,the use of codon AAG may be closely related to the rapid changes of proteins under heat stress.At 30 ? and40 ?,the contribution of AAG is 24% and 13%,respectively.Through the enrichment of highly expressed transcripts under the two heat stresses,it is found that genes with significant differences in expression after heat stress and genes with no significant differences have different functions.Gene functions with insignificant differences in transcript expression under heat stress are mainly concentrated in ribosomes,nucleosomes and photosynthesis,while transcripts with significant differences mainly have protein folding,thermal response,and redox functions.Compared with the control,the content of 16 amino acids quantified under heat stress increased,and only the content of aspartic acid decreased.