Genome-wide Analysis Of Hsp70 Gene Family And Cloning Of TaHsp70-47 Gene In Wheat

Wheat(Triticum aestivum L.)is one of the important food crops in China.In recent years,as greenhouse gases have increased,global temperatures have risen,causing huge losses in wheat production.Therefore,it is an important content of current research to mine heat resistance related genes and cultivate new varieties of heat-resistant wheat.Heat shock proteins(Hsps)are a kind of special proteins induced by high temperature,drought,low temperature,high salt,heavy metal ions and hormones.They play a significant role in plant growth and development,resistance to various abiotic stress especially in high temperature stress,and it exists widely in various organisms.Among them,Hsp70 is a type of heat shock protein with a molecular weight between 66～78k Da,and is one of the important factors to improve the high temperature tolerance of plants.In this study,through the bioinformatics analysis methods,the Hsp70 gene family were identified from the genome of wheat,and then the physical and chemical properties,phylogeny,gene structure,physical location,gene replication events,promoter elements and expression patterns were analyed.At the same time,a wheat TaHsp70 gene(TaHsp70-47)was selected from the wheat Hsp70 gene family for cloning and expression analysis.The main findings are as follows:1.A total of 110 TaHsp70 s have been identified from the genome of wheat,and named as TaHsp70-1～TaHsp70-110 according to their positions on the chromosome.Analysis of its physical and chemical properties revealed that the TaHsp70 s are mainly located in cytoplasmic,mitochondrial,chloroplast and endoplasmic reticulum,and the molecular mass and isoelectric point are also different.Phylogenetic evolution indicates that the wheat,Hsp70 genes can be divided into two major subfamilies,Dna K and HSP110/SSE,which can be further subdivided into 7 smaller families.At the same time,there are similar gene structures and conserved motifs among Hsp70 gene members of the same subfamily.2.The results of GO annotation indicated that wheat Hsp70 genes are widely involved in the physiological process of molecular function.By analyzing the upstream cis-acting elements of TaHsp70 s,it was found that the upstream of TaHsp70 s contain multiple elements involved in growth and development,adversity stress,hormone response and light response.Further analysis found that multiple genes upstream contain one or more heat shock element(Hse),indicating that it may plays an important role in regulating the expression of TaHsp70 s.Analysis of gene replication events found that wheat Hsp70 genesproduced a total of 9 tandem duplications and 79 segmental duplications gene pairs,and 55,51 colinear gene pairs with rice and brachypodium distachyum respectively.And the ratio of ka/ks between all collinear gene pairs are less than 1,indicating that they have been subjected to purification selection.3.The analysis of expression pattern analysis showed that TaHsp70 s were expressed in different tissues and showed specificity.Analysis of transcriptome data under drought and heat stress showed that multiple TaHsp70 s would significantly up-regulate expression under high temperature stress.It shows that it plays an important role in high temperature stress.Ten wheat Hsp70 genes were randomly selected for q RT-PCR analysis,the results showed that the TaHsp70 s had tissue expression specificity,and showed up-regulation and down-regulation expressions under both heat and drought stress,these results shows that ten Hsp70 genes can participate in plant growth and development and respond to a variety of abiotic stresses.4.The length of cds is 1956 bp in TaHsp70-47 gene,encodes 651 amino acids,and has a molecular weight of 71287.60 Da.Analysis found that it has a typical Hsp70 domain,and its end contains the cytoplasmic heat shock protein 70 signature sequence of EEVD.The result of q RT-PCR showed that the TaHsp70-47 was highly expressed in root and lowest in grain;under heat stress,the expression of TaHsp70-47 gene was significantly up-regulated,and its expression was increased as the stress treatment time increased it began to decrease,but also higher than the control level;under drought stress,the TaHsp70-47 gene also showed an up-regulation and then down-regulation expression pattern,indicating that it can respond to high temperature drought stress.