Identification,Phylogeny And Expression Profiling Of BHLH Transcription Factor Family In Barley

As an ancient cultivated crop in the world,barley has rich value in nutritional.However,with the change of climate,the production and quality improvement of barley are constrained by a variety of harsh environmental factors.To alleviate the damage caused by environmental factors,the transcription factors(TFs)of barley are widely involved in the physiological and biochemical processes,biosynthesis,metabolism,and regulation of signal hormones.The basic helix-loop-helix(bHLH)transcription factors are the second largest family in plant that widely participate in plant growth and development,stress,biosynthesis,and signal hormone regulation.And with the development of plant genome-wide sequencing technology,more and more plant bHLH transcription factors have been identified.In this study,the bioinformatics methods were used to identify the bHLH genes within the whole genome of barley,and then analyzed the evolutionary relationship,gene location,gene structure,motifs and expression patterns.Subsequently,22 HvbHLH genes were randomly selected for quantitative real-time PCR to analyze the expression of HvbHLHs in roots,stems,leaves,inflorescences and under abscisic acid,gibberellin,and salt treatments.The results of this study are as follows:1.A total of 103 HvbHLHs have been identified by searching for the barley genome,protein database.All HvbHLH genes were located on 7 chromosomes in barley and were named HvbHLH001 to HvbHLH103,based on their chromosomal location.Most barley bHLH proteins were localized in the nuclear,and they are different in molecular weight and isoelectric point.2.The NJ phylogenetic tree was constructed using the full length bHLH proteins from barley,A.thaliana,and rice,429 bHLH proteins were divided into 24 subfamilies,and the HvbHLHs are in 18 subfamiles.The same family shared the similar motifs and gene structure.3.The results of gene duplication events indicated that a total of 9 gene pairs were identified as duplicated genes and they have undergone a strong purifying selection.The analysis of synteny showed that compared with rice,the HvbHLH genes are more homologous to sorghum and maize.4.The GO annotation results indicated that all HvbHLH proteins can bind to DNA,and most barley bHLH proteins will participate in the metabolism and regulation process.The protein-protein interaction network was constructed using the orthology-based method,found that 69 HvbHLHs were involved in the regulatory network and 204 network branches were identified.5.Promoter analysis showed that the HvbHLH genes can be regulated by multiple cis-acting elements.Most of the HvbHLH genes contain cis-acting elements in their promoter regions,which associated with light and abscisic acid response.It indicated that the expression of HvbHLH genes may be regulated by abscisic acid and light.6.The transcriptome data of 99 HvbHLHs in 16 tissues were downloaded for use as resource to analyze the expression patterns.Exclude in 5mm inflorescence,99 HvbHLH genes have different expression levels in 15 tissues.Indicated,the HvbHLH genes are involved in the growth and development of 15 tissues.7.The qRT-PCR results of 22 HvbHLH genes showed that the bHLH genes of barley have tissue-specific and most HvbHLHs are upregurated by tree trements.