Transcriptional Dynamics Of Spike Development In Wild Barley And Comparison With Cultivated Barley

As the fourth largest cereal crop in the world,barley(Hordeum vulgare L.)is widely used for food,feeding and brewing,thus increasing its production hold the special significance to mankind’s social and economic development.The yield of barley is determined by the development of the spike.The study of the transcriptional dynamic profile of spike development in wild barley is helpful to analyze the grain development process of barley,and to identify excellent genes that are crucial to spike development.However,the study on the transcriptome of spike in wild barley is relatively litter.RNA editing is one of the most important post-transcriptional regulation approach,which is of great significance in the process of plant growth and development,but the research on RNA editing events in wild barley is rarely reported.Therefore,this study used Israeli wild barley as the research object and performed transcriptome analysis based on high-throughput RNA-Seq technique to construct the transcriptional dynamic profile of wild barley spike,then identified RNA editing events to explore its impacts on spike development.Finally,combined with the transcriptome data of cultivated barley(clipper)from public databases,the difference of spike transcriptome profile between wild and cultivated barley was also analyzed.Here are the mainly achieved results:1.The analysis of the RNA-seq data about the four developmental stages(3DPA,8DPA,13 DPA,18DPA)of wild barley spike was performed.A total of 17,163 expressed genes were identified.Gene expression analysis showed that most of the genes were most actively transcribed during the pre-storage phase.and there was a drastic change in transcription activity between pre-storage phase and storage phase.Differential expression analysis identified a total of 11,273 significantly DEGs,which were significantly related to the biological processes or pathways related to biosynthesis,metabolic processes,transport,and stress resistance.A total of 635 TF coding genes were identified among DEGs.Among them,the NAC,AP2/ERF-ERF and MYB families play an important role in wild barley growth and development,grain maturation and response to environmental stress.2.2,004 RNA editing sites were finally identified from the above eight transcriptome data by using the barley reference genome;the overall trend,the number of RNA editing events and the length of the chromosome where they are located are positively correlated;on the genome of wild barley,the number of RNA editing events in the CDS is far greater than the UTR,which indicates that most RNA editing events can cause changes of encoded protein sequence.Analysis of the characteristics of RNA editing events during the development of wild barley spike revealed that among the 12 types of RNA editing,four editing types(A->G,C->T,G->A and T->C)occupy quantitative advantages;The RNA editing event caused the changes of 723 codons,258 of them were synonymous edits,430 of them were non-synonymous edits,and 35 of them were nonsense edits;There were 205 RNA editing events that caused changes in amino acid hydrophilic,hydrophobicity and stop codons,accounting for 10.23%.RNA editing genes contain a series of genes related to starch and sugar metabolism processes.The functional enrichment analysis of all RNA editing differentially expressed genes revealed that these genes were mainly enriched in biological processes related to metabolism,biosynthesis and protein.And these genes were related to the regulation of life activities during the development of wild barley spike.3.The dynamic transcription profile of wild barley and cultivated barley were compared by using the transcriptome data of cultivated barley(clipper)in public databases.The analysis of the common expressed genes of wild barley and cultivated barley showed that these genes were significantly enriched in organelles,catalysis,metabolism regulation and resistance,and played an important role in life activities.Specific expression genes about methyltransferase,secondary wall biosynthesis,ribosomal protein have been found in cultivated barley,and specific expression genes about cadmium resistance,anthocyanin synthesis and calmodulin have been found in wild barley.These genes provided a basis for breeding of barley.